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Sample records for alloy-690 inconel

  1. Corrosion testing of INCONEL alloy 690 for PWR steam generators

    International Nuclear Information System (INIS)

    INCONEL alloy 690, an austenitic, high-chromium modification of INCONEL alloy 600, was developed to resist stress-corrosion cracking and general corrosion in hightemperature aqueous environments associated with nuclear steam generators. Tests in nitric acid and nitric-hydrofluoric acid show that the high chromium content provides alloy 690 with good resistance to highly oxidizing environments over a wide range of high temperatures and oxygen concentrations, in the presence of crevices and lead or chloride contamination. Alloy 690 releases a negligible amount of material when exposed to high-velocity water at elevated temperatures. In constant extension rate tests, alloy 690 resists crack propagation in a deaerated 10 pct solution of sodium hydroxide better than alloy 600. Long-time tests also suggest greater resistance to intergranular attack in deaerated caustic solutions and to the oxidation of radioactive waste disposal involving nitric-hydrofluoric acid dissolution and vitrification

  2. A Study on Fretting Behavior in Room Temperature for Inconel Alloy 690

    Science.gov (United States)

    Kwon, Jae Do; Chai, Young Suck; Bae, Yong Tak; Choi, Sung Jong

    The initial crack under fretting condition occurs at lower stress amplitude and lower cycles of cyclic loading than that under plain fatigue condition. The fretting damage, for example, can be observed in fossil and nuclear power plant, aircraft, automobile and petroleum chemical plants etc. INCONEL alloy 690 is a high-chromium nickel alloy having excellent resistance to many corrosive aqueous media and high-temperature atmospheres. This alloy is used extensively in the industries of nuclear power, chemicals, heat-treatment and electronics. In this paper, the effect of fretting damage on fatigue behavior for INCONEL alloy 690 was studied. Also, various kinds of tests on mechanical properties such as hardness, tension and plain fatigue tests are performed. Fretting fatigue tests were carried out with flat-flat contact configuration using a bridge type contact pad and plate type specimen. Through these experiments, it is found that the fretting fatigue strength decreased about 43% compared to the plain fatigue strength. In fretting fatigue, the wear debris is observed on the contact surface, and the oblique micro-cracks are initiated at an earlier stage. These results can be used as the basic data in a structural integrity evaluation of heat and corrosion resistant alloy considering fretting damages.

  3. The comparison of corrosion resistance between Baosteel's alloy 690 tube and foreign alloy 690 tube

    International Nuclear Information System (INIS)

    Alloy 690 having excellent corrosion resistance is widely used for SG tubes. The intergranular corrosion and pitting corrosion resistance of Baosteel's alloy 690 tube, Country A alloy 690 tube and Country B alloy 690 tube have been analysed by comparison. It shows that: The intergranular corrosion of Baosteel's alloy 690 tube tested complied with ASTM G28 Standard could satisfy the technical requirement. However.some of Baosteel's alloy 690 tube in intergranular corrosion resistance had less performance than Country A. In addition, pitting corrosion tested with ASTM G48 Standard shown the Baosteel's alloy 690 tube better than Country B. (authors)

  4. Steam tests of Alloy 600 and Alloy 690 mechanical plugs

    International Nuclear Information System (INIS)

    In 1988-89, randomly selected heats of Inconel 600 TT plugs were laboratory tested to determine the extent and distribution of carbide precipitation in the microstructure and their resistance to primary water stress corrosion cracking (PWSCC) in a 400 C doped steam autoclave. Early results indicated a ranking could be established between microstructure and PWSCC potential. Corrosion tests were extended to include Alloy 690 plugs after a top plug release occurred due to circumferential cracking above the expander. Destructive examination of pulled plugs confirmed the accuracy of the laboratory results which showed corrosion resistance can be correlated with the density of intergranular carbides and the doped steam test method did provide an accelerated method for assessing the relative PWSCC of mechanical plugs. To date, 70 Inconel 690 plugs, representing 17 heat treatment lots, have been tested and all plugs remain crack-free after 1000 hour exposure in doped steam. 4 figs

  5. Hot Isostatic Pressing (HIP) Model Developments for P/M Alloy 690N{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    J.W. Sears; J. Xu

    2001-08-30

    Powder Metallurgy (P/M) Alloy 690N{sub 2}, the P/M derivative of Inconel 690 (IN 690), has been shown to have a higher elevated temperature yield strength and superior stress corrosion cracking (SCC) resistance than IN 690. The property improvements seen in P/M Alloy 690N{sub 2} are due to interstitial nitrogen strengthening and precipitation hardening resulting from the formation of fine titanium/chromium--carbo-nitrides. The application of P/M Alloy 690N{sub 2} has had limited use, because of the high costs involved in producing wrought products from powder. Hot Isostatic Pressing (HIP) modeling to produce near net shapes should provide a more economical route for exploiting the benefits of Alloy 690N{sub 2}. The efforts involved in developing and verifying the P/M Alloy 690N{sub 2} HIP model are disclosed. Key to the deployment of HIP modeling is the development of the method to fabricate HIP powder containers via laser powder deposition.

  6. Underwater laser beam welding of Alloy 690

    International Nuclear Information System (INIS)

    Stress Corrosion Clacking (SCC) has been reported at Alloy 600 welds between nozzles and safe-end in Pressurized Water Reactor (PWR) plant. Alloy 690, which has higher chromium content than Alloy 600, has been applied for cladding on Alloy 600 welds for repairing damaged SCC area. Toshiba has developed Underwater Laser Beam Welding technique. This method can be conducted without draining, so that the repairing period and the radiation exposure during the repair can be dramatically decreased. In some old PWRs, high-sulfur stainless steel is used as the materials for this section. It has a high susceptibility of weld cracks. Therefore, the optimum welding condition of Alloy 690 on the high-sulfur stainless steel was investigated with our Underwater Laser Beam Welding unit. Good cladding layer, without any crack, porosity or lack of fusion, could be obtained. (author)

  7. Galvanic Corrosion between Alloy 690 and Magnetite in Alkaline Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Soon-Hyeok Jeon

    2015-12-01

    Full Text Available The galvanic corrosion behavior of Alloy 690 coupled with magnetite has been investigated in an alkaline solution at 30 °C and 60 °C using a potentiodynamic polarization method and a zero resistance ammeter. The positive current values were recorded in the galvanic couple and the corrosion potential of Alloy 690 was relatively lower. These results indicate that Alloy 690 behaves as the anode of the pair. The galvanic coupling between Alloy 690 and magnetite increased the corrosion rate of Alloy 690. The temperature increase led to an increase in the extent of galvanic effect and a decrease in the stability of passive film. Galvanic effect between Alloy 690 and magnetite is proposed as an additional factor accelerating the corrosion rate of Alloy 690 steam generator tubing in secondary water.

  8. Galvanic Corrosion between Alloy 690 and Magnetite in Alkaline Aqueous Solutions

    OpenAIRE

    Soon-Hyeok Jeon; Geun-Dong Song; Do Haeng Hur

    2015-01-01

    The galvanic corrosion behavior of Alloy 690 coupled with magnetite has been investigated in an alkaline solution at 30 °C and 60 °C using a potentiodynamic polarization method and a zero resistance ammeter. The positive current values were recorded in the galvanic couple and the corrosion potential of Alloy 690 was relatively lower. These results indicate that Alloy 690 behaves as the anode of the pair. The galvanic coupling between Alloy 690 and magnetite increased the corrosion rate of All...

  9. Technical basis for reexamination interval for alloy 690 PWR reactor vessel top head penetration nozzles

    International Nuclear Information System (INIS)

    Of the 65 currently operating PWRs in the U.S., reactor vessel (RV) heads at 40 of these units have been replaced with heads having Alloy 690 nozzles. This study combines Alloy 600/82/182 and Alloy 690/52/152 plant experience and laboratory data for the development and application of deterministic and probabilistic models used in predicting risks associated with PWSCC degradation in RV heads having Alloy 600 or Alloy 690 nozzles. The objective is to propose an inspection regime for RV heads with Alloy 690 nozzles based on absolute and relative risk assessment, the latter in comparison to risks in RV heads having Alloy 600 nozzles with inspection internals simulated in accordance with current requirements in the U.S. Because of its chromium content of approximately 30%, Alloy 690 has greatly improved resistance to PWSCC in comparison to that for Alloy 600. The PWSCC resistance of Alloy 690 has been demonstrated through no observed plant PWSCC despite over 24 calendar years of service in steam generator tube and thick-walled component applications. To incorporate this resistance, the model for RV heads with Alloy 690 nozzles is founded on a factor of improvement approximation, which relates well-established initiation and growth prediction for Alloy 600 materials to Alloy 690 materials through a simple scaling transformation. To support this approximation, the authors applied existing laboratory data and operating experience with Alloy 690 and its weld metals Alloys 52 and 152, and compared them to that of Alloy 600 and Alloys 82 and 182. Application of factors of improvement on a conservative basis shows that it is appropriate that the current interval for volumetric or surface examination of the Alloy 690 RV head nozzles in U.S. PWRs be extended to a nominal 20 calendar years. (authors)

  10. SCC Behavior of Alloy 690 in Leaded Aqueous Solution

    International Nuclear Information System (INIS)

    Alloy 690 (Ni 60wt%, Cr 30wt%, Fe 10wt%) is used and planned to use as a heat exchanger tube of the steam generator (SG) and an alternative of Alloy 600 (Ni 75wt%, Cr 15wt%, Fe 10wt%) due to a relatively high stress corrosion cracking (SCC) susceptibility of Alloy 600 under operating condition of nuclear power plant (NPP). Secondary water pH which affects SCC behavior substantially is widely spanned from acid to alkaline in crevice depending on water chemistry control, water chemistry in crevice, plant specific condition, etc. Especially, specific chemical species are accumulated in the crevice of the sludge leading to a specific condition of crevice chemistry. Among these chemical species, lead is known to be one of the most deleterious species in the reactor coolants that cause SCC of the alloy. Even Alloy 690 is not strong in alkaline solution with lead. Lead has been effectively detected in all tubesheet samples, crevice deposits and surface scales removed from SGs. Typical concentrations are 100 to 500 ppm but in some plants, concentrations as high as 2,000 to 10,000ppm has been detected. The best method to prevent lead induced SCC (PbSCC) is to eliminate the harmful lead from the NPP chemistry, which is not possible and most NPPs are already contaminated by lead. Moreover only a very low level of sub ppm affects PbSCC. Therefore the mechanistic understanding of PbSCC is very crucial to control and mitigate PbSCC. It is expected that an addition of lead into a solution modifies the oxide property considering that a passivity of oxide is directly related to SCC behavior. A finding of the way to avoid this modification can give us a key to control PbSCC such as an inhibitor. In the present work, an SCC susceptibility was investigated in the presence of lead and NiB as an inhibitor as well as in the absence of both impurities by using a slow strain rate tensile (SSRT) test. Moreover the oxides formed on Alloy 690 in aqueous solutions with and without lead were

  11. Origins of Negative Strain Rate Dependence of Stress Corrosion Cracking Initiation in Alloy 690, and Intergranular Crack Formation in Thermally Treated Alloy 690

    Science.gov (United States)

    Kim, Young Suk; Kim, Sung Soo

    2016-09-01

    We show that enhanced stress corrosion cracking (SCC) initiation in cold-rolled Alloy 690 with decreasing strain rate is related to the rate of short-range ordering (SRO) but not to the time-dependent corrosion process. Evidence for SRO is provided by aging tests on cold-rolled Alloy 690 at 623 K and 693 K (350 °C and 420 °C), respectively, which demonstrate its enhanced lattice contraction and hardness increase with aging temperature and time, respectively. Secondary intergranular cracks formed only in thermally treated and cold-rolled Alloy 690 during SCC tests, which are not SCC cracks, are caused by its lattice contraction by SRO before SCC tests but not by the orientation effect.

  12. Origins of Negative Strain Rate Dependence of Stress Corrosion Cracking Initiation in Alloy 690, and Intergranular Crack Formation in Thermally Treated Alloy 690

    Science.gov (United States)

    Kim, Young Suk; Kim, Sung Soo

    2016-07-01

    We show that enhanced stress corrosion cracking (SCC) initiation in cold-rolled Alloy 690 with decreasing strain rate is related to the rate of short-range ordering (SRO) but not to the time-dependent corrosion process. Evidence for SRO is provided by aging tests on cold-rolled Alloy 690 at 623 K and 693 K (350 °C and 420 °C), respectively, which demonstrate its enhanced lattice contraction and hardness increase with aging temperature and time, respectively. Secondary intergranular cracks formed only in thermally treated and cold-rolled Alloy 690 during SCC tests, which are not SCC cracks, are caused by its lattice contraction by SRO before SCC tests but not by the orientation effect.

  13. The Effects of Processing Parameters on Microstructure and Properties of Laser Deposited PM Alloy 690N{sub 2} Powder

    Energy Technology Data Exchange (ETDEWEB)

    J.W. Sears

    2002-04-05

    Powder Metallurgy (PM) Alloy 690N{sub 2}, the PM derivative of Inconel 690 (IN 690), has been shown to have a higher elevated temperature yield strength and superior stress corrosion cracking (SCC) resistance than conventionally processed IN 690. The property improvements seen in Alloy PM 690N{sub 2} are due to interstitial nitrogen strengthening and precipitation hardening resulting from the formation of fine Titanium/Chromium-nitrides. The application of Alloy PM 690N{sub 2} has had limited use due to the high costs involved in producing wrought products from powder. Laser Powder Deposition (LPD) offers another technique to take advantage of PM 690N{sub 2} properties. Three different variations of the Alloy 690 chemistry have been deposited, PM chemistry-nitrogen atomized (PM 690N{sub 2}), Ingot Metallurgy (IM) chemistry--nitrogen atomized (IM 690N{sub 2}), and IM chemistry--argon atomized (IM 690Ar). The microstructural and mechanical property variations of these LPD deposited materials are reported. Alloy PM 690N{sub 2} powder was laser deposited at rates from .1 to over 12 cubic inches per hour at laser input powers ranging from 250 to 5000 watts using both CO{sub 2} and Nd:YAG lasers. in all cases a fully dense material has been produced. There is a question however of how the properties of this material respond over such a wide range of parameters. An attempt has been made to correlate the processing conditions with the resultant microstructures and properties. The effects of LPD on the microstructural features and properties of Alloy PM 690N{sub 2} are discussed.

  14. Influence of silica on stress corrosion cracking of Alloy 600 and Alloy 690

    International Nuclear Information System (INIS)

    Silicate is a major constituent of sludge on the tubesheet region of PWR steam generators, where stress corrosion cracking (SCC) of the steam generator tubing generally occurs in nuclear power plants. In this work, the effects of silicate on SCC of Alloy 600 and Alloy 690 have been studied in 10 % NaOH and 40 % NaOH with and without 2 g/l SiO2 at 315 degC. The experiments were performed using C-ring specimens at 200 mV above the corrosion potential. The stress at the apex of the C-ring specimen ranged from about 300 MPa to about 600 MPa. Polarization behaviors of Alloy 600 and Alloy 690 were also studied. High temperature mill annealed Alloy 600, sensitized Alloy 600, thermally treated Alloy 600 and thermally treated Alloy 690 were used for the SCC and polarization test. Composition profiles of the deposit layer on Alloy 600 and Alloy 690 were examined with an Auger electron microscope. The degree of sensitization was evaluated with a modified Huey test and TEM-EDX. Effects of silica on SCC of Alloy 600 and Alloy 690 are discussed in terms of polarization behavior and the oxide layer composition. (author) Key Words: stress corrosion cracking, Alloy 600, Alloy 690, polarization curves, AES, TEM, NaOH, silica

  15. Stress corrosion cracking growth rate of TT alloy 690 and its weld joint in simulated PWR primary water

    International Nuclear Information System (INIS)

    Recently, some researchers reported that the SCC growth rate (SCCGR) of cold worked thermally treated (TT) Alloy 690 was significantly different in heat by heat. But, author has hypothesized that these high SCCGRs in cold worked TT Alloy 690 could be due to the metallurgical characteristics of these heats. In order to confirm this hypothesis, this study has been started in the author's laboratory, and the following 4 new evidences were obtained. First, microcracks of carbides and voids were observed in eutectic M23C6 GB carbides (primary carbides) for cold rolled laboratory heat after as cast or lightly forged condition or for chemical composition simulated Bettis'TT Alloy 690 heat, after cold rolling, before SCC test. However, microcracks in primary carbides along grain boundaries and voids were rarely detected in the cold rolled commercial heat of TT Alloy 690 used for CRDM penetrations. Secondly, the SCCGR observed in TT Alloy 690 was different in each hot working process and each heat. Comparing the SCCGRs for all heats of cold worked TT Alloy 690, the SCCGR decreased with increasing of Vickers hardness. However, in same heats of cold worked TT Alloy 690, the SCCGR increased with increasing of Vickers hardness. Thirdly, the SCCGR in cold rolled TT Alloy 690 should be integrated by the effect of hardness or cold working ratio and by the effect of existing ratio of primary M23C6 carbides with cracks and Voids due to chemical composition and the fabrication process of TT Alloy 690. Fourthly, it is argued that the high SCCGRs in highly cold rolled TT Alloy 690 are not representative of the practical situation with TT Alloy 690 in service for CRDM adapter nozzles etc. The high SCCGR of highly cold rolled TT Alloy 690 is not thought to be an accurate tool in predicting the possibility of cracking of TT Alloy 690 for CRDM adapter nozzles. (author)

  16. Experimental and Theoretical Investigation of Three Alloy 690 Mockup Components: Base Metal and Welding Induced Changes

    Directory of Open Access Journals (Sweden)

    Rickard R. Shen

    2014-01-01

    Full Text Available The stress corrosion cracking (SCC resistance of cold deformed thermally treated (TT Alloy 690 has been questioned in recent years. As a step towards understanding its relevancy for weld deformed Alloy 690 in operating plants, Alloy 690 base metal and heat affected zone (HAZ microstructures of three mockup components have been studied. All mockups were manufactured using commercial heats and welding procedures in order to attain results relevant to the materials in the field. Thermodynamic calculations were performed to add confidence in phase identification as well as understanding of the evolution of the microstructure with temperature. Ti(C,N banding was found in all materials. Bands with few large Ti(C,N precipitates had negligible effect on the microstructure, whereas bands consisting of numerous small precipitates were associated with locally finer grains and coarser M23C6 grain boundary carbides. The Ti(C,N remained unaffected in the HAZ while the M23C6 carbides were fully dissolved close to the fusion line. Cold deformed solution annealed Alloy 690 is believed to be a better representation of this region than cold deformed TT Alloy 690.

  17. On the influence of manufacturing practices on the SCC behavior of Alloy 690 steam generator tubing

    International Nuclear Information System (INIS)

    Thermally treated (TT) Alloy 690 is the tubing materials of choice for replacement steam generators (RSGs) throughout the world. It is manufactured using a variety of processing methods with regards to melt practice and thermomechanical forming. Studies assessing the IGSCC resistance of Alloy 690 TT SG tubing have identified a variability in the corrosion performance of nominally identical alloys. While tubing of comparable bulk chemistry may exhibit variations in microchemistry as a result of different melt practice, the correlation between melt practice and SCC resistance is difficult to assess due to other contributing factors. The other contributing factors are identified in this investigation as microstructural features whose generation is dependent on features of particular strain-anneal forming methods by which SG tubes are fabricated. In this study the microstructural characteristics which appear to affect inservice corrosion performance of Alloy 690 TT SG tubes were evaluated. The studies included extensive microstructural examinations in addition to CERT tests performed on actual Alloy 690 TT nuclear SG tubing. The CERT test results indicate that Alloy 690 TT tubing processed at higher mill anneal temperatures display the highest degree of stress corrosion cracking (SCC) resistance. This observation is discussed with reference to carbide distributions, textural aspects and grain boundary orientation character

  18. The influence of copper on the SCC of alloy 600 and alloy 690 steam generator tubes

    International Nuclear Information System (INIS)

    Capsule tests have been performed on alloy 600 and alloy 690 steam generator tubes in acid sulfate environments. The most important result is that alloy 690, which is completely immune in this type of environment, becomes very susceptible to SCC in the presence of copper, even when it is added to the solution under the metallic form. Although the role of copper is not fully understood, its influence can not be explained only by an effect on the electrochemical potential. Complexation, adsorption and diffusion properties of copper could play an important role. (authors)

  19. Effect of scratch on crack initiation of alloy 690TT in high temperature high pressure water

    International Nuclear Information System (INIS)

    Full text of publication follows: This paper aims to investigate the effect of scratch on crack initiation of Alloy 690. The corrosion and stress corrosion of scratched Alloy 690 were studied using scanning electrochemical microscopy (SECM) and scanning electron microscopy (SEM). The results showed that scratch caused residual compressive stress underneath the scratch, dissolution was preferentially active at scratches and intergranular cracks initiated at the bottom of scratch after immersion in high temperature water. At the macro-compressive stressed area, localized tensile stress caused by oxide jacking could initiate crack. (authors)

  20. Corrosion behavior of Alloy 690 and Alloy 693 in simulated nuclear high level waste medium

    Energy Technology Data Exchange (ETDEWEB)

    Samantaroy, Pradeep Kumar; Suresh, Girija; Paul, Ranita [Corrosion Science and Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Kamachi Mudali, U., E-mail: kamachi@igcar.gov.in [Corrosion Science and Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Raj, Baldev [Corrosion Science and Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India)

    2011-11-15

    Highlights: > Alloy 690 and Alloy 693, both possess good corrosion resistance in simulated HLW. > SEM and EDS confirms the presence of Cr rich precipitates for both the alloys. > Passive film stability of Alloy 690 was found to be higher than Alloy 693. > Both alloys possess few micro pits even at a concentration of 100 ppm Cl{sup -} ion. - Abstract: Nickel based alloys are candidate materials for the storage of high level waste (HLW) generated from reprocessing of spent nuclear fuel. In the present investigation Alloy 690 and Alloy 693 are assessed by potentiodynamic anodic polarization technique for their corrosion behavior in 3 M HNO{sub 3}, 3 M HNO{sub 3} containing simulated HLW and in chloride medium. Both the alloys were found to possess good corrosion resistance in both the media at ambient condition. Microstructural examination was carried out by SEM for both the alloys after electrolytic etching. Compositional analysis of the passive film formed on the alloys in 3 M HNO{sub 3} and 3 M HNO{sub 3} with HLW was carried out by XPS. The surface of Alloy 690 and Alloy 693, both consists of a thin layer of oxide of Ni, Cr, and Fe under passivation in both the media. The results of investigation are presented in the paper.

  1. Prevention of microcracking by REM addition to alloy 690 filler metal in laser clad welds

    International Nuclear Information System (INIS)

    Effect of REM addition to alloy 690 filler metal on microcracking prevention was verified in laser clad welding. Laser clad welding on alloy 132 weld metal or type 316L stainless steel was conducted using the five different filler metals of alloy 690 varying the La content. Ductility-dip crack occurred in laser clad welding when La-free alloy 690 filler metal was applied. Solidification and liquation cracks occurred contrarily in the laser cladding weld metal when the 0.07mass%La containing filler metal was applied. In case of laser clad welding on alloy 132 weld metal and type 316L stainless steel, the ductility-dip cracking susceptibility decreased, and solidification/liquation cracking susceptibilities increased with increasing the La content in the weld metal. The relation among the microcracking susceptibility, the (P+S) and La contents in every weld pass of the laser clad welding was investigated. Ductility-dip cracks occurred in the compositional range (atomic ratio) of La/(P+S) 0.99(on alloy 132 weld metal), >0.90 (on type 316L stainless steel), while any cracks did not occur at La/(P+S) being between 0.21-0.99 (on alloy 132 weld metal) 0.10-0.90 (on type 316L stainless steel). Laser clad welding test on type 316L stainless steel using alloy 690 filler metal containing the optimum La content verified that any microcracks did not occurred in the laser clad welding metal. (author)

  2. STRAIN CORRELATIONS IN ALLOY 690 MATERIALS USING ELECTRON BACKSCATTER DIFFRACTION AND VICKERS HARDNESS

    Energy Technology Data Exchange (ETDEWEB)

    Overman, Nicole R.; Toloczko, Mychailo B.; Olszta, Matthew J.; Bruemmer, Stephen M.

    2014-03-09

    High chromium, nickel-base Alloy 690 exhibits an increased resistance to stress corrosion cracking (SCC) in pressurized water reactor (PWR) primary water environments over lower chromium alloy 600. As a result, Alloy 690 has been used to replace Alloy 600 for steam generator tubing, reactor pressure vessel nozzles and other pressure boundary components. However, recent laboratory crack-growth testing has revealed that heavily cold-worked Alloy 690 materials can become susceptible to SCC. To evaluate reasons for this increased SCC susceptibility, detailed characterizations have been performed on as-received and cold-worked Alloy 690 materials using electron backscatter diffraction (EBSD) and Vickers hardness measurements. Examinations were performed on cross sections of compact tension specimens that were used for SCC crack growth rate testing in simulated PWR primary water. Hardness and the EBSD integrated misorientation density could both be related to the degree of cold work for materials of similar grain size. However, a microstructural dependence was observed for strain correlations using EBSD and hardness which should be considered if this technique is to be used for gaining insight on SCC growth rates

  3. Characterization of microstructure, local deformation and microchemistry in Alloy 690 heat-affected zone and stress corrosion cracking in high temperature water

    Science.gov (United States)

    Lu, Zhanpeng; Chen, Junjie; Shoji, Tetsuo; Takeda, Yoichi; Yamazaki, Seiya

    2015-10-01

    With increasing the distance from the weld fusion line in an Alloy 690 heat-affected zone, micro-hardness decreases, kernel average misorientation decreases and the fraction of Σ3 boundaries increases. Chromium depletion at grain boundaries in the Alloy 690 heat-affected zone is less significant than that in an Alloy 600 heat-affected zone. Alloy 690 heat-affected zone exhibits much higher IGSCC resistance than Alloy 600 heat-affected zone in simulated pressurized water reactor primary water. Heavily cold worked Alloy 690 exhibits localized intergranular stress corrosion cracking. The effects of metallurgical and mechanical properties on stress corrosion cracking in Alloy 690 are discussed.

  4. PWSCC crack growth rate of alloy 690 to simulate actual plant material

    International Nuclear Information System (INIS)

    In order to understand the PWSCC crack growth rate of domestically produced alloy 690, alloy 690 materials were obtained from two companies which supply materials that are used in actual plants. PWSCC crack growth rates of cold worked alloy TT690 were measured under simulated PWR primary water conditions. The crack growth rates of 20% cold-worked alloy TT690 from both companies were less than 5×10-11 m/s, and the crack growth rates were not as fast as reported from Bettis. Also it was observed that there was up to about 2.5 times difference in the crack growth rates of TT690 of the two companies. (author)

  5. Alloy 690 in PWR type reactors; Aleaciones base niquel en condiciones de primario de los reactores tipo PWR

    Energy Technology Data Exchange (ETDEWEB)

    Gomez Briceno, D.; Serrano, M.

    2005-07-01

    Alloy 690, used as replacement of Alloy 600 for vessel head penetration (VHP) nozzles in PWR, coexists in the primary loop with other components of Alloy 600. Alloy 690 shows an excellent resistance to primary water stress corrosion cracking, while Alloy 600 is very susceptible to this degradation mechanisms. This article analyse comparatively the PWSCC behaviour of both Ni-based alloys and associated weld metals 52/152 and 82/182. (Author)

  6. Effects of crack tip plastic zone on corrosion fatigue cracking of alloy 690(TT) in pressurized water reactor environments

    International Nuclear Information System (INIS)

    Alloy 690(TT) is widely used for steam generator tubes in pressurized water reactor (PWR), where it is susceptible to corrosion fatigue. In this study, the corrosion fatigue behavior of Alloy 690(TT) in simulated PWR environments was investigated. The microstructure of the plastic zone near the crack tip was investigated and labyrinth structures were observed. The relationship between the crack tip plastic zone and fatigue crack growth rates and the environment factor Fen was illuminated

  7. Stress corrosion cracking of alloys 690, 800, and 600 in acid environments containing copper oxides

    International Nuclear Information System (INIS)

    Secondary side stress corrosion cracking (SCC) of steam generator (SG) tubes may be due to the formation of an acid environment in crevices, as demonstrated for several Belgian PWR plants. The susceptibility of alloys 600 and 800 in this type of environment, which had been partially evidenced by several laboratory works, has been confirmed by capsule tests performed at Laborelec, whereas the SCC resistance of alloy 690 always appeared excellent. Capsule tests have been recently conducted at 320 C with the same heats of tubings in the same acid solutions (cationic resins + magnetite + sodium silicate, with or without lead, and sodium sulfate + iron sulfate, with or without lead oxide) containing CuO and Cu2O. It appeared that the SCC resistance of the three alloys was generally reduced by the addition of copper oxides, at least when the cover gas did not contain hydrogen. The situation was particularly dramatic for the capsules made of alloy 690 tubing: most of them developed deep cracks, sometimes throughwall (the shortest time to failure being less than 50 h) whereas the same solutions without copper oxides had produced no cracking at all in alloy 690 capsules exposed during more than 2,000 h. Although the corrosion is reduced in presence of hydrazine or at lower concentration, copper oxides probably contribute significantly to the degradation of the tubes in alloy 600, at least in SG's forming acid sulfate crevice environments. This is also an issue for the new SG's, especially for those equipped with tubes in alloy 690 TT, particularly for the top of the tubesheet which is a critical deposit area since the high stresses and strains resulting from the expansion of the tube in the tubesheet lead to a risk of circumferential cracking at the transition

  8. Irradiation Tests of Alloy 690 Steam Generator Tube Material of the SMART in HANARO

    International Nuclear Information System (INIS)

    The System-integrated Modular Advanced ReacTor (SMART) is one of the most advanced SMRs. The Korean government decided to obtain the standard design approval on SMART from the Korean licensing authority by 2011. Because the SMART steam generators are located inside the reactor vessel, the degradation of the fracture toughness of the Alloy 690 heat exchanger tube should be clearly determined for a design lifetime neutron fluence. However, the neutron irradiation characteristics of the alloy are barely known. Therefore, an irradiation plan of the Alloy 690 materials to obtain the neutron irradiation characteristics of the alloy using the HANARO irradiation capsules was planned. The target of fast neutron fluence of Alloy 690 was determined to be 1x1018 n/cm2, 1x1019 n/cm2, and 1x1020 n/cm2 (E>1.0 MeV), considering the maximum lifetime neutron fluence of 1.1x1018 n/cm2 of the SMART steam generator. To obtain these neutron fluences, three different irradiation capsules were scheduled and successfully irradiated in the OR5 and CT test holes of the HANARO. The target of irradiation temperature of the specimens was determined as 250 ± 10 .deg. C, considering the operating temperature of 247 .deg. C∼282 .deg. C of the steam generator tube having the highest neutron fluence. Generally, the neutron irradiation degradation effect appears more clearly in a lower temperature. The obtained material properties of the irradiated Alloy 690 specimens will be very valuable to acquire the standard design approval of SMART from the Korean licensing authority

  9. Role of microstructure in caustic stress corrosion cracking of Alloy 690

    International Nuclear Information System (INIS)

    Alloy 690 has been selected for nuclear heat transport system tubing application in recent commercial reactor plants due to its resistance to multiple types of corrosion attack. Typical corn final heat treatments for this material are a mill-anneal (MA, approximately 1,070 C) to completely dissolve the carbides and develop the final grain structure plus a thermal treatment (TT, approximately 700 C) to precipitate carbides at the grain boundaries. Tubing with grain boundary carbides and no or few intragranular carbides has been found resistant to intergranular stress corrosion cracking (IGSCC) in caustic environments. In this work, first, Alloy 690 plate was subjected to a variety of MA and MA-TT heat treatments to create microstructures of carbide-decorated grain boundaries and undecorated boundaries. Caustic IGSCC test results were consistent with tubing data. Second, experiments were conducted to understand the mechanism by which caustic-corrosion resistance is imparted to Alloy 690 by grain boundary carbides. Tubing with a fully-developed MA-TT carbide microstructure was strained and heat-treated to create a mixed microstructure of new grain boundaries with no carbide precipitate decoration, intermixed with intragranular carbide strings from prior grain boundaries. Caustic SCC performance of this material was identical to that of material with the MA-TT carbide-decorated grain boundaries. This work suggests that the fundamental cause of good IGSCC resistance of MA-TT Alloy 690 in caustic does not derive solely from grain boundary carbides. It is suggested that matrix strength, as measured by yield stress, could be a controlling factor

  10. Effect of Residual Strain Induced by Cold Working on PWSCC of Alloy 690

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung Woo; Hwang, Seong Sik; Lim, Yun Soo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-10-15

    PWSCC has been widely reported to occur in the inside of the steam generator (SG) tubing, and in other instrumentation nozzles such as the control rod drive mechanism (CRDM) penetrations, especially on those surfaces having a dissimilar metal welds (DMW) or those heavily machined. Under an abnormal working procedure or without a sufficient post-heat treatment for stress relaxation, a high tensile stress can persist after welding or cold working of the alloys. Variation of a strain field is also accompanied by the cold working or machining process. The conventional method for measuring the residual strain is a micro-hardness test, which has a limitation owing to the presence of precipitates and grain boundaries in the matrix of the test specimen. A new technique of electron backscatter diffraction (EBSD) has recently been applied to residual strain analysis on a micro-scale to overcome this limitation. This work is concerning a quantitative analysis of the local residual strain by EBSD and its effect on the PWSCC of Alloy 690 CRDM materials. In this work, the local residual strain of Alloy 690 CRDM materials cold-worked at various plastic strain levels was quantitatively evaluated using an EBSD analysis. From KAM maps, it was confirmed that the residual strain increased with cold-working, and a higher strain was concentrated at the grain boundary than in the matrix. The severe strain field localized at the grain boundary accelerated the inter-grannular growth of PWSCC of Alloy 690.

  11. Corrosion inhibition of steam generator tubesheet by Alloy 690 cladding in secondary side environments

    Energy Technology Data Exchange (ETDEWEB)

    Hur, Do Haeng, E-mail: dhhur@kaeri.re.kr; Choi, Myung Sik; Lee, Deok Hyun; Han, Jung Ho; Shim, Hee Sang

    2013-11-15

    Denting is a phenomenon that a steam generator tube is distorted by a volume expansion of corrosion products of the tube support and tubesheet materials adjacent to the tube. Although denting has been mitigated by a modification of the design and material of the tube support structures, it has been an inevitable concern in the crevice region of the top of tubesheet. This paper provides a new technology to prevent denting by cladding the secondary surface of the tubesheet with a corrosion resistant material. In this study, Alloy 690 material was cladded onto the surface of an SA508 tubesheet to a thickness of about 9 mm. The corrosion rates of the original SA508 tubesheet and the Alloy 690 clad material were measured in acidic and alkaline simulated environments. Using Alloy 690 cladding, the corrosion rate of the tubesheet within a magnetite sludge pile decreased by a factor of 680 in 0.1 M NiCl{sub 2} solution at 300 °C, and by a factor of 58 in 2 M NaOH solution at 315 °C. This means that denting can drastically be prevented by cladding the secondary tubesheet surface with corrosion resistant materials.

  12. Effect of Residual Strain Induced by Cold Working on PWSCC of Alloy 690

    International Nuclear Information System (INIS)

    PWSCC has been widely reported to occur in the inside of the steam generator (SG) tubing, and in other instrumentation nozzles such as the control rod drive mechanism (CRDM) penetrations, especially on those surfaces having a dissimilar metal welds (DMW) or those heavily machined. Under an abnormal working procedure or without a sufficient post-heat treatment for stress relaxation, a high tensile stress can persist after welding or cold working of the alloys. Variation of a strain field is also accompanied by the cold working or machining process. The conventional method for measuring the residual strain is a micro-hardness test, which has a limitation owing to the presence of precipitates and grain boundaries in the matrix of the test specimen. A new technique of electron backscatter diffraction (EBSD) has recently been applied to residual strain analysis on a micro-scale to overcome this limitation. This work is concerning a quantitative analysis of the local residual strain by EBSD and its effect on the PWSCC of Alloy 690 CRDM materials. In this work, the local residual strain of Alloy 690 CRDM materials cold-worked at various plastic strain levels was quantitatively evaluated using an EBSD analysis. From KAM maps, it was confirmed that the residual strain increased with cold-working, and a higher strain was concentrated at the grain boundary than in the matrix. The severe strain field localized at the grain boundary accelerated the inter-grannular growth of PWSCC of Alloy 690

  13. SCC behavior of alloy 690 from a CDRM mock-up

    International Nuclear Information System (INIS)

    Stress corrosion cracking (SCC) response of Alloy 690 when the material has been subjected to nonuniform cold working is of interest to understand the behavior of the weld heat affected zone (HAZ) of Alloy 690 in which localised plastic strain exists due to weld shrinkage. This has a special interest in the case of control-rod-drive mechanisms (CRDM) of vessel head. To simulate these conditions during last years many crack growth rate (CGR) data were obtained in deformed material by cold work (rolling, forging or tensile straining), up to 40% of cold working. However, it is unclear to what extent this simulation procedure reproduces the conditions of the material in a CRDM. A research project is being carried out in order to obtain CGR data in realistic situations existing in operating power plants, by the use of CT specimens extracted from CRDMs. This presentation shows the characterization and some results of crack growth rate data on Alloy 690 TT base metal/HAZ/weld metal using specimens made from a CRDM mock-up. It has been fabricated following the usual procedures used for the RPV head fabrication for the Spanish PWR NPP. (authors)

  14. Prediction of microcracking in laser overly welds of alloy 690 to type 316L stainless steel

    International Nuclear Information System (INIS)

    The occurrence of ductility-dip crack in the laser overlay welds of alloy 690 to type 316L stainless steel was predicted by the mechanical and metallurgical approaches. Ductility-dip temperature ranges (DTRs) of alloy 690 laser overlay welds were estimated by Varestraint test during GTA welding. The grain boundary segregation of impurity elements such as P and S was numerically analyzed based on the non-equilibrium cosegregation theory when the welding speed and the amounts of P and S in the weld metal were varied. In accordance with the repression approximation between the DTR and the calculated grain boundary concentrations of P and S, the DTRs of alloy 690 were computed in laser overlay welding. The estimated DTR in laser overlay welds was reduced with an increase in welding speed and with a decrease in the amounts of P and S in the weld metal. Ductility-dip cracking in laser overlay welds was predicted by the plastic strain-temperature curve intersected the DTR. The plastic strain in laser overlay welding was numerically analyzed using the thermo elasto-plastic finite element method. The plastic strain-temperature curve in laser overlay welds intersected the DTR at decreased welding speed and increased (P+S) content in the weld metal. The predicted results of ductility-dip cracking in laser overlay welds were approximately consistent with experiment results. It follows that ductility-dip cracking in laser overlay welds could be successfully predicted based on the estimated DTR from grain boundary segregation analysis combined with the computed plastic strain by FEM analysis. (author)

  15. XPS analysis of zinc injection effects on general corrosion of nickel-base alloy 690

    International Nuclear Information System (INIS)

    The effects of zinc addition on behaviors of general corrosion behaviors of nickel-base alloy 690 were investigated in simulated PWR primary water. After exposed in solutions with zinc concentration of o and 50 ppb for 1500 h, oxide films developed on surface of specimens were analyzed by using XPS. The result shows that Zn partly replaces Ni and Fe in NiCr2O4 and FeCr2O4 in the inner oxide layer and forms ZnCr2O4. (authors)

  16. Analyze the test methods for intergranular corrosion-resistance of nickel-based alloys 690

    International Nuclear Information System (INIS)

    The corrosion resistance effective of steam generator heat tubing in PWR nuclear power build highly demanding and direct impact on the reliability of the nuclear power unit to the technical performance and safety. Nickel-based Alloy 690 is the best material for nuclear SG heat tubing. Heat of the damage is caused by various types of corrosion, mainly is intergranular corrosion and stress corrosion cracking. Tests to verify the stability of heat transfer performance and application reliability. Analyze the chemical and electrochemical immersion (EPR) corrosion methods to provide the basic theory for experimental verification of the stability and engineering applications reliability of heat transfer. (authors)

  17. Effect of surface cold work on corrosion of Alloy 690TT in high temperature high pressure water

    International Nuclear Information System (INIS)

    This paper aims to investigate the effect of surface cold work on corrosion of Alloy 690TT. The Alloy 690TT was mechanical ground and electro polished respectively and immersed in primary water at DO = 2 ppm and DH = 2.5ppm respectively. The microstructure of surface and the compositions and morphology of the surface film on Alloy 690TT after immersion test were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Auger electron spectroscopy (AES) and focused ion beam (FIB). The results showed that feather-like oxide with decorated polyhedral oxide formed on ground surface and needle-like oxide with decorated polyhedral oxide formed on electro-polished surface. (author)

  18. Characterization of Different on the Oxidation Behaviours Surface States and Its Effects of Alloy 690TT

    Institute of Scientific and Technical Information of China (English)

    Zhiming Zhang; Jianqiu Wang; En-Hou Han; Wei Ke

    2012-01-01

    Alloy 690TT samples with four kinds of surface states were prepared: 1) ground to 400 grit; 2) ground to 1500 grit; 3) mechanically polished (MP) and 4) electro-polished (EP). The surface morphologies and the surface skin layers' microstructures of these samples were characterized systematically using various methods and the effects of surface states on the oxidation behaviours of Alloy 690TT were also discussed. The results showed that surface roughness and micro-hardness decreased gradually from the ground to EP surfaces. The grains in the near-surface layers of the ground and MP surfaces had been refined and the residual strains were also very high. The dislocations on the ground surfaces were mainly parallel dislocation lines. The thickness of the superficial cold-worked layers decreased gradually from the ground surfaces to polished surfaces. The oxide morphologies and oxidation rate depended greatly on the surface states of samples. Cold-working by grinding treatments could benefit the outward diffusion of metallic atoms and the nucleation of surface oxides and then accelerate the growth of surface oxide films.

  19. Influence of surface roughness on the corrosion behavior of Alloy 690TT in PWR primary water

    International Nuclear Information System (INIS)

    Highlights: • Surface roughness effect on the corrosion rate of Alloy 690 is provided. • Surface micro-hardness decreased as the roughness value decreased. • Cr-enriched polyhedral oxide particles were formed on the ground surfaces. • Ni-enriched strip-like oxides were formed on the polished surfaces. • Corrosion rate decreased with a decrease in the roughness value. - Abstract: The purpose of this work is to investigate the effect of surface roughness on the corrosion behavior of Alloy 690TT steam generator tube material in simulated primary water at 330 °C. The surface roughness was controlled in the range of 710–25 nm by mechanical grinding and polishing method. Surface hardness gradually decreased with a decrease in the roughness value. Polyhedral oxide particles were formed on the ground surfaces, whereas the mixed oxides of a polyhedral and strip-like type were observed on the polished surface. The corrosion rate decreased by about 64% as the roughness values decreased from 710 to 150 nm. However, no further changes were observed in the range of 150–25 nm

  20. Grain growth and intergranular carbide precipitation in nickel-base alloy 690

    International Nuclear Information System (INIS)

    The grain growth and precipitation behavior of intergranular carbides in Nickel-base alloy 690 were studied through microscopic equipment. The experimental grain growth data showed a classical growth equation, and carbon atoms in solid solution were found to have a strong drag effect on grain boundary migration. The precipitation of intergranular carbides, identified as Cr-rich M23C6, was retarded (or suppressed) on the low angle grain boundaries and the special boundaries expressed by the coincidence site lattice model, compared to that on the random high angle grain boundaries. The results of intergranular M23C6 carbide precipitation are explained in terms of the influence of grain boundary energy. (orig.)

  1. Localized corrosion behavior of scratches on nickel-base Alloy 690TT

    International Nuclear Information System (INIS)

    Localized corrosion of scratched Alloy 690TT was studied using scanning electrochemical microscopy (SECM) in 10 wt.% NaOH solution and atomic force microscopy (AFM) after short-time oxidation tests in high temperature high pressure water at 250 oC. The results show that the scratches detected by SECM displayed more extensive electrochemical activity. The scratch groove and the whole deformed region caused by scratching as anode corresponded to the peak of tip current. The oxides formed in 250 oC high purity pressurized water nucleated preferentially at the scratch groove and grew faster than non-scratched surface. The nano-grained scratch groove has more electrochemical reactivity than mechanical twins at scratch banks. The intense localized corrosion could contribute to crack initiation at the bottom of scratch groove.

  2. Influences of Carbon Content and Thermal Treatment(TT) on the Microstructure and Corrosion Resistance of Steam Generator Tubing Alloy 690 of Nuclear Power plant(II)

    International Nuclear Information System (INIS)

    Influences of carbon content and thermal treatment on the microstructure, mechanical property and corrosion resistance of Alloy 690 were studied. OM, SEM, TEM, and XRD analysis were used to study the microstructural changes of the alloys. Mechanical properties were investigated by means of tension test and Rockwell hardness tests, and corrosion resistance was evaluated using the anodic polarization tests and boiling 65% nitric acid immersion test. Increasing thermal treatment temperature and time, the size of carbide was increased. The form of the intergranular carbide in Alloy 690TT was M23C6 type. Increasing carbon content of the alloys, maximum tensile strength was obtained when TT temperature was low and this behavior seemed to be attributed to carbide volume fraction and distribution. In the case of low carbon Alloy 690, anodic polarization resistance of Alloy 690TT was lower than that of the annealed alloy, but increasing carbon content of the alloys, its resistance of Alloy 690TT was better than that of Alloy 690MA. However, Alloy 690TT treated at 700 .deg. C-10hrs showed the maximum intergranular corrosion rate

  3. Stress-corrosion-cracking testing of INCONEL alloys 600 and 690 In high-temperature caustic

    International Nuclear Information System (INIS)

    This study determined the effects of composition, heat treatment, and microstructure on the resistance of INCONEL alloy 690 to stress-corrosion cracking in caustic. The results were compared with the effects of the same factors on INCONEL alloy 600. Both alloys were evaluated in the annealed condition and after a post-anneal exposure to 7040C (13000F) for 15 hours. Resistance to SCC was determined by constant-extension-rate tests (CERT) in deaerated 10% sodium hydroxide at 288 to 3160C (550 to 6000F)

  4. Analysis of surface film of alloy 690TT with various surface finish in high temperature high pressure water

    International Nuclear Information System (INIS)

    Full text of publication follows: This paper aims to investigate the effect of surface state on corrosion and stress corrosion of Alloy 690. The surface conditions contained shot peening, mechanical polished and electro-polished. The composition and morphology structure of the surface film formed on Alloy 690 with different surface conditions were studied using X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The thicknesses of cold worked layer at various surface finishes were different. The dislocation structure with various surface finish was studied using transmission electron microscopy (TEM). The nano-plate structure of Ni-rich oxide formed on mechanical polished surface and nano-needle structure of Ni-rich oxide formed on electro-polished surface. (authors)

  5. Corrosion Control of Alloy 690 by Shot Peening and Electropolishing under Simulated Primary Water Condition of PWRs

    OpenAIRE

    Kyung Mo Kim; Hee-Sang Shim; Myung Ji Seo; Do Haeng Hur

    2015-01-01

    This work clarifies the effect of surface modifications on the corrosion rate of Alloy 690, a nickel-based alloy for steam generator tubes, under the simulated test conditions of the primary water chemistry in nuclear power plants. The surface stress was modified by the shot peening and electropolishing methods. The shot peening treatment was applied using ceramic beads with different intensities by varying the air pressure and projection angle. The corrosion rate was evaluated by gravimetric...

  6. The Effects of Heat Treatments on the M23C6 Carbide Evolution and Grain Boundary Serration in Alloy 690

    International Nuclear Information System (INIS)

    Some laboratory tests revealed that Alloy 690 is resistant to IGSCC in various environments. With a prolonged service life and improved performance being demanded by the nuclear energy industry, however, the need to improve the resistance to intergranular failure in Alloy 690 should also be considered. The present work is an attempt to elucidate the effects of various heat treatments on the evolutions of intergranular carbide precipitation and the grain boundary serration (GBS) in Alloy 690 to acquire a high resistance to intergranular degradations. By isothermal treatments at 720 .deg. C for 0.1-100 hr after solution annealing, most of the grain boundaries except for the coherent twin boundaries were decorated with well-developed M23C6 carbides. The discontinuous precipitates were initiated on the grain boundary even by a heat treatment of 0.1 hr, and covered the entire grain boundary region within a heat treatment of 10 hr. With a long aging time of 100 hr, intragranular Cr carbides were precipitated on the imperfections such as the dislocations and stacking faults GBS could be introduced by a slow cooling process in this alloy, and occurred in a limited temperature range of 990-900 .deg. C under the present heat treatment conditions. The grain boundaries had a convex shape into the incoherent grain, from which it is believed that the grain boundary shape is closely associated with the grain boundary migration during serration in this alloy

  7. Corrosion Control of Alloy 690 by Shot Peening and Electropolishing under Simulated Primary Water Condition of PWRs

    Directory of Open Access Journals (Sweden)

    Kyung Mo Kim

    2015-01-01

    Full Text Available This work clarifies the effect of surface modifications on the corrosion rate of Alloy 690, a nickel-based alloy for steam generator tubes, under the simulated test conditions of the primary water chemistry in nuclear power plants. The surface stress was modified by the shot peening and electropolishing methods. The shot peening treatment was applied using ceramic beads with different intensities by varying the air pressure and projection angle. The corrosion rate was evaluated by gravimetric analysis and the surface was analyzed by scanning electron microscopy (SEM. The corrosion rate of Alloy 690 was evaluated from the influence of the stress state on the metal surface. Based on the observation of the surface after the corrosion test, the oxide composition and its structure were affected by the surface modifications. The corrosion behavior of Alloy 690 was distinguished by the shot peening intensity on the surface, and additional electropolishing was effective at reducing the dissolution of nickel ions from the metal surface.

  8. Correlation between General Corrosion Behavior and Eddy Current Noise of Alloy 690 Steam Generator Tube

    International Nuclear Information System (INIS)

    Nickel and its oxides are released from the surface of steam generator tubes into the primary water. Released nickel and cobalt is activated to Co-58 and Co-60 in the reactor core by a neutron flux, respectively. These activated corrosion products are the main source of high radiation fields and occupational radiation exposure. In addition, some of the corrosion products redeposit on the fuel cladding, hinder the heat transfer, increase the corrosion rate of the fuel cladding, and finally induce an axial offset anomaly. This phenomenon can decrease core shutdown margin, and thus lead to a down-rating of a plant. Recently, many researchers have reported that the surface states of Alloy 690 tubes affect the corrosion product formation and its release in simulated primary water environments. Meanwhile, the surface states of steam generator tubes affect the noise level of eddy current testing. Noise signals arising from the tubes degrade the probability of detection and sizing accuracy of the defects. The corrosion behavior was closely correlated to the tube noise measured using a rotating probe, while it was not related to the noise measured using a bobbin probe. It is suggested that the tube noise value measured using a rotating pancake coil probe can be a decisive measure to estimate the corrosion behavior of tubing

  9. Fracture toughness of alloy 690 and EN52 welds in air and water

    Science.gov (United States)

    Brown, C. M.; Mills, W. J.

    2002-06-01

    The effect of low- and high-temperature water with high hydrogen on the fracture toughness of alloy 690 and its weld, EN52, was characterized using elastic-plastic J IC methodology. While both materials display excellent fracture resistance in air and elevated-temperature (>93 °C) water, a dramatic degradation in toughness is observed in 54 °C water. The loss of toughness is associated with a hydrogen-induced intergranular cracking mechanism, where hydrogen is picked up from the water. Comparison of the cracking behavior in low-temperature water with that for hydrogen-precharged specimens tested in air indicates that the critical local hydrogen content required to cause low-temperature embrittlement is on the order of 120 to 160 ppm. Loading-rate studies show that cracking resistance is improved at rates above ˜ 1000 MPa √m/h, because there is insufficient time to produce grain-boundary embrittlement. Electron fractographic examinations were performed to correlate cracking behavior with microstructural features and operative fracture mechanisms.

  10. Effect of surface stress states on the corrosion behavior of alloy 690

    International Nuclear Information System (INIS)

    The test environment simulated the primary water chemistry in PWRs. Dissolved oxygen (DO), dissolved hydrogen (DH), pH and conductivity were monitored at room temperature using sensors manufactured by Orbisphere and Mettler Toledo. The temperature and pressure were maintained at 330 .deg. C and 150 bars during the corrosion test. The condition of the test solution was lithium (LiOH) 2 ppm and boron (H3BO4) 1,200 ppm, DH 35 cc/kg (STP) and less than 5 ppb DO. The flow rate of the loop system was 3.8 L/hour. Corrosion tests were conducted for 500 hours. The corrosion release rate was evaluated by a gravimetric analysis method using a two-step alkaline permanganate-ammonium citrate (AP/AC) descaling process. Compressive residual stress is induced by shot peening treatment but its value reveals some different trend between the shot peening intensity on the surface of Alloy 690 TT. A higher shot peening intensity causes a reduction in the corrosion rate and it is considered that the compressive residual stress beneath the surface layer suppresses the metal ion transfer in an alloy matrix

  11. Influence of Temperature on the Strain Controlled Fatigue Behaviour of Alloy 690 Tube Material

    International Nuclear Information System (INIS)

    Strain controlled fatigue tests for hot-extruded tube material of Alloy 690 (Sandvik Sanicro 69) have been performed at room temperature (RT) and at elevated temperature (204 deg. C). The influences of temperature on the cyclic deformation behaviour and the fatigue life have been investigated. The influence of temperature on the fatigue life is relatively small in the temperature range investigated. However, the fatigue behaviour at elevated temperature is quite different from that at RT. A second cyclic strain hardening was observed at 204 deg. C. The possible mechanisms have been investigated using transmission electron microscopy. Besides dislocation mechanism, the interactions between moving dislocations and stacking faults and between interstitial atoms and moving dislocations could also contribute to this secondary cyclic strain hardening. The formation of micro-twins during cyclic loading at 204 deg. C and its influence on the cyclic stress-strain response were also discussed. Temperature affects both fatigue crack initiation and propagation behaviour. Increase in temperature promotes duplex slipping process, which causes the formation of striation. (authors)

  12. Correlation between General Corrosion Behavior and Eddy Current Noise of Alloy 690 Steam Generator Tube

    Energy Technology Data Exchange (ETDEWEB)

    Hur, Do Haeng; Choi, Myung Sik; Lee, Deok Hyun; Shim, Hee-Sang [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    Nickel and its oxides are released from the surface of steam generator tubes into the primary water. Released nickel and cobalt is activated to Co-58 and Co-60 in the reactor core by a neutron flux, respectively. These activated corrosion products are the main source of high radiation fields and occupational radiation exposure. In addition, some of the corrosion products redeposit on the fuel cladding, hinder the heat transfer, increase the corrosion rate of the fuel cladding, and finally induce an axial offset anomaly. This phenomenon can decrease core shutdown margin, and thus lead to a down-rating of a plant. Recently, many researchers have reported that the surface states of Alloy 690 tubes affect the corrosion product formation and its release in simulated primary water environments. Meanwhile, the surface states of steam generator tubes affect the noise level of eddy current testing. Noise signals arising from the tubes degrade the probability of detection and sizing accuracy of the defects. The corrosion behavior was closely correlated to the tube noise measured using a rotating probe, while it was not related to the noise measured using a bobbin probe. It is suggested that the tube noise value measured using a rotating pancake coil probe can be a decisive measure to estimate the corrosion behavior of tubing.

  13. A comparing study of alloy 600 and alloy 690 on resistance to intergranular stress corrosion cracking(IGSCC)

    International Nuclear Information System (INIS)

    In order to compare the effect of senitization on the intergranular stress corrosion cracking(IGSCC) between Alloy 600 and Alloy 690, these alloys have been sensitized for 1 to 100 hours at 700 .deg. C. The degree of sensitization(DOS) has evaluated by the ratio of Ir(the maximum current density at anodic scan) to Ia(the maximum current density at reverse scan) in the modified double loop EPR(electrochemical potentiokinetic reactivation) test in 0.01M H2SO4 + 0.0001M KSCN at 25 .deg. C and at scan rate of 0.5mV/sec. The susceptibility to IGSCC has been measured in 0.01M Na2S4O6 solution using CERT(constant extension rate tester) at strain rate of 1.0 x 10-6S-1. With increasing sensitization time the DOS of Alloy 600 increases to the maximum value at 5 hours and decreases gradually due to the replenishment of Cr to the Cr-depleted grain boundaries. For Alloy 600 samples except those sensitized for less than 1 hour, the DOS measured by the modified EPR test parallel to susceptibility to IGSCC revealed by the ratio of strain to failure (εf, Na2S4O6/εf, Air). It appears that the susceptibility to IGSCC is closely associated with the depth in Cr-depleted concentration profile across grain boundary. For the sensitized Alloy 690 samples exhibited extremely low value of Ir/Ia less than 0.074% and also were immune to IGSCC. The good resistance of Alloy 690 to IGSCC is considered to be attributed to the higher Cr concentration to avoid serious Cr-depletion problems adjacent to grain boundary

  14. Precipitated phases and corrosion behavior in the dissimilar alloy 690-SUS 304L joints formed by EBW and GTAW

    International Nuclear Information System (INIS)

    This study investigates the correlation between the microstructure and the corrosion resistance properties of the fusion zone of Alloy 690-SUS 304L stainless steel dissimilar weldments formed by electron beam welding (EBW). The effects of the EBW process are evaluated by comparing the microstructure and corrosion resistance properties of the EBW weldment with those of Alloy 690-SUS 304L weldment formed by gas tungsten arc welding (GTAW). The experimental results reveal that the interdendritic region of the fusion zone of the EBW weldment contains fine TiN precipitates and Cr-Ni rich phases. The TiN precipitates are originated from the Alloy 690 base metal, while the Cr-Ni rich phases, a new formation of precipitates, is precipitated in the region around TiN during solidification. Microscopic analysis of the samples following a modified Huey test indicates that the matrix around TiN precipitate and the Cr-Ni rich phase precipitate provide the preferred sites for corrosion pit initiation. Due to the rapid cooling in the EBW process, relatively fewer and smaller TiN precipitates and Cr-Ni rich phases are formed in the weldment. Consequently, only limited corrosive pitting is observed which indicates better interdendritic corrosion resistance properties in comparison to joints with GTAW process. Furthermore, rapid solidification in the fusion zone results not only the suppression of chromium carbide precipitation but also the chromium depletion at the grain boundaries. As a result, the intergranular corrosion resistance and interdendritic corrosion resistance of the EBW weldment are significantly higher than that of the GTAW weldment. (author)

  15. Influence of Zn Addition on Oxide Films on Alloy 690 in High Temperature Water

    Institute of Scientific and Technical Information of China (English)

    HAI; Zheng-yin; WANG; Hui; XINChang-sheng; CAI; Min

    2013-01-01

    The application of zinc injection at pressurized water reactors(PWRs)shows great benefits in radiation field reduction,mitigating primary water stress corrosion cracking(PWSCC)initiation and some crack propagation of structure materials.It is widely used in the PWRs all over the world and AP1000 is about to use Zn addition technique to modify the water chemistry.Inconel 690 is a regular structural material for

  16. Development of graded Ni-YSZ composite coating on Alloy 690 by Pulsed Laser Deposition technique to reduce hazardous metallic nuclear waste inventory

    International Nuclear Information System (INIS)

    Highlights: → Pre-mature failure of vitrification furnaces not only delays nuclear waste immobilization process but also generates new type of wastes. → To prevent this, Ni-YSZ compositionally graded coating has been developed for Alloy 690 through Pulsed Laser Deposition technique. → Detail characterization of the coating and its behavior under simulated plant condition identifies Ni-YSZ composite coating as a suitable diffusion barrier material. - Abstract: Alloy 690 based 'nuclear waste vitrification furnace' components degrade prematurely due to molten glass-alloy interactions at high temperatures and thereby increase the volume of metallic nuclear waste. In order to reduce the waste inventory, compositionally graded Ni-YSZ (Y2O3 stabilized ZrO2) composite coating has been developed on Alloy 690 using Pulsed Laser Deposition technique. Five different thin-films starting with Ni80YSZ20 (Ni 80 wt% + YSZ 20 wt%), through Ni60YSZ40 (Ni 60 wt% + YSZ 40 wt%), Ni40YSZ60 (Ni 40 wt% + YSZ 60 wt%), Ni20YSZ80 (Ni 20 wt% + YSZ 80 wt%) and Ni0YSZ100 (Ni 0 wt% + YSZ 100 wt%), were deposited successively on Alloy 690 coupons. Detailed analyses of the thin-films identify them as homogeneous, uniform, pore free and crystalline in nature. A comparative study of coated and uncoated Alloy 690 coupons, exposed to sodium borosilicate melt at 1000 oC for 1-6 h suggests that the graded composite coating could substantially reduced the chemical interactions between Alloy 690 and borosilicate melt.

  17. Cation Release Mitigation on the Primary Surface of Alloy 690 Steam Generator Tubes via Electrochemical Surface Modification

    Energy Technology Data Exchange (ETDEWEB)

    Shim, Heesang; Kim, Kyung Mo; Seo, Myung Ji; Han, Jung Ho; Hur, Do Haeng [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-05-15

    The Co-60 and Co-58, major contaminations sources, are formed respectively by neutron activation of Co-59 and Ni-58. Co-59 is originated from various constituting materials such as hardfacing parts (Stellite{sup TM}, Haynes), an impurity in steam generator (SG) tubes, and stainless steel pipes. Ni-58 is mainly released out from the SG tube surface which is about 70% of the total area exposed to the primary coolant. Thus, the corrosion release of Ni ion can be a severe problem at the plant using SG tubes of Ni-based alloys such as Alloy 600 and 690 having high Ni contents. This work provides a mitigation method for the cation corrosion release of commercial Alloy 690 SG tubes in a primary coolant system through electropolishing (EP) surface modification. We modified the inside surface of a commercial Alloy 690 SG tube to investigate the influence of surface condition on the corrosion release rate in the primary coolant system. The change in surface morphologies of corrosion products is negligible, while the corrosion release rate revealed a remarkable improvement by electropolishing of primary surface. In particular, the corrosion release rate is mainly dependent on the surface roughness as a function of EP time. The lowest corrosion release rate was obtained from the sample electro polished for 8 min.

  18. Effect of surface roughness on corrosion behavior of Alloy 690TT in simulated primary coolant of PWRs

    International Nuclear Information System (INIS)

    The corrosion products transported into the primary coolant may be activated in the core or re-deposited on the surface of components in primary coolant system including fuel cladding. Nickel cations released from the steam generator tubes cause the serious problems in PWRs, for instance, radiation exposure during maintenance operation, occurrence of axial offset anomaly (AOA) and reduction in plant operation. Some studies have been carried out to characterize the oxide layer grown on a Ni-base alloy in primary water chemical condition, especially on morphology and chemical composition. The oxide layer was deemed to a duplex structure composed to an inner Cr rich layer and an outer spinel layer rich in iron or nickel. The composition and morphology of oxide layer are affected by surface finish, operating condition, and water chemistry. Above all, surface roughness, which is one of the commercial requirements for steam generator tube of PWRs, is extremely important in terms of corrosion degradation and corrosion products. In this study, we report the effect of surface roughness on corrosion behavior in simulated primary water at 330 .deg. C and at 150 bar. The surface roughness was controlled to evaluate its difference in corrosion property using mechanical grinding and polishing method. It was measured using a surface profiler and morphology of oxide layer was investigated with FESEM. The corrosion rate of Alloy 690TT samples was calculated by descale-gravimetric analysis. We investigate the effect of surface roughness on corrosion behavior of Alloy 690TT in the simulated primary coolant environments of a pressurized water reactor. Surface roughness of samples were controlled from 716 nm to 25 nm to evaluate for the effect of surface roughness on corrosion behavior Polyhedral oxide particles were formed on the grounded surfaces, whereas the mixed oxides of polyhedral and needle-like structure formed on the polished surface. The corrosion rate of samples was

  19. ELECTROCHEMICAL BEHAVIOR OF ALLOY 690 IN NaCl SOLUTION%690合金在NaCl溶液中的电化学行为研究

    Institute of Scientific and Technical Information of China (English)

    乔岩欣; 任爱; 刘飞华

    2012-01-01

    The electrochemical behavior of alloy 690 in NaCl were investigated by means of potentiodynamic polarization curves,electrochemical impendence spectrum and current-time transient curves.Alloy 690 exhibited anodic passivation behavior in tested solution.The corrosion rate of alloy 690 increased with the increase of NaCl concentration in tested solution.The passive film of alloy 690 formed in 1%NaCl was relatively compact compared with that in 0.1%NaCl at applied potential of 0.2 V.The corrosion current density of alloy 690 in 1%NaCl(I_(p1)) was higher than that in 0.1%NaCl(I_(P2)) when passivation periods less than 1096 s.The value of I_(p1) was lower than I_(P2) when passivation periods longer than 1096 s.%利用动电位极化曲线、电化学阻抗谱和电流-时间响应曲线对690合金在NaCl溶液中的电化学行为进行了研究。结果表明,690合金在不同浓度的NaCl溶液中均表现出阳极钝化现象,腐蚀速率随NaCl浓度的升高而增加。钝化后690合金的耐蚀性提高,在1%NaCl溶液中生成的钝化膜较致密。钝化时间小于1096 S时690合金在0.1%NaCl中的腐蚀电流密度低于其在1%NaCl中的腐蚀电流密度,当钝化时间大于1096 s时690合金在0.1%NaCl中的腐蚀电流密度反而高于其在1%NaCl中的腐蚀电流密度。

  20. Cracking behavior and microstructure of austenitic stainless steels and alloy 690 irradiated in BOR-60 reactor, phase I.

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y.; Chopra, O. K.; Soppet, W. K.; Shack, W. J.; Yang, Y.; Allen, T. R.; Univ. of Wisconsin at Madison

    2010-02-16

    Cracking behavior of stainless steels specimens irradiated in the BOR-60 at about 320 C is studied. The primary objective of this research is to improve the mechanistic understanding of irradiation-assisted stress corrosion cracking (IASCC) of core internal components under conditions relevant to pressurized water reactors. The current report covers several baseline tests in air, a comparison study in high-dissolved-oxygen environment, and TEM characterization of irradiation defect structure. Slow strain rate tensile (SSRT) tests were conducted in air and in high-dissolved-oxygen (DO) water with selected 5- and 10-dpa specimens. The results in high-DO water were compared with those from earlier tests with identical materials irradiated in the Halden reactor to a similar dose. The SSRT tests produced similar results among different materials irradiated in the Halden and BOR-60 reactors. However, the post-irradiation strength for the BOR-60 specimens was consistently lower than that of the corresponding Halden specimens. The elongation of the BOR-60 specimens was also greater than that of their Halden specimens. Intergranular cracking in high-DO water was consistent for most of the tested materials in the Halden and BOR-60 irradiations. Nonetheless, the BOR-60 irradiation was somewhat less effective in stimulating IG fracture among the tested materials. Microstructural characterization was also carried out using transmission electron microscopy on selected BOR-60 specimens irradiated to {approx}25 dpa. No voids were observed in irradiated austenitic stainless steels and cast stainless steels, while a few voids were found in base and grain-boundary-engineered Alloy 690. All the irradiated microstructures were dominated by a high density of Frank loops, which varied in mean size and density for different alloys.

  1. Materials Reliability Program Resistance to Primary Water Stress Corrosion Cracking of Alloys 690, 52, and 152 in Pressurized Water Reactors (MRP-111)

    Energy Technology Data Exchange (ETDEWEB)

    Xu, H. [Framatome ANP, Inc., Lynchburg, VA (United States); Fyfitch, S. [Framatome ANP, Inc., Lynchburg, VA (United States); Scott, P. [Framatome ANP, SAS, Paris (France); Foucault, M. [Framatome ANP, SAS, Le Creusot (France); Kilian, R. [Framatome ANP, GmbH, Erlangen (Germany); Winters, M. [Framatome ANP, GmbH, Erlangen (Germany)

    2004-03-01

    Over the last thirty years, stress corrosion cracking in PWR primary water (PWSCC) has been observed in numerous Alloy 600 component items and associated welds, sometimes after relatively long incubation times. Repairs and replacements have generally utilized wrought Alloy 690 material and its compatible weld metals (Alloy 152 and Alloy 52), which have been shown to be very highly resistant to PWSCC in laboratory experiments and have been free from cracking in operating reactors over periods already up to nearly 15 years. It is nevertheless prudent for the PWR industry to attempt to quantify the longevity of these materials with respect to aging degradation by corrosion in order to provide a sound technical basis for the development of future inspection requirements for repaired or replaced component items. This document first reviews numerous laboratory tests, conducted over the last two decades, that were performed with wrought Alloy 690 and Alloy 52 or Alloy 152 weld materials under various test conditions pertinent to corrosion resistance in PWR environments. The main focus of the present review is on PWSCC, but secondary-side conditions are also briefly considered.

  2. Effect of water chemistry on the oxide film on Alloy 690 during simulated hot functional testing of a pressurised water reactor

    International Nuclear Information System (INIS)

    Highlights: ► Influence of hot functional test chemistry on Alloy 690 oxidation studied by EIS/XPS. ► Increase in LiOH concentration leads to a higher dissolution rate of the oxide. ► Higher boric acid content leads to more efficient passivation of the surface. ► Oxidation parameters estimated by comparison of results to the Mixed-Conduction Model. - Abstract: Electrochemical impedance spectroscopic measurements to follow the oxidation of Alloy 690 in high-temperature water environments simulating hot functional test (HFT) chemistries are presented and discussed. The thickness and in-depth composition of the formed oxides is estimated by X-ray photoelectron spectroscopy. Kinetic and transport parameters of the oxidation process are estimated by quantitative comparison of the results with the mixed-conduction model for oxide films. Based on the influence of LiOH and H3BO3 concentrations on the parameter values, conclusions for the relationship between HFT water chemistry and the electrical and electrochemical properties of the passive layer on reactor coolant circuit surfaces are drawn.

  3. Materials Reliability Program Resistance to Primary Water Stress Corrosion Cracking of Alloys 690, 52, and 152 in Pressurized Water Reactors (MRP-111)

    International Nuclear Information System (INIS)

    Over the last thirty years, stress corrosion cracking in PWR primary water (PWSCC) has been observed in numerous Alloy 600 component items and associated welds, sometimes after relatively long incubation times. Repairs and replacements have generally utilized wrought Alloy 690 material and its compatible weld metals (Alloy 152 and Alloy 52), which have been shown to be very highly resistant to PWSCC in laboratory experiments and have been free from cracking in operating reactors over periods already up to nearly 15 years. It is nevertheless prudent for the PWR industry to attempt to quantify the longevity of these materials with respect to aging degradation by corrosion in order to provide a sound technical basis for the development of future inspection requirements for repaired or replaced component items. This document first reviews numerous laboratory tests, conducted over the last two decades, that were performed with wrought Alloy 690 and Alloy 52 or Alloy 152 weld materials under various test conditions pertinent to corrosion resistance in PWR environments. The main focus of the present review is on PWSCC, but secondary-side conditions are also briefly considered

  4. The role of Hydrogen and Creep in Intergranular Stress Corrosion Cracking of Alloy 600 and Alloy 690 in PWR Primary Water Environments ? a Review

    Energy Technology Data Exchange (ETDEWEB)

    Rebak, R B; Hua, F H

    2004-07-12

    Intergranular attack (IGA) and intergranular stress corrosion cracking (IGSCC) of Alloy 600 in PWR steam generator environment has been extensively studied for over 30 years without rendering a clear understanding of the essential mechanisms. The lack of understanding of the IGSCC mechanism is due to a complex interaction of numerous variables such as microstructure, thermomechanical processing, strain rate, water chemistry and electrochemical potential. Hydrogen plays an important role in all these variables. The complexity, however, significantly hinders a clearer and more fundamental understanding of the mechanism of hydrogen in enhancing intergranular cracking via whatever mechanism. In this work, an attempt is made to review the role of hydrogen based on the current understanding of grain boundary structure and chemistry and intergranular fracture of nickel alloys, effect of hydrogen on electrochemical behavior of Alloy 600 and Alloy 690 (e.g. the passive film stability, polarization behavior and open-circuit potential) and effect of hydrogen on PWSCC behavior of Alloy 600 and Alloy 690. Mechanistic studies on the PWSCC are briefly reviewed. It is concluded that further studies on the role of hydrogen on intergranular cracking in both inert and primary side environments are needed. These studies should focus on the correlation of the results obtained at different laboratories by different methods on materials with different metallurgical and chemical parameters.

  5. Optimisation of the water chemistry during hot functional test of a PWR for improved stability of the passive film on alloy 690

    International Nuclear Information System (INIS)

    In the present paper, an attempt is made to quantify the effect of water chemistry in simulated Hot Functional Test (HFT) conditions on the electrical and electrochemical properties, and thus the stability and protective ability of the passive film formed on Alloy 690 as the main PWR steam generator material. For the purpose, a calculation procedure to interpret simultaneously electrochemical impedance and surface analytical results is used to obtain first-hand estimates of the interfacial rate constants of oxidation of individual alloy constituents (Ni, Cr and Fe), the diffusion coefficient of oxygen vacancies, as well as field strength in the growing oxide. The main conclusion that can be drawn from both experimental and calculation results is that increasing LiOH concentration in the simulated HFT water leads to higher dissolution rates, higher metal oxidation and transport rates through the oxide. In other words, the oxide is the more defective, the higher the concentration of Li in the electrolyte is. Conversely, boron added as H3BO3 was found to have a beneficial effect that counter-acts the accelerating influence of LiOH. On the basis of our experiments and their interpretation, a HFT water chemistry with low to intermediate LiOH contents and boron addition as H3BO3 seems to produce films that exhibit improved electrochemical stability and thus enhanced resistance against corrosion. (authors)

  6. Study of the stress corrosion of the alloys 690 and 600 in PWR primary water, influence of the fabrication processes of steam generators tubes on the crack initiation phase

    International Nuclear Information System (INIS)

    To date, the causes for the failure of the alloy 600 PWRSCC and the non sensitivity of alloy 690 are not understood. The influence of the fabrication route on the sensitivity of these alloys is also poorly known. In these conditions, it is difficult to appreciate the safety margin offered by alloy 690, today massively used in PWR. The aim of the present study is to bring discriminating elements regarding mechanisms proposed to explain alloy 600 cracking in PWR primary water. To do so, a detailed characterisation of the oxide layers, but also of the consequences of the growth of these layers on the underlying materials, was realised for both concerned materials. The goal of this study is also to estimate the influence of the fabrication on the sensitivity of both alloys. For that purpose, a detailed characterisation of the industrial inside surfaces of SG's tubes was realised. Then, SCC tests were realised to estimate the harmfulness of the observed defects for both superficial layers. The results obtained plead for a SCC mechanism based on the internal oxidation of the material. In this mechanism, the important intergranular diffusion of the oxygen is made possible by a binding effect between interstitial oxygen atoms and vacancies produced by the selective oxidation of chromium. As regards the industrial surfaces, the elaboration of tubes is susceptible to induce some different properties to the surface material in comparison to the bulk material. When the tubes are shaped (dudgenning, arching,..) this layer can induced the formation of defect which can propagate, i.e. crack initiation, on alloy 600 and defects on alloy 690. (author)

  7. Characterisation of Oxides Formed on the Internal Surface of Steam Generator Tubes in Alloy 690 Corroded in the Primary Environment of Pressurised Water Reactors

    International Nuclear Information System (INIS)

    Since the end of the 1990s, EDF R and D has been studying the phenomenon of corrosion product release from Steam Generator tubes in order to minimize the Source Term of the contamination and radiation exposure during operation and maintenance of Pressurised Water Reactors. With the BOREAL loop, release tests in primary water at 325 deg. C were performed on various Steam Generator tubes made of alloy 690. The experimental conditions of these tests (chemistry, temperature and hydraulics) were the same for all the tests but the results showed various behaviours towards release. For some tubes, the release was weak whereas for others, it was higher; the release rate of the tubes decreased more or less quickly with time. In order to explain these results, the internal surface of the tubes was characterised before and after the tests. Before the tests, various parameters were studied; the main parameters were the roughness, the impurities, the grain size and the cold work. The results demonstrated that it was not easy to quantify the influence of each parameter on release and to differentiate the tubes. A new parameter was proposed to characterise the internal extreme surface of SG tubes: the surface nano-hardness by nano-indentation measurements. The tubes were also observed and analysed by SEM, (X)TEM. Data obtained by (X)TEM revealed differences of the surface state (layer of perturbed microstructure, density of dislocations, grain size, impurities, initial oxide,...). After the tests, the oxides formed on the internal surface and the underlying material of the samples were characterised by SEM, (X)TEM and SIMS. The examinations showed various types of oxides. For some tubes, a duplex oxide scale was identified, for the others, only one oxide scale was observed. For equivalent durations of corrosion, the thickness of the enriched - chromium oxide layer can vary from 5 nm to 100 nm and the chemical composition can be different. The examinations of the underlying

  8. MICROSTRUCTURE NEAR SCRATCH ON ALLOY 690TT AND STRESS CORROSION INDUCED BY SCRATCHING%690TT合金划痕显微组织及划伤诱发的应力腐蚀

    Institute of Scientific and Technical Information of China (English)

    孟凡江; 王俭秋; 韩恩厚; 庄子哲雄; 柯伟

    2011-01-01

    测试表明,690TT合金划痕周围形成了加工硬化区,范围可达100 μm.TEM及EBSD-OIM组织观察发现,划痕沟槽处的基体组织出现了一定程度的纳米化.在330℃碱溶液中的浸泡实验表明,划伤诱发了690TT合金应力腐蚀裂纹的萌生和扩展,划伤过程中形成的变形晶界、孪晶界以及产生的微观裂纹成为应力腐蚀裂纹优先萌生的位置.Pb的存在使氧化膜变得疏松,加速了基体的溶解和氧化.随着溶液中Pb含量的增加,划伤诱发的应力腐蚀裂纹长度随之增加.690TT合金表面划伤严重降低了材料抵抗应力腐蚀开裂的能力.%The microstructure and stress corrosion cracking (SCC) behavior of scratched zone on alloy 690TT were studied by using microhardness, TEM, EBSD-OIM and immersion experiment in caustic solution. It was found that a deformed hardening layer with a dimension range of 100 /xm was produced near the scratch. TEM and EBSD-OIM observations showed that the grains at shallow surface of scratch groove were refined to nano-size. SCC tests for scratched alloy 690TT were performed in caustic solution at high temperature with or without addition of lead oxides. The results showed that SCC cracks initiated and propagated at scratch banks and scratch grooves. Grain boundaries, twin boundaries deformed and microcracks produced during scratching process are preferential sites for SCC. The oxide films formed on scratch groove were loosed by lead. The SCC crack length increased with increase of lead content. Scratched alloy 690TT is susceptible to SCC.

  9. High cycle fatigue properties of inconel 690

    International Nuclear Information System (INIS)

    Inconel 690 is presently used as sleeve material and a replacement alloy in degraded steam generators, as well as the material for new steam generators. But Inconel 690 has low thermal conductivity which are 3-8% less than that of Inconel 600 at operating temperature. For the same power output, conduction area must be increased. As a result, more fluid induced vibration can cause a fatigue damage of Inconel 690. High cycle fatigue ruptures occurred in the U-bend regions of North Anna Unit 1 and Mihama Unit 2 steam generators. At this study, the effect of temperature on fatigue crack growth rate in Inconel 690 steam generator tube was investigated at various temperature in air environment. With increasing temperature, fatigue crack growth rate increased and grain size effect decreased. Chromium carbides which have large size and semi-continuous distribution in the grain boundaries decreased fatigue crack growth rate

  10. Microstructure Investigation of Modified Inconel 706 Superalloys

    OpenAIRE

    Kindrachuk, Vitaliy

    2006-01-01

    In dieser Arbeit wird die Nickel-Basis-Superlegierung Inconel 706 untersucht. Die Legierung ist stabil in einem Temperaturbereich bis zu 650°C und findet Anwendung bei der Herstellung von Gas- und Dampfturbinen. Das Ziel ist die Legierung zu optimieren um den Einsatz bei 700°C und eine Lebensdauer im Bereich von 200 000 h zu ermöglichen. Zwei Modifizierungen von Inconel 706 werden betrachtet: Rhenium (Re)-zulegiertes Inconel 706 und die Legierung DT 706 mit geänderter Zusammensetzung. Die Mik...

  11. Development of INCONEL 600 precision tube (1)

    Energy Technology Data Exchange (ETDEWEB)

    Joo, Yeong Han; Jo, Bong Hyeon; Lee, Dong Hee; Kim, Wan Kyo; Jeong, Pyeong Keun; Yoon, Hwang Lo; Chio, Seok Sik [Sammi Steel Co. Ltd., Changwon (Korea, Republic of)

    1994-07-01

    Steam generator, being connected with nuclear fuel reactor is one of the most important part of nuclear power plant and consists of a large number of INCONEL 600 tubes. Approximately 160 tons of tubes are needed for a single nuclear power plant. All of INCONEL 600 steam generator tubes for domestic nuclear power plants have been imported. The aim of this research is to develop INCONEL 600 precision tubes for steam generator of nuclear power plant. If this research is conducted successfully, we can produce nuclear fuel tubes, Ni-alloy precision tubes and stainless steel precision tubes for many purposes and technology of INCONEL 600 steam generator tubes are similar to those of other tubes above mentioned. In the current study, development of preliminary manufacturing process of INCONEL 600 precision tubes for steam generator and investigation of material`s metallurgical characteristics were conducted. The main scope of this research is as follows. First, the preliminary manufacturing process design was conducted after investigations of foreign manufacturing processes and technical reports. Second, the results of investigations of material`s metallurgical characteristics through the manufacturing process were applied to the production technology of tentative INCONEL 600 precision tubes for sample. Third, preliminary process routes were established and samples of INCONEL 600 precision tube were produced by this process. As the results of this research, 14 pieces of INCONEL 600 precision tubes were produced by preliminary manufacturing process and the material`s metallurgical characteristics were investigated through the processes. But the SCC test could not be conducted due to the absence of equipment. In order to apply the results of SCC test to the manufacturing process, we need a SCC tester which can simulate SCC characteristics under high temperature and high pressurized circulating water. 95 refs., 55 figs., 20 tabs.

  12. Total hemispherical emissivity of Inconel 718

    International Nuclear Information System (INIS)

    Highlights: • We have measured the total hemispherical emissivity for Inconel 718 from about 600–1250 K. • Oxidation in air at 1073 K resulted in an increase in emissivity. • Sandblasting of Inconel 718 was also observed to increase the emissivity. • Coating of graphite powder onto the ‘as-received’ Inconel 718 showed no increase in the emissivity. • Coating of graphite powder onto the 220 grit sandblasted Inconel 718 did show an increase in emissivity. - Abstract: Total hemispherical emissivity for Inconel 718 was measured in anticipation of its application in Very High Temperature Gas Reactors (VHTRs). A majority of current emissivity data for Inconel 718 is in the form of spectral measurements. The data presented here were obtained with an experimental apparatus based on the standard ASTM C835-06 for total hemispherical emittance. Measurements of Inconel 718 were made for four different surface types including: (i) ‘as-received’ from the manufacturer, (ii) oxidized in air and humidified helium, (iii) sandblasted with aluminum oxide powder, and (iv) with a thin coating of nuclear grade graphite powder (grade NGB-18). The emissivity for the ‘as-received’ sample ranged from 0.21 to 0.28 in the temperature interval from 760 K to 1275 K. Oxidation in air at 1073 K resulted in an increase in emissivity into the range from 0.2 at 650 K to 0.52 at 1200 K. There was no dependence on the oxidation times studied here. Oxidation with humidified helium at 1073 K produced less of an increase in emissivity than the oxidation in air but there was an increase up to the range from 0.2 at 600 K to 0.35 at 1200 K. Sandblasting of Inconel 718 was also observed to increase the emissivity up to the range from 0.43 at 780 K to 0.53 at 1270 K when 60 grit sized powder was used and up to the range from 0.45 at 683 K to 0.57 at 1267 K when 120 and 220 grit sized powders were used. Coating of graphite powder onto the ‘as-received’ Inconel 718 showed no increase

  13. Total hemispherical emissivity of Inconel 718

    Energy Technology Data Exchange (ETDEWEB)

    Keller, Benjamin P.; Nelson, Shawn E.; Walton, Kyle L.; Ghosh, Tushar K.; Tompson, Robert V.; Loyalka, Sudarshan K., E-mail: LoyalkaS@missouri.edu

    2015-06-15

    Highlights: • We have measured the total hemispherical emissivity for Inconel 718 from about 600–1250 K. • Oxidation in air at 1073 K resulted in an increase in emissivity. • Sandblasting of Inconel 718 was also observed to increase the emissivity. • Coating of graphite powder onto the ‘as-received’ Inconel 718 showed no increase in the emissivity. • Coating of graphite powder onto the 220 grit sandblasted Inconel 718 did show an increase in emissivity. - Abstract: Total hemispherical emissivity for Inconel 718 was measured in anticipation of its application in Very High Temperature Gas Reactors (VHTRs). A majority of current emissivity data for Inconel 718 is in the form of spectral measurements. The data presented here were obtained with an experimental apparatus based on the standard ASTM C835-06 for total hemispherical emittance. Measurements of Inconel 718 were made for four different surface types including: (i) ‘as-received’ from the manufacturer, (ii) oxidized in air and humidified helium, (iii) sandblasted with aluminum oxide powder, and (iv) with a thin coating of nuclear grade graphite powder (grade NGB-18). The emissivity for the ‘as-received’ sample ranged from 0.21 to 0.28 in the temperature interval from 760 K to 1275 K. Oxidation in air at 1073 K resulted in an increase in emissivity into the range from 0.2 at 650 K to 0.52 at 1200 K. There was no dependence on the oxidation times studied here. Oxidation with humidified helium at 1073 K produced less of an increase in emissivity than the oxidation in air but there was an increase up to the range from 0.2 at 600 K to 0.35 at 1200 K. Sandblasting of Inconel 718 was also observed to increase the emissivity up to the range from 0.43 at 780 K to 0.53 at 1270 K when 60 grit sized powder was used and up to the range from 0.45 at 683 K to 0.57 at 1267 K when 120 and 220 grit sized powders were used. Coating of graphite powder onto the ‘as-received’ Inconel 718 showed no increase

  14. Weldability of Inconel 718 - a review

    International Nuclear Information System (INIS)

    The report discusses the main issues related to weldability of Inconel 718. How the problem of strain age cracking during post weld treatment is avoided in this alloy has also been discussed. It also elaborates phases present in the alloys of 718 and its solidification metallurgy

  15. Bending of pipes with inconel cladding

    Energy Technology Data Exchange (ETDEWEB)

    Nachpitz, Leonardo; Menezes, Carlos Eduardo B.; Vieira, Carlos R. Tavares [Primus Processamento de Tubos S.A. (PROTUBO), Macae, RJ (Brazil)

    2009-07-01

    The high-frequency induction bending process, using API pipes coated with Inconel 625 reconciled to a mechanical transformation for a higher degree of resistance, was developed through a careful specification and control of the manufacturing parameters and inherent heat treatments. The effects of this technology were investigated by a qualification process consisting of a sequence of tests and acceptance criteria typically required by the offshore industry, and through the obtained results was proved the effectiveness of this entire manufacturing process, without causing interference in the properties and the quality of the inconel cladding, adding a gain of resistance to the base material, guaranteed by the requirements of the API 5L Standard. (author)

  16. Economical Inconel 718%经济型Inconel 718合金

    Institute of Scientific and Technical Information of China (English)

    狄志高; 黄漫

    2012-01-01

    为了降低Inconel 718合金的生产成本,设计了常规方案和经济方案两种试验方案:常规方案用纯金属冶炼718合金,经济方案用铌铁合金替代金属铌、用铬铁合金替代金属铬冶炼718合金.运用两种方案在真空感应炉内分别冶炼了一炉718合金并浇铸成锭,将两支铸锭按照相同的工艺参数进行扩散退火、轧制成材及热处理,随后取样进行力学性能及金相组织分析.试验结果表明,用两种方案冶炼的718合金均能满足国内优质Inconel718合金的技术标准,且用铌铁合金替代金属铌、用铬铁合金替代金属铬冶炼的Inconel 718合金可降低18%的原料成本.%In order to decrease the production costs of Inconel 718 alloy, two kinds of test programs were designed including conventional program and economical program. The conventional program was designed to smelt Inconel 718 alloy with elemental metal. The economical program was designed to smelt Inconel 718 alloy with Nb-Fe and Cr-Fe instead of metal Nb and Cr. Two heats of 718 alloy were smelted separately by two kinds of test programs in vacuum induction furnace, molten alloy were casted to two ingots. Under the same processing parameter, two ingots were carried out diffusion annealing, roll forming and heat treatment. Specimens were taken to analyze the mechanical properties and metallurgical structure. The testing results show Inconel 718 alloy by both kinds of test programs can reach domestic technical standard of superior alloy. Compared with conventional program, economical program of using Nb-Fe and Cr-Fe instead of metal Nb and Cr can decrease 18% costs of the raw material.

  17. Bending of pipes with inconel cladding; Curvamento de tubos revestidos com inconel

    Energy Technology Data Exchange (ETDEWEB)

    Nachpitz, Leonardo; Menezes, Carlos Eduardo B.; Vieira, Carlos R. Tavares [PROTUBO, Macae, RJ (Brazil)

    2008-07-01

    The pipes used in offshore equipment, such as wet Christmas trees, sub sea manifolds and rigid platform risers, as well as some pipes for refineries and ships, must have mechanical resistance to high pressure and also be resistant to corrosion from acids. Some special materials, such as stainless steel, duplex and super duplex steel are used to resolve this problem, but the cost is very high. Besides the problem of cost, these materials have other drawbacks, such as the difficulty of welding them, a technology mastered in few countries. As a better alternative, the use has been increasing of carbon steel and API pipes coated internally with inconel by welding deposition. This groundbreaking technology, of proven efficiency, has a far superior cost-benefit relation. Carbon steel and API pipes, besides having better mechanical resistance to high pressure and corrosion resistance, can be fabricated with technology mastered worldwide. Nickel alloys, such as inconel, are highly resistant to corrosion and temperature, and in these aspects are better than stainless steels. The pipes for transportation equipment and for refining hydrocarbons, as mentioned above, require various turns and special geometries, which generally are solved by the use of bends and spools made by high-frequency induction. This technology, already well established for various carbon and stainless steels, was developed to work with pipes coated internally with inconel (inconel cladding). Therefore, our work describes the process of fabricating bends from API steel pipes with inconel cladding, demonstrating the efficacy of this technology along with its quality gains and cost reduction. (author)

  18. Corrosion Performance of Inconel 625 in High Sulphate Content

    Science.gov (United States)

    Ismail, Azzura

    2016-05-01

    Inconel 625 (UNS N06625) is a type of nickel-chromium-molybdenum alloy with excellent corrosion resistance in a wide range of corrosive media, being especially resistant to pitting and crevice corrosion. However, in aggressive environment, Inconel 625 will suffer corrosion attack like other metals. This research compared the corrosion performance of Inconel 625 when exposed to higher sulphate content compared to real seawater. The results reveal that Inconel 625 is excellent in resist the corrosion attack in seawater. However, at increasing temperature, the corrosion resistance of this metal decrease. The performance is same in seawater with high sulphate content at increasing temperature. It can be concluded that sulphate promote perforation on Inconel 625 and become aggressive agents that accelerate the corrosion attack.

  19. Hot tensile tests of Inconel 718

    Science.gov (United States)

    1980-01-01

    The physical metallurgy of near-solidus integranular cracking in Inconel 718 welds was investigated. The data, although inconclusive, suggest at least two mechanisms which might explain intergranular cracking (microfissuring) in the heat-affected zone of several high temperature alloys. One theory is based on the separation of intergranular liquid while the other involves mechanical failure of solid ligaments surrounded by intergranular liquid. Both mechanisms concentrate strain in the grain boundaries resulting in low strain (1%) intergranular brittleness. The mechanisms reported might also pertain to the physical metallurgy of casting, powder metallurgy sintering and hot isostatic pressing.

  20. Thermo-Physical Properties of Selected Inconel

    Directory of Open Access Journals (Sweden)

    Krajewski P.K.

    2014-10-01

    Full Text Available The paper brings results of examinations of main thermo-physical properties of selected Inconel alloys, i.e. their heat diffusivity, thermal conductivity and heat capacity, measured in wide temperature range of 20 – 900 oC. Themathematical relationships of the above properties vs. temperature were obtained for the IN 100 and IN 713C alloys. These data can be used when modelling the IN alloys solidification processes aimed at obtaining required structure and properties as well as when designing optimal work temperature parameters.

  1. Hydrogen embrittlement of sensitized inconel 600

    International Nuclear Information System (INIS)

    Tensile tests under cathodic charging were carried out on sensitized Inconel 600 alloy poly crystals. The maximum sensitivity of hydrogen embrittlement (HE) was recognized on the specimen sensitized at 973K, and the specimen fractured with intercrystalline mode. The effect of cold working before the sensitized treatment was recognized in the sensitivity of HE and the morphology of fractured surface. When the prestrain increased, the sensitivity of HE was decreased and the fracture morphology changed from intercrystalline to transgranular. On the single crystal specimen, no effect was recognized in both the sensitized temperature and the cold working before sensitization. Intercrystalline and transcrystalline cracks occurred on the surface of polycrystal specimen by hydrogen charging under no loading condition. Also, the cracks on the surface of single crystal specimen were produced along {001} planes hydrogen under the same condition. (author)

  2. Fatigue strength on superalloy Inconel 600

    International Nuclear Information System (INIS)

    In this paper, the strain controlled fatigue test at room temperature in air and the fractographic study on superalloy Inconel 600 are performed. From the test results, the relations between nominal stresses and number of cycles are obtained to show that the stress increases slightly in the early period, then remains stable at constant value for a subsequent long period, and then steeply drops immediately before the final failure. The relationships on strain amplitude with fatigue life are introduced. The values of fictitious stress amplitude calculated from the test results are just lying between the two best fit curves from ASME, Sec. III, Division I, Appendix Table 1.9.1/2 in 1983 and Transaction of ASME, Nov. 1977, p. 584. From the microscopic examination of the fatigue fracture, there are three failure process zones: fatiguecrack origin appearance zone, stable radial spread zone, and final fast fracture zone. (author)

  3. Manifestations of DSA in austenitic stainless steels and inconel alloys

    International Nuclear Information System (INIS)

    The aim of the investigation was to examine and compare different types of DSA (Dynamic Strain Aging) manifestations in AISI 316 austenitic stainless steel (SS) and Inconel 600 and Inconel 690 alloys by means of slow strain rate tensile testing, mechanical loss spectrometry (internal friction) and transmission electron microscopy (TEM). Another aim was to determine differences in the resulting dislocation structures and internal friction response of materials showing and not showing DSA behaviour

  4. Circular Vibration Planing of Inconel 718

    Science.gov (United States)

    Hettiarachchi, Nandita Kalyanakumara; Moriwaki, Toshimichi; Shibasaka, Toshiro; Nakamoto, Keiichi

    Circular vibration milling (CVM) is achieved by vibrating a milling cutter about the machine tool spindle axis in a circular path, in addition to its rotary motion. CVM has been proven capable of producing better surface finishes on difficult to cut materials. However, the CVM process is far slower than conventional milling process. In circular vibration planing (CVP) process, the cutting tool is clamped without rotation and fed at a speed comparable to the feed speed of conventional milling. By superimposing circular vibration motion, necessary cutting speed could be achieved keeping the feed speed at realistic values. Inconel 718 was machined by CVP and conventional milling at a similar feed rate. It was observed that CVP could reduce tool wear and hence produce better surface finishes than conventional milling. A geometric simulation showed a major difference between uncut chip shapes of the two processes. The difference of uncut chip shapes suggests that in CVP process, less rubbing occurs between tool flank face and work before the tool penetrates in to the work to form a chip. The reduced rubbing of the flank face is proposed as the reson for reduced tool wear in CVP when compared with conventional milling.

  5. Weldability testing of Inconel trademark filler metals

    International Nuclear Information System (INIS)

    This paper presents the findings of a research program aimed at quantifying the weld solidification cracking susceptibility and weld metal liquation cracking susceptibility of Inconel trademark filler materials 52, 82, 152 and 182 deposited on a variety of materials intended for pressurized water reactor applications. A cursory investigation on the repair weldability of Filler Metal 52 using the Gleeble trademark thermo-mechanical simulation technique is also included. The brittle temperature range (BTR) in the fusion zone and HAZ was determined using the longitudinal-Varestraint test and spot-Varestraint test, respectively, and used as a weldability index for quantification of susceptibility to weld solidification cracking and HAZ liquation cracking. Results from this study showed that Filler Metals 52 exhibited the best resistance to both weld solidification cracking and weld metal liquation cracking followed by 82, 152 and 182 for the base metal combinations tested in this study. Repair weldability study suggested that the resistance to weld metal liquation cracking of 52 all weld metal would not be significantly reduced after ten times of weld simulation at peak temperatures of 900 C and 1,300 C

  6. Hardness and electrochemical behavior of ceramic coatings on Inconel

    Directory of Open Access Journals (Sweden)

    C. SUJAYA

    2012-03-01

    Full Text Available Thin films of ceramic materials like alumina and silicon carbide are deposited on Inconel substrate by pulsed laser deposition technique using Q-switched Nd: YAG laser. Deposited films are characterized using UV-visible spectrophotometry and X-ray diffraction. Composite microhardness of ceramic coated Inconel system is measured using Knoop indenter and its film hardness is separated using a mathematical model based on area-law of mixture. It is then compared with values obtained using nanoindentation method. Film hardness of the ceramic coating is found to be high compared to the substrates. Corrosion behavior of substrates after ceramic coating is studied in 3.5% NaCl solution by potentiodynamic polarization and electrochemical impedance spectroscopy measurements. The Nyquist and the Bode plots obtained from the EIS data are fitted by appropriate equivalent circuits. The pore resistance, the charge transfer resistance, the coating capacitance and the double layer capacitance of the coatings are obtained from the equivalent circuit. Experimental results show an increase in corrosion resistance of Inconel after ceramic coating. Alumina coated Inconel showed higher corrosion resistance than silicon carbide coated Inconel. After the corrosion testing, the surface topography of the uncoated and the coated systems are examined by scanning electron microscopy.

  7. Stainless steel 301 and Inconel 718 hydrogen embrittlement

    Science.gov (United States)

    Allgeier, R. K.; Forman, R.

    1970-01-01

    Conditions and results of tensile tests of 26 Inconel 718 and four cryoformed stainless steel specimens are presented. Conclusions determine maximum safe hydrogen operating pressure for cryogenic pressure vessels and provide definitive information concerning flaw growth characteristics under the most severe temperature and pressure conditions

  8. Precipitation Study in Inconel 625 Alloy by Positron Annihilation Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    M.Ahmad; W. Ahmad; M.A.Shaikh; Mahmud Ahmad; M.U. Rajput

    2003-01-01

    Precipitation in Inconel 625 alloy has been studied by positron annihilation spectroscopy and electron microscopy. The observeddependence of annihilation characteristics on aging time is attributed to the change of the positron state due to the increaseand decrease of the density and size of the γ″ precipitates. Hardness measurements and lifetime measurements are in goodagreement.

  9. Detecting Grain-Boundary Chromium Depletion in Inconel 600

    Science.gov (United States)

    Airey, G. P.; Vaia, A. R.; Pessall, N.; Aspden, R. G.

    1981-11-01

    Techniques to evaluate grain-boundary chromium depletion in Inconel Alloy 600 were investigated. Procedures studied were a modified Huey test, reactivation polarization, magnetic permeability measurements, and eddy current measurements. Results from these tests were correlated with susceptibility to stress-assisted intergranular cracking in polythionic acid. Thermally treated Inconel Alloy 600 steam generator tubing was the principal source of material evaluated, but experimental heats of Ni-Cr-Fe alloys with 8-18 wt.% Cr were prepared to determine the critical chromium level below which stress-assisted intergranular cracking occurs; this critical chromium content was found to be between 9.8 and 11.7 wt.%. All four techniques were considered suitable to evaluate grain-boundary chromium depletion; the modified Huey test and reactivation polarization technique showed a greater sensitivity than the magnetic permeability and eddy current measurements.

  10. Microstructure and oxidation behaviour of aluminized coating of inconel 625

    International Nuclear Information System (INIS)

    Microstructural and oxidation characteristics of aluminized coated Inconel 625 have been examined using scanning electron microscopy (SEM) and fine-probe spot and linescan EDS microanalysis techniques. The formation of slowly growing adherent metallic coatings is essential for protection against the severe environments. Aluminising of the superalloy samples was carried out by pack cementation process at 900 deg. C. in an argon atmosphere. The samples were subsequently oxidized in air at various temperatures to examine performance of the pack aluminized coated alloy. The microstructural changes that occurred in the aluminized layer at various exposure temperature and time were examined to study the oxidation behavior and formation of different phases in the aluminized coating deposited on Inconel 625. (author)

  11. Creep-rupture tests of internally pressurized Inconel 702 tubes

    Science.gov (United States)

    Gumto, K. H.

    1973-01-01

    Seamless Inconel 702 tubes with 0.375-in. outside diameter and 0.025-in. wall thickness were tested to failure at temperatures from 1390 to 1575 F and internal helium pressures from 700 to 1800 psi. Lifetimes ranged from 29 to 1561 hr. The creep-rupture strength of the tubes was about 70 percent lower than that of sheet specimens. Larson-Miller correlations and photomicrographs of some specimens are presented.

  12. Stress corrosion cracking of Inconel in high temperature water

    International Nuclear Information System (INIS)

    Some Inconel samples were subjected to hot water corrosion testing (350 deg. C), under stress slightly above the elastic limit. It has been observed that different types of alloys - with or without titanium - could suffer serious intergranular damage, including a complete rupture, within a three months period. In one case, we observed an unusual intergranular phenomenon which appeared quite different from common intergranular corrosion. (author)

  13. Tritium Permeability of Incoloy 800H and Inconel 617

    Energy Technology Data Exchange (ETDEWEB)

    Philip Winston; Pattrick Calderoni; Paul Humrickhouse

    2012-07-01

    Design of the Next Generation Nuclear Plant (NGNP) reactor and its high-temperature components requires information regarding the permeation of fission generated tritium and hydrogen product through candidate heat exchanger alloys. Release of fission-generated tritium to the environment and the potential contamination of the helium coolant by permeation of product hydrogen into the coolant system represent safety basis and product contamination issues. Of the three potential candidates for high-temperature components of the NGNP reactor design, only permeability for Incoloy 800H has been well documented. Hydrogen permeability data have been published for Inconel 617, but only in two literature reports and for partial pressures of hydrogen greater than one atmosphere, far higher than anticipated in the NGNP reactor. To support engineering design of the NGNP reactor components, the tritium permeability of Inconel 617 and Incoloy 800H was determined using a measurement system designed and fabricated at Idaho National Laboratory. The tritium permeability of Incoloy 800H and Inconel 617, was measured in the temperature range 650 to 950°C and at primary concentrations of 1.5 to 6 parts per million volume tritium in helium. (partial pressures of 10-6 atm)—three orders of magnitude lower partial pressures than used in the hydrogen permeation testing. The measured tritium permeability of Incoloy 800H and Inconel 617 deviated substantially from the values measured for hydrogen. This may be due to instrument offset, system absorption, presence of competing quantities of hydrogen, surface oxides, or other phenomena. Due to the challenge of determining the chemical composition of a mixture with such a low hydrogen isotope concentration, no categorical explanation of this offset has been developed.

  14. Tritium Permeability of Incoloy 800H and Inconel 617

    Energy Technology Data Exchange (ETDEWEB)

    Philip Winston; Pattrick Calderoni; Paul Humrickhouse

    2011-09-01

    Design of the Next Generation Nuclear Plant (NGNP) reactor and its high-temperature components requires information regarding the permeation of fission generated tritium and hydrogen product through candidate heat exchanger alloys. Release of fission-generated tritium to the environment and the potential contamination of the helium coolant by permeation of product hydrogen into the coolant system represent safety basis and product contamination issues. Of the three potential candidates for high-temperature components of the NGNP reactor design, only permeability for Incoloy 800H has been well documented. Hydrogen permeability data have been published for Inconel 617, but only in two literature reports and for partial pressures of hydrogen greater than one atmosphere, far higher than anticipated in the NGNP reactor. To support engineering design of the NGNP reactor components, the tritium permeability of Inconel 617 and Incoloy 800H was determined using a measurement system designed and fabricated at Idaho National Laboratory. The tritium permeability of Incoloy 800H and Inconel 617, was measured in the temperature range 650 to 950 C and at primary concentrations of 1.5 to 6 parts per million volume tritium in helium. (partial pressures of 10-6 atm) - three orders of magnitude lower partial pressures than used in the hydrogen permeation testing. The measured tritium permeability of Incoloy 800H and Inconel 617 deviated substantially from the values measured for hydrogen. This may be due to instrument offset, system absorption, presence of competing quantities of hydrogen, surface oxides, or other phenomena. Due to the challenge of determining the chemical composition of a mixture with such a low hydrogen isotope concentration, no categorical explanation of this offset has been developed.

  15. Thermal stability and environmental compatibility of Inconel 617

    International Nuclear Information System (INIS)

    The thermal stability and environmental compatibility of Inconel 617, a prime nuclear process heat steam reformer candidate alloy, are described in this paper. This commercially available wrought nickel-base alloy has excellent high-temperature strength but is subject to loss of toughness and ductility due to thermal instability. Work done to improve the thermal stability of this alloy is discussed. Room-temperature tensile and toughness data and microstructural information for Inconel 617 specimens exposed at elevated temperatures are presented. Preliminary data indicate that controlling the chemistry of Inconel 617 can provide a substantial improvement in thermal stability. Preliminary work to define the range of high-temperature gas-cooled reactor (HTGR) primary coolant compositions within which minimal deleterious gas/metal reactions occur with Inconel 617 is described. Within this gas chemistry range a stable surface oxide forms and only slight carburization occurs. In other gas chemistry ranges, rapid carburization or decarburization can occur. The gas corrosion experiments discussed are part of a series of relatively short-term exposures to HTGR helium in which the effects of different H2O concentrations (0.01 to 1.0 Pa) were determined as a function of the systematic variation of a second constituent (CO and CH4 for this work) in the test gas. The composition of the basic HTGR helium was 40 Pa H2, 4 Pa CO, 0.02 Pa CO2, 2 Pa CH4 in helium at 0.2 MPa. Two other CO levels (1 and 12 Pa) and one additional CH4 level (0.63 Pa) were used in these experiments. Experimental exposure methods are discussed and the results of gas-metal interaction studies are presented. These results include carbon analyses and optical and scanning electron microscopy to determine the morphology and type of surface and subsurface microstructures. (author). 15 refs, 6 figs, 5 tabs

  16. Effects of pre-deformation in topological characterization of inconel 600 submitted to isothermal treatments

    International Nuclear Information System (INIS)

    INCONEL 600 samples were performed at thermal treatment between 5500C and 7900C during 3 hours after uniaxial tension testing. At each pair hardening-temperature were determined the microhardness and microstrostructure. With the objetive of to determine the influence of the hardening up to INCONEL's mechanical behavior, were plotted microhardness X temperature. (Author)

  17. Mechanical properties and microstructure evaluation of powder bed fused inconel 625 nickel alloy

    Energy Technology Data Exchange (ETDEWEB)

    Brand, Michael J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-04-19

    The objectives of this report were to optimize and fabricate full density Inconel 625 samples using direct metal laser fusion, an additive manufacturing process; and to compare and evaluate precipitation and solid solution strengthening of Inconel 625 produced by PBF to conventional processed material.

  18. Characterization of Strain-Induced Precipitation in Inconel 718 Superalloy

    Science.gov (United States)

    Calvo, Jessica; Penalva, Mariluz; Cabrera, José María

    2016-06-01

    Inconel 718 presents excellent mechanical properties at high temperatures, as well as good corrosion resistance and weldability. These properties, oriented to satisfy the design requirements of gas turbine components, depend on microstructural features such as grain size and precipitation. In this work, precipitation-temperature-time diagrams have been derived based on a stress relaxation technique and the characterization of precipitates by scanning electron microscopy. By using this methodology, the effect of strain accumulation during processing on the precipitation kinetics can be determined. The results show that the characteristics of precipitation are significantly modified when plastic deformation is applied, and the kinetics are slightly affected by the amount of total plastic deformation.

  19. Solidification paths in modified Inconel 625 weld overlay material

    DEFF Research Database (Denmark)

    Chandrasekaran, Karthik; Tiedje, Niels Skat; Hald, John

    2009-01-01

    . Metallographic analysis of solidified samples of Inconel 625 with addition of selected elements is compared with thermodynamic modelling of segregation during solidification. The influence of changes in the melt chemistry on the formation of intermetallic phases during solidification is shown. In particular......, focus is put on how the composition of the dendrite core is affected by modifications to the alloy. It has previously been shown that when the overlay material corrodes, the corrosion take place in the dendrite core. Therefore, the discussion will be directed towards explaining the extent to which the...

  20. Tribological behavior of inconel 718 in sodium cooled reactor environments

    International Nuclear Information System (INIS)

    Results of the present study on the tribological behavior of Inconel 718 in a sodium environment are summarized as follows: (a) Stroke lengths less than or equal to one-half the test pin diameter result in higher friction coefficients. (b) At elevated temperatures, the formation of a lubricative surface film can significantly influence the frictional behavior. (c) Tangential forces present during static dwell periods result in greater bonding tendencies. (d) Increasing contact pressure during static dwell periods results in lower breakaway friction coefficients

  1. Grain size refinement of inconel 718 thermomechanical processing

    International Nuclear Information System (INIS)

    Inconel 718 is a Ni-Fe precipitation treated superalloy. It presents good thermal fatigue properties when the material has small grain size. The aim of this work is to study the grain size refinement by thermomechanical processing, through observations of the microstructural evolution and the influence of some of the process variables in the final grain size. The results have shown that this refinement occured by static recrystallization. The presence of precipitates have influenced the final grain size if the deformations are below 60%. For greater deformations the grain size is independent of the precipitate distribution in the matrix and tends to a limit size of 5 μm. (author)

  2. Material properties of a dissimilar metal weld Inconel 600/ Inconel 82 weld filler/ Carbon Steel (Gr.106 B)

    International Nuclear Information System (INIS)

    Inconel 600 pipes welded to Carbon-Steel are used in CANDU nuclear reactors. Fracture of these welded pipes has important consequences in term of safety, and therefore their mechanical properties need to be better understood. In this study, the weld region was analyzed at various length-scales using optical microscopy, micro hardness testing, small and large scale tensile testing, and Digital Image Correlation (DIC). Micro-hardness profiles showed variations across the weld and through thickness and were justified in terms of residual stresses. Local stress-strain curves were built using DIC and showed good agreement with stress-strain curves obtained from miniature tensile samples. (author)

  3. Surface Integrity of Inconel 718 by Ball Burnishing

    Science.gov (United States)

    Sequera, A.; Fu, C. H.; Guo, Y. B.; Wei, X. T.

    2014-09-01

    Inconel 718 has wide applications in manufacturing mechanical components such as turbine blades, turbocharger rotors, and nuclear reactors. Since these components are subject to harsh environments such as high temperature, pressure, and corrosion, it is critical to improve the functionality to prevent catastrophic failure due to fatigue or corrosion. Ball burnishing as a low plastic deformation process is a promising technique to enhance surface integrity for increasing component fatigue and corrosion resistance in service. This study focuses on the experimental study on surface integrity of burnished Inconel 718. The effects of burnishing ball size and pressure on surface integrity factors such as surface topography, roughness, and hardness are investigated. The burnished surfaces are smoother than the as-machined ones. Surface hardness after burnishing is higher than the as-machined surfaces, but become stable over a certain burnishing pressure. There exists an optimal process space of ball sized and burnishing pressure for surface finish. In addition, surface hardness after burnishing is higher than the as-machined surfaces, which is confirmed by statistical analysis.

  4. Signals produced by inconel mineral insulated coaxial cables in neutron and gamma ray fields

    International Nuclear Information System (INIS)

    Mineral insulated (MI) cables used with self-powered flux detectors in CANDU reactors employ Inconel 600 as the sheath and core-wire material, and MgO as the insulation. A study was undertaken to obtain a more fundamental understanding of the current producing processes in such MI cables and to determine how these processes are related to cable geometries. A number of Inconel-Inconel cables were irradiated in the NRU, ZED-2, and Pool Test reactors at CRNL and a Gammacel-220 60Co irradiator. Additional data were obtained from the Bruce Nuclear Generating Station-A. (auth)

  5. The effect of laser pulse tailored welding of Inconel 718

    Science.gov (United States)

    Mccay, T. Dwayne; Mccay, Mary Helen; Sharp, C. Michael; Womack, Michael G.

    1990-01-01

    Pulse tailored laser welding has been applied to wrought, wrought grain grown, and cast Inconel 718 using a CO2 laser. Prior to welding, the material was characterized metallographically and the solid state transformation regions were identified using Differential Scanning Calorimetry and high temperature x-ray diffraction. Bead on plate welds (restrained and unrestrained) were then produced using a matrix of pulse duty cycles and pulsed average power. Subsequent characterization included heat affected zone width, penetration and underbead width, the presence of cracks, microfissures and porosity, fusion zone curvature, and precipitation and liquated region width. Pedigree welding on three selected processing conditions was shown by microstructural and dye penetrant analysis to produce no microfissures, a result which strongly indicates the viability of pulse tailored welding for microfissure free IN 718.

  6. Corrosion of Inconel X750 in simulated BWR core environment

    International Nuclear Information System (INIS)

    The corrosion tests of Inconel X750 in the simulated core environment by using an irradiated test loop were performed. From the experiments, the followings were clarified; 1. corrosion rate was proportional to minus cubic root of the time and the value was evaluated to be 19±4 mdm after one year, 2. the value was markedly high compared to other reported experimental data, but it had a good coincidence with the value evaluated from activity balance data in actual BWR plants, 3. the most important chemical specie which affected the corrosion behavior was identified to be hydrogen peroxide, and 4. the rate of specimens pre-filmed in the high temperature atmosphere at 700deg C for 5 hrs was reduced to be one third or less than that of specimens pre-oxidized in steam at 390deg C for 13 hrs which was the same condition for actual BWR fuel springs. (author)

  7. Thermal fatigue behavior of cast superalloy Inconel 713LC

    Energy Technology Data Exchange (ETDEWEB)

    Mansuri, Mohammadreza; Hadavi, Seyed Mohammadmehdi; Zangeneh-Madar, Karim; Abaszade, Hasan; Zare, Esmail; Hejazi, Seyed Amir [MA University, Tehran (Iran, Islamic Republic of). Dept. of Materials Engineering

    2014-11-15

    The thermal fatigue behavior of superalloy Inconel 713LC was investigated at peak temperatures of 900, 1 000 and 1 100 C. Thermal fatigue tests were performed on self-constraint single-edge V-type notch specimens. The effect of the maximum temperature, T{sub max} in the thermal cycles on the crack characteristics was studied. Under identical test conditions a comparable crack propagation rate was observed for all three peak temperatures. The results showed that cycle numbers for crack initiation decreased while crack propagation rate increased with the increase in peak temperature. Therefore, it was concluded that in the current experimental conditions, thermal fatigue resistance reduced dramatically with the rise of upper temperature. Through optical microscopy and scanning electron microscopy observation, it was found that the primary cracks generally propagated along a preferential direction. Microstructure changes after thermal fatigue are also discussed on the basis of scanning electron microscopy observation.

  8. RESPONSE SURFACE METHODOLOGY IN FINISH TURNING INCONEL 718

    Directory of Open Access Journals (Sweden)

    M. Aruna,

    2010-09-01

    Full Text Available Machining of hard materials used in aerospace applications require hard and tough cutting tools. Ceramic tools and cermets are used in machining of nickel alloys for such applications. In this study finish turning of Inconel 718 is carried out with cermet tools. Cutting parameters are designed using Taguchi’s DOE and the experiments are conducted for the designed parameters. The surface finish measurement is carried for the various conditions and data obtained are used to build up the mathematical surface model using response surface methodology. The adequacy of the developed mathematical model is proved by ANOVA. The findings of this study show new results and the second order model was quite adequate.

  9. Microstructure of irradiated inconel 706 fuel pin cladding

    International Nuclear Information System (INIS)

    A fuel pin from the HEDL-P-60 experiment with a cladding of solutionannealed Inconel 706 breached in an apparently brittle manner at a position 12.7 cm above the bottom of the fuel column with a crack of 5.72 cm in length after 5.0 atomic percent burnup in Experimental Breeder Reactor (EBR-II). Temperatures (time-averaged midwall) and fast fluences for the fractured area range from 4470C and 5.5 X 1022 neutrons (n)/cm2 to 5260C and 6.1 X 1022 n/cm2 (E > 0.1 MeV). Specimens of the fractured fuel pin section were successfully prepared and examined in both a scanning electron microscope and a transmission electron microscope. The fracture surfaces of the breached section showed brittle intergranular fracture characteristics for both the axial and circumferential cracks. Formation of γ in the matrix near the breach confirmed that the irradiation temperature at the breached area was below 5000C, in agreement with other estimates of the temperature for the area, 447 to 5260C. A hexagonal /eta/-phase, Ni3 (titanium, niobium), precipitated at boundaries near the breach. A more extensive /eta/-phase coating at grain boundaries was found in a section irradiated at 6500C. The /eta/-phase plates at grain boundaries are expected to have a detrimental effect on alloy ductility. A plane of weakness in this region along the (111) slip planes will develop in Inconel 706 because the /eta/-plates have a (111) habit relationship with the matrix

  10. Mechanical properties of hot deformed Inconel 718 and X750

    Directory of Open Access Journals (Sweden)

    A. Nowotnik

    2012-02-01

    Full Text Available Purpose: Variations of a flow stress vs. true strain illustrate behavior of material during plastic deformation. Stress-strain relationship is generally evaluated by a torsion, compression and tensile tests.Design/methodology/approach: Compression tests were carried out on precipitations hardenable nickel based superalloys of Inconel 718 and X750 at constant true strain rates of 10-4, 4x10-4s-1 within temperature through which precipitation hardening phases process occurred (720-1150°C using thermomechanical simulator Gleeble and dilatometer Baehr 850D/L equipped with compression unit. True stress-true strain curves analysis of hot deformed alloys were described.Findings: On the basis of received flow stress values activation energy of a high-temperature deformation process was estimated. Mathematical dependences (σpl -T i σpl - ε and compression data were used to determine material’s constants. These constants allow to derive a formula that describes the relationship between strain rate (ε, deformation temperature (T and flow stress σpl.Research limitations/implications: Study the flow stress will be continued on the samples after the aging process.Practical implications: The results of high-temperature deformation of the examined Inconel alloys may possibly find some practical use in the workshop practice to predict a flow stress values, but only within particular temperature and strain rate ranges. The results of the study can be used in the aerospace industry to produce blades for jet engines.Originality/value: The results of the study can be used in the aerospace industry to produce blades for jet engines.

  11. Application of eddy current inspection to the Inconel weld of BWR internals

    International Nuclear Information System (INIS)

    In order to definite the basic specifications of application of ECT (Eddy Current Test) to Inconel weld of BWR internals, the inspection and numerical analysis were carried out. The characteristics of the existing ECT probe were studied by making sample as same as CRD stud tube, measuring the relative permeability and electric conductivity of Inconel and alloy and evaluating ECT probe. On the basis of the results obtained, the basic specifications were determined and a new eddy current probe for inspection was designed and produced. The new ECT probe was able to detect small notch in Inconel weld, to classify the defects by eddy current inspection signal and sizing the length and depth. It is concluded that the new ECT probe is able to apply the Inconel weld of BWR internals. (S.Y.)

  12. Effect of carbide on hydrogen environment embrittlement of Inconel 718

    International Nuclear Information System (INIS)

    Tensile properties of Inconel 718 Ni-base superalloy were investigated in high-pressure hydrogen and in argon at room temperature. The effect of Nb-Ti carbide on hydrogen environment embrittlement (HEE) of the superalloy was also examined. The results obtained are as follows: (1) Hydrogen decreased elongation, reduction of area and ultimate tensile strength of the superalloy. HEE increased with decreasing the strain rate. Dimple rupture was mainly observed in argon, but brittle transgranular and intergranular fracture were observed in hydrogen. The crack initiation occurred at carbides both in argon and in hydrogen. Then the crack propagated in the matrix with ductile fracture in argon and with brittle fracture in hydrogen, respectively. (2) The finite element analysis (FEA) was applied to the crack initiation of the superalloy during the monotonic tensile process with the FEA model, which contained one particle at the center surrounded by the matrix. The effect of the shape of the particle on the maximum effective stress in the particle was simulated. The maximum effective stress in the particle increased markedly with increasing the average stress above the proof stress. The increasing order of the maximum effective stress depended on the shape of the particle. It was reasonable that the maximum effective stress in the carbide is high enough to break the carbide itself. It was also expected that the control of the shape of the carbide could improve HEE of the superalloy. (author)

  13. Swelling and microstructure of neutron irradiated Inconel 706

    International Nuclear Information System (INIS)

    The swelling behaviour and the related microstructure evolution of SA INCONEL 706 irradiated up to 100dpa in Phenix as stressed tube samples and fuel pins are described. The TEM observations of the irradiated samples and corresponding unirradiated specimens annealed at the same irradiation temperature show that neutron irradiation induces the intragranular nucleation of a high density of Ni3 Ti-η platelets and small cavities which do not grow up to 100dpa. At higher temperature, it is shown that the swelling is responsible of the major part of the deformation. TEM examinations of thin foils prepared from pins areas irradiated at 5900C confirm that substantial void swelling can occur in the regions where the high density of finely distributed η platelets give place to a cellular η phase which tends to spread over the grains. At least we discuss about the correlation between the microstructure evolution under irradiation and the swelling resistance and the mechanical properties observed on this irradiated material

  14. Barium silicate glass/Inconel X-750 interaction. [PWR

    Energy Technology Data Exchange (ETDEWEB)

    Kelsey, Jr., P. V.; Siegel, W. T.; Miley, D. V.

    1980-01-01

    Water reactor safety programs at the Idaho National Engineering Laboratory have required the development of specialized instrumentation. An example is the electrical conductivity-sensitive liquid level transducer developed for use in pressurized-water reactors (PWRs) in which the operation of the sensing probe relies upon the passage of current through the water between the center pin of the electrode and its shell such that when water is present the resulting voltage is low, and conversely, when water is absent the voltage is high. The transducer's ceramic seal is a hot-pressed glass ceramic; its metal housing is Inconel X-750. The ceramic material provides an essential dielectric barrier between the center pin and the outer housing. The operation of the probe as well as the integrity of the PWR environment requires a hermetically-bonded seal between the ceramic and the metal. However, during testing, an increasing number of probe assemblies failed owing to poor glass-to-metal seals as well as void formation within the ceramic. Therefore, a program was initiated to characterize the metallic surface with respect to pre-oxidation treatment and determine optimum conditions for wetting and bonding of the metal by the glass to obtain baseline data relevant to production of acceptable transducer seals.

  15. Counter permeation of deuterium and hydrogen through Inconel 600

    International Nuclear Information System (INIS)

    Permeation of hydrogen isotopes through a high-temperature alloy used for heat exchanger and reformer tubes is an important problem in the hydrogen production system connected to the High-Temperature Engineering Test Reactor (HTTR). An objective of this study is to investigate an effect of existence of hydrogen (H2) in a tube outside on the amount of permeated deuterium (D2) through the tube. It was found that the amount of permeated D2 decrease with increasing the partial pressure of H2 in the tube outside when the partial pressure of D2 in the tube is lower than 100 Pa and that of H2 in the tube outside is larger than 10 kPa. The amount of permeated D2 on counter permeation process was predicted quantitatively by using the effectiveness factor for diffusivity of deuterium in Inconel 600 and by taking into account of the equilibrium state for the hydrogen isotopes including HD molecules on the surface. From the results obtained in this study, it is supposed that the amount of tritium permeated from the primary circuit of the HTTR to the utilization system will be reduced by the existence of high pressure H2 in the steam reformer tube in the HTTR hydrogen production system. (author)

  16. Barium silicate glass/Inconel X-750 interaction

    International Nuclear Information System (INIS)

    Water reactor safety programs at the Idaho National Engineering Laboratory have required the development of specialized instrumentation. An example is the electrical conductivity-sensitive liquid level transducer developed for use in pressurized-water reactors (PWRs) in which the operation of the sensing probe relies upon the passage of current through the water between the center pin of the electrode and its shell such that when water is present the resulting voltage is low, and conversely, when water is absent the voltage is high. The transducer's ceramic seal is a hot-pressed glass ceramic; its metal housing is Inconel X-750. The ceramic material provides an essential dielectric barrier between the center pin and the outer housing. The operation of the probe as well as the integrity of the PWR environment requires a hermetically-bonded seal between the ceramic and the metal. However, during testing, an increasing number of probe assemblies failed owing to poor glass-to-metal seals as well as void formation within the ceramic. Therefore, a program was initiated to characterize the metallic surface with respect to pre-oxidation treatment and determine optimum conditions for wetting and bonding of the metal by the glass to obtain baseline data relevant to production of acceptable transducer seals

  17. Friction Freeform Fabrication of Superalloy Inconel 718: Prospects and Problems

    Science.gov (United States)

    Dilip, J. J. S.; Janaki Ram, G. D.

    2013-12-01

    Friction Freeform Fabrication is a new solid-state additive manufacturing process. The present investigation reports a detailed study on the prospects of this process for additive part fabrication in superalloy Inconel 718. Using a rotary friction welding machine and employing alloy 718 consumable rods in solution treated condition, cylindrical-shaped multi-layer friction deposits (10 mm diameter) were successfully produced. In the as-deposited condition, the deposits showed very fine grain size with no grain boundary δ phase. The deposits responded well to direct aging and showed satisfactory room-temperature tensile properties. However, their stress rupture performance was unsatisfactory because of their layered microstructure with very fine grain size and no grain boundary δ phase. The problem was overcome by heat treating the deposits first at 1353 K (1080 °C) (for increasing the grain size) and then at 1223 K (950 °C) (for precipitating the δ phase). Overall, the current study shows that Friction Freeform Fabrication is a very useful process for additive part fabrication in alloy 718.

  18. [INVITED] Laser treatment of Inconel 718 alloy and surface characteristics

    Science.gov (United States)

    Yilbas, B. S.; Ali, H.; Al-Aqeeli, N.; Karatas, C.

    2016-04-01

    Laser surface texturing of Inconel 718 alloy is carried out under the high pressure nitrogen assisting gas. The combination of evaporation and melting at the irradiated surface is achieved by controlling the laser scanning speed and the laser output power. Morphological and metallurgical changes in the treated surface are analyzed using the analytical tools including optical, electron scanning, and atomic force microscopes, energy dispersive spectroscopy, and X-ray diffraction. Microhardnes and friction coefficient of the laser treated surface are measured. Residual stress formed in the surface region is determined from the X-ray diffraction data. Surface hydrophobicity of the laser treated layer is assessed incorporating the sessile drop method. It is found that laser treated surface is free from large size asperities including cracks and the voids. Surface microhardness increases significantly after the laser treatment process, which is attributed to the dense layer formation at the surface under the high cooling rates, dissolution of Laves phase in the surface region, and formation of nitride species at the surface. Residual stress formed is compressive in the laser treated surface and friction coefficient reduces at the surface after the laser treatment process. The combination of evaporation and melting at the irradiated surface results in surface texture composes of micro/nano-poles and pillars, which enhance the surface hydrophobicity.

  19. Hydrostatic Stress Effect on the Yield Behavior of Inconel 100

    Science.gov (United States)

    Allen, Phillip A.; Wilson, Christopher D.

    2003-01-01

    Classical metal plasticity theory assumes that hydrostatic stress has negligible effect on the yield and postyield behavior of metals. Recent reexaminations of classical theory have revealed a significant effect of hydrostatic stress on the yield behavior of various geometries. Fatigue tests and nonlinear finite element analyses (FEA) of Inconel 100 (IN100) equal-arm bend specimens and new monotonic tests and nonlinear finite element analyses of IN100 smooth tension, smooth compression, and double-edge notch tension (DENT) test specimens have revealed the effect of internal hydrostatic tensile stresses on yielding. Nonlinear FEA using the von Mises (yielding is independent of hydrostatic stress) and the Drucker-Prager (yielding is linearly dependent on hydrostatic stress) yield functions were performed. A new FEA constitutive model was developed that incorporates a pressure-dependent yield function with combined multilinear kinematic and multilinear isotropic hardening using the ABAQUS user subroutine (UMAT) utility. In all monotonic tensile test cases, the von Mises constitutive model, overestimated the load for a given displacement or strain. Considering the failure displacements or strains for the DENT specimen, the Drucker-Prager FEM s predicted loads that were approximately 3% lower than the von Mises values. For the failure loads, the Drucker Prager FEM s predicted strains that were up to 35% greater than the von Mises values. Both the Drucker-Prager model and the von Mises model performed equally-well in simulating the equal-arm bend fatigue test.

  20. Experimental Investigations during Dry EDM of Inconel - 718

    Science.gov (United States)

    BHANDARE, A. S.; DABADE, U. A.

    2016-02-01

    Dry EDM is a modification of the conventional EDM process in which the liquid dielectric is replaced by a gaseous medium. Tubular tool electrodes are used and as the tool rotates, high velocity gas is supplied through it into the discharge gap. The flow of high velocity gas into the gap facilitates removal of debris and prevents excessive heating of the tool and work piece at the discharge spots. It is now known that apart from being an environment- friendly process, other advantages of the dry EDM process are low tool wear, lower discharge gap, lower residual stresses, smaller white layer and smaller heat affected zone. Keeping literature review into consideration, in this paper, an attempt has been made by selecting compressed air as a dielectric medium, with Inconel - 718 as a work piece material and copper as a tool electrode. Experiments are performed using Taguchi DoE orthogonal array to observe and analyze the effects of different process parameters to optimize the response variables such as material removal rate (MRR), surface roughness (Ra) and tool wear rate (TWR). In the current work, a unit has been developed to implement dry EDM process on existing oil based EDM machine.

  1. Low-temperature embrittlement of Ti-6Al-4V and Inconel-718 by high pressure hydrogen

    Science.gov (United States)

    Chandler, W. T.; Walter, R. J.

    1970-01-01

    Notched specimens of titanium alloy and Inconel-718 exhibit little reduction of notch strength at certain low temperatures under 2000 lb/sq in. hydrogen, unnotched specimens are not embrittled at these temperatures. The degree of Inconel-718 embrittlement is lower than earlier observations under 1000 lb/sq in. hydrogen.

  2. Effect of pulse energy and density on laser peening of Inconel 600 without a protective coating

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Joung Soo; Choi, Jong Wan; Chung, Chinman [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Han, Weon JIn; Park, Kwang Soo [Doosan Heavy Industries and Construction Co., Ltd., Changwon (Korea, Republic of)

    2014-05-15

    In this study, a laser peening process without protective coating on an Inconel 600 plate is being developed for application to a BMI (bottom mounted instrument) J-weld and nozzle inner wall in a PWR reactor vessel to prevent PWSCC occurring in weld areas during operating nuclear power plants. To obtain the optimum peening conditions, laser peening was performed in water at different peening parameters to obtain the maximum compressive residual stress and depth on the Alloy 600 plate. From a study on laser peening without a protective surface coating, the effect of its process has been proved to be high enough to prevent Inconel 600 material for stress corrosion cracking. The effect of laser peening on susceptibility to stress corrosion cracking of Inconel 600 was confirmed by stress corrosion cracking tests; no stress corrosion cracking was occurred in a laser-peened specimen, while an un-peened specimen failed by cracking in a very short period of testing time.

  3. Effects of Cations on Corrosion of Inconel 625 in Molten Chloride Salts

    Science.gov (United States)

    Zhu, Ming; Ma, Hongfang; Wang, Mingjing; Wang, Zhihua; Sharif, Adel

    2016-04-01

    Hot corrosion of Inconel 625 in sodium chloride, potassium chloride, magnesium chloride, calcium chloride and their mixtures with different compositions is conducted at 900°C to investigate the effects of cations in chloride salts on corrosion behavior of the alloy. XRD, SEM/EDS were used to analyze the compositions, phases, and morphologies of the corrosion products. The results showed that Inconel 625 suffers more severe corrosion in alkaline earth metal chloride molten salts than alkaline metal chloride molten salts. For corrosion in mixture salts, the corrosion rate increased with increasing alkaline earth metal chloride salt content in the mixture. Cations in the chloride molten salts mainly affect the thermal and chemical properties of the salts such as vapor pressure and hydroscopicities, which can affect the basicity of the molten salt. Corrosion of Inconel 625 in alkaline earth metal chloride salts is accelerated with increasing basicity.

  4. Oxide films in laser additive manufactured Inconel 718

    International Nuclear Information System (INIS)

    A continuous-wave 5 kW fiber laser welding system was used in conduction mode to deposit Inconel® alloy 718 (IN718) by employing filler wire on as-serviced IN718 parent material (PM) substrates. The direct laser deposited (DLD) coupons and as-serviced IN718 PM were then evaluated through tensile testing. To understand the failure mechanisms, the tensile fracture surfaces of the as-serviced IN718 PM, DLD and DLD-PM samples were analyzed using scanning electron microscopy. The fracture surfaces revealed the presence of both Al2O3 and Cr2O3 films, although the latter was reasoned to be the main oxide in IN718. Both the experimental observations and thermodynamic analysis indicated that oxidation of some alloying elements in IN718 cannot be completely avoided during manufacturing, whether in the liquid state under vacuum (for casting, the electron beam melting, welding and/or deposition) or with inert gas protection (for welding or laser deposition). The exposed surface of the oxide film on the fracture surface has poor wetting with the metal and thus can constitute a lack of bonding or a crack with either the metal and/or another non-wetted side of the oxide film. On the other hand, the wetted face of the oxide film has good atom-to-atom contact with the metal and may nucleate some intermetallic compounds, such as Laves, Ni3Nb-δ, Nb-rich MC and γ′ compounds. The potential of their nucleation on Cr2O3 was assessed using planar disregistry. Coherent planes were found between these intermetallics and Cr2O3

  5. Characterization of serrated yielding in service exposed Inconel 625 alloy

    International Nuclear Information System (INIS)

    The Alloy-625 is an austentic alloy which is being used for a variety of components in the aerospace, marine, chemical and nuclear industries. Tensile tests have been carried out on service exposed Inconel 625 ammonia cracker tube used at heavy water production plant to study the effect of microstructure on the mechanical properties of the material. Owing to temperature gradient during in service condition the microstructure was different in top (T), middle (M) and bottom (B) sections of the tube. The stress-strain curve obtained from conventional tensile test was found to exhibit serrated yielding with in an intermediate temperature regime of 250-600 °C. Both normal and inverse Portevin-Le Chatelier (PLC) effect could be identified at lower and higher temperature regime respectively. The normal behavior was associated with type (A+B) serrations and interstitial atom C was held responsible for the aging of dislocations in this region. On the contrary, the serrations were of type C in nature in inverse PLC regime and were attributed to the locking of dislocations by substitutional Mo atoms. Further analyses of activation energy and transition temperature for normal to inverse PLC dynamics, supported with Transmission Electron Microscopy (TEM) observation revealed that the basic deformation mechanism was different in M and B samples than that in the T samples. While the deformation in T samples were achieved by usual dislocation migration, in M and B samples it was through the propagation of stacking faults in large γ” precipitates. The transition temperature from normal to inverse PLC dynamics also varied appreciably in T samples than that of the M and B ones which could be explained in terms of the delayed depletion of Mo solutes in solution for T samples. (author)

  6. Formation of the oxide films on Inconel 718 for the IVHM grapple assembly

    International Nuclear Information System (INIS)

    The objective of this test was to determine conditions for producing an iridescent colored oxide on Inconel 718 parts within a very limited schedule. The goal was to develop a process that would be compatible with the normal precipitation hardening treatment and, at the same time, produce a satisfactory film on surfaces that have been machined after precipitation hardening. Conditions for producing the film could not degrade the hardness of the Inconel 718. The purpose of the oxide was to reduce the possibility of wear and galling on bearing surfaces of the In-Vessel Handling Machine (IVHM) grapple mechanism during its pre-operational acceptance test

  7. Identification of dynamically precipitated phases in hot-working Inconel 718 alloy

    OpenAIRE

    A. Nowotnik; J. Sieniawski; G. Mrówka-Nowotnik

    2008-01-01

    Purpose: The main purpose of this paper was to analyze how localized flow/structural inhomogeneties that may develop during hot deformation can affect a precipitated phases and to determine what kind of particles are present in the microstructure of hot-worked Inconel 718 superalloy.Design/methodology/approach: Compression tests were carried out on precipitations hardenable nickel based superalloy of Inconel 718 at constant true strain rates of 10-4 and 4x10-4s-1 at temperature of 720 and 850...

  8. Inconel alloy 625 clad steel for application in wet scrubber systems

    International Nuclear Information System (INIS)

    Test panels from INCONEL 625 clad plate were successfully installed in two wet flue gas scrubber systems. In one system INCONEL 625 clad plate was located in the roof section of the absorber just ahead of the outlet ducting. The test plates, including weld seams, showed no signs to corrosion after six months of exposure. In the other scrubber test plates located in the outlet duct of an I.D. fan house, in the stack lining, and in the absorber quench area were unattacked after nine months

  9. The Design Concept of a Steam Generator Cassette Mock-Up for ISI of Helical Tubes in SMART Steam Generator

    International Nuclear Information System (INIS)

    The SMART reactor steam generator is composed of 8 Steam Generator Cassettes (SGC) and each the SGC has a once-through-type, helical-coil-tube bundle structure using INCONEL alloy 690 tubes. The SGC installed in reactor vessel is a kind of heat exchanger made of INCONEL alloy 690 tubes. This paper introduces the design concepts of an SGC mock-up for the test probe insertion ability of In- Service Inspection (ISI). The backgrounds of selected tube material, size and tube composition are described

  10. The Design Concept of a Steam Generator Cassette Mock-Up for ISI of Helical Tubes in SMART Steam Generator

    Energy Technology Data Exchange (ETDEWEB)

    Choung, Yun Hang; Kim, Dong Ok; Park, Jin Seok; Lee, Won Jae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2009-10-15

    The SMART reactor steam generator is composed of 8 Steam Generator Cassettes (SGC) and each the SGC has a once-through-type, helical-coil-tube bundle structure using INCONEL alloy 690 tubes. The SGC installed in reactor vessel is a kind of heat exchanger made of INCONEL alloy 690 tubes. This paper introduces the design concepts of an SGC mock-up for the test probe insertion ability of In- Service Inspection (ISI). The backgrounds of selected tube material, size and tube composition are described.

  11. Metallurgical and mechanical properties of Inconel 600 and stellite; Estudio del comportamiento mecanico-metalurgico de alceacion inconel 600 y estelita

    Energy Technology Data Exchange (ETDEWEB)

    Cstillo, Martin; Villa, Gabriel; Vite, Manuel [Instituto Politecnico Nacional, Mexico D.F. (Mexico); Palacios, Francisco [Instituto Nacional de Investigacion Nuclear (ININ), Estado de Mexico (Mexico); Hernandez, Luis H; Urriolagoita, Guillermo [Instituto Politecnico Nacional, Mexico D.F. (Mexico)

    2005-01-15

    The present work studies the metallurgical and mechanical properties of two alloys, Inconel 600 and stellite, which are within the group of high hardness alloys or superalloys, which are deposited through the electrical weld process to the metallic arc with coated electrode (SMAW) and thereinafter analyzed through electron microscopy, diffractometry and abrasion, Impact and hardness test. The relationship between the microstructure and the final properties of the coating (hardness and abrasion wear resistance) was observed. [Spanish] Este trabajo presenta el estudio sobre las propiedades metalurgicas y mecanicas de dos aleaciones, inconel 600 y estelita, clasificadas dentro del grupo de aleaciones de alta dureza o superaleaciones; las cuales fueron depositadas mediante el proceso de soldadura electrica al arco metalico con electrodo revestido (SMAW) y fueron analizadas mediante microscopia electronica (SEM), difractometria pruebas de abrasion, impacto y dureza. Se observo la relacion entre la microstructura y las propiedades del recubrimiento, como son: dureza, resistencia a la abrasion, resistencia al impacto, ente otras.

  12. An assessment of microstructure, mechanical properties and corrosion resistance of dissimilar welds between Inconel 718 and 310S austenitic stainless steel

    International Nuclear Information System (INIS)

    In the present study, dissimilar welding between Inconel 718 nickel-base superalloy and 310S austenitic stainless steel using gas tungsten arc welding process was performed to determine the relationship between the microstructure of the welds and the resultant mechanical and corrosion properties. For this purpose, three filler metals including Inconel 625, Inconel 82 and 310 stainless steel were used. Microstructural observations showed that weld microstructures for all filler metals were fully austenitic. In tension tests, welds produced by Inconel 625 and 310 filler metals displayed the highest and the lowest ultimate tensile strength, respectively. The results of Charpy impact tests indicated that the maximum fracture energy was related to Inconel 82 weld metal. According to the potentiodynamic polarization test results, Inconel 82 exhibited the highest corrosion resistance among all tested filler metals. Finally, it was concluded that for the dissimilar welding between Inconel 718 and 310S, Inconel 82 filler metal offers the optimum properties at room temperature. - Highlights: • Three filler metals including Inconel 625, Inconel 82 and 310 SS were used. • A columnar to equiaxed dendritic structure was seen for IN-625 weld metal. • A granular austenitic microstructure obtained for Inconel 82 weld metal. • Microstructure of 310 weld metal includes solidification cracks along SSGB. • IN-82 weld metal showed the highest corrosion potential

  13. Laser aided direct metal deposition of Inconel 625 superalloy: Microstructural evolution and thermal stability

    International Nuclear Information System (INIS)

    Direct metal deposition technology is an emerging laser aided manufacturing technology based on a new additive manufacturing principle, which combines laser cladding with rapid prototyping into a solid freeform fabrication process that can be used to manufacture near net shape components from their CAD files. In the present study, direct metal deposition technology was successfully used to fabricate a series of samples of the Ni-based superalloy Inconel 625. A high power CO2 laser was used to create a molten pool on the Inconel 625 substrate into which an Inconel 625 powder stream was delivered to create a 3D object. The structure and properties of the deposits were investigated using optical and scanning electron microscopy, X-ray diffraction and microhardness test. The microstructure has been found to be columnar dendritic in nature, which grew epitaxially from the substrate. The thermal stability of the dendritic morphology was investigated in the temperature range 800-1200 deg. C. These studies demonstrate that Inconel 625 is an attractive material for laser deposition as all samples produced in this study are free from relevant defects such as cracks, bonding error and porosity.

  14. The study of welding residual stress test technology on inconel 690 alloy

    International Nuclear Information System (INIS)

    The influence factors in measuring residual stress of Inconel 690 alloy with blind hole method. The fit between hole, strain gauge, and drilling depth were studied. The coefficients of A and B were determined. The satisfactory data were obtained in measuring residual stress of butt weld by above research results. (authors)

  15. Evaluation of the susceptibility to intergranular corrosion in the nickel base alloy inconel 718

    International Nuclear Information System (INIS)

    The behaviour of the Inconel 718 relating to the intergranular corrosion resistance in asreceived condition and in two states of sensitization is studied. The recommendation insert inn the ASTM G-28 and DIN 50.914 has been followed. (E.G.)

  16. Effect of reduction of strategic columbium additions in Inconel 718 alloy on the structure and properties

    International Nuclear Information System (INIS)

    The amount of columbium which can be removed from Inconel alloy 718 without degrading its high temperature properties was determined. The elements that are substituted are: vanadium and tungsten together and separately increasing the molybdenum level from 3.0% to 5.8% and increasing the boron to 0.04%

  17. Incompatibility between Zircaloy-2 and Inconel X-750 during Temperature Transients

    DEFF Research Database (Denmark)

    Warren, M. R.; Rørbo, Kaj; Adolph, Eivind

    1975-01-01

    The incompatibility of Zircaloy-2 and Inconel X-750 has been investigated between 1000°C and 1200°C (1200°C being the currently allowable maximum temperature in the acceptance criteria for ECCS for water reactors). It has been found for the temperatures of 1000°C and 1200°C that oxide thicknesses...

  18. Comparison of corrosion behavior between fusion cladded and explosive cladded Inconel 625/plain carbon steel bimetal plates

    International Nuclear Information System (INIS)

    Highlights: ► Both explosive and fusion cladding aggravate the corrosion resistance of Inconel 625. ► Fusion cladding is more detrimental to nonuniform corrosion resistance. ► Single-layered fusion coat does not show any repassivation ability. ► Adding more layers enhance the corrosion resistance of fusion cladding Inconel 625. ► High impact energy spoils the corrosion resistance of explosive cladding Inconel 625. -- Abstract: One of the main concerns in cladding Inconel 625 superalloy on desired substrates is deterioration of corrosion resistance due to cladding process. The present study aims to compare the effect of fusion cladding and explosive cladding procedures on corrosion behavior of Inconel 625 cladding on plain carbon steel as substrate. Also, an attempt has been made to investigate the role of load ratio and numbers of fusion layers in corrosion behavior of explosive and fusion cladding Inconel 625 respectively. In all cases, the cyclic polarization as an electrochemical method has been applied to assess the corrosion behavior. According to the obtained results, both cladding methods aggravate the corrosion resistance of Inconel 625. However, the fusion cladding process is more detrimental to nonuniform corrosion resistance, where the chemical nonuniformity of fusion cladding superalloy issuing from microsegregation, development of secondary phases and contamination of clad through dilution hinders formation of a stable passive layer. Moreover, it is observed that adding more fusion layers can enhance the nonuniform corrosion resistance of fusion cladding Inconel 625, though this resistance still remains weaker than explosive cladding superalloy. Also, the results indicate that raising the impact energy in explosive cladding procedure drops the corrosion resistance of Inconel 625.

  19. Hydrogen Permeability of Incoloy 800H, Inconel 617, and Haynes 230 Alloys

    International Nuclear Information System (INIS)

    A potential issue in the design of the NGNP reactor and high-temperature components is the permeation of fission generated tritium and hydrogen product from downstream hydrogen generation through high-temperature components. Such permeation can result in the loss of fission-generated tritium to the environment and the potential contamination of the helium coolant by permeation of product hydrogen into the coolant system. The issue will be addressed in the engineering design phase, and requires knowledge of permeation characteristics of the candidate alloys. Of three potential candidates for high-temperature components of the NGNP reactor design, the hydrogen permeability has been documented well only for Incoloy 800H, but at relatively high partial pressures of hydrogen. Hydrogen permeability data have been published for Inconel 617, but only in two literature reports and for partial pressures of hydrogen greater than one atmosphere, far higher than anticipated in the NGNP reactor. The hydrogen permeability of Haynes 230 has not been published. To support engineering design of the NGNP reactor components, the hydrogen permeability of Inconel 617 and Haynes 230 were determined using a measurement system designed and fabricated at the Idaho National Laboratory. The performance of the system was validated using Incoloy 800H as reference material, for which the permeability has been published in several journal articles. The permeability of Incoloy 800H, Inconel 617 and Haynes 230 was measured in the temperature range 650 to 950 C and at hydrogen partial pressures of 10-3 and 10-2 atm, substantially lower pressures than used in the published reports. The measured hydrogen permeability of Incoloy 800H and Inconel 617 were in good agreement with published values obtained at higher partial pressures of hydrogen. The hydrogen permeability of Inconel 617 and Haynes 230 were similar, about 50% greater than for Incoloy 800H and with similar temperature dependence.

  20. Identification of dynamically precipitated phases in hot-working Inconel 718 alloy

    Directory of Open Access Journals (Sweden)

    A. Nowotnik

    2008-12-01

    Full Text Available Purpose: The main purpose of this paper was to analyze how localized flow/structural inhomogeneties that may develop during hot deformation can affect a precipitated phases and to determine what kind of particles are present in the microstructure of hot-worked Inconel 718 superalloy.Design/methodology/approach: Compression tests were carried out on precipitations hardenable nickel based superalloy of Inconel 718 at constant true strain rates of 10-4 and 4x10-4s-1 at temperature of 720 and 850°C. The dynamic behaviour were explained through observation of the microstructure using standard optical, scanning and transmission electron microscopy. Precipitated phases were identified using EDS technique and based on selected area diffraction pattern.Findings: Microstructural observations of deformed at high temperatures, previously solution treated Inconel superalloy revealed non uniform deformation effects. Distribution of molybdenum- and niobium-rich carbides affected by localized flow was found. Microstructural examination of the alloy also shown shear banding penetrating through the whole grains.Practical implications: The experiments on hot deformation of age hardenable Inconel 718 superalloy and the analysis of dynamic precipitation process have a practical aspect. This interaction could become an important feature of high temperature performance and may also influence the production of specific structures of this material.Originality/value: Even though the number of research has focused on the hot deformation behaviour of Inconel 718, there is still scarcity of data referring to the analysis of dynamic structural processes which operate during hot deformation of this precipitation hardenable alloy: in particular dynamic precipitation and dynamic particles coarsening.

  1. Fretting wear behavior of Inconel 690 in hydrazine environments%Inconel 690在联氨溶液中的磨损行为

    Institute of Scientific and Technical Information of China (English)

    张晓宇; 任平弟; 彭金方; 朱旻昊

    2014-01-01

    The friction and wear behaviors of Inconel 690 flat against Si3Ni4 ball were investigated using a hydraulic fretting test rig equipped with a liquid container device. The loads of 20-80 N, reciprocating amplitudes of 80-200 μm and two different environments (distilled water and hydrazine solution at temperatures from 25 to 90 °C) were selected. The results show that the ratio of Ft/Fn is lower in distilled water than that in hydrazine solution at the same temperature in the slip regime. Both the ratio of Ft/Fn and wear volume gradually increase with increasing medium temperature under the given normal load and displacement amplitude. Besides the displacement amplitude and load, temperature also plays an important role for wear behavior of Inconel 690 material. The increase of temperature could reduce the concentration of dissolved oxygen, and promote the absorption reaction of hydrazine and dissolved oxygen. As a result, the oxidative corrosion rate is obviously lowered. Abrasive wear and delamination wear are the main mechanisms of Inconel 690 in distilled water. However, in hydrazine solution the cracks accompanied by abrasive wear and delamination wear are the main mechanisms.%在控制法向载荷分别为20、50和80 N,位移幅值分别为80、150和200μm的两种不同环境下,以Si3N4陶瓷球/Inconel690平面接触的方式,在PLINT高温微动试验机上进行微动腐蚀试验,循环次数为2×104。结果表明:在滑移区,当载荷、位移幅值一定时,相同温度联氨溶液中的稳态摩擦因数比其在蒸馏水中高;稳态摩擦因数随溶液的温度增加而增加;磨损体积随溶液温度增加而增加。Inconel 690在联氨溶液摩擦过程中,磨损程度除受到位移幅值、荷载影响以外,温度对磨损体积有显著影响。温度的增加即降低溶液的溶解氧又促进联胺与溶解氧的吸收反应,起到降低氧化腐蚀的作用。在蒸馏水中Inconel 690合金材料的磨损

  2. Effect of Orientation on Tensile Properties of Inconel 718 Block Fabricated with Electron Beam Freeform Fabrication (EBF3)

    Science.gov (United States)

    Bird, R. Keith; Atherton, Todd S.

    2010-01-01

    Electron beam freeform fabrication (EBF3) direct metal deposition processing was used to fabricate an Inconel 718 bulk block deposit. Room temperature tensile properties were measured as a function of orientation and location within the block build. This study is a follow-on activity to previous work on Inconel 718 EBF3 deposits that were too narrow to allow properties to be measured in more than one orientation

  3. Mode conversion of guided waves in Inconel tubes with Ni coating

    International Nuclear Information System (INIS)

    Electrosleeving is one of the promising methods to repair a defective steam generator tubing in the nuclear power plant. It requires a nondestructive inspection in order to verify the structural Integrity in the coated region. In this study, a feasibility of ultrasonic guided wave for Inconel tube with Ni coating was investigated. Phase and group velocity dispersion curves for Inconel tube with Ni coating were calculated to get an optimum condition of guided wave propagation. An eight-segments ultrasonic transducer was designed and fabricated to generate L(0,2) mode, and receive signals around circumference. The received signal from the beginning of Ni coating showed almost similar amplitude along the angular circumference and matched to longitudinal L(0,2) mode. However, the received signals from the end of Ni coating were different along the angular circumferences. It seems that the longitudinal mode be converted to flexural mode at the end of Ni coating.

  4. Laser Additive Melting and Solidification of Inconel 718: Finite Element Simulation and Experiment

    Science.gov (United States)

    Romano, John; Ladani, Leila; Sadowski, Magda

    2016-03-01

    The field of powdered metal additive manufacturing is experiencing a surge in public interest finding uses in aerospace, defense, and biomedical industries. The relative youth of the technology coupled with public interest makes the field a vibrant research topic. The authors have expanded upon previously published finite element models used to analyze the processing of novel engineering materials through the use of laser- and electron beam-based additive manufacturing. In this work, the authors present a model for simulating fabrication of Inconel 718 using laser melting processes. Thermal transport phenomena and melt pool geometries are discussed and validation against experimental findings is presented. After comparing experimental and simulation results, the authors present two correction correlations to transform the modeling results into meaningful predictions of actual laser melting melt pool geometries in Inconel 718.

  5. Role of refractory elements in modifying the service life of Inconel 625 ammonia cracker tubes

    International Nuclear Information System (INIS)

    Inconel 625 is the preferred material of cracker tube/components for cracking of enriched ammonia in NH3-H2 Mono-thermal Chemical Exchange Process based heavy water production plants in India.These tubes are designed for a service life of 100,000 h at operating temperatures between 550 to 650 °C. Refractory elements play important roles in imparting the necessary service life to Inconel 625. Under operating conditions, they undergo precipitation reactions which significantly undermines the service life of these tubes due to precipitation induced hardening and embrittlement. This paper present how the service life of cracker tubes is affected by the precipitation of phases bearing refractory elements, and also the necessary heat treatment required to rejuvenate the alloy. (author)

  6. Effect of δ Phase on Hydrogen Embrittlement of Inconel 718 by Notch Tensile Tests

    Institute of Scientific and Technical Information of China (English)

    Liufa LIU; Chen LU; Wenjiang DING; Akio Hirose; Kojiro F.Kobayashi

    2005-01-01

    The effect of δ phase on the hydrogen embrittlement (HE) sensitivity of Inconel 718 was investigated by conducting notch tensile tests. Notch tensile specimens with various precipitation morphologies of δ phase were prepared with different heat treatments, and hydrogen was charged into the tensile specimens before tensile tests via a cathodic charging process. The loss of notch tensile strength (NTS) due to the charged hydrogen was used to evaluate the hydrogen embrittlement sensitivity. The results show that δ phase has deleterious effect on NTSs, and the fracture of hydrogen-charged specimens initiated near the notch surfaces. The loss of NTS caused by precharged hydrogen can be greatly decreased by dissolving δ phase. δ-free Inconel 718 alloy is proposed for the applications in hydrogen environments.

  7. Nondestructive inspection assessment of eddy current and electrochemical analysis to separate inconel and stainless steel alloys

    Energy Technology Data Exchange (ETDEWEB)

    Moore, D.G.; Sorensen, N.R.

    1998-02-01

    This report presents a nondestructive inspection assessment of eddy current and electrochemical analysis to separate inconel alloys from stainless steel alloys as well as an evaluation of cleaning techniques to remove a thermal oxide layer on aircraft exhaust components. The results of this assessment are presented in terms of how effective each technique classifies a known exhaust material. Results indicate that either inspection technique can separate inconel and stainless steel alloys. Based on the experiments conducted, the electrochemical spot test is the optimum for use by airframe and powerplant mechanics. A spot test procedure is proposed for incorporation into the Federal Aviation Administration Advisory Circular 65-9A Airframe & Powerplant Mechanic - General Handbook. 3 refs., 70 figs., 7 tabs.

  8. Microstructure and mechanical properties of Inconel 617 degraded at high temperature with atmosphere

    International Nuclear Information System (INIS)

    Full text of publication follows. Inconel 617 is a candidate tube material of intermediate heat-exchanger and hot gas duct for high temperature gas-cooled reactors (HTGR) for hydrogen production. The microstructure and mechanical properties of Inconel 617 were investigated after exposure at 1050 deg C in air and helium. Oxide layers were observed by cross-section image. The de-lamination of oxide layer occurs because of the difference of thermal expansion coefficient between oxide layer and matrix. The depth of Cr-depleted zone and internal oxide increased with exposure time. It was observed that the carbide phase was changed on grain boundary during exposure. These carbides were coarsened increasing exposure time. High temperature compression test and hardness test were carried out after aging at 1050 deg C. The changes of yield strength and hardness were observed with increasing aging time. (authors)

  9. Solute redistribution and Rayleigh number in the mushy zone during directional solidification of Inconel 718

    Institute of Scientific and Technical Information of China (English)

    Wang Ling; Dong Jianxin; Liu Lin; Zhang Lei

    2009-01-01

    The interdendritic segregation along the mushy zone of directionally solidified superalloy Inconel 718has been measured by scanning electron microscope (SEM) and energy dispersion analysis spectrometry (EDAX)techniques and the corresponding liquid composition profile was presented. The liquid density and Rayleigh number (Ra) profiles along the mushy zone were calculated as well. It was found that the liquid density difference increased from top to bottom in the mushy zone and there was no density inversion due to the segregation of Nb and Mo. However carbide formation in the freezing range and the preferred angle of the odentated dendrite array could prompt the fluid flow in the mushy zone although there was no liquid density inversion. The largest relative Rayleigh number appeared at 1,326℃ for Inconel 718 where the fluid flow most easily occurred.

  10. Microsegregation and Rayleigh number variation during the solidification of superalloy Inconel 718

    Institute of Scientific and Technical Information of China (English)

    Ling Wang; Jianxin Dong; Yuliang Tian; Lei Zhang

    2008-01-01

    The microstructure and composition of the residual liquid at different temperatures were investigated by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometer (EDX) associated with the Thermo-calc software calculation of the equilibrium phase diagrams of Inconel 718 and segregated liquid. The liquid density difference and Rayleigh number variation dur-ing solidification were estimated as well. It is found that the heavy segregation of Nb in liquid prompts the precipitation of δ and Laves phase directly from liquid and the resultant quenched liquid microstructure consists of pro-eutectic γ+eutectic, or complete eutectic according to the content of Nb from low to high. The liquid density increases with decreasing temperature during the solidi-fication of Inconel 718 and the liquid density difference is positive. The largest relative Rayleigh number occurs at 1320℃ when the liquid fraction is about 40vol%.

  11. Effect of thermal stabilization on the low-temperature stress-corrosion cracking of Inconel 600

    International Nuclear Information System (INIS)

    The propensity to low-temperature stress-corrosion cracking (SCC) of thermally stabilized Inconel 600 in sulfur-bearing environments has been investigated using U-bends and slow-strain-rate testing. The results have been compared with those of sensitized Inconel 600. The potential dependence of crack-propagation rate has been established in a single test by using several U-bends held at different potentials, by choosing an appropriate electrical circuitry. The difference in SCC susceptibility of the sensitized and stabilized materials is discussed in terms of the grain-boundary chromium depletion and resulting intergranular attack in boiling ferric sulfate-sulfuric acid tests, and electrochemical potentiokinetic reactivation (EPR) tests. 10 figures

  12. Effect of thermal stabilization on the low-temperature stress-corrosion cracking of Inconel 600

    Energy Technology Data Exchange (ETDEWEB)

    Bandy, R.; van Rooyen, D.

    1983-01-01

    The propensity to low-temperature stress-corrosion cracking (SCC) of thermally stabilized Inconel 600 in sulfur-bearing environments has been investigated using U-bends and slow-strain-rate testing. The results have been compared with those of sensitized Inconel 600. The potential dependence of crack-propagation rate has been established in a single test by using several U-bends held at different potentials, by choosing an appropriate electrical circuitry. The difference in SCC susceptibility of the sensitized and stabilized materials is discussed in terms of the grain-boundary chromium depletion and resulting intergranular attack in boiling ferric sulfate-sulfuric acid tests, and electrochemical potentiokinetic reactivation (EPR) tests. 10 figures.

  13. Studies on the weldability, microstructure and mechanical properties of activated flux TIG weldments of Inconel 718

    International Nuclear Information System (INIS)

    This research article addresses the joining of 5 mm thick plates of Inconel 718 by activated flux tungsten inert gas (A-TIG) welding process using SiO2 and TiO2 fluxes. Microstructure studies inferred the presence of Nb rich eutectics and/or laves phase in the fusion zone of the A-TIG weldments. Tensile studies corroborated that the ultimate tensile strength of TiO2 flux assisted weldments (885 MPa) was better compared to SiO2 flux assisted weldments (815 MPa) and the failure was observed in the parent metal for both the cases. Impact test results portrayed that both the weldments were inferior in toughness as compared to the parent metal, which was due to the presence of oxide inclusions. Also, the study investigated the structure–property relationships of the A-TIG weldments of Inconel 718

  14. Precipitation and Cr depletion profiles of Inconel 182 during heat treatments and laser surface melting

    OpenAIRE

    Baoa, Gang; Yamamoto, Motomichi; Shinozaki, Kenji

    2009-01-01

    Thermodynamic and kinetic modeling was conducted to simulate Cr depletion profiles near grain boundaries in Inconel 182 during heat treatments and laser surface melting (LSM) using Thermo-Calc and DICTRA code. The effect of Nb addition was also considered in the modeling. Based on the good agreement with Cr concentration distributions during the heat treatments measured experimentally, Cr depletion profiles adjacent to grain boundaries during the heat treatments and the LSM process were model...

  15. High temperature environmental interactions of Inconel 617: A paper study for the TEF

    Energy Technology Data Exchange (ETDEWEB)

    Korinko, P.S.

    2000-06-16

    Inconel alloy 617 has been selected as the material of choice for the retort of the furnace for the Tritium Extraction Facility. To monitor retort performance and suitability for continued service, representative sample coupons should be suspended on the inside (process side) and outside (annulus side) of the retort for periodic metallographic analysis or hardness testing. Surface dealloying and hardness could be used to monitor the ``health'' of the retort in this surveillance program.

  16. Effect of heat treatment on fatigue crack growth rate of inconel 690

    International Nuclear Information System (INIS)

    The effects of heat treatment on fatigue crack growth rates (FCGRs) of Inconel 690 have been investigated in terms of carbide morphology and grain size. Cycling tests in air at room temperature have shown that FCGR in low stress intensity factor range (ΔK) region can be effectively reduced by increasing the grain boundary carbide precipitate size and grain size. Decrease in FCGR is attributed to the crack tip blunting at the precipitates of grain boundary chromium carbides

  17. Mechanical Behaviour of Inconel 718 Thin-Walled Laser Welded Components for Aircraft Engines

    OpenAIRE

    Enrico Lertora; Chiara Mandolfino; Carla Gambaro

    2014-01-01

    Nickel alloys are very important in many aerospace applications, especially to manufacture gas turbines and aero engine components, where high strength and temperature resistance are necessary. These kinds of alloys have to be welded with high energy density processes, in order to preserve their high mechanical properties. In this work, CO2 laser overlap joints between Inconel 718 sheets of limited thickness in the absence of postweld heat treatment were made. The main application of this kin...

  18. Mechanical and electrochemical properties of inconel alloy 617 after refurbishment through heat treatment

    OpenAIRE

    Kawthar-Ali, Mahmoud H.

    2002-01-01

    The transition piece in gas turbine is an important component, which joins the combustion chamber to the turbine nozzles. These pieces are made from an alloy that resist high temperature and thermal loading and being considerably expensive. The high operating temperature and thermal fatigue limit the lifetime of such component Consequently, the life extension of the alloy through sound refurbishment process is in demand. The refurbishment of Inconel 617 alloy after 37000 hours of operation in...

  19. MODELING AND SIMULATION OF DYNAMIC RECRYSTALLIZATION AND GRAIN GROWTH DURING HOT WORKING OF INCONEL 783 SUPERALLOY

    OpenAIRE

    JONG-TAEK YEOM; EUN JEOUNG JUNG; JEE HOON KIM; JEOUNG HAN KIM; JAE-KEUN HONG; NHO-KWANG PARK; KOOK-JOO KIM; SEUNG-SIK CHOI

    2010-01-01

    In this study, the modeling of recrystallization and grain growth was investigated to predict the microstructure evolution during hot working of INCONEL 783 superalloy (Alloy 783). The recrystallization model was constructed on the basis of the Avrami formation. A least-square optimization technique was used to determine several important parameters within the model from isothermal heat treatment and hot compression test results. High temperature compression tests were carried out under diffe...

  20. Relationship between ferromagnetic properties and grain size of Inconel alloy 600

    International Nuclear Information System (INIS)

    Inconel alloy 600 is widely used in steam generator tubings where sensitization due to chromium depletion occurs at grain boundaries and the sensitization induces tubing failures. Though the alloy usually exhibits paramagnetic properties, it shows ferromagnetic properties along grain boundaries when chromium depletion occurs. This means that magnetic nondestructive evaluation of sensitization is possible. Therefore, as a fundamental study to develop magnetic nondestructive evaluation technique for sensitization, the relationship between ferromagnetic properties and grain size in Inconel 600 was investigated using isothermal heat treatment. The grain was controlled using solution annealing, and then, specimens were heat treated at 873, 923, and 973 K within 400 h. The saturation magnetization increases as heat treatment time increases and eventually peaks. The peak time depends on the heat treatment temperature. The coercivity increases during the initial heat treatment stage, and decreases as the duration of heat treatment increases. The maximum saturation magnetization decreases as the grain diameter increases and is inversely proportional to the grain diameter squared, which is consistent with the fact that the ferromagnetic phase only formed along grain boundaries. - Highlights: • Relationship between ferromagnetism and grain size in Inconel 600 was clarified. • The saturation magnetization increases and eventually peaks during heat treatment. • The coercivity increases during the initial heat treatment stage, and then decreases. • The saturation magnetization is inversely proportional to the grain diameter squared. • The magnetic property changes are explained by the Cr depletion at grain boundaries

  1. Increase in structural stability by control of precipitation in alloys derived from Inconel 718

    International Nuclear Information System (INIS)

    The alloys studied are derived from Inconel 718 by increasing the ratio R=(Ti+Al)/Nb, which favor precipitation of the γ'-Ni3(Ti,Al) phase during aging at the expense of the metastable γ''-Ni3Nb phase responsible for considerable hardening of the reference alloy. It was possible in this way to define a region of the composition space R and S (S=Ti+Al+Nb) such that any alloy of this region gives rise to an original precipitation where the particles consist of γ' phase cubes plated on all six faces with the γ'' phase. These compact morphology precipitates show great stability of nature, size and shape at steady temperatures up to around 700 deg C, unlike Inconel 718 where the growth of the γ'' plates and their subsequent conversion to the stable β-Ni3Nb phase cause the alloy to age rapidly above 600 deg C. A comparison of the mechanical properties of Inconel 718 and one of the compact morphology precipitation alloys shows that for the derived alloy these properties can be as good or better after the aging treatment (hardness, tensile strength, short-term creep, low-cycle fatigue) and distinctly improved after long maintenance at temperatures of 700 deg C or above (hardness, long-term creep)

  2. The Evaluation of Crevice Corrosion of Inconel-600 and 304 Stainless Steel in Reductive Decontamination Solutions

    International Nuclear Information System (INIS)

    In this sturdy, we investigated the characteristics of corrosion to Inconel-600 and type 304 stainless steel which are mainly used for the steam generator and primary system of PWR reactor respectively. We conducted the corrosion test for the HYBRID (HYdrazine Based metal Ion Reductive decontamination) which was developed in KAERI, Citrox and Oxalic acid solutions used in reductive decontamination of the inner surface of PWR. Since Citrox and oxalic acid solution were well-known conventional decontamination solutions, it is meaningful to compare the corrosion result of HYBRID with those solutions to confirm the corrosion compatibility. In order to obtain visible results in a limited time, we conducted the crevice corrosion tests under harsh condition. According to the results of crevice corrosion tests, we can conclude that metals such as type 304 stainless steel and Inconel-600 in HYBRID are very stable against crevice corrosion. On the other hand, those metals in Citrox and oxalic acid solutions were very susceptible to the crevice corrosion. Especially when using the oxalic acid solution, severe corrosion was observed not only Inconel-600 but also 304 stainless steel. The degree of corrosion can be expressed as; HYBRID << Citrox < OA. Conclusively, our results support that the HYBRID is more stable to the corrosion of structural materials in primary system than other Citrox and oxalic acid solutions. This finding will appoint the HYBRID solution as a candidate to solve the corrosion problem which is often issued by existing chemical decontamination processes

  3. The Evaluation of Crevice Corrosion of Inconel-600 and 304 Stainless Steel in Reductive Decontamination Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Junyoung; Park, Sangyoon; Won, Huijun; Choi, Wangkyu; Moon, Jeikwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Park, Sojin [Chungnam National Univ., Daejeon (Korea, Republic of)

    2014-05-15

    In this sturdy, we investigated the characteristics of corrosion to Inconel-600 and type 304 stainless steel which are mainly used for the steam generator and primary system of PWR reactor respectively. We conducted the corrosion test for the HYBRID (HYdrazine Based metal Ion Reductive decontamination) which was developed in KAERI, Citrox and Oxalic acid solutions used in reductive decontamination of the inner surface of PWR. Since Citrox and oxalic acid solution were well-known conventional decontamination solutions, it is meaningful to compare the corrosion result of HYBRID with those solutions to confirm the corrosion compatibility. In order to obtain visible results in a limited time, we conducted the crevice corrosion tests under harsh condition. According to the results of crevice corrosion tests, we can conclude that metals such as type 304 stainless steel and Inconel-600 in HYBRID are very stable against crevice corrosion. On the other hand, those metals in Citrox and oxalic acid solutions were very susceptible to the crevice corrosion. Especially when using the oxalic acid solution, severe corrosion was observed not only Inconel-600 but also 304 stainless steel. The degree of corrosion can be expressed as; HYBRID << Citrox < OA. Conclusively, our results support that the HYBRID is more stable to the corrosion of structural materials in primary system than other Citrox and oxalic acid solutions. This finding will appoint the HYBRID solution as a candidate to solve the corrosion problem which is often issued by existing chemical decontamination processes.

  4. Impact of shelf life on measured prompt fraction of spare Inconel in-core flux detectors

    International Nuclear Information System (INIS)

    Prompt fraction measurements associated with spare self-powered Inconel In-Core Flux Detectors (ICFDs) carried out a few years after installation on Shut Down System number 1 (SDS1) and Reactor Regulating System (RRS) at Darlington Nuclear Generating Station (DNGS), were found to be lower than those of the original detectors. These detectors, spares and originals, were manufactured in the late 80s, however, the former were kept at manufacturer's warehouse and latter were installed in the reactor core within a few years after manufacturing. Although the prompt fractions of the spare detectors were relatively low, the electronic/electrical behavior of the spare detectors was intact. The first batch of the original detectors performed as per the design requirements. Therefore, it is suspected that during shelf life, spare Inconel in-core flux detectors underwent changes that lowered their measured values of prompt fraction, which were taken within a few years after installation in the reactor. Detailed study of detectors' material composition and impurity concentrations revealed no association with the lower prompt fraction measurements. The evaluation of the limited data of the original and spare Inconel ICFDs installed at Darlington showed: 1. The reduction in prompt fraction was roughly proportional to the shelf life of the detectors; and 2. The rate of reduction in prompt fraction during storage was about double the rate of reduction during operation in the reactor. Above observations were based on the data provided by DNGS for a few detectors. The purpose of this paper is two fold, firstly to present the results of the complete study carried out to investigate the cause of relatively low prompt fractions measured on spare SDS1 and RRS Inconel ICFDs at DNGS, and secondly to generate interest/awareness within other CANDU utilities to add to the database of prompt fractions of spare Inconel ICFDs measured after installation. The data will help to improve statistical

  5. Porosity reduction in Nd-YAG laser welding of stainless steel and inconel alloy by using a pulsed wave

    International Nuclear Information System (INIS)

    This study investigates the influence of the Nd-YAG laser power wave mode on the porosity and mechanical properties of SUS 304L and inconel 690 weldments. Initially, a rectangular laser power waveform is specified. The output is then progressively changed from a pulsed wave mode to a continuous wave mode by reducing the value of ΔP (ΔP = Pp-Pb, where Pp is the peak power and Pb is the base power) to zero. Bead-on-plate (BOP) and butt welding are performed at a constant mean output power (1.7 kW). The BOP results demonstrate that the depth/width (D/W) ratio of both materials increases with ΔP and attains a maximum value when full penetration just occurs. The D/W ratio and the travel speed for full penetration are higher for SUS 304L than for inconel 690. In butt-welds of inconel 690 and SUS 304L, the porosity ratio decreases from 7.1% to 0.5% and from 2.1% to 0.5%, respectively, as ΔP increases from 0 to 2780 W. Therefore, the tensile strength and percentage elongation are enhanced significantly in inconel 690. The degree of porosity reduction in inconel 690 exceeds that of SUS 304L. This suggests that the viscosity of the molten inconel 690 metal is higher than that of SUS 304L. Consequently, the effect of porosity reduction due to the increase in molten metal fluidity caused by increasing ΔP is greater for inconel 690 than for SUS 304L

  6. Surface Roughness and Tool Wear on Cryogenic Treated CBN Insert on Titanium and Inconel 718 Alloy Steel

    Science.gov (United States)

    Thamizhmanii, S.; Mohideen, R.; Zaidi, A. M. A.; Hasan, S.

    2015-12-01

    Machining of materials by super hard tools like cubic boron nitride (cbn) and poly cubic boron nitride (pcbn) is to reduce tool wear to obtain dimensional accuracy, smooth surface and more number of parts per cutting edge. wear of tools is inevitable due to rubbing action between work material and tool edge. however, the tool wear can be minimized by using super hard tools by enhancing the strength of the cutting inserts. one such process is cryogenic process. this process is used in all materials and cutting inserts which requires wear resistance. the cryogenic process is executed under subzero temperature -186° celsius for longer period of time in a closed chamber which contains liquid nitrogen. in this research, cbn inserts with cryogenically treated was used to turn difficult to cut metals like titanium, inconel 718 etc. the turning parameters used is different cutting speeds, feed rates and depth of cut. in this research, titanium and inconel 718 material were used. the results obtained are surface roughness, flank wear and crater wear. the surface roughness obtained on titanium was lower at high cutting speed compared with inconel 718. the flank wear was low while turning titanium than inconel 718. crater wear is less on inconel 718 than titanium alloy. all the two materials produced saw tooth chips.

  7. Reaction of Inconel 690 and 693 in Iron Phosphate Melts: Alternative Glasses for Waste Vitrification

    International Nuclear Information System (INIS)

    The corrosion resistance of candidate materials used for the electrodes (Inconel 690 and 693) and the melt contact refractory (Monofrax K-3) in a Joule Heated Melter (JHM) has been investigated at the University of Missouri-Rolla (UMR) during the period from June 1, 2004 to August 31, 2005. This work was supported by the U.S. Department of Energy (DOE) Office of Biological and Environmental Research (DE-FG02-04ER63831). The unusual properties and characteristics of iron phosphate glasses, as viewed from the standpoint of alternative glasses for vitrifying nuclear and hazardous wastes which contain components that make them poorly suited for vitrification in borosilicate glass, were recently discovered at UMR. The expanding national and international interest in iron phosphate glasses for waste vitrification stems from their rapid melting and chemical homogenization which results in higher furnace output, their high waste loading that varies from 32 wt% up to 75 wt% for the Hanford LAW and HLW, respectively, and the outstanding chemical durability of the iron phosphate wasteforms which meets all present DOE requirements (PCT and VHT). The higher waste loading in iron phosphate glasses, compared to the baseline borosilicate glass, can reduce the time and cost of vitrification considerably since a much smaller mass of glass will be produced, for example, about 43% less glass when the LAW at Hanford is vitrified in an iron phosphate glass according to PNNL estimates. In view of the promising performance of iron phosphate glasses, information is needed for how to best melt these glasses on the scale needed for practical use. Melting iron phosphate glasses in a JHM is considered the preferred method at this time because its design could be nearly identical to the JHM now used to melt borosilicate glasses at the Defense Waste Processing Facility (DWPF), Westinghouse Savannah River Co. Therefore, it is important to have information for the corrosion of candidate electrode

  8. Microstructures and microhardness at fusion boundary of 316 stainless steel/Inconel 182 dissimilar welding

    International Nuclear Information System (INIS)

    Microstructures and microhardness at fusion boundary of a weld joint were investigated in a 316 stainless steel/Inconel 182 dissimilar weldment. The results showed that there were two alternately distributed typical fusion boundaries, a narrow random boundary (possessed 15% in length) with a clear sharp interface and an epitaxial fusion one with (100)BM//(100)WM at the joint interface. The composition transition, microstructure and hardness across the fusion boundary strongly depended on the type of the fusion boundary. For the random boundary, there was a clear sharp interface and the composition transition with a width of 100 μm took place symmetrically across the grain boundary. For the epitaxial fusion one, however, there were Type-I and Type-II grain boundaries perpendicular and parallel to the epitaxial fusion boundary, respectively. The composition transition took place in the Inconel 182 weld side. Σ3 boundaries in the HAZ of 316SS side and Σ5 grain boundaries in weld metal were usually observed, despite the type of fusion boundary, however the former was much more in epitaxial fusion boundary. Microhardness was continuously decreased across the random fusion boundary from the side of Inconel 182 to 316SS, but a hardening phenomenon appeared in the epitaxial fusion boundary zone because of its fine cellular microstructure. - Highlights: • Two typical fusion boundaries alternately distributed in the fusion interface • The microstructure, composition and hardness across fusion boundary depended on its type. • Different regions in welded joint have different special CSL value boundaries. • Hardening phenomenon only appeared in the epitaxial fusion boundary

  9. Normal spectral emittance of Inconel 718 aeronautical alloy coated with yttria stabilized zirconia films

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Fernandez, L. [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Industria de Turbo Propulsores, S.A., Planta de Zamudio, Edificio 300, 48170 Zamudio, Bizkaia (Spain); Campo, L. del [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Perez-Saez, R.B., E-mail: raul.perez@ehu.es [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Tello, M.J. [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain)

    2012-02-05

    Highlights: Black-Right-Pointing-Pointer Emittance of Inconel 718 coated with plasma sprayed yttria stabilized zirconia. Black-Right-Pointing-Pointer The coating is opaque for {lambda} > 9 {mu}m and semi-transparent for {lambda} < 9 {mu}m. Black-Right-Pointing-Pointer In the semi-transparent region the emittance decreases with coating thickness. Black-Right-Pointing-Pointer 300 {mu}m thick coatings are still semi-transparent. Black-Right-Pointing-Pointer In the opaque region the surface roughness determines the emittance level. - Abstract: Knowledge of the radiative behaviour of the yttria stabilized zirconia (YSZ) thermal barrier coatings (TBCs) is needed to perform radiative heat transfer calculations in industrial applications. In this paper, normal spectral emittance experimental data of atmospheric plasma sprayed (PS) YSZ films layered on Inconel 718 substrates are shown. The spectral emittance was measured between 2.5 and 22 {mu}m on samples with film thicknesses ranging from 20 to 280 {mu}m. The samples were heated in a controlled environment, and the emittance was measured for several temperatures between 330 and 730 Degree-Sign C. The dependence of the spectral emittance with film thickness, surface roughness and temperature has been studied and compared with the available results for YSZ TBCs obtained by electron-beam physical vapour deposition. The PS-TBC samples show a Christiansen point at {lambda} = 12.8 {mu}m. The films are semi-transparent for {lambda} < 9 {mu}m, and opaque for {lambda} > 9 {mu}m. In the semi-transparent region, the contribution of the radiation emitted by the Inconel 718 substrate to the global emittance of the samples is analysed. In addition, the influence of the roughness in the emittance values in the opaque spectral region is discussed. Finally, the total normal emittance is obtained as a function of the TBC thickness.

  10. Microstructures and microhardness at fusion boundary of 316 stainless steel/Inconel 182 dissimilar welding

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wei, E-mail: wang_wei_310@163.com [National Center for Materials Service Safety, University of Science and Technology Beijing, Beijing 100083 (China); Lu, Yonghao, E-mail: lu_yonghao@mater.ustb.edu.cn [National Center for Materials Service Safety, University of Science and Technology Beijing, Beijing 100083 (China); Ding, Xianfei, E-mail: xfding@ustb.edu.cn [National Center for Materials Service Safety, University of Science and Technology Beijing, Beijing 100083 (China); Shoji, Tetsuo, E-mail: tshoji@fri.niche.tohoku.ac.jp [National Center for Materials Service Safety, University of Science and Technology Beijing, Beijing 100083 (China); Fracture and Reliability Research Institute, Tohoku University, 6-6-01, Aramaki Aoba, Aoba-ku, Sendai City 980-8579 (Japan)

    2015-09-15

    Microstructures and microhardness at fusion boundary of a weld joint were investigated in a 316 stainless steel/Inconel 182 dissimilar weldment. The results showed that there were two alternately distributed typical fusion boundaries, a narrow random boundary (possessed 15% in length) with a clear sharp interface and an epitaxial fusion one with (100){sub BM}//(100){sub WM} at the joint interface. The composition transition, microstructure and hardness across the fusion boundary strongly depended on the type of the fusion boundary. For the random boundary, there was a clear sharp interface and the composition transition with a width of 100 μm took place symmetrically across the grain boundary. For the epitaxial fusion one, however, there were Type-I and Type-II grain boundaries perpendicular and parallel to the epitaxial fusion boundary, respectively. The composition transition took place in the Inconel 182 weld side. Σ3 boundaries in the HAZ of 316SS side and Σ5 grain boundaries in weld metal were usually observed, despite the type of fusion boundary, however the former was much more in epitaxial fusion boundary. Microhardness was continuously decreased across the random fusion boundary from the side of Inconel 182 to 316SS, but a hardening phenomenon appeared in the epitaxial fusion boundary zone because of its fine cellular microstructure. - Highlights: • Two typical fusion boundaries alternately distributed in the fusion interface • The microstructure, composition and hardness across fusion boundary depended on its type. • Different regions in welded joint have different special CSL value boundaries. • Hardening phenomenon only appeared in the epitaxial fusion boundary.

  11. Segregation behaviour and phase developments during solidification of Inconel 625; effect of iron and carbon

    DEFF Research Database (Denmark)

    Højerslev, Christian; Tiedje, Niels; Hald, John

    2004-01-01

    The key to improve the performance of Inconel 625 weld overlays applied for corrosion resistance in waste incinerator plants is to understand the solidification process: At present, enhanced resistance against fireside corrosion in waste incinerator boilers is commonly achieved by overlay welding...... performed on representative samples of the weld overlay using a combination of X-ray diffraction and scanning electron microscopy. It was found that the concentration of niobium and molybdenum was larger in the interdendritic matrix (denoted ƒ×ID) compared to the dendrite core (ƒ×DC). In addition, both...

  12. Prediction of Solidification and Microstructure of Inconel Alloy Using Numerical Simulation

    International Nuclear Information System (INIS)

    Test castings of Inconel 713LC nickel alloy were prepared by pouring into shell molds in vacuum furnace. The temperature was experimentally measured in the course of solidification and cooling, and the structure was evaluated in as-cast condition. Applying thermal insulation of shells, the dependence of the structure of castings on cooling rate was monitored on test castings. The solidification pattern was solved numerically, using the ProCAST simulation program. Parameters for the simulation of as-cast structure were sought using the CAFÉ module of the ProCAST program. Calculation parameters were established with the experimentally determined temperature curves and structure.

  13. Influence of Overloads on Dwell Time Fatigue Crack Growth in Inconel 718

    OpenAIRE

    Saarimäki, Jonas; Moverare, Johan; Eriksson, Robert; Johansson, Sten

    2014-01-01

    Inconel 718 is one of the most commonly used superalloys for high temperature applications in gasturbines and aeroengines and is for example used for components such as turbine discs. Turbine discs can be subjected to temperatures up to ~700 °C towards the outer radius of the disc. During service, the discs might start to develop cracks due to fatigue and long dwell times. Additionally, temperature variations during use can lead to large thermal transients during start-up and shutdown which c...

  14. Modelling of high temperature fatigue crack growth in Inconel 718 under hold time conditions

    OpenAIRE

    Gustafsson, David; Lundström, Erik; Simonsson, Kjell

    2013-01-01

    Inconel 718 is a frequently used material for gas turbine applications at temperatures up to 650 °C. The main load cycle for such components is typically defined by the start-up and shut-down of the engine. It generally includes hold times at high temperatures, which have been found to have a potential for greatly increasing the fatigue crack growth rate with respect to the number of load cycles. However, these effects may be totally or partly cancelled by other load features, such as overloa...

  15. Summary of Studies of Aging and Environmental Effects on Inconel 617 and Haynes 230

    International Nuclear Information System (INIS)

    A number of very high temperature helium-cooled reactors have been built and operated for extended periods. The helium coolant in the primary circuit has been found to contain low levels of impurities after steady-state operation that can lead to an environmental degradation of the high temperature alloys used for internals and heat exchangers. Depending on the impurity concentration and the temperature, high temperature alloys can undergo oxidation, carburization, or decarburization. The concentration of H2O and CO is of particular interest because they essentially control the oxygen partial pressure and carbon activity, respectively. The optimum coolant chemistry for long-term stability of high temperature alloys is slightly oxidizing and results in formation of a tenacious and protective Cr2O3 scale. The most critical metallic component of the Next Generation Nuclear Plant (NGNP) is the heat exchanger. Inconel 617 is the primary candidate alloy for this application because of its superior creep resistance. The mechanisms of environmental interaction between this alloy and prototype Very High Temperature Reactor (VHTR) helium chemistries have been extensively studied. A modified type of Ellingham diagram that maps the ranges of carbon activity and oxygen partial pressure that result in each of the degradation mechanisms has been developed. The NGNP materials program has designed and built three test loops to extend previous studies on environmental effects of prototype impure helium on Inconel 617 by increasing temperatures and using test coupons that incorporate fusion welds in controlled impurity experiments. In addition, parallel studies have been initiated with a less well-characterized alloy, Haynes 230. The goal of this work is to determine the range of gas chemistries that give rise to stable oxide formation for these alloys at temperatures up to 1000 C. Stability of the microstructure and properties of Inconel 617 and Haynes 230 after extended exposure to

  16. THERMODYNAMIC MODELING OF THE SURFACE LAYER STRUCTURE ON INCONEL 600 OXIDIZED IN A CONTROLLED ATMOSPHERE

    Directory of Open Access Journals (Sweden)

    Abdallah Haouam

    2012-03-01

    Full Text Available Samples of Inconel 600 were isothermally oxidized in a controlled atmosphere with a special mounting at high-temperature oxidation. Along with this experimental study, a simulation of thermodynamic behavior of the material in the same oxidation conditions was carried out using the Thermo-Calc code. The thermodynamic modeling is able to predict the phase nature and its distribution in the structure of the surface layer resulting from the corrosion of the material in thermodynamic equilibrium in the absence of mechanical stress. The results of this simulation are supplemented to results obtained from the analysis by glow discharge spectrometry (GDS which is performed on the samples tested.

  17. Spectral Emittance of Uncoated and Ceramic-Coated Inconel and Type 321 Stainless Steel

    Science.gov (United States)

    Richmond, Joseph C.; Stewart, James E.

    1959-01-01

    The normal spectral emittance of Inconel and type 321 stainless steel with different surface treatments was measured at temperatures of 900, 1,200, 1,500, and 1,800 F over a wavelength range of 1.5 to 15 microns. The measurements involved comparison of the radiant energy emitted by the heated specimen with that emitted by a comparison standard at the same temperature by means of a recording double-beam infrared spectrophotometer. The silicon carbide comparison standard had previously been calibrated against a laboratory black-body furnace. Surface treatments included electropolishing, sandblasting, electro-polishing followed by oxidation in air for 1/2 hour at 1,800 F, sandblasting followed by oxidation in air for 1/2 hour at 1,800 F, application of National Bureau of Standards coating A-418, and application of NBS ceramic coating N-143. The normal spectral emittance of both alloys in the electropolished condition was low and decreased very slightly with increasing wavelength while in the sandblasted condition it was somewhat higher and did not vary appreciably with wavelength. The oxidation treatment greatly increased the normal spectral emittance of both the electropolished and sandblasted type 321 stainless steel specimens and of the electropolished Inconel specimens and introduced some spectral selectivity into the curves. The oxidation increased the normal spectral emittance of the sandblasted Inconel specimens only moderately. Of the specimens to which a coating about 0.002 inch thick was applied, those coated with A-418 had higher emittance at all wavelengths than did those coated with N-143, and the coated specimens of Inconel had higher spectral emittance at all wavelengths than did the corresponding specimens of type 321 stainless steel. Both coatings were found to be partially transparent to the emitted energy at this thickness but essentially opaque at a thickness of 0.005 inch. Coated specimens with 0.005 inch or more of coating did not show the effect

  18. Influence of microstructure in corrosion behavior of an Inconel 600 commercial alloy in 0.1 M sodium thiosulfate solution

    International Nuclear Information System (INIS)

    The Inconel 600 is used in diverse components of BWR and PWR type reactors, where diverse cases of intergranular stress corrosion have been presented. It has been reported susceptibility to the corrosion of this alloy, in presence of thiosulfates, which come from the degradation of the ion exchange resins of water treatments that use the reactors. The objective of this work is to study the influence of metallurgical condition in the corrosion velocity of Inconel 600 commercial alloy, in a 0.1 M thiosulfates solution. (Author)

  19. Exfoliation on stainless steel and inconel produced by 0.8-4 MeV helium iom bombardment

    International Nuclear Information System (INIS)

    In order to try and outline the energy dependence of surface deformations such as exfoliation and flaking on candidate CTR first-wall materials, stainless steel and two types of inconels were bombarded by 0.8, 1 and 4 MeV helium ions. All the bombarded spots could be characterized by large exfoliations covering almost the total implanted area. No spontaneous rupture was observed except on one type of inconel where flaking took place right after reaching the critical dose. After mechanical opening of the formations, similar inner morphology was found as in our previous studies on gold. (orig.)

  20. Exfoliation on stainless steel and inconel produced by 0.8-4 MeV helium ion bombardment

    International Nuclear Information System (INIS)

    Trying to outline the energy dependence of surface deformations such as exfoliation and flaking on candidate CTR first-wall materials, stainless steel and two types of inconels were bombarded by 0.8, 1 and 4 MeV helium ions. All the bombarded spots could be characterized by by large exfoliations covering almost the total implanted area. No spontaneous rupture was observed except on one type of inconel where flaking took place right after reaching the critical dose. After mechanical opening of the formations, similar inner morphology was found as in our previous studies on gold. (author)

  1. Surface Integrity and Structural Stability of Broached Inconel 718 at High Temperatures

    Science.gov (United States)

    Chen, Z.; Peng, R. Lin; Moverare, J.; Avdovic, P.; Zhou, J. M.; Johansson, S.

    2016-04-01

    The current study focused on the surface integrity issues associated with broaching of Inconel 718 and the structural stability of the broached specimen at high temperatures, mainly involving the microstructural changes and residual stress relaxation. The broaching operation was performed using similar cutting conditions as that used in turbo machinery industries for machining fir-tree root fixings on turbine disks. Thermal exposure was conducted at 723 K, 823 K, and 923 K (450 °C, 550 °C, and 650 °C) for 30, 300, and 3000 hours, respectively. Surface cavities and debris dragging, sub-surface cracks, high intensity of plastic deformation, as well as the generation of tensile residual stresses were identified to be the main issues in surface integrity for the broached Inconel 718. When a subsequent heating was applied, surface recrystallization and α-Cr precipitation occurred beneath the broached surface depending on the applied temperature and exposure time. The plastic deformation induced by the broaching is responsible for these microstructural changes. The surface tension was completely relaxed in a short time at the temperature where surface recrystallization occurred. The tensile layer on the sub-surface, however, exhibited a much higher resistance to the stress relief annealing. Oxidation is inevitable at high temperatures. The study found that the surface recrystallization could promote the local Cr diffusion on the broached surface.

  2. KWU experience with Inconel X-750 and today's philosophy for high strength materials selection

    International Nuclear Information System (INIS)

    KWU uses Inconel-X-750 in BWR and PWR in structural components both for reactor pressure vessel internals and for fuel assembly and control assembly. Operating experience has been gained over more than 15 years. Common mode damage due to intercrystalline stress corrosion cracking (IGSCC) did not occur. The components can be divided into two categories: fasteners and guides such as bolts, nuts and centering fixtures, and springs in the form of helical-, disc- and leaf-springs. With respect to fasteners and guides, only singular cases of damages have occurred. The cause of the damage can be narrowed down and tracked back to unsuitable heat treatment of the material (anneal at 885 degree C) combined with design-related individual peak stresses, or to high secondary stresses due to thermal expansion in localized areas. With respect to spring assemblies, with one exception, no IGSCC damage has yet been observed. This is true despite the fact that, in particular, helical-springs are used in large numbers in a wide variety of components. The present procedure for selecting materials for use in high-strength components is primarily based on internationally-published experience and more important on our own investigations and operating experience. According to this experience, Inconel-X-750 is susceptible to IGSCC (even in favorable heat-treated conditions) only is sufficiently high tensile stresses are present

  3. Effect of thermal exposure on microstructure and nano-hardness of broached Inconel 718

    Directory of Open Access Journals (Sweden)

    Chen Zhe

    2014-01-01

    Full Text Available Inconel 718 is a high strength, heat resistant superalloy that is used extensively for components in hot sections of gas turbine engines. This paper presents an experimental study on the thermal stability of broached Inconel 718 in terms of microstructure and nano-hardness. The broaching process used in this study is similar to that used in gas turbine industries for machining fir-tree root fixings on turbine discs. Severe plastic deformation was found under the broached surface. The plastic deformation induces a work-hardened layer in the subsurface region with a thickness of ∼50 μm. Thermal exposure was conducted at two temperatures, 550 ∘C and 650 ∘C respectively, for 300 h. Recrystallization occurs in the surface layer during thermal exposure at 550 ∘C and α-Cr precipitates as a consequence of the growth of recrystallized δ phases. More recrystallized grains with a larger size form in the surface layer and the α-Cr not only precipitates in the surface layer, but also in the sub-surface region when the thermal exposure temperature goes up to 650 ∘C. The thermal exposure leads to an increase in nano-hardness both in the work-hardened layer and in the bulk material due to the coarsening of the main strengthening phase γ′′.

  4. Analysis of Deformation in Inconel 718 When the Stress Anomaly and Dynamic Strain Aging Coexist

    Science.gov (United States)

    Follansbee, Paul S.

    2016-09-01

    Deformation in Inconel 718 in the presence of combined effects of the stress anomaly and dynamic strain aging is analyzed according to an internal state variable model formulation. The analysis relies on the availability of experimental data in regimes of behavior where both the stress anomaly and dynamic strain aging are absent. A model that introduces two internal state variables—one characterizing interactions of dislocations with solute atoms and one characterizing interaction of dislocations with precipitates—is shown to adequately describe the temperature and strain-rate dependence of the yield stress in several superalloy systems. Strain hardening is then added with a third internal state variable to enable description of the full stress-strain curve. These equations are extrapolated into regimes where the stress anomaly and dynamic strain aging are present to identify signatures of their effects and to compare to similar analyses in a variety of metal systems. Dynamic strain aging in Inconel 718 follows similar trends to those observed previously. The magnitude of the stress anomaly tracks measurements of stress vs test temperature in pure Ni3Al. Several trends in the strain-rate sensitivity of elevated temperature deformation in superalloys are identified based on limited availability of measurements over a wide range of strain rates or tests using strain-rate changes.

  5. Control of the kerf size and microstructure in Inconel 738 superalloy by femtosecond laser beam cutting

    Science.gov (United States)

    Wei, J.; Ye, Y.; Sun, Z.; Liu, L.; Zou, G.

    2016-05-01

    Femtosecond laser beam cutting is becoming widely used to meet demands for increasing accuracy in micro-machining. In this paper, the effects of processing parameters in femtosecond laser beam cutting on the kerf size and microstructure in Inconel 738 have been investigated. The defocus, pulse width and scanning speed were selected to study the controllability of the cutting process. Adjusting and matching the processing parameters was a basic enhancement method to acquire well defined kerf size and the high-quality ablation of microstructures, which has contributed to the intensity clamping effect. The morphology and chemical compositions of these microstructures on the cut surface have been characterized by a scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Additionally, the material removal mechanism and oxidation mechanism on the Inconel 738 cut surface have also been discussed on the basis of the femtosecond laser induced normal vaporization or phase explosion, and trapping effect of the dangling bonds.

  6. Surface Integrity and Structural Stability of Broached Inconel 718 at High Temperatures

    Science.gov (United States)

    Chen, Z.; Peng, R. Lin; Moverare, J.; Avdovic, P.; Zhou, J. M.; Johansson, S.

    2016-07-01

    The current study focused on the surface integrity issues associated with broaching of Inconel 718 and the structural stability of the broached specimen at high temperatures, mainly involving the microstructural changes and residual stress relaxation. The broaching operation was performed using similar cutting conditions as that used in turbo machinery industries for machining fir-tree root fixings on turbine disks. Thermal exposure was conducted at 723 K, 823 K, and 923 K (450 °C, 550 °C, and 650 °C) for 30, 300, and 3000 hours, respectively. Surface cavities and debris dragging, sub-surface cracks, high intensity of plastic deformation, as well as the generation of tensile residual stresses were identified to be the main issues in surface integrity for the broached Inconel 718. When a subsequent heating was applied, surface recrystallization and α-Cr precipitation occurred beneath the broached surface depending on the applied temperature and exposure time. The plastic deformation induced by the broaching is responsible for these microstructural changes. The surface tension was completely relaxed in a short time at the temperature where surface recrystallization occurred. The tensile layer on the sub-surface, however, exhibited a much higher resistance to the stress relief annealing. Oxidation is inevitable at high temperatures. The study found that the surface recrystallization could promote the local Cr diffusion on the broached surface.

  7. Effect of temperature on fatigue crack growth rate in inconel 690

    International Nuclear Information System (INIS)

    The effect of temperature on fatigue crack growth rate in Inconel 690 steam generator tube was investigated at room temperature, 150 .deg. C, 300 .deg. C and 400 .deg. C in air environment. Fatigue tests was performed on compact tension(CT) specimens made to thickness 8mm. Heat treatment was performed to obtain various microstructures. Tests was conducted at load ratio 0.1, at frequency 10Hz using sinusoidal waveform. Crack length was monitored by compliance method using sensor probe. Tensile tests was performed to obtain yield strength for fatigue test at each testing temperature. Fracture modes were studied using scanning electron microscopy(SEM). Tensile properties of Inconel 690 were dependent on grain size and testing temperature. As temperature and grain size increased, yield strength decreased. At temperature above 300 .deg. C, the serrations which were an evidence of dynamic strain aging (DSA) were observed for all cases of materials. Fatigue crack growth rate decreased with increasing grain size. At low Δ K, grain size effect was significant at room temperature, which was due to roughness induced crack closure. With increasing temperature, fatigue crack growth rate increased and grain size effect decreased. Chormium carbides which have large size and semi-continuous distribution in the grain boundaries decreased fatigue crack growth rate

  8. Effect of Powder-Suspended Dielectric on the EDM Characteristics of Inconel 625

    Science.gov (United States)

    Talla, Gangadharudu; Gangopadhyay, S.; Biswas, C. K.

    2016-02-01

    The current work attempts to establish the criteria for powder material selection by investigating the influence of various powder-suspended dielectrics and machining parameters on various EDM characteristics of Inconel 625 (a nickel-based super alloy) which is nowadays regularly used in aerospace, chemical, and marine industries. The powders include aluminum (Al), graphite, and silicon (Si) that have significant variation in their thermo-physical characteristics. Results showed that powder properties like electrical conductivity, thermal conductivity, density, and hardness play a significant role in changing the machining performance and the quality of the machined surface. Among the three powders, highest material removal rate was observed for graphite powder due to its high electrical and thermal conductivities. Best surface finish and least radial overcut (ROC) were attained using Si powder. Maximum microhardness was found for Si due to its low thermal conductivity and high hardness. It is followed by graphite and aluminum powders. Addition of powder to the dielectric has increased the crater diameter due to expansion of plasma channel. Powder-mixed EDM (PMEDM) was also effective in lowering the density of surface cracks with least number of cracks obtained with graphite powder. X-ray diffraction analysis indicated possible formation of metal carbides along with grain growth phenomenon of Inconel 625 after PMEDM.

  9. Structural characteristics of nickel super alloy INCONEL 713LC after heat treatment

    Directory of Open Access Journals (Sweden)

    A. Hernas

    2007-04-01

    Full Text Available Purpose: Aircraft industry often uses nickel super-alloys for blades of jet engine turbines. This paper summarises analysis of influence of heat treatment on structural characteristics of nickel super-alloy INCONEL 713LC.Design/methodology/approach: Experimental investigation castings made of commercially produced nickel super-alloy INCONEL 713LC. Material was after heat treatment subjected to detailed structural analysis with use of methods of light microscopy (LM, or scanning electron microscopy (SEM on microscopes OLYMPUS IX71 and JEOL JSM 50A.Findings: Mode of optimum heat treatment was proposed. On the basis of obtained results it is possible to recommend a heat treatment, which would consist of heating and dwell at the temperature exceeding 1240°C (min. 1260°C, so that precipitates at the grain boundaries dissolve completely, with subsequent slow cooling down to the temperature of approx. 940-950°C, so that there occurs intensive intra-granular precipitation of inter-metallic phase γ’.Research limitations/implications: The experiment was limited by occurrence a void in cast alloys.Practical implications: Aircraft industry often uses nickel super-alloys for blades of jet engine turbines.Originality/value: On the basis of obtained results it is possible to recommend the most suitable heat treatment, which produce intensive intra-granular precipitation of inter-metallic phase γ’. It was received a new know-how in this field.

  10. Microstructures and mechanical behavior of Inconel 718 fabricated by selective laser melting

    International Nuclear Information System (INIS)

    In this study Inconel 718 cylinders were fabricated by selective laser melting in either argon or nitrogen gas from a pre-alloyed powder. As-fabricated cylinders oriented in the build direction (z-axis) and perpendicular to the build direction (x-axis) exhibited columnar grains and arrays of γ″ (body-centered tetragonal) Ni3Nb oblate ellipsoidal precipitates oriented in a strong [2 0 0] texture determined by combined optical metallography, transmission electron microscopy, and X-ray diffraction analysis. Fabricated and hot isostatic pressed (HIP) components exhibited a more pronounced [2 0 0] columnar γ″ phase precipitate architecture parallel to the laser beam or build direction (spaced at ∼0.8 μm), and a partially recrystallized fcc grain structure. Fabricated and annealed (1160 °C for 4 h) components were ∼50% recrystallized and the recrystallized regions contained spheroidal γ′ precipitates distributed in a dense field of fine γ″ precipitates. The γ″ precipitates were always observed to be coincident with {1 0 0} planes of the γ-fcc NiCr matrix. Some δ phase precipitates in the unrecrystallized/recrystallized interfaces and recrystallized grain boundaries were also observed in the annealed samples. The microindentation (Vickers) hardness was 3.9 GPa for the as-fabricated materials, 5.7 GPa for the HIP material, and 4.6 GPa for the annealed material. Corresponding tensile properties were comparable with wrought Inconel 718 alloy.

  11. Laser post-processing of Inconel 625 made by selective laser melting

    Science.gov (United States)

    Witkin, David; Helvajian, Henry; Steffeney, Lee; Hansen, William

    2016-04-01

    The effect of laser remelting of surfaces of as-built Selective Laser Melted (SLM) Inconel 625 was evaluated for its potential to improve the surface roughness of SLM parts. Many alloys made by SLM have properties similar to their wrought counterparts, but surface roughness of SLM-made parts is much higher than found in standard machine shop operations. This has implications for mechanical properties of SLM materials, such as a large debit in fatigue properties, and in applications of SLM, where surface roughness can alter fluid flow characteristics. Because complexity and netshape fabrication are fundamental advantages of Additive Manufacturing (AM), post-processing by mechanical means to reduce surface roughness detracts from the potential utility of AM. Use of a laser to improve surface roughness by targeted remelting or annealing offers the possibility of in-situ surface polishing of AM surfaces- the same laser used to melt the powder could be amplitude modulated to smooth the part during the build. The effects of remelting the surfaces of SLM Inconel 625 were demonstrated using a CW fiber laser (IPG: 1064 nm, 2-50 W) that is amplitude modulated with a pulse profile to induce remelting without spallation or ablation. The process achieved uniform depth of melting and improved surface roughness. The results show that with an appropriate pulse profile that meters the heat-load, surface features such as partially sintered powder particles and surface connected porosity can be mitigated via a secondary remelting/annealing event.

  12. Mechanical Behaviour of Inconel 718 Thin-Walled Laser Welded Components for Aircraft Engines

    Directory of Open Access Journals (Sweden)

    Enrico Lertora

    2014-01-01

    Full Text Available Nickel alloys are very important in many aerospace applications, especially to manufacture gas turbines and aero engine components, where high strength and temperature resistance are necessary. These kinds of alloys have to be welded with high energy density processes, in order to preserve their high mechanical properties. In this work, CO2 laser overlap joints between Inconel 718 sheets of limited thickness in the absence of postweld heat treatment were made. The main application of this kind of joint is the manufacturing of a helicopter engine component. In particular the aim was to obtain a specific cross section geometry, necessary to overcome the mechanical stresses found in these working conditions without failure. Static and dynamic tests were performed to assess the welds and the parent material fatigue life behaviour. Furthermore, the life trend was identified. This research pointed out that a full joint shape control is possible by choosing proper welding parameters and that the laser beam process allows the maintenance of high tensile strength and ductility of Inconel 718 but caused many liquation microcracks in the heat affected zone (HAZ. In spite of these microcracks, the fatigue behaviour of the overlap welds complies with the technical specifications required by the application.

  13. Effect of service exposure on fatigue crack propagation of Inconel 718 turbine disc material at elevated temperatures

    International Nuclear Information System (INIS)

    In this study, the fatigue crack propagation behavior of Inconel 718 turbine disc with different service times from 0 to 4229 h was investigated at 738 and 823 K. No notable change in microstructural features, other than the increase in grain size, was observed with increasing service time. With increasing service time from 0 to 4229 h, the fatigue crack propagation rates tended to increase, while the ΔKth value decreased, in low ΔK regime and lower Paris' regime at both testing temperatures. The fractographic observation using a scanning electron microscope suggested that the elevated temperature fatigue crack propagation mechanism of Inconel 718 changed from crystallographic cleavage mechanism to striation mechanism in the low ΔK regime, depending on the grain size. The fatigue crack propagation mechanism is proposed for the crack propagating through small and large grains in the low ΔK regime, and the fatigue crack propagation behavior of Inconel 718 with different service times at elevated temperatures is discussed. - Highlights: • The specimens were prepared from the Inconel 718 turbine disc used for 0 to 4229 h. • FCP rates were measured at 738 and 823 K. • The ΔKth values decreased with increasing service time. • The FCP behavior showed a strong correlation with the grain size of used turbine disc

  14. Effect of Double Aging Heat Treatment on the Short-Term Creep Behavior of the Inconel 718

    Science.gov (United States)

    Caliari, Felipe Rocha; Candioto, Kátia Cristiane Gandolpho; Couto, Antônio Augusto; Nunes, Carlos Ângelo; Reis, Danieli Aparecida Pereira

    2016-04-01

    This research studies the effect of double aging heat treatment on the short-term creep behavior of the superalloy Inconel 718. The superalloy, received in the solution treated state, was subjected to an aging treatment which comprises a solid solution at 1095 °C for 1 h, a first aging step of 955 °C for 1 h, then aged at 720 and 620 °C, 8 h each step. Creep tests at constant load mode, under temperatures of 650, 675, 700 °C and stress of 510, 625 and 700 MPa, were performed before and after heat treatment. The results indicate that after the double aging heat treatment creep resistance is increased, influenced by the presence of precipitates γ' and γ″ and its interaction with the dislocations, by grain size growth (from 8.20 to 7.23 ASTM) and the increase of hardness by approximately 98%. Creep parameters of primary and secondary stages have been determined. There is a breakdown relationship between dot{\\upvarepsilon }_{s} and stress at 650 °C of Inconel 718 as received, around 600 MPa. By considering the internal stress values, effective stress exponent, effective activation energy, and TEM images of Inconel 718 double aged, it is suggested that the creep mechanism is controlled by the interaction of dislocations with precipitates. The fracture mechanism of Inconel 718 as received is transgranular (coalescence of dimples) and mixed (transgranular-intergranular), whereas the Inconel 718 double aged condition crept surfaces evidenced the intergranular fracture mechanism.

  15. Effect of Double Aging Heat Treatment on the Short-Term Creep Behavior of the Inconel 718

    Science.gov (United States)

    Caliari, Felipe Rocha; Candioto, Kátia Cristiane Gandolpho; Couto, Antônio Augusto; Nunes, Carlos Ângelo; Reis, Danieli Aparecida Pereira

    2016-06-01

    This research studies the effect of double aging heat treatment on the short-term creep behavior of the superalloy Inconel 718. The superalloy, received in the solution treated state, was subjected to an aging treatment which comprises a solid solution at 1095 °C for 1 h, a first aging step of 955 °C for 1 h, then aged at 720 and 620 °C, 8 h each step. Creep tests at constant load mode, under temperatures of 650, 675, 700 °C and stress of 510, 625 and 700 MPa, were performed before and after heat treatment. The results indicate that after the double aging heat treatment creep resistance is increased, influenced by the presence of precipitates γ' and γ″ and its interaction with the dislocations, by grain size growth (from 8.20 to 7.23 ASTM) and the increase of hardness by approximately 98%. Creep parameters of primary and secondary stages have been determined. There is a breakdown relationship between dot{\\upvarepsilon }_{{s}} and stress at 650 °C of Inconel 718 as received, around 600 MPa. By considering the internal stress values, effective stress exponent, effective activation energy, and TEM images of Inconel 718 double aged, it is suggested that the creep mechanism is controlled by the interaction of dislocations with precipitates. The fracture mechanism of Inconel 718 as received is transgranular (coalescence of dimples) and mixed (transgranular-intergranular), whereas the Inconel 718 double aged condition crept surfaces evidenced the intergranular fracture mechanism.

  16. Modeling of precipitation and Cr depletion profiles of Inconel 600 during heat treatments and LSM procedure

    International Nuclear Information System (INIS)

    A model based on the thermodynamic and kinetic was conducted to simulate the Cr depletion profiles near the grain boundary in Inconel 600 during the heat treatments and laser surface melting (LSM) process using Thermo-Calc and Dictra code. Based on the good agreement of Cr concentration distribution during heat treatments measured by experiments, the microsegregation of Cr induced by cellular microstructure formed during the LSM process was also modeled. The Cr depletion profile was evaluated using the Cr depletion area below the critical Cr concentration for intergranular cracking/intergranular stress corrosion cracking (IGC/IGSCC) susceptibility (8 mass%). Comparing with the result of Streicher test, the Cr depletion area calculated showed good coherence with the IGC/IGSCC susceptibility. The sample after SR + LTS treatment with the largest Cr depletion area showed the worst IGC/IGSCC resistance, while, the sample after LSM process with the smaller Cr depletion area showed the excellent IGC/IGSCC resistance

  17. EXPERIMENTAL INVESTIGATION AND THERMODYNAMIC CALCULATION ON PHASE PRECIPITATION OF INCONEL 740

    Institute of Scientific and Technical Information of China (English)

    S.Q. Zhao; Y. Jiang; J.X. Dong; X.S. Xie

    2006-01-01

    A novel nickel-based superalloy INCONEL 740 was under development for application in ultra-supercritical superheater tubers above 750℃. The precipitation behaviors of η phase andγ′ particles of the alloy were investigated through experimental study and phase computation.Experimental results showed that η phase formed a Widmanst(a)tten pattern structure following long-term exposure at elevated temperatures and that the coarsening of γ′ particle follows a cube rate law: (r)3 ∝t. Thermodynamic calculation results showed that Al and Ti had an important effect on the precipitation behavior of γ′ and η phases. Two suggested novel modified alloys, wherein the Al and Ti contents were modified, were designed and melted for the experimental study. The preliminary results indicated that the modified alloys exhibited higher structural stability following long-term exposure at 750℃ till 5000h.

  18. Properties of Inconel 625 mesh structures grown by electron beam additive manufacturing

    International Nuclear Information System (INIS)

    Relationships between electron beam parameters (beam current, beam speed, and beam focus) and physical properties (mass, diameter, elastic modulus, and yield strength) have been investigated for Inconel 625 mesh cubes fabricated using an additive manufacturing technology based on electron beam melting. The elastic modulus and yield strength of the mesh cubes have been systematically varied by approximately a factor of ten by changing the electron beam parameters. Simple models have been used to understand these relationships. Structural anisotropies of the mesh associated with the layered build architecture have been observed and may contribute, along with microstructural anisotropies, to the anisotropic mechanical properties of the mesh. Knowledge of this kind is likely applicable to other metal and alloy systems and is essential to rapidly realize the full potential of this burgeoning technology

  19. MICROSTRUCTURES AND THE STRUCTURE STABILITY OF INCONEL 725, A NEW AGE-HARDENABLE CORROSION RESISTANT SUPERALLOY

    Institute of Scientific and Technical Information of China (English)

    J.X. Dong; M.C. Zhang; S.K. Mannan

    2003-01-01

    INCONEL725 is a highly corrosion resistant nickel based alloy capable of being age-hardened to high strength levels. The microstructure observations and the phase iden-tification after a standard heat treatment were investigated. The results show thatmary carbide phase TiC, as well as M6C carbide and a little extent MC (mainly TiC)precipitates which nucleate mainly at grain boundaries. An isothermal aging studywas carried out on this alloy for up to 10 000 hours at 593℃. This additional agingdid not affect the tensile strength. However, microstructures show that the thermalexposure has a little additional effect. With increasing the exposure time, the size ofcipitated at grain boundaries have an increased and complex tendency on a few grainboundaries. The experimental results illustrate the excellent structure stability of theage-hardenable IN725 at 593℃.

  20. Thermal expansion studies on Inconel-600[reg] by high temperature X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Raju, S. E-mail: sraju@igcar.ernet.in; Sivasubramanian, K.; Divakar, R.; Panneerselvam, G.; Banerjee, A.; Mohandas, E.; Antony, M.P

    2004-02-01

    The lattice thermal expansion characteristics of Inconel-600[reg] have been studied by high temperature X-ray diffraction (HT-XRD) technique in the temperature range 298-1200 K. Altogether four experimental runs were conducted on thin foils of about 75-100 {mu}m thickness. The diffraction profiles have been accurately calibrated to offset the shift in 2{theta} values introduced by sample buckling at elevated temperatures. The corrected lattice parameter data have been used to estimate the instantaneous and mean linear thermal expansion coefficients as a function of temperature. The thermal expansion values estimated in the present study show a fair degree of agreement with other existing dilatometer based bulk thermal expansion estimates. The lattice parameter for this alloy at 300 K is found to be 0.3549(1) nm. The mean linear thermal expansivity is found to be 11.4 x 10{sup -6} K{sup -1}.

  1. A study on fretting fatigue life for the Inconel alloy 600 at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Jae-do [Department of Mechanical Engineering, Yeungnam University, Kyongsan (Korea, Republic of); Park, Dae-kyu [Graduate School of Mechanical Engineering, Yeungnam University, Kyongsan (Korea, Republic of); Woo, Seung-wan [Department of Mechanical Engineering, Yeungnam University, Kyongsan (Korea, Republic of); Yoon, Dong-hwan [Graduate School of Mechanical Engineering, Yeungnam University, Kyongsan (Korea, Republic of); Chung, Ilsup, E-mail: ilchung@yu.ac.k [Department of Mechanical Engineering, Yeungnam University, Kyongsan (Korea, Republic of)

    2010-10-15

    Fatigue tests of the Inconel 600, a type of nickel-chromium based heat resistant alloy used for steam generator tubes in nuclear power plants, were carried out. Temperature increase to 320 {sup o}C did not change the fatigue strength much, but the fretting condition caused a significant reduction in the fatigue strength. The reduction at 10{sup 7} cycles was about 70% for both of room and the high temperatures. An apparatus to realize the fretting condition has been developed and instrumented to measure the normal and friction forces. The bridge type of contact pad was fabricated of SUS 409 stainless steel. Fracture surfaces and wear scars were observed by electron microscope and the profiles of wear scar were measured by non-contact 3D-profiler.

  2. Processing and Microstructural Evolution of Superalloy Inconel 718 during Hot Tube Extrusion

    Institute of Scientific and Technical Information of China (English)

    Shihong ZHANG; Zhongtang WANG; Bing QIAO; Yi XU; Tingfeng XU

    2005-01-01

    The processing parameters of tube extrusion for superalloy Inconel 718 (IN 718), such as slug temperature, tools temperature, choice of lubricant, extrusion ratio and extrusion speed, were determined by experiment in this paper. An appropriate temperature range recommended for the slug is 1080~1120℃, and the temperature range recommended for the tools is 350~500℃. The microstructural evolution of superalloy IN 718 during tube extrusion was analyzed.With the increase of the deformation the cross crystal grains were slightly refined. While the vertical crystal grain is elongated evidently and the tensile strength increased along the axial rake. Glass lubricants have to be spread on the slug surface after being heated to 150~200℃, vegetable oil or animal oil can be used as the lubricant on the surface of the tools to reduce the extrusion force remarkably.

  3. Intercrystalline Stress Corrosion of Inconel 600 Inspection Tubes in the Aagesta Reactor

    International Nuclear Information System (INIS)

    Intercrystalline stress corrosion cracking has occurred in the Aagesta reactor in three so-called inspection tubes made of Inconel 600. The tubes had been exposed to 217 deg C light water, containing 1-4 ppm LiOH (later KOH) but only small amounts of oxygen, chloride and other impurities. Some of the circumferential cracks developed in or at crevices on the outside surface. At these positions constituents dissolved in the water may have concentrated. The crevices are likely to have contained a gas phase, mainly nitrogen. Local boiling in the crevices may also have occurred. Some few cracks were also found outside the crevice region. Irradiation effects can be neglected. No surface contamination could be detected except for a very minor fluoride content (1 μg/cm2). The failed tubes had been subjected to high stresses, partly remaining from milling, partly induced by welding operations. The possibility that stresses slightly above the 0.2 per cent offset yield strength have occurred at the operating temperature cannot be excluded. The cracked tube material contained a large amount of carbide particles and other precipitates, both at grain boundaries and in the interior of grains. The particles appeared as stringers in circumferential zones. Zones depleted in precipitates were found along grain boundaries. The failed tube turned out to have an unusually high mechanical strength, likely due to a combination of some kind of ageing process and cold work (1.0 - 1.3 per cent plastic strain). Laboratory exposures of stressed surplus material in high purity water and in 1 M LiOH at 220 deg C showed some pitting but no cracking after 6800 h and 5900 h respectively. Though the encountered failures may have developed because of influence of some few or several of the above-mentioned detrimental factors, the actual cause cannot be stated with certainty. In the literature information is given concerning intercrystalline stress corrosion cracking of Inconel 600 both in caustic

  4. Supplementary Microstructural Features Induced During Laser Surface Melting of Thermally Sprayed Inconel 625 Coatings

    Science.gov (United States)

    Ahmed, Nauman; Voisey, K. T.; McCartney, D. G.

    2014-02-01

    Laser surface melting of thermally sprayed coatings has the potential to enhance their corrosion properties by incorporating favorable microstructural changes. Besides homogenizing the as-sprayed structure, laser melting may induce certain microstructural modifications (i.e., supplementary features) in addition to those that directly improve the corrosion performance. Such features, being a direct result of the laser treatment process, are described in this paper which is part of a broader study in which high velocity oxy-fuel sprayed Inconel 625 coatings on mild-steel substrates were treated with a diode laser and the modified microstructure characterized using optical and scanning electron microscopy and x-ray diffraction. The laser treated coating features several different zones, including a region with a microstructure in which there is a continuous columnar dendritic structure through a network of retained oxide stringers.

  5. Deformation characteristics of {delta} phase in the delta-processed Inconel 718 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H.Y., E-mail: haiyanzhang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Zhang, S.H., E-mail: shzhang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Cheng, M. [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Li, Z.X. [Beijing Institute of Aeronautica1 Materials, Beijing 100095 (China)

    2010-01-15

    The hot working characteristics of {delta} phase in the delta-processed Inconel 718 alloy during isothermal compression deformation at temperature of 950 deg. C and strain rate of 0.005 s{sup -1}, were studied by using optical microscope, scanning electron microscope and quantitative X-ray diffraction technique. The results showed that the dissolution of plate-like {delta} phase and the precipitation of spherical {delta} phase particles coexisted during the deformation, and the content of {delta} phase decreased from 7.05 wt.% to 5.14 wt.%. As a result of deformation breakage and dissolution breakage, the plate-like {delta} phase was spheroidized and transferred to spherical {delta} phase particles. In the center with largest strain, the plate-like {delta} phase disappeared and spherical {delta} phase appeared in the interior of grains and grain boundaries.

  6. Gas carburization of Inconel 617. Advanced Gas Cooled Reactor Materials Program

    International Nuclear Information System (INIS)

    This report describes the progress in the Advanced Gas Cooled Reactor Materials Program on efforts to produce uniformly carburized specimens of Inconel 617 with different carbon levels. This material will be used to determine the effect of carbon content on the mechanical properties and physical properties important for design and use of components in the primary circuit of an advanced HTGR system. The results of gas carburization and high temperature homogenization heat treatments are discussed. Also described are electron microprobe analysis methods for measuring the carbon gradients in the carburized and homogenized material. Recommendations are given for additional work needed to increase the homogeneity of carburized material and for producing material with uniform carbon concentration. Recommendations for improving the accuracy of the EPMA carbon gradient analyses also are included

  7. Texture-Induced Anisotropy in an Inconel 718 Alloy Deposited Using Electron Beam Freeform Fabrication

    Science.gov (United States)

    Tayon, W.; Shenoy, R.; Bird, R.; Hafley, R.; Redding, M.

    2014-01-01

    A test block of Inconel (IN) 718 was fabricated using electron beam freeform fabrication (EBF(sup 3)) to examine how the EBF(sup 3) deposition process affects the microstructure, crystallographic texture, and mechanical properties of IN 718. Tests revealed significant anisotropy in the elastic modulus for the as-deposited IN 718. Subsequent tests were conducted on specimens subjected to a heat treatment designed to decrease the level of anisotropy. Electron backscatter diffraction (EBSD) was used to characterize crystallographic texture in the as-deposited and heat treated conditions. The anisotropy in the as-deposited condition was strongly affected by texture as evidenced by its dependence on orientation relative to the deposition direction. Heat treatment resulted in a significant improvement in modulus of the EBF(sup 3) product to a level nearly equivalent to that for wrought IN 718 with reduced anisotropy; reduction in texture through recrystallization; and production of a more homogeneous microstructure.

  8. Deformation characteristics of δ phase in the delta-processed Inconel 718 alloy

    International Nuclear Information System (INIS)

    The hot working characteristics of δ phase in the delta-processed Inconel 718 alloy during isothermal compression deformation at temperature of 950 deg. C and strain rate of 0.005 s-1, were studied by using optical microscope, scanning electron microscope and quantitative X-ray diffraction technique. The results showed that the dissolution of plate-like δ phase and the precipitation of spherical δ phase particles coexisted during the deformation, and the content of δ phase decreased from 7.05 wt.% to 5.14 wt.%. As a result of deformation breakage and dissolution breakage, the plate-like δ phase was spheroidized and transferred to spherical δ phase particles. In the center with largest strain, the plate-like δ phase disappeared and spherical δ phase appeared in the interior of grains and grain boundaries.

  9. EXPERIMENTAL INVESTIGATION OF INCONEL 718 DURING DIE-SINKING ELECTRIC DISCHARGE MACHINING

    Directory of Open Access Journals (Sweden)

    PUSHPENDRA S BHARTI,

    2010-11-01

    Full Text Available This work investigates the machining characteristics of Inconel 718 during die-sinking electric discharge machining process with copper as tool electrode. Experiments have been carried out to see the effects of input parameters like shape factor, pulse-on-time, discharge current, duty cycle, gap voltage, flushing pressure and tool electrode lift time on performance measures like material removal rate, surface roughness and tool wear rate. Taguchi’s method has been used as Design of Experiments technique for experimental investigation. Experiments have been designed as per Taguchi’s L36 orthogonal array. Analysis of variance (ANOVA is employed to indicate the level of significance of machining parameters. Discharge current and pulse-on time are found the most influential common input parameter on each performance measure. Duty cycle and tool electrode lift time are found the least influential parameters.

  10. An experimental study on fretting wear behavior of cross-contacting Inconel 690 tubes

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Ilsup, E-mail: ilchung@yu.ac.kr [School of Mechanical Engineering, Yeungnam University, 214-1 Daedong, Kyungsan 712-749 (Korea, Republic of); Lee, Myungho [R and D Institute, STX Metal, 67-14 Sinchon-dong, Changwon 642-370 (Korea, Republic of)

    2011-10-15

    Highlights: > A fretting wear tester employing a piezoelectric actuator has been developed. > Inconel 690 tubes were tested in RT ambient and 80 deg. C in-water conditions. > The dependence of the wear rate on the work rate is in bilinear fashion. > SEM photos show the transition is due to the change of the fretting wear regime. > Easier debris discharge and the extensive abrasion yields higher wear rate in water. - Abstract: A fretting wear test rig employing a piezoelectric actuator has been developed, which is equipped with a heating and water circulation system. The fretting wear tests of cross-contacting Inconel 690 tubes, which is widely used for power plant steam generator, have been carried out in room temperature ambient and 80 deg. C in-water conditions. Maximum normal load was 55 N, and the sliding amplitude was below 50 {mu}m. Scars of the mixed-slip and the gross-slip fretting wear have been measured in terms of scar diameter and wear volume. From the relationship between the work rate and the wear rate, a threshold of work rate has been defined, and this is found to be closely related with fretting wear regimes. The wear coefficients have been evaluated in the gross-slip regime. Distinct fretting wear mechanisms have been observed for the two different test conditions from SEM microphotographs. The crack formation, large particle separation and resulting third body effect were significant in room temperature ambient condition. The protective nature of the tribologically transformed layers coupled with non-uniform contact results in the lower wear coefficient while smooth wear scar and extensive abrasion produces higher wear volume in the other condition.

  11. Microstructure evolution and mechanical properties of Inconel 740H during aging at 750 °C

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Chong, E-mail: chongyan871210@sina.com [School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Central Iron and Steel Research Institute, Beijing 100084 (China); Zhengdong, Liu [Central Iron and Steel Research Institute, Beijing 100084 (China); Godfrey, Andy; Wei, Liu [School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Yuqing, Weng [Central Iron and Steel Research Institute, Beijing 100084 (China)

    2014-01-01

    The microstructure evolution of Inconel 740H during aging at 750 °C for up to 3000 h was investigated by means of optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), three-dimensional atom probe (3DAP) analysis and micro-phase analysis. The mechanical properties of samples after aging were also studied. The grain size increased substantially during the whole aging period. Two different types of grain boundary carbides were observed; block-shaped and needle-shaped. Both were identified to be M{sub 23}C{sub 6} by selected area diffraction measurements. The grain boundary carbides did not coarsen significantly during aging, with the weight fraction increasing only from 0.20% to 0.28%. In contrast, a much higher coarsening rate of γ′ precipitates was observed, as evidenced from both TEM observations and SAXS analysis. 3DAP was used to study the elemental partitioning behavior between γ′ precipitates and γ matrix as well as the evolution in width of the γ/γ′ interface. A large increase in the width of γ/γ′ interfaces was seen between 1000 h and 3000 h aging. In addition, for the sample aged at 750 °C for 3000 h, Cr enrichment on the γ matrix side of the γ/γ′ interface was found. Tensile tests at 750 °C of the aged samples showed a gradual decrease in elevated-temperature yield strength after 500 h, when this alloy was over-aged. The critical precipitate size for the transition from precipitate cutting by weakly coupled dislocations to strongly coupled dislocations for Inconel 740H was calculated to be approximately 50 nm, which agrees well with the experiment measurements of elevated-temperature yield strength. The room temperature impact toughness of all samples decreased during aging as the grain size kept growing.

  12. Effect of cold drawing ratio on γ′ precipitation in Inconel X-750

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Jeong Won [Department of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); Research and Development Center, KOS Limited, Yangsan 626-230 (Korea, Republic of); Seong, Baek Seok [Neutron Science Division, HANARO Center, Korea Atomic Energy Research Institute, Daejon 305-353 (Korea, Republic of); Jeong, Hi Won; Yoo, Young Soo [Advanced Metallic Materials Division, Korea Institute of Materials Science, Changwon 642-831 (Korea, Republic of); Choi, Yoon Suk [Department of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); Kang, Namhyun, E-mail: nhkang@pusan.ac.kr [Department of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of)

    2014-10-15

    Inconel X-750 is a Ni-based precipitation-hardened superalloy having large tensile and fracture strengths. In the study, X-750 wires were cold drawn to different extents. Small angle neutron scattering was employed to quantitatively measure the size and volume fraction of the γ′ phase as a function of the cold drawing ratio (DR) and aging temperature. The presence and size of γ′ precipitates were confirmed by transmission electron microscopy. The drawing ratio had an important effect on the volume fraction of the γ′ precipitates. However, the size of the precipitates was independent on the drawing ratio. The specimen with the minimum drawing ratio (DR0) produced the largest volume fraction of γ′ as compared with large drawing ratio (DR) specimens such as DR17 and DR42. The small volume fraction of the γ′ phase for a sizeable drawing ratio was associated with the large amount of nucleation sites for secondary carbides, M{sub 23}C{sub 6}, and the fast diffusion path, i.e., dislocation, needed to form M{sub 23}C{sub 6}. A Cr depletion zone around the secondary carbides raised the solubility of γ′. Therefore, the significant drawing ratio contributing to the large volume fraction of the secondary carbides decreased the volume fraction of the γ′ precipitates in Inconel X-750. - Highlights: • The volume fraction of secondary carbides increased with the drawing ratio. • The volume fraction of γ′ decreased as the drawing ratio increased. • The drawing ratio affected the γ′ volume fraction with no variation of the γ' size. • The volume fraction of γ′ was affected by the secondary carbide volume fraction.

  13. Effect of cold drawing ratio on γ′ precipitation in Inconel X-750

    International Nuclear Information System (INIS)

    Inconel X-750 is a Ni-based precipitation-hardened superalloy having large tensile and fracture strengths. In the study, X-750 wires were cold drawn to different extents. Small angle neutron scattering was employed to quantitatively measure the size and volume fraction of the γ′ phase as a function of the cold drawing ratio (DR) and aging temperature. The presence and size of γ′ precipitates were confirmed by transmission electron microscopy. The drawing ratio had an important effect on the volume fraction of the γ′ precipitates. However, the size of the precipitates was independent on the drawing ratio. The specimen with the minimum drawing ratio (DR0) produced the largest volume fraction of γ′ as compared with large drawing ratio (DR) specimens such as DR17 and DR42. The small volume fraction of the γ′ phase for a sizeable drawing ratio was associated with the large amount of nucleation sites for secondary carbides, M23C6, and the fast diffusion path, i.e., dislocation, needed to form M23C6. A Cr depletion zone around the secondary carbides raised the solubility of γ′. Therefore, the significant drawing ratio contributing to the large volume fraction of the secondary carbides decreased the volume fraction of the γ′ precipitates in Inconel X-750. - Highlights: • The volume fraction of secondary carbides increased with the drawing ratio. • The volume fraction of γ′ decreased as the drawing ratio increased. • The drawing ratio affected the γ′ volume fraction with no variation of the γ' size. • The volume fraction of γ′ was affected by the secondary carbide volume fraction

  14. Recyclability Study on Inconel 718 and Ti-6Al-4V Powders for Use in Electron Beam Melting

    Science.gov (United States)

    Nandwana, Peeyush; Peter, William H.; Dehoff, Ryan R.; Lowe, Larry E.; Kirka, Michael M.; Medina, Francisco; Babu, Sudarsanam S.

    2016-02-01

    Powder bed-based additive manufacturing technologies offer a big advantage in terms of reusability of the powders over multiple cycles that result in cost savings. However, currently there are no standards to determine the factors that govern the powder reuse times. This work presents the results from a recyclability study conducted on Inconel 718 and Ti-6Al-4V powders. It has been found that the Inconel 718 powders are chemically stable over a large number of cycles and their reuse time is limited by physical characteristics of powders such as flowability. Ti-6Al-4V, on the other hand, finds its reuse time governed by the oxygen pick up that occurs during and in between build cycles. The detailed results have been presented.

  15. A study on the thermal expansion characteristics of Inconel-82 filler wire by high temperature X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Panneerselvam, G.; Antony, M.P. [Fuel Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603 102 (India); Raju, S.; Jose, R.; Divakar, R.; Mohandas, E. [Materials Characterization Group, Physical Metallurgy Section, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603 102 (India); Sivasubramanian, K. [Safety Engineering Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603 102 (India)

    2004-01-01

    The lattice parameter (a) change with respect to temperature (T) has been measured by high temperature X-ray diffraction (HT-XRD) technique for Inconel-82 filler wire used in the TIG welding of a dissimilar joint involving Inconel-600 and commercially pure iron. By taking proper precautions to minimise the temperature gradient across the sample thickness, and by suitably calibrating the shift in 2{theta} produced as a result of sample buckling at high temperatures, we could obtain fairly reliable estimates of lattice parameter in the temperature range 300-1200 K. The lattice parameter and the coefficient of mean linear thermal expansion at 300 K, have been found to be 3.546(2)x10{sup -10} m and 11.03x10{sup -6} K{sup -1}, respectively.

  16. Ultrasonic measurements for in-service assessment of wrought Inconel 625 cracker tubes of heavy water plants

    International Nuclear Information System (INIS)

    The degradation in mechanical properties of Inconel 625 ammonia cracker tubes occurs during the service for long duration in heavy water plants. The present study brings out the possibility of using Poisson's ratio (derived from measurement of time of flight of ultrasonic waves) in combination with hardness measurements, as an effective non-destructive tool for assessment of in-service degradation of Inconel 625 cracker tubes and qualification of re-solution annealing heat treatment for their rejuvenation. Further, the study also indicates the feasibility of extending the life of some of the tubes beyond the presently followed 120 000 h, before they are taken up for re-solution annealing, without affecting their serviceability. However, further studies are required to identify quantitative criterion for Poisson's ratio and hardness values, for deciding on the basis for removal of the tubes for rejuvenation

  17. Experimental Study of Direct Laser Deposition of Ti-6Al-4V and Inconel 718 by Using Pulsed Parameters

    Directory of Open Access Journals (Sweden)

    Kamran Shah

    2014-01-01

    Full Text Available Laser direct metal deposition (LDMD has developed from a prototyping to a single metal manufacturing tool. Its potential for creating multimaterial and functionally graded structures is now beginning to be explored. This work is a first part of a study in which a single layer of Inconel 718 is deposited on Ti-6Al-4V substrate. Single layer tracks were built at a range of powder mass flow rates using a coaxial nozzle and 1.5 kW diode laser operating in both continuous and pulsed beam modes. This part of the study focused on the experimental findings during the deposition of Inconel 718 powder on Ti-6Al-4V substrate. Scanning electron microscopy (SEM and X-ray diffraction analysis were performed for characterization and phase identification. Residual stress measurement had been carried out to ascertain the effects of laser pulse parameters on the crack development during the deposition process.

  18. Determination of Constitutive Equation for Thermo-mechanical Processing of INCONEL 718 Through Double Multivariate Nonlinear Regression Analysis

    Science.gov (United States)

    Hussain, Mirza Zahid; Li, Fuguo; Wang, Jing; Yuan, Zhanwei; Li, Pan; Wu, Tao

    2015-07-01

    The present study comprises the determination of constitutive relationship for thermo-mechanical processing of INCONEL 718 through double multivariate nonlinear regression, a newly developed approach which not only considers the effect of strain, strain rate, and temperature on flow stress but also explains the interaction effect of these thermo-mechanical parameters on flow behavior of the alloy. Hot isothermal compression experiments were performed on Gleeble-3500 thermo-mechanical testing machine in the temperature range of 1153 to 1333 K within the strain rate range of 0.001 to 10 s-1. The deformation behavior of INCONEL 718 is analyzed and summarized by establishing the high temperature deformation constitutive equation. The calculated correlation coefficient ( R) and average absolute relative error ( AARE) underline the precision of proposed constitutive model.

  19. Determination of mass attenuation coefficients and effective atomic numbers for Inconel 738 alloy for different energies obtained from Compton scattering

    International Nuclear Information System (INIS)

    Highlights: ► Mass attenuation coefficient of Inconel 738 superalloy was measured. ► Gamma-ray energies were changed by Compton scattering technique. ► Effective atomic number and electron density are also calculated. ► All parameters decrease with increased energy. ► The experimental values are in good agreement with theoretical ones. - Abstract: The mass attenuation coefficient of Inconel 738 superalloy has been measured at different gamma ray energies by using the Compton scattering technique. The theoretical values of mass attenuation coefficient of a glass sample were calculated using WinXCom program. The effective atomic number and electron density are also calculated. The results showed that the mass attenuation coefficients, effective atomic number and electron density increase with the decrease in gamma ray energies which is in good agreement with theoretical values (less than 2% error)

  20. Fatigue behaviour of a cast nickel-based superalloy Inconel 792-5A at 700 degree C:

    OpenAIRE

    Kruml, Tomáš; Obrtlík, Karel; Petrenec, Martin; POLÁK, Jaroslav

    2006-01-01

    Cylindrical specimens of a cast polycrystalline superalloy, Inconel 792-5A, were cyclically strained under total strain control at 700 compositumC up to the point of fracture. Cyclic hardening curves, the cyclic stress-strain curve and the fatigue-life curve were recorded. The dislocation recorded structure was studied using the technique of oriented foils in a transmission electron microscope. Scanning electron microscopy was used to investigate the surface relief. High amplitude straining i...

  1. Investigation of surface integrity in high-speed ball end milling of cantilever shaped thin plate of Inconel 718

    OpenAIRE

    N.N. Bhopale; R.S. Pawade

    2012-01-01

    The paper addresses the effects of cutting speed and feed on the work piece deflection and surface integrity during milling of cantilever shaped Inconel 718 plate under different cutter orientations. The experiments were conducted on a CNC vertical milling machine using 10 mm diameter TiAlN coated solid carbide ball end milling cutter. Surface integrity is assessed in terms of micro hardness beneath the machined surface. The micro-hardness profile shows different patterns at various cutting p...

  2. Experimental and modeling results of creep-fatigue life of Inconel 617 and Haynes 230 at 850 °C

    Science.gov (United States)

    Chen, Xiang; Sokolov, Mikhail A.; Sham, Sam; Erdman, Donald L., III; Busby, Jeremy T.; Mo, Kun; Stubbins, James F.

    2013-01-01

    Creep-fatigue testing of Ni-based superalloy Inconel 617 and Haynes 230 were conducted in the air at 850 °C. Tests were performed with fully reversed axial strain control at a total strain range of 0.5%, 1.0% or 1.5% and hold time at maximum tensile strain for 3, 10 or 30 min. In addition, two creep-fatigue life prediction methods, i.e. linear damage summation and frequency-modified tensile hysteresis energy modeling, were evaluated and compared with experimental results. Under all creep-fatigue tests, Haynes 230 performed better than Inconel 617. Compared to the low cycle fatigue life, the cycles to failure for both materials decreased under creep-fatigue test conditions. Longer hold time at maximum tensile strain would cause a further reduction in both material creep-fatigue life. The linear damage summation could predict the creep-fatigue life of Inconel 617 for limited test conditions, but considerably underestimated the creep-fatigue life of Haynes 230. In contrast, frequency-modified tensile hysteresis energy modeling showed promising creep-fatigue life prediction results for both materials.

  3. Experimental and modeling results of creep–fatigue life of Inconel 617 and Haynes 230 at 850 °C

    International Nuclear Information System (INIS)

    Creep–fatigue testing of Ni-based superalloy Inconel 617 and Haynes 230 were conducted in the air at 850 °C. Tests were performed with fully reversed axial strain control at a total strain range of 0.5%, 1.0% or 1.5% and hold time at maximum tensile strain for 3, 10 or 30 min. In addition, two creep–fatigue life prediction methods, i.e. linear damage summation and frequency-modified tensile hysteresis energy modeling, were evaluated and compared with experimental results. Under all creep–fatigue tests, Haynes 230 performed better than Inconel 617. Compared to the low cycle fatigue life, the cycles to failure for both materials decreased under creep–fatigue test conditions. Longer hold time at maximum tensile strain would cause a further reduction in both material creep–fatigue life. The linear damage summation could predict the creep–fatigue life of Inconel 617 for limited test conditions, but considerably underestimated the creep–fatigue life of Haynes 230. In contrast, frequency-modified tensile hysteresis energy modeling showed promising creep–fatigue life prediction results for both materials.

  4. Experimental and modeling results of creep fatigue life of Inconel 617 and Haynes 230 at 850 C

    International Nuclear Information System (INIS)

    Creep fatigue testing of Ni-based superalloy Inconel 617 and Haynes 230 were conducted in the air at 850 C. Tests were performed with fully reversed axial strain control at a total strain range of 0.5%, 1.0% or 1.5% and hold time at maximum tensile strain for 3, 10 or 30 min. In addition, two creep fatigue life prediction methods, i.e. linear damage summation and frequency-modified tensile hysteresis energy modeling, were evaluated and compared with experimental results. Under all creep fatigue tests, Haynes 230 performed better than Inconel 617. Compared to the low cycle fatigue life, the cycles to failure for both materials decreased under creep fatigue test conditions. Longer hold time at maximum tensile strain would cause a further reduction in both material creep fatigue life. The linear damage summation could predict the creep fatigue life of Inconel 617 for limited test conditions, but considerably underestimated the creep fatigue life of Haynes 230. In contrast, frequency-modified tensile hysteresis energy modeling showed promising creep fatigue life prediction results for both materials.

  5. Pitting resistance of TiN deposited on Inconel 600 by plasma-assisted chemical vapor deposition

    International Nuclear Information System (INIS)

    TiN films were deposited on Inconel 600 by PACVD using the gaseous mixture of TiCl4, N2, H2, and Ar in order to increase the pitting resistance of Inconel 600. The pitting resistance was examined using a potentiodynamic polarization technique with a chloride solution. The effect of chloride concentration in the electrolyte on the pitting potential was also investigated. Inconel 600 coated with TiN film shows a superior pitting resistance to that without TiN film in condition that the thickness of the film is greater than a certain critical value. As the deposition temperature as well as the RF power increases, the residual Cl concentration in the film decreases, resulting in the improvement of the pitting resistance. However, the TiN films deposited at too high RF powers, even though the Cl concentration in TiN film is very small, show inferior pitting resistance, which is due to the formation of the network type microvoids structure. ((orig.))

  6. Novel microstructural growth in the surface of Inconel 625 by the addition of SiC under electron beam melting

    International Nuclear Information System (INIS)

    Electron beam melting is being used to modify the microstructure of the surfaces of materials due to its ability to cause localized melting and supercooling of the melt. This article presents an experimental study on the surface modification of Ni-based superalloy (Inconel 625) reinforced with SiC ceramic particles under electron beam melting. Scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction techniques have been applied to characterize the resulted microstructure. The results revealed growth of novel structures like wire, rod, tubular, pyramid, bamboo and tweezers type morphologies in the modified surface. In addition to that fibrous like structure was also observed. Formation of thin carbon sheet has been found at the regions of decomposed SiC. Electron beam modified surface of Inconel 625 alloy has been hardened twice as compared to the as-received samples. Surface hardening effect may be attributed to both the formation of the novel structures as well as the introduction of Si and C atom in the lattice of Inconel 625 alloy.

  7. Probabilistic Material Strength Degradation Model for Inconel 718 Components Subjected to High Temperature, Mechanical Fatigue, Creep and Thermal Fatigue Effects

    Science.gov (United States)

    Bast, Callie Corinne Scheidt

    1994-01-01

    This thesis presents the on-going development of methodology for a probabilistic material strength degradation model. The probabilistic model, in the form of a postulated randomized multifactor equation, provides for quantification of uncertainty in the lifetime material strength of aerospace propulsion system components subjected to a number of diverse random effects. This model is embodied in the computer program entitled PROMISS, which can include up to eighteen different effects. Presently, the model includes four effects that typically reduce lifetime strength: high temperature, mechanical fatigue, creep, and thermal fatigue. Statistical analysis was conducted on experimental Inconel 718 data obtained from the open literature. This analysis provided regression parameters for use as the model's empirical material constants, thus calibrating the model specifically for Inconel 718. Model calibration was carried out for four variables, namely, high temperature, mechanical fatigue, creep, and thermal fatigue. Methodology to estimate standard deviations of these material constants for input into the probabilistic material strength model was developed. Using the current version of PROMISS, entitled PROMISS93, a sensitivity study for the combined effects of mechanical fatigue, creep, and thermal fatigue was performed. Results, in the form of cumulative distribution functions, illustrated the sensitivity of lifetime strength to any current value of an effect. In addition, verification studies comparing a combination of mechanical fatigue and high temperature effects by model to the combination by experiment were conducted. Thus, for Inconel 718, the basic model assumption of independence between effects was evaluated. Results from this limited verification study strongly supported this assumption.

  8. Service experience and stress corrosion of Inconel 600 bellows expansion joints in turbine-steam environments

    International Nuclear Information System (INIS)

    Over 100 Inconel 600 single and 2-ply expansion joints exposed to less than 3800C high purity water for times up to 12 years at 100 to 250 psig have experienced failures in only 7 cases. Mill annealed sheets are gas tungsten welded and may or may not be stress relieved. Design and structural details are given; statistics on number of joints and service times are listed. Details of 7 failures include pressures, boiler type, water treatment, turbine inlet conditions, temperatures and other parameters. Steam was greater than 3150C and 140 psig. Deposits from failed joints showed magnetite, various carbonates, calcium, silicates, and sodium orthophosphate. The sulfate anion was found also in some locations. Microscopic examination of failed zones showed carbide aggregations. Hydroxide and sodium ions were found in cracks. Failures were attributed to caustic stress corrosion cracking resulting from excursions of water treatment chemicals. Laboratory tests were made of stressed samples in high purity, low oxygen water, boiling ferric sulfate, inhibited sulfuric acid, potassium-sodium hydroxide; in 2700C air with fused caustic-steam environments was 25 ksi. Silicon dioxide promoted cracking in K-NaOH. Annealed specimens did not crack in 3300C high purity water even after pickling in nitric-hydrofluoric acid. Caustic concentrations over 50 percent were necessary for cracking

  9. Lattice strain development in Inconel-690 under bi-axial compression and tension

    Science.gov (United States)

    Toda, Rebecca Midori

    Nuclear reactor steam generator tubes, manufactured from Nickel alloys such as Inconel 690 (INC690), are potentially susceptible to failure by Stress Corrosion Cracking where crack initiation may be exacerbated by internal stress fields. A more comprehensive understanding of this potential failure mechanism was gained via an exploration of a model of INC690.s behaviour under Constrained loading conditions in compression and tension. An Elasto-Plastic Self-Consistent (EPSC) model was used to predict the lattice stresses and strains resulting from Constrained loading in INC690 for four crystallographic planes. The internal strain fields generated under such conditions were shown to be markedly different from those developed under Uniaxial loading. Finite Element Modeling was used to design tensile and compression samples as well as a testing rig that would allow the application of a compressive load along one axis of the specimen with simultaneous constraint along another and free-deformation along the third. Lattice strain measurements were done for both compressive and tensile loading using Time-Of-Flight neutron diffraction. The predicted and experimental values showed reasonable agreement; mainly in terms of crystallographic plane interaction and behaviour. Iterative computer modeling was used to achieve a more realistic depiction of the lattice strains developed. This research allowed for an extension on the Uniaxial findings by examining the material's behaviour under more complex loading that better approximates steam generator tube operating conditions.

  10. Influence of overloads on dwell time fatigue crack growth in Inconel 718

    International Nuclear Information System (INIS)

    Inconel 718 is one of the most commonly used superalloys for high temperature applications in gasturbines and aeroengines and is for example used for components such as turbine discs. Turbine discs can be subjected to temperatures up to ∼700 °C towards the outer radius of the disc. During service, the discs might start to develop cracks due to fatigue and long dwell times. Additionally, temperature variations during use can lead to large thermal transients during start-up and shutdown which can lead to overload peaks in the normal dwell time cycle. In this study, tests at 550 °C with an overload prior to the start of each dwell time, have been performed. The aim of the investigation was to get a better understanding of the effects of overloads on the microstructure and crack mechanisms. The microstructure was studied using electron channelling contrast imaging (ECCI). The image analysis toolbox in Matlab was used on cross sections of the cracks to quantify: crack length, branch length, and the number of branches in each crack. It was found that the amount of crack branching increases with an increasing overload and that the branch length decreases with an increasing overload. When the higher overloads were applied, the dwell time effect was almost cancelled out. There is a strong tendency for an increased roughness of the crack path with an increasing crack growth rate

  11. Examination of inconel X-750 screw of Chooz-A internal components

    International Nuclear Information System (INIS)

    During the 1984/85 routine shutdown of CHOOZ-A pressurized water reactor, several bolt heads of the core barrel joint were found broken after 100 000 hours of operation. These failures were attributed to intergranular strengths corrosion cracking of the Inconel X-750 bolts. However, to state more precisely the origin of failures, additional mechanical tests (microhardness, tensile tests) and metallurgical examinations (fractography, optical and electron microscopy) have been performed on irradiated bolts. The microhardness measurements reveal a marked hardening which happens between 3.4 and 6.5 104h, then saturates for longer operation time. The tensile tests at room temperature show a decrease in total elongation, yield and ultimate strengths, which seems related with the value of release torque. On the other hand, TEM examinations allow to detect a significant change in Inc. X-750 microstructure after 100000 h operation. This change mainly includes additional precipitation during operation at 2700C and nucleation of defects induced by irradiation at low fluence (dislocation loops and bubbles or microvoids). In conclusion, to explain the observed failures, both thermal ageing and irradiation effects have to be taken in account

  12. Investigation of INCONEL X750 screws from internal structures of Chooz-A reactor

    International Nuclear Information System (INIS)

    During the 1984/85 routine shutdown of CHOOZ-A pressurized water reactor, several bolt heads of the core barrel joint were found broken after 100 000 hours of operation. These failures were attributed to intergranular strengths corrosion cracking of the Inconel X-750 bolts. Additional mechanical tests (microhardness, tensile tests) and metallurgical examinations (fractography, optical and electron microscopy) have been performed on irradiated bolts. The microhardness measurements reveal a marked hardening which happens between 3.4 and 6.5 104h, then saturates for longer operation time. The tensile tests at room temperature show a decrease in total elongation, yield and ultimate strengths, which seems related with the value of release torque. TEM examinations allow to detect a significant change in Inc. X-750 microstructure after 100000 h operation. This change mainly includes additional precipitation during operation at 2700C and nucleation of defects induced by irradiation at low fluence (dislocation loops and bubbles or microvoids). In conclusion, both thermal ageing and irradiation effects have to be taken in account

  13. Mechanical Characterization of an Additively Manufactured Inconel 718 Theta-Shaped Specimen

    Science.gov (United States)

    Cakmak, Ercan; Watkins, Thomas R.; Bunn, Jeffrey R.; Cooper, Ryan C.; Cornwell, Paris A.; Wang, Yanli; Sochalski-Kolbus, Lindsay M.; Dehoff, Ryan R.; Babu, Sudarsanam S.

    2016-02-01

    Two sets of "theta"-shaped specimens were additively manufactured with Inconel 718 powders using an electron beam melting technique with two distinct scan strategies. Light optical microscopy, mechanical testing coupled with a digital image correlation (DIC) technique, finite element modeling, and neutron diffraction with in situ loading characterizations were conducted. The cross-members of the specimens were the focus. Light optical micrographs revealed that different microstructures were formed with different scan strategies. Ex situ mechanical testing revealed each build to be stable under load until ductility was observed on the cross-members before failure. The elastic moduli were determined by forming a correlation between the elastic tensile stresses determined from FEM, and the elastic strains obtained from DIC. The lattice strains were mapped with neutron diffraction during in situ elastic loading; and a good correlation between the average axial lattice strains on the cross-member and those determined from the DIC analysis was found. The spatially resolved stresses in the elastic deformation regime are derived from the lattice strains and increased with applied load, showing a consistent distribution along the cross-member.

  14. 3D imaging and characterisation of strengthening particles in inconel 718 using FIB tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kruk, Adam; Gruszczynski, Adam; Czyrska-Filemonowicz, Aleksandra [AGH University of Science and Technology, Faculty of Metals Engineering and Industrial Computer Science, Al. A. Mickiewicza 30, 30-059 Krakow (Poland)

    2011-07-01

    The Inconel 718 is a commercial nickel-base superalloy, widely used for critical pieces in turbine engines. Its microstructure consists of the {gamma} matrix and strengthening coherent nanoparticles {gamma}' and {gamma}''. In the present work FIB tomography technique was used for imaging and characterisation of strengthening particles. FIB tomography is based on a serial sectioning procedure using a FIB/SEM dual beam workstation. Repeated removal of layers as thin as several nm for some hundred times allows to investigate at total a volume of some {mu}m3 with a voxel size as 2.5 nm x 2.5 nm x 2.5 nm. 3D mapping of nanoparticles with high Z-resolution by serial FIB slicing (in a distance of about 2.5 nm) and SEM imaging was performed. Ga ion beam at 30 kV was used to perform a precise in-situ milling. The SEM images at accelerating voltage 1.5 kV were taken with using ESB detector. The real 3D-data of precipitates obtained by FIB tomography, open a new possibility for microstructure analysis of materials for industrial applications.

  15. Biaxial thermal creep of Inconel 617 and Haynes 230 at 850 and 950 °C

    International Nuclear Information System (INIS)

    The biaxial thermal creep behavior of Inconel 617 and Haynes 230 at 850 and 950 °C was investigated. Biaxial stresses were generated using the pressurized tube technique. The detailed creep deformation and fracture mechanism have been studied. Creep curves for both alloys showed that tertiary creep accounts for a greater portion of the materials’ life, while secondary creep only accounts for a small portion. Fractographic examinations of the two alloys indicated that nucleation, growth, and coalescence of creep voids are the dominant micro-mechanisms for creep fracture. At 850 °C, alloy 230 has better creep resistance than alloy 617. When subjected to the biaxial stress state, the creep rupture life of the two alloys was considerably reduced when compared to the results obtained by uniaxial tensile creep tests. The Monkman–Grant relation proves to be a promising method for estimating the long-term creep life for alloy 617, whereas alloy 230 does not follow the relation. This might be associated with the significant changes in the microstructure of alloy 230 at high temperatures

  16. Biaxial thermal creep of Inconel 617 and Haynes 230 at 850 and 950 °C

    Energy Technology Data Exchange (ETDEWEB)

    Tung, Hsiao-Ming, E-mail: hmtung2@gmail.com [Institute of Nuclear Energy Research, Longtan, Taoyuan 32546, Taiwan, ROC (China); Mo, Kun; Stubbins, James F. [Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, 104 South Wright Street, Urbana, IL 61801 (United States)

    2014-04-01

    The biaxial thermal creep behavior of Inconel 617 and Haynes 230 at 850 and 950 °C was investigated. Biaxial stresses were generated using the pressurized tube technique. The detailed creep deformation and fracture mechanism have been studied. Creep curves for both alloys showed that tertiary creep accounts for a greater portion of the materials’ life, while secondary creep only accounts for a small portion. Fractographic examinations of the two alloys indicated that nucleation, growth, and coalescence of creep voids are the dominant micro-mechanisms for creep fracture. At 850 °C, alloy 230 has better creep resistance than alloy 617. When subjected to the biaxial stress state, the creep rupture life of the two alloys was considerably reduced when compared to the results obtained by uniaxial tensile creep tests. The Monkman–Grant relation proves to be a promising method for estimating the long-term creep life for alloy 617, whereas alloy 230 does not follow the relation. This might be associated with the significant changes in the microstructure of alloy 230 at high temperatures.

  17. Biaxial thermal creep of Inconel 617 and Haynes 230 at 850 and 950 °C

    Science.gov (United States)

    Tung, Hsiao-Ming; Mo, Kun; Stubbins, James F.

    2014-04-01

    The biaxial thermal creep behavior of Inconel 617 and Haynes 230 at 850 and 950 °C was investigated. Biaxial stresses were generated using the pressurized tube technique. The detailed creep deformation and fracture mechanism have been studied. Creep curves for both alloys showed that tertiary creep accounts for a greater portion of the materials' life, while secondary creep only accounts for a small portion. Fractographic examinations of the two alloys indicated that nucleation, growth, and coalescence of creep voids are the dominant micro-mechanisms for creep fracture. At 850 °C, alloy 230 has better creep resistance than alloy 617. When subjected to the biaxial stress state, the creep rupture life of the two alloys was considerably reduced when compared to the results obtained by uniaxial tensile creep tests. The Monkman-Grant relation proves to be a promising method for estimating the long-term creep life for alloy 617, whereas alloy 230 does not follow the relation. This might be associated with the significant changes in the microstructure of alloy 230 at high temperatures.

  18. Radiation blistering in Inconel-625 due to 100 KeV helium ion irradiation

    International Nuclear Information System (INIS)

    The objective of this study was to determine whether the change of angle of incidence of an ion beam impinging on surface blisters during their growth phase (before exfoliation) could influence the blister skin thickness and the blister crater depth. Polished, polycrystalline Inconel-625 samples were irradiated at room temperature and at normal incidence to the major sample surface with 100 keV helium ions to a total dose of 6.24x1018 ions/cm2. The results revealed that many exfoliated blisters leave craters which have two or three concentric pits. The blister skin thickness near the center of the blister was found to agree well with the calculated projected range of 100 keV He ions in nickel. However, the blister skin thickness of some exfoliated blisters along the edge of the fracture surface showed different thicknesses. A model is proposed to explain the observed blister crater/blister fracture features in terms of a change of angle of incidence of the incident ions to the surface during the growth phase of surface blisters. (orig.)

  19. Analisis Kegagalan Retak dan Teknologi Perbaikan Sudu Turbin Jenis Inconel 792 pada Pesawat Terbang

    Directory of Open Access Journals (Sweden)

    Suharno .

    2013-01-01

    Full Text Available Penelitian untuk melakukan analisis terhadap kegagalan retak telah dilakukan pada sudu turbin dari Auxiliary Power Unit (APU pesawat terbang. Bahan sudu turbin adalah paduan super  Inconel 792. Pengujian yang dilakukan meliputi inspeksi visual, pengujian komposisi kimia, fractography, pengujian kekerasan, dan metalografi.Hasilnya menunjukkan bahwa patah dimulai dari celah dan retak makro dan kemudian menjalar/merambat menjadi retak terbuka di permukaan.Hal ini kemungkinan disebabkan oleh mekanisme retak panas selama perbaikan las sebelumnya. Kandungan Aluminium dan Titanium yang tinggi pada logam las, menjadikan material menjadi rapuh, hal ini ditunjukkan oleh fitur intergranular dibandingkan dengan aspek pembelahan transgranular menunjukkan bahwa keuletan pada lasan rendah. Dibandingkan dengan sudu yang tidak rusak (gagal, ukuran butir dari sudu turbin yang rusak adalah sangat berbeda menunjukkan eksposisi terhadap panas baik dari siklus termal pengelasan atau lingkungan operasi normal pada suhu tinggi.Teknik perbaikan lebih lanjut dikembangkan berdasarkan keberhasilan PQTR yang di uji dengan kekerasan mikro, destructive dan non destructive test.Untuk tujuan ini maka dipilih las GTAW yang diikuti dengan solution dan aging treatment.

  20. Molding Properties of Inconel 718 Feedstocks Used in Low-Pressure Powder Injection Molding

    Directory of Open Access Journals (Sweden)

    Fouad Fareh

    2016-01-01

    Full Text Available The impact of binders and temperature on the rheological properties of feedstocks used in low-pressure powder injection molding was investigated. Experiments were conducted on different feedstock formulations obtained by mixing Inconel 718 powder with wax-based binder systems. The shear rate sensitivity index and the activation energy were used to study the degree of dependence of shear rate and temperature on the viscosity of the feedstocks. The injection performance of feedstocks was then evaluated using an analytical moldability model. The results indicated that the viscosity profiles of feedstocks depend significantly on the binder constituents, and the secondary binder constituents play an important role in the rheological behavior (pseudoplastic or near-Newtonian exhibited by the feedstock formulations. Viscosity values as low as 0.06 to 2.9 Pa·s were measured at high shear rates and high temperatures. The results indicate that a feedstock containing a surfactant agent exhibits the best moldability characteristics.

  1. Analytical methods to characterize heterogeneous raw material for thermal spray process: cored wire Inconel 625

    Science.gov (United States)

    Lindner, T.; Bonebeau, S.; Drehmann, R.; Grund, T.; Pawlowski, L.; Lampke, T.

    2016-03-01

    In wire arc spraying, the raw material needs to exhibit sufficient formability and ductility in order to be processed. By using an electrically conductive, metallic sheath, it is also possible to handle non-conductive and/or brittle materials such as ceramics. In comparison to massive wire, a cored wire has a heterogeneous material distribution. Due to this fact and the complex thermodynamic processes during wire arc spraying, it is very difficult to predict the resulting chemical composition in the coating with sufficient accuracy. An Inconel 625 cored wire was used to investigate this issue. In a comparative study, the analytical results of the raw material were compared to arc sprayed coatings and droplets, which were remelted in an arc furnace under argon atmosphere. Energy-dispersive X-ray spectroscopy (EDX) and X-ray fluorescence (XRF) analysis were used to determine the chemical composition. The phase determination was performed by X-ray diffraction (XRD). The results were related to the manufacturer specifications and evaluated in respect to differences in the chemical composition. The comparison between the feedstock powder, the remelted droplets and the thermally sprayed coatings allows to evaluate the influence of the processing methods on the resulting chemical and phase composition.

  2. Experimental Investigation and Optimization of Response Variables in WEDM of Inconel - 718

    Science.gov (United States)

    Karidkar, S. S.; Dabade, U. A.

    2016-02-01

    Effective utilisation of Wire Electrical Discharge Machining (WEDM) technology is challenge for modern manufacturing industries. Day by day new materials with high strengths and capabilities are being developed to fulfil the customers need. Inconel - 718 is similar kind of material which is extensively used in aerospace applications, such as gas turbine, rocket motors, and spacecraft as well as in nuclear reactors and pumps etc. This paper deals with the experimental investigation of optimal machining parameters in WEDM for Surface Roughness, Kerf Width and Dimensional Deviation using DoE such as Taguchi methodology, L9 orthogonal array. By keeping peak current constant at 70 A, the effect of other process parameters on above response variables were analysed. Obtained experimental results were statistically analysed using Minitab-16 software. Analysis of Variance (ANOVA) shows pulse on time as the most influential parameter followed by wire tension whereas spark gap set voltage is observed to be non-influencing parameter. Multi-objective optimization technique, Grey Relational Analysis (GRA), shows optimal machining parameters such as pulse on time 108 Machine unit, spark gap set voltage 50 V and wire tension 12 gm for optimal response variables considered for the experimental analysis.

  3. Influence of the Oxygen Partial Pressure on the Oxidation of Inconel 617 Alloy at High Temperature

    International Nuclear Information System (INIS)

    Ni-based superalloy Inconel 617 (IN617) is one of the main candidate structural materials for high temperature components (heat exchanger) of the gas-cooled fast reactor (GFR), a possible candidate for generation IV nuclear reactor. The material in operating conditions will be exposed to impure He at a temperature of around 850 C. The impurities are expected to be oxidizing (such as O2, H2O) but since no feedback experience is available for this type of reactor, the level of impurities is completely unknown. Hence, an attempt has been made to understand the influence of oxygen partial pressure on oxide composition and on the oxidation mechanisms of IN617 at 850 C. To achieve this, oxidation tests were performed at 3 different range of partial pressure: 10-5, 0. 2 and 200 mbar. Tests were performed from 1 h to 28 days and the obtained oxide layers were characterized using MEB, EDX, XPS, XRD and GD-OES. The oxide layers were mainly composed of chromia containing TiO2 and thickening with time. Aluminium oxide formed internally. Other oxides were detected in the scale, such as NiO, CoO, MoO3 and MnO2, except for the lowest oxygen partial pressure experiments, where a selective oxidation took place. The scale-growth mechanism was cationic for low and medium oxygen partial pressure conditions. A growth following a transient oxidation mechanism was observed for high oxygen partial pressure. (authors)

  4. Effect of Grain Size Distribution on Processing Maps for Isothermal Compression of Inconel 718 Superalloy

    Science.gov (United States)

    Wang, Jianguo; Liu, Dong; Hu, Yang; Yang, Yanhui; Zhu, Xinglin

    2016-02-01

    Cylindrical specimens of Inconel 718 alloys with three types of grain size distribution were used in the compression tests and processing maps were developed in 940-1040 °C and 0.001-10 s-1. The equiaxed fine grain is more effective on the dynamic softening behavior. For partial recrystallized microstructure, the peak efficiency of power dissipation occurs at the strain rate of 0.001 s-1, and the temperature range of 1000-1020 °C. In order to obtain homogeneous microstructure with fine grains, the partial recrystallized microstructure should be deformed at the low temperature and slow strain rates. The area fraction of instability domains decreases with strain increasing. The peak efficiency of power dissipation increases with average grain size decreasing. The efficiency of power dissipation will be stimulated by the precipitation of δ phase at slow strain rate of 0.001-0.01 s-1, and the initial deformed substructure at the strain rate of 0.1-1 s-1. Equiaxed fine grain is the optimum state for forging process and dynamic recrystallization. The grain size distribution has slight influence on the microstructure evolution at high temperatures.

  5. Microstructural evolution and mechanical properties of Inconel 718 after thermal exposure

    International Nuclear Information System (INIS)

    Inconel 718 was subjected to various heat treatments, i.e., solution heat treatment, standard ageing treatment and standard ageing plus 700 °C thermal exposure. The mechanical properties of the alloys were determined using tensile tests and Charpy pendulum impact tests at 650 °C and room temperature, respectively. The highest yield strength of 988 MPa was attained in the standard aged specimen, whereas a maximum impact toughness of 217 J cm−2 was attained in the solution-treated specimen. After thermal exposure, the mechanical properties of the specimens degrade. Both the yield strength and impact toughness decreased monotonically with increasing thermal exposure time. Subjected to a 10000-h long-term thermal exposure, the yield strength dramatically decreased to 475 MPa (almost 50% of the maximum strength), and the impact toughness reduced to only 18 J cm−2. The microstructures of the specimens were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Coarsening of γ′ and γ″ and the transformation of γ″ to δ-Ni3Nb was observed after thermal exposure. However, a complete transformation from metastable γ″ to δ-Ni3Nb was never accomplished, even after the 10000-h long-term thermal exposure. Based on the obtained experimental results, the effects of the microstructural evolution on the mechanical properties are discussed

  6. A comparative study on fiber laser and CO2 laser welding of Inconel 617

    International Nuclear Information System (INIS)

    Highlights: • The difference change of weld bead geometry occurs in fiber and CO2 laser welding. • The melting efficiency in fiber laser and CO2 laser welding is analyzed. • Secondary dendrite arm spacing and cooling rate in two laser weldings is studied. • The second phase in two laser welding with different heat input is investigated. - Abstract: A comparative study on the influence of fiber laser welding (FLW) and CO2 laser welding (CLW) on the weld bead geometry and the microstructure of fusion zone (FZ) of Inconel 617 was investigated. In CLW joints, the weld bead geometry is Y-type shape. In FLW joints, the weld bead geometry transforms from Y-type to I-type with the decrease of the heat input. The minimum heat input required to achieve the full penetration of the weldment in FLW is lower than the CLW. The melting efficiency in FLW is higher than that in CLW. From the top to the root regions, the secondary dendrite arm spacing (SDAS) in fiber laser welded FZ undergoes a smaller change than that in CO2 laser welded FZ. The elements of Ti, Mo, Cr and Co segregate into the interdendritic regions both in FLW and CLW process. The second phases in CLW with the highest input of 360 J/mm are much larger and more than ones in FLW with the highest heat input of 210.5 J/mm

  7. Microstructural evolution and mechanical properties of Inconel 718 after thermal exposure

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Z.S., E-mail: yuzaisong@tpri.com.cn [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, No. 28, Xianning West Road, Xi’an 710049 (China); Xi' an Thermal Power Research Institute Co. Ltd., No. 136, Xingqing Road, Xi’an 710032 (China); Zhang, J.X. [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, No. 28, Xianning West Road, Xi’an 710049 (China); Yuan, Y.; Zhou, R.C.; Zhang, H.J.; Wang, H.Z. [Xi' an Thermal Power Research Institute Co. Ltd., No. 136, Xingqing Road, Xi’an 710032 (China)

    2015-05-14

    Inconel 718 was subjected to various heat treatments, i.e., solution heat treatment, standard ageing treatment and standard ageing plus 700 °C thermal exposure. The mechanical properties of the alloys were determined using tensile tests and Charpy pendulum impact tests at 650 °C and room temperature, respectively. The highest yield strength of 988 MPa was attained in the standard aged specimen, whereas a maximum impact toughness of 217 J cm{sup −2} was attained in the solution-treated specimen. After thermal exposure, the mechanical properties of the specimens degrade. Both the yield strength and impact toughness decreased monotonically with increasing thermal exposure time. Subjected to a 10000-h long-term thermal exposure, the yield strength dramatically decreased to 475 MPa (almost 50% of the maximum strength), and the impact toughness reduced to only 18 J cm{sup −2}. The microstructures of the specimens were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Coarsening of γ′ and γ″ and the transformation of γ″ to δ-Ni{sub 3}Nb was observed after thermal exposure. However, a complete transformation from metastable γ″ to δ-Ni{sub 3}Nb was never accomplished, even after the 10000-h long-term thermal exposure. Based on the obtained experimental results, the effects of the microstructural evolution on the mechanical properties are discussed.

  8. Structure and Properties of the Aluminide Coatings on the Inconel 625 Superalloy

    Science.gov (United States)

    Adamiak, Stanisław; Bochnowski, Wojciech; Dziedzic, Andrzej; Filip, Ryszard; Szeregij, Eugeniusz

    2016-01-01

    The research samples used in this study were based on the Inconel 625 alloy; the examined samples were coated with aluminide films deposited in a low-activity chemical vapor deposition (CVD) process. The samples' microstructure was investigated with optical and electron microscopy and energy dispersive X-ray spectroscopy analysis. Hardness measurements were performed using Vickers and Berkovich test methods. The adhesion of the aluminide coating was determined by fractography. It was shown that the fracture mechanism was different for the respective zones of the aluminide coating and the substrate material. The outer zone of the aluminide coating is characterized by an intercrystalline fracture, with a small contribution of transcrystalline fracture within individual grains (large crystallites in the bottom of the zone, composed of smaller crystallites, also show an intercrystalline fracture). The substrate material exhibited a ductile intercrystalline fracture. Based on this investigation, an increase of the microhardness of the material occurring at loads below 0.2 N was observed. When determining microhardness of aluminide coating it is necessary to take into account the optimal choice of the indentation tip.

  9. Microhardness and microstructure evolution of TiB2 reinforced Inconel 625/TiB2 composite produced by selective laser melting

    Science.gov (United States)

    Zhang, Baicheng; Bi, Guijun; Nai, Sharon; Sun, Chen-nan; Wei, Jun

    2016-06-01

    In this study, micron-size TiB2 particles were utilized to reinforce Inconel 625 produced by selective laser melting. Exceptional microhardness 600-700 HV0.3 of the composite was obtained. In further investigation, the microstructure and mechanical properties of Inconel 625/TiB2 composite can be significantly influenced by addition of TiB2 particles during SLM. It was found that the long directional columnar grains observed from SLM-processed Inconel 625 were totally changed to fine dendritic matrix due to the addition of TiB2 particles. Moreover, with laser energy density (LED) of 1200 J/m, a Ti, Mo rich interface around TiB2 particles with fine thickness can be observed by FESEM and EDS. The microstructure evolution can be determined by different laser energy density (LED): under 1200 J/m, γ phase in dendrite grains; under 600 J/m, γ phase in combination of dendritic and acicular grains; under 400 J/m, γ phase acicular grains. Under optimized LED 1200 J/m, the dynamic nanohardness (8.62 GPa) and elastic modulus (167 GPa) of SLM-processed Inconel 625/TiB2 composite are higher compared with those of SLM-processed Inconel 625 (3.97 GPa and 135 GPa, respectively).

  10. High Temperature Oxidation Behavior of Inconel Alloy 740H in Pure Steam%Inconel 740H 合金在纯水蒸气环境中的高温氧化行为

    Institute of Scientific and Technical Information of China (English)

    鲁金涛; 杨珍; 徐松乾; 赵海平; 赵新宝; 谷月峰

    2015-01-01

    The oxidation behavior of Inconel alloy 740 H in dynamic pure steam at 750 ℃ was studied with high temperature oxidation test.The results show that the mass gain of Inconel alloy 740 H during oxidation followed a parabolic law approximately.The oxide products grew coarse with the increase of oxidation time.The scale morphology was significantly different from those after oxidation in dry air.But non obvious cracks and spallation were observed.After oxidation for 100 h,the protective Cr2 O 3 film formed on the surface.The thickness of oxide film increased with time increasing.After oxidation for 1 000 h,the oxide film was composed of Cr2 O 3 and a small amount of (Mn,Ni)Cr2 O 4 spinel.Beneath the oxide scale,chromium depletion region was found and a small amount of inner oxides identified as Al2 O 3 and TiO 2 were observed.%通过高温氧化试验研究了 Inconel 740 H 合金在750℃的动态纯水蒸气环境中的氧化行为。结果表明:Inconel 740 H 合金的氧化增重近似遵循抛物线规律,随氧化时间的延长氧化产物粗大;氧化膜形貌与在干燥空气中氧化的明显不同,但未发现明显的氧化膜开裂和剥落现象;合金氧化100 h 后形成连续的 Cr2 O 3氧化膜,氧化膜厚度随着氧化时间的增加而增大;氧化1000 h后形成的氧化膜主要由 Cr2 O 3和少量的(Mn,Ni)Cr2 O 4尖晶石组成,靠近氧化膜的合金内部出现明显的贫铬区,并伴生少量的 Al2 O 3和 TiO 2内氧化产物。

  11. Influence of Strengthening Elements on Precipitation of Thermodynamic Equilibrium Phases in Inconel Alloy 740H%Inconel 740H主要强化元素对热力学平衡相析出行为的影响

    Institute of Scientific and Technical Information of China (English)

    符锐; 林富生; 赵双群; 迟成宇

    2013-01-01

    Thermodynamic calculation was carried out on the Ni-based Inconel alloy 740H for 700 ℃ advanced ultra supercritical (A-USC) superheaters and reheaters,so as to study the influence of the main strengthening elements on precipitation of the equilibrium phases.Results show that both γ' and M23C6 in the alloy have a good stability in a wide temperature range.Elements Al,Ti and Nb affect much but element Co influences little on the precipitation of phases γ',ηand σ,in which Al promotes the precipitation and stabilization of γ' and σ,but suppresses the precipitation of η,while Ti and Nb promote precipitation of all the phases γ',ηand σ.Elements C and Cr respectively affect much on the precipitation quantity and temperature of M23C6.The composition of Inconel alloy 740H can be optimized by reasonably control the mass fractions of elements Al,Ti,Nb,C,Cr and Co.%对700℃等级超超临界电站过热器/再热器管材所用镍基高温合金Inconel 740H进行热力学相计算并研究了主要析出强化元素对其平衡析出相析出行为的影响.结果表明:合金中γ '相和M23C6碳化物稳定温度范围较宽;Al、Ti和Nb3种元素对γ'相、η相和σ相的析出行为影响较大,而Co元素对其影响不大,其中Al对γ'相和σ相的析出和稳定有促进作用,对η相却有抑制作用,Ti和Nb对γ'相、η相和σ相均有促进作用;C对M23C6碳化物析出量的影响显著,而Cr对M23C6的析出温度影响显著.将Al、Ti、Nb、C和Cr的质量分数控制在一定范围内并适当减小Co的质量分数,可以使Inconel 740H合金的成分范围得到一定的优化.

  12. Liquid Oxygen Rotating Friction Ignition Testing of Aluminum and Titanium with Monel and Inconel for Rocket Engine Propulsion System Contamination Investigation

    Science.gov (United States)

    Peralta, S.; Rosales, Keisa R.; Stoltzfus, Joel M.

    2009-01-01

    Metallic contaminant was found in the liquid oxygen (LOX) pre-valve screen of the shuttle main engine propulsion system on two orbiter vehicles. To investigate the potential for an ignition, NASA Johnson Space Center White Sands Test Facility performed (modified) rotating friction ignition testing in LOX. This testing simulated a contaminant particle in the low-pressure oxygen turbo pump (LPOTP) and the high-pressure oxygen turbo pump (HPOTP) of the shuttle main propulsion system. Monel(R) K-500 and Inconel(R) 718 samples represented the LPOTP and HPOTP materials. Aluminum foil tape and titanium foil represented the contaminant particles. In both the Monel(R) and Inconel(R) material configurations, the aluminum foil tape samples did not ignite after 30 s of rubbing. In contrast, all of the titanium foil samples ignited regardless of the rubbing duration or material configuration. However, the titanium foil ignitions did not propagate to the Monel and Inconel materials.

  13. Effect of specimen geometry on low-cycle fatigue property of Inconel 617 at HTGR temperatures

    International Nuclear Information System (INIS)

    In order to select a suitable specimen geometry for the evaluation of environment effect on fatigue property at HTGR temperatures, comparison was made between low-cycle fatigue strengths obtained for two types of specimens, solid cylindrical and hourglass specimens. A set of low-cycle fatigue tests were carried out on Ni-base wrought alloy Inconel 617 at 800 deg C and 1000 deg C in air and helium 4-nine purity. Strain was measured by two types of extensometers; (1) Hourglass specimen with a diametral extensometer, (2) Solid cylindrical specimen with a diametral extensometer, and (3) Solid cylindrical specimen with an axial extensometer. In all cases, the axial strain was controlled. The life of the hourglass specimens was consistently longer than that of the solid cylindrical specimens in both environments. The life of test type (2) was nearly equal to that of type (1) in air, but in helium the life of type (2) was between those (1) and (3). The effects of segregation and grain size on the specimen geometry were discussed. In the cases of the specimens machined at right angle to the segregation layer and those with fine grains, the difference of the lives obtained for two types of specimens increased. Furthermore, the difference of crack initiation behaviors in air and helium was discussed. The internal oxidation layer and the decarburized zone were observed near the specimen surface in helium, and more surface cracks occured in helium than in air. These may be related to the larger difference in lives of two types of specimens in helium, compared to in air. (author)

  14. Parametric modeling and optimization of laser scanning parameters during laser assisted machining of Inconel 718

    Science.gov (United States)

    Venkatesan, K.; Ramanujam, R.; Kuppan, P.

    2016-04-01

    This paper presents a parametric effect, microstructure, micro-hardness and optimization of laser scanning parameters (LSP) on heating experiments during laser assisted machining of Inconel 718 alloy. The laser source used for experiments is a continuous wave Nd:YAG laser with maximum power of 2 kW. The experimental parameters in the present study are cutting speed in the range of 50-100 m/min, feed rate of 0.05-0.1 mm/rev, laser power of 1.25-1.75 kW and approach angle of 60-90°of laser beam axis to tool. The plan of experiments are based on central composite rotatable design L31 (43) orthogonal array. The surface temperature is measured via on-line measurement using infrared pyrometer. Parametric significance on surface temperature is analysed using response surface methodology (RSM), analysis of variance (ANOVA) and 3D surface graphs. The structural change of the material surface is observed using optical microscope and quantitative measurement of heat affected depth that are analysed by Vicker's hardness test. The results indicate that the laser power and approach angle are the most significant parameters to affect the surface temperature. The optimum ranges of laser power and approach angle was identified as 1.25-1.5 kW and 60-65° using overlaid contour plot. The developed second order regression model is found to be in good agreement with experimental values with R2 values of 0.96 and 0.94 respectively for surface temperature and heat affected depth.

  15. Microstructural Evolution and Mechanical Properties of Inconel 625 Alloy during Pulsed Plasma Arc Deposition Process

    Institute of Scientific and Technical Information of China (English)

    Fujia Xu; Yaohui Lv; Yuxin Liu; Fengyuan Shu; Peng He; Binshi Xu

    2013-01-01

    Pulsed plasma arc deposition (PPAD),which combines pulsed plasma cladding with rapid prototyping,is a promising technology for manufacturing near net shape components due to its superiority in cost and convenience of processing.In the present research,PPAD was successfully used to fabricate the Ni-based superalloy Inconel 625 components.The microstructures and mechanical properties of deposits were investigated by scanning electron microscopy (SEM),optical microscopy (OM),transmission electron microscopy (TEM) with energy dispersive spectrometer (EDS),microhardness and tensile testers.It was found that the as-deposited structure exhibited homogenous columnar dendrite structure,which grew epitaxially along the deposition direction.Moreover,some intermetallic phases such as Laves phase,minor MC (NbC,TiC) carbides and needle-like δ-Ni3Nb were observed in γ-Ni matrix.Precipitation mechanism and distribution characteristics of these intermetallic phases in the as-deposited 625 alloy sample were analyzed.In order to evaluate the mechanical properties of the deposits,microhardness was measured at various location (including transverse plane and longitudinal plane).The results revealed hardness was in the range of 260-285 HVo.2.In particular,microhardness at the interface region between two adjacent deposited layers was slightly higher than that at other regions due to highly refined structure and the disperse distribution of Laves particles.Finally,the influence of precipitation phases and fabrication strategies on the tensile properties of the as-deposited samples was investigated.The failure modes of the tensile specimens were analyzed with fractography.

  16. Probabilistic and microstructural aspects of fatigue cracks initiation in Inconel 718

    International Nuclear Information System (INIS)

    Thermomechanical treatments have been recently developed to produce Inconel 718DA (Direct Aged). This alloy optimisation leads to an increase of the fatigue life but also the scatter. The aim of this study is on the one hand the understanding of the fatigue crack initiation mechanisms and on the other hand the modelling of the fatigue life and the scatter. An experimental study showed that the fatigue cracks were initiated from carbide particles in fine grain alloy. Interrupted tensile tests show that the particles cracking occurred at the first quarter of the fatigue cycle. Fatigue behaviour tests were also performed on various grain size 718 alloys. The last experimental part was devoted to measurements of the low cycle fatigue crack growth rates using a high focal distance microscope. For these tests, EDM micro-defects were used for the fatigue crack initiation sites. This method was also used to observe the small fatigue crack coalescence. A fatigue life model is proposed. It is based on the three fatigue crack initiation mechanisms competition: particle crack initiation on the surface, internal particle crack initiation and Stade I crack initiation. The particle fatigue crack initiation is supposed instantaneous at a critical stress level. The Tanaka and Mura model is used for analysing the Stage I crack initiation number of cycles. The fatigue crack growth rate was analysed using the Tomkins model identified on the small fatigue crack growth rate measurements. The proposed fatigue life model decomposed in three levels: a deterministic one and two probabilistic with and without crack coalescence. (author)

  17. Identifying and Understanding Environment-Induced Crack propagation Behavior in Ni-based Superalloy INCONEL 617

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Longzhou

    2012-11-30

    The nickel-based superalloy INCONEL 617 is a candidate material for heat exchanger applications in the next-generation nuclear plant (NGNP) system. This project will study the crack propagation process of alloy 617 at temperatures of 650°C-950°C in air under static/cyclic loading conditions. The goal is to identify the environmental and mechanical damage components and to understand in-depth the failure mechanism. Researchers will measure the fatigue crack propagation (FCP) rate (da/dn) under cyclic and hold-time fatigue conditions, and sustained crack growth rates (da/dt) at elevated temperatures. The independent FCP process will be identified and the rate-controlled sustained loading crack process will be correlated with the thermal activation equation to estimate the oxygen thermal activation energy. The FCP-dependent model indicates that if the sustained loading crack growth rate, da/dt, can be correlated with the FCP rate, da/dn, at the full time dependent stage, researchers can confirm stress-accelerated grain-boundary oxygen embrittlement (SAGBOE) as a predominate effect. Following the crack propagation tests, the research team will examine the fracture surface of materials in various cracking stages using a scanning electron microscope (SEM) and an optical microscope. In particular, the microstructure of the crack tip region will be analyzed in depth using high resolution transmission electron microscopy (TEM) and electron energy loss spectrum (EELS) mapping techniques to identify oxygen penetration along the grain boundary and to examine the diffused oxygen distribution profile around the crack tip. The cracked sample will be prepared by focused ion beam nanofabrication technology, allowing researchers to accurately fabricate the TEM samples from the crack tip while minimizing artifacts. Researchers will use these microscopic and spectroscopic results to interpret the crack propagation process, as well as distinguish and understand the environment or

  18. Neutron Imaging for Selective Laser Melting Inconel Hardware with Internal Passages

    Science.gov (United States)

    Tramel, Terri L.; Norwood, Joseph K.; Bilheux, Hassina

    2014-01-01

    Additive Manufacturing is showing great promise for the development of new innovative designs and large potential life cycle cost reduction for the Aerospace Industry. However, more development work is required to move this technology into space flight hardware production. With selective laser melting (SLM), hardware that once consisted of multiple, carefully machined and inspected pieces, joined together can be made in one part. However standard inspection techniques cannot be used to verify that the internal passages are within dimensional tolerances or surface finish requirements. NASA/MSFC traveled to Oak Ridge National Lab's (ORNL) Spallation Neutron Source to perform some non-destructive, proof of concept imaging measurements to assess the capabilities to understand internal dimensional tolerances and internal passages surface roughness. This presentation will describe 1) the goals of this proof of concept testing, 2) the lessons learned when designing and building these Inconel 718 test specimens to minimize beam time, 3) the neutron imaging test setup and test procedure to get the images, 4) the initial results in images, volume and a video, 4) the assessment of using this imaging technique to gather real data for designing internal flow passages in SLM manufacturing aerospace hardware, and lastly 5) how proper cleaning of the internal passages is critically important. In summary, the initial results are very promising and continued development of a technique to assist in SLM development for aerospace components is desired by both NASA and ORNL. A plan forward that benefits both ORNL and NASA will also be presented, based on the promising initial results. The initial images and volume reconstruction showed that clean, clear images of the internal passages geometry are obtainable. These clear images of the internal passages of simple geometries will be compared to the build model to determine any differences. One surprising result was that a new cleaning

  19. Effects of solution heat treatment on the microstructure and hardness of Inconel 740 superalloy prepared by electron beam smelting

    International Nuclear Information System (INIS)

    Highlights: • Electron beam smelting, a new method, was used to prepare the Inconel 740 superalloy. • The effect of solution heat treatment on electron beam smelting 740 was investigated. • TiNiSi phase’s content changes exponentially with solution temperature increasing. • γ′ precipitates coarsening occurs at 1150 °C, higher temperature cause their solution. • γ″ phase transformed into Nb0.03Ni3Ti0.97 phase at 1210 °C. - Abstract: Electron beam smelting (EBS) was used to prepare the Inconel 740 superalloy. The microstructure and hardness of Inconel 740 were investigated both under hot working condition and followed by solution heat treatment under high temperature ranging from 1120 to 1210 °C for 30 min. The results show that fine γ′ nucleus and primary MC carbides exist in the hot working superalloy. With increasing temperature of solution treatment, TiNiSi phase is gradually solutionized into the matrix, whose volume fraction decreases exponentially. γ′ precipitates coarsening occurs at 1150 °C, while higher temperature solution treatment leads to the solution of γ′ precipitates. γ″ phase has been found keeping a stringent coherent relationship with Nb0.03Ni3Ti0.97 phase at 1180 °C, and utterly transformed into Nb0.03Ni3Ti0.97 phase at 1210 °C. The hardness of the solution-treated superalloy is lower than that of hot working, the value decreases at first and then increases with increasing of solution temperature, which is attributed to dislocations interaction and localized shear stress caused by γ′ precipitates and local stress fields

  20. Effects of solution heat treatment on the microstructure and hardness of Inconel 740 superalloy prepared by electron beam smelting

    Energy Technology Data Exchange (ETDEWEB)

    You, Xiaogang [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116023 (China); Key Laboratory for Solar Energy Photovoltaic System of Liaoning Province, Dalian 116023 (China); Tan, Yi, E-mail: tanyi@dlut.edu.cn [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116023 (China); Key Laboratory for Solar Energy Photovoltaic System of Liaoning Province, Dalian 116023 (China); Li, Jiayan; Li, Pengting [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116023 (China); Key Laboratory for Solar Energy Photovoltaic System of Liaoning Province, Dalian 116023 (China); Dong, Chuang [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116023 (China); Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian 116023 (China); Shi, Shuang; Liao, Jiao; Qin, Shiqiang [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116023 (China); Key Laboratory for Solar Energy Photovoltaic System of Liaoning Province, Dalian 116023 (China)

    2015-07-25

    Highlights: • Electron beam smelting, a new method, was used to prepare the Inconel 740 superalloy. • The effect of solution heat treatment on electron beam smelting 740 was investigated. • TiNiSi phase’s content changes exponentially with solution temperature increasing. • γ′ precipitates coarsening occurs at 1150 °C, higher temperature cause their solution. • γ″ phase transformed into Nb{sub 0.03}Ni{sub 3}Ti{sub 0.97} phase at 1210 °C. - Abstract: Electron beam smelting (EBS) was used to prepare the Inconel 740 superalloy. The microstructure and hardness of Inconel 740 were investigated both under hot working condition and followed by solution heat treatment under high temperature ranging from 1120 to 1210 °C for 30 min. The results show that fine γ′ nucleus and primary MC carbides exist in the hot working superalloy. With increasing temperature of solution treatment, TiNiSi phase is gradually solutionized into the matrix, whose volume fraction decreases exponentially. γ′ precipitates coarsening occurs at 1150 °C, while higher temperature solution treatment leads to the solution of γ′ precipitates. γ″ phase has been found keeping a stringent coherent relationship with Nb{sub 0.03}Ni{sub 3}Ti{sub 0.97} phase at 1180 °C, and utterly transformed into Nb{sub 0.03}Ni{sub 3}Ti{sub 0.97} phase at 1210 °C. The hardness of the solution-treated superalloy is lower than that of hot working, the value decreases at first and then increases with increasing of solution temperature, which is attributed to dislocations interaction and localized shear stress caused by γ′ precipitates and local stress fields.

  1. Influence of a treatment of age hardening on the mechanical properties of Inconel 625 in the presence of hydrogen gas

    International Nuclear Information System (INIS)

    Inconel 625 presents good mechanical properties and has excellent corrosion behaviour with temperatures being able to reach 1000oC. These mechanical properties are obtained by a heat treatment of structural hardening. Utilization of this super alloy for hydrogen gas must be preceded by a study of its embrittlement. The method of rupture of the discs, under hydrogen pressure or helium pressure has to undertake this study at ambient temperature. We show that for this material, obtaining the mechanical characteristics, by the heat treatment of hyper-hardening and by application of structural hardening, the ambient temperature of a catastrophic embrittlement vis-a-vis hydrogen gas

  2. Effect of thermal barrier coating on low cycle fatigue behavior of cast Inconel 713LC at 900 °C

    Czech Academy of Sciences Publication Activity Database

    Obrtlík, Karel; Hutařová, S.; Čelko, L.; Juliš, M.; Podrábský, T.; Šulák, Ivo

    Zurich : Trans Tech Publications, 2014 - (Clark, G.; Wang, C.), s. 848-853 ISBN 978-3-03835-008-8. ISSN 1022-6680. - (Advanced Materials Research. 891-892). [Fatigue 2014 - International Fatigue Congress /11./. Melbourne (AU), 02.03.2014-07.03.2014] R&D Projects: GA ČR(CZ) GAP107/11/2065; GA MPO FR-TI4/030 Institutional support: RVO:68081723 Keywords : High temperature fatigue * TBC * Inconel 713LC * Fatigue life Subject RIV: JL - Materials Fatigue, Friction Mechanics

  3. Low Cycle Fatigue and Analysis of the Cyclic Stress-strain Response in Superalloy Inconel 738LC

    Czech Academy of Sciences Publication Activity Database

    Tobiáš, Jiří; Chlupová, Alice; Petrenec, Martin; Polák, Jaroslav

    Praha: Institute of Theoretical and Applied Mechanics AS CR, v.v.i, 2012 - (Náprstek, J.; Fischer, C.), s. 1407-1411 ISBN 978-80-86246-40-6. [Engineering Mechanics 2012 /18./. Svratka (CZ), 14.05.2012-17.05.2012] R&D Projects: GA ČR(CZ) GAP204/11/1453 Institutional support: RVO:68081723 Keywords : low cycle fatigue * Inconel 738LC * hardening/softening curves * cyclic stress-strain curve * fatigue life curve Subject RIV: JL - Materials Fatigue, Friction Mechanics http://www.engmech.cz/2012/proceedings/

  4. Surface residual stress distributions in as-bent Inconel 600 U-bend and Incoloy 800 90-degree bend tubing samples

    International Nuclear Information System (INIS)

    Selected data showing typical macroscopic residual stress distributions in U-bent Inconel 600 and 90 degrees bends in Incoloy 800 are presented. The results indicate regions of both high magnitude tension and compression in the longitudinal direction around the circumference of the bends at the apex. The microscopic residual stress, or percent plastic strain and macroscopic residual distributions in the surface of cross-roll straightened and ground Inconel 600 tubing are described. The results indicate a compressive surface layer accompanied by a yield strength gradient from 90 ksi at the surface to 30 ksi at a depth of 0.003 in

  5. X-ray photoelectron spectroscopy study of the passive films formed on thermally sprayed and wrought Inconel 625

    Science.gov (United States)

    Bakare, M. S.; Voisey, K. T.; Roe, M. J.; McCartney, D. G.

    2010-11-01

    There is a well known performance gap in corrosion resistance between thermally sprayed corrosion resistant coatings and the equivalent bulk materials. Interconnected porosity has an important and well known effect, however there are additional relevant microstructural effects. Previous work has shown that a compositional difference exists between the regions of resolidified and non-melted material that exist in the as-sprayed coatings. The resolidified regions are depleted in oxide forming elements due to formation of oxides during coating deposition. Formation of galvanic cells between these different regions is believed to decrease the corrosion resistance of the coating. In order to increase understanding of the details of this effect, this work uses X-ray photoelectron spectroscopy (XPS) to study the passive films formed on thermally sprayed coatings (HVOF) and bulk Inconel 625, a commercially available corrosion resistant Ni-Cr-Mo-Nb alloy. Passive films produced by potentiodynamic scanning to 400 mV in 0.5 M sulphuric acid were compared with air-formed films. The poorer corrosion performance of the thermally sprayed coatings was attributed to Ni(OH) 2, which forms a loose, non-adherent and therefore non-protective film. The good corrosion resistance of wrought Inconel 625 is due to formation of Cr, Mo and Nb oxides.

  6. Catalyst-assisted vertical growth of carbon nanotubes on Inconel coated commercial copper foil substrates versus sputtered copper films

    International Nuclear Information System (INIS)

    We have compared the growth of multi-walled carbon nanotubes using thermal chemical vapor deposition (CVD) on two types of substrates, copper foils and sputtered copper films. In both cases an initial 12 nm thin film of Inconel is first deposited on the Cu before growing the nanotubes. The Inconel thin film can act as both a catalyst for nanotube growth as well as a support for the additional Fe catalyst that is supplied in the form of ferrocene during CVD growth. The surfaces of the underlying copper substrates are very different and play a role in the resulting carbon nanotube density. A quantitative analysis of the density and alignment of the resulting carbon nanotubes using scanning electron microscopy shows that the smooth surface of the sputtered copper substrate leads to improvement in vertical growth and density of nanotubes as opposed to the much rougher electropolished Cu foil. We show that this is related to the differences in catalyst islands distributions and graphitic crystallinity seen on the surfaces of the two types of substrates after heating the samples in the CVD chamber. This demonstrates that the surface of the starting substrate plays an important role in the subsequent catalyst surface distribution and therefore the resulting nanotube density.

  7. Effect of Wire Material on Productivity and Surface Integrity of WEDM-Processed Inconel 706 for Aircraft Application

    Science.gov (United States)

    Sharma, Priyaranjan; Chakradhar, D.; Narendranath, S.

    2016-07-01

    Inconel 706 is a recently developed superalloy for aircraft application, particularly in turbine disk which is among the most critical components in the gas turbine engines. Recently, wire electrical discharge machining (WEDM) attained success in machining of gas turbine components which require complex shape profiles with high precision. To achieve the feasibility in machining of these components, the research work has been conducted on Inconel 706 superalloy using WEDM process. And, the effect of different wire materials (i.e., hard brass wire, diffused wire, and zinc-coated wire) on WEDM performance characteristics such as cutting speed, surface topography, surface roughness, recast layer formation, residual stresses, and microstructural and metallurgical alterations have been investigated. Even though, zinc-coated wire exhibits improved productivity, hard brass wire was found to be beneficial in terms of improved surface quality of the machined parts. Additionally, lower tensile residual stresses were obtained with hard brass wire. However, diffused wire has a moderate effect on productivity and surface quality. Under high discharge energy, higher elemental changes were observed and also the white layer was detected.

  8. Ultrasonic Sensor Signals and Optimum Path Forest Classifier for the Microstructural Characterization of Thermally-Aged Inconel 625 Alloy

    Directory of Open Access Journals (Sweden)

    Victor Hugo C. de Albuquerque

    2015-05-01

    Full Text Available Secondary phases, such as laves and carbides, are formed during the final solidification stages of nickel-based superalloy coatings deposited during the gas tungsten arc welding cold wire process. However, when aged at high temperatures, other phases can precipitate in the microstructure, like the γ'' and δ phases. This work presents an evaluation of the powerful optimum path forest (OPF classifier configured with six distance functions to classify background echo and backscattered ultrasonic signals from samples of the inconel 625 superalloy thermally aged at 650 and 950 \\(^\\circ\\C for 10, 100 and 200 h. The background echo and backscattered ultrasonic signals were acquired using transducers with frequencies of 4 and 5 MHz. The potentiality of ultrasonic sensor signals combined with the OPF to characterize the microstructures of an inconel 625 thermally aged and in the as-welded condition were confirmed by the results. The experimental results revealed that the OPF classifier is sufficiently fast (classification total time of 0.316 ms and accurate (accuracy of 88.75% and harmonic mean of 89.52 for the application proposed.

  9. Study on the microstructure, mechanical property and residual stress of SLM Inconel-718 alloy manufactured by differing island scanning strategy

    Science.gov (United States)

    Lu, Yanjin; Wu, Songquan; Gan, Yiliang; Huang, Tingting; Yang, Chuanguang; Junjie, Lin; Lin, Jinxin

    2015-12-01

    Inconel-718 has received an extensive using in mold industry. The selective laser melting (SLM) is providing an ideal means for manufacturing mold insert with complex geometrical features and internal architecture. During the manufacturing of high quality mold inserts with conformal cooling channel, the parameters play a vital role in the SLM process. In the study, the Inconel-718 alloys were manufactured by SLM with 2×2 mm2, 3×3 mm2, 5×5 mm2, and 7×7 mm2 island scanning strategies. The microstructure, mechanical property, and residual stress were investigated by optical microscope, tensile test and Vickers micro-indentation, respectively. It can be found that the relative density increased with enlarging the island size; the results on the microstructure indicated that the cracks and more pores were detected in the 22-specimen; whilst the microstructures of all specimens were composed of fine dendritic grains, cellular, and columnar structures; the tensile testing suggested that the ultimate tensile strength and yield strength of all samples was similar; while the outcome of the residual stress showed that the value of residual stress was ranked in the following sequence: 22-specimenprocessing application in SLM. Through integrated into account, the 55-scanning strategy is a promising candidate for manufacturing of mold inserts.

  10. Influence of INCONEL 625 composition on the activation characteristics of the vacuum vessel of experimental fusion tokamaks

    International Nuclear Information System (INIS)

    The radioactive inventory, the decay heat and the contact dose rate of permanent components such as the vacuum vessel of two experimental fusion tokamaks, the compact IGNITOR-ULT and the ITER-EDA fusion machines, are evaluated by using the ENEA-Bologna integrated methodology. The vacuum vessel material considered is the INCONEL 625. The neutron flux is calculated using the VITAMIN-C 171-group library, based on EFF-2 data and the 1-D transport code XSDRNPM in the S8-P3 approximation. The ANITA-2 code, using updated cross sections and decay data libraries based on EAF-3 and IRDF90 evaluation files is used for activation calculations. The fusion neutron source has been normalised to a neutron first wall load of 2 MW/m2 and 1 MW/m2 for IGNITOR-ULT and ITER, respectively. The material irradiation have been described by multistep time histories, resulting in the designed total fluence. Variations in the composition of INCONEL 625 have been assessed and their impact on the activation characteristics are discussed, also from the point of view of waste disposal. (orig.)

  11. Spectral effects on stress relaxation of Inconel X-750 springs in CANDU reactors

    Energy Technology Data Exchange (ETDEWEB)

    Griffiths, M.; Butcher, F.J.; Ariani, I.; Douglas, S. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Garner, F.A.; Greenwood, L. [Pacific Northwest National Laboratory, Richland, Washington (United States)

    2008-07-01

    CANDU reactors have been operating for periods up to about 25 years. During this time there are changes to the nuclear reactor core components that are a function of operating environment and time. It is important to know how the properties of critical core components are likely to change over the life of a reactor and therefore their behaviours are characterised long before the end of the reactor design life. Tests are typically conducted in materials test reactors. The behaviour of a material is often characterised as a function of fast neutron fluence and the expected effect of operating time is established by simply extrapolating as a function of fluence. This may be appropriate when the neutron energy spectrum for the materials test reactor matches closely the neutron spectrum where the component resides in the power reactor. However, in cases where the spectrum is very different one has to convert the accumulated dose into a unit that is common in its effect on the material properties. For many property changes in nuclear reactor cores this unit is displacements per atom (dpa). There are different processes that cause atomic displacements and the main ones have to be included in any dpa calculation in order to accurately predict how a given component will perform. One property that is significantly affected by irradiation is stress. Irradiation-induced stress relaxation is a phenomenon that has been used as a method for studying in-reactor creep. Stress relaxation also results in a loss of tension in springs if these springs are in a reactor core environment. This paper describes the stress relaxation of Inconel X-750 in the National Research Universal (NRU) materials test reactor and relates this to the expected relaxation of springs that are installed in the periphery of CANDU reactors. The results show that spectral effects are particularly significant for certain components at the edge of the CANDU reactor core where the neutron spectrum is changing

  12. Metallographic study of cracks formation factors in Inconel 718 and waspaloy during welding by electron beam and the tungsten inert gas process

    International Nuclear Information System (INIS)

    Study of physico-chemical aspects of cracks formation during welding of Inconel 718 and waspaloy. In both alloys cracks are caused by an intergranular or interdendritic decohesion at the level of liquid films under stress produced by the welding thermal cycle. Constraints repartition, liquation and external sollicitations influence are studied

  13. INCONEL 690 CORROSION IN WTP (WASTE TREATMENT PLANT) HLW (HIGH LEVEL WASTE) GLASS MELTS RICH IN ALUMINUM & BISMUTH & CHROMIUM OR ALUMINUM/SODIUM

    Energy Technology Data Exchange (ETDEWEB)

    KRUGER AA; FENG Z; GAN H; PEGG IL

    2009-11-05

    Metal corrosion tests were conducted with four high waste loading non-Fe-limited HLW glass compositions. The results at 1150 C (the WTP nominal melter operating temperature) show corrosion performance for all four glasses that is comparable to that of other typical borosilicate waste glasses, including HLW glass compositions that have been developed for iron-limited WTP streams. Of the four glasses tested, the Bi-limited composition shows the greatest extent of corrosion, which may be related to its higher phosphorus content. Tests at higher suggest that a moderate elevation of the melter operating temperature (up to 1200 C) should not result in any significant increase in Inconel corrosion. However, corrosion rates did increase significantly at yet higher temperatures (1230 C). Very little difference was observed with and without the presence of an electric current density of 6 A/inch{sup 2}, which is the typical upper design limit for Inconel electrodes. The data show a roughly linear relationship between the thickness of the oxide scale on the coupon and the Cr-depletion depth, which is consistent with the chromium depletion providing the material source for scale growth. Analysis of the time dependence of the Cr depletion profiles measured at 1200 C suggests that diffusion of Cr in the Ni-based Inconel alloy controls the depletion depth of Cr inside the alloy. The diffusion coefficient derived from the experimental data agrees within one order of magnitude with the published diffusion coefficient data for Cr in Ni matrices; the difference is likely due to the contribution from faster grain boundary diffusion in the tested Inconel alloy. A simple diffusion model based on these data predicts that Inconel 690 alloy will suffer Cr depletion damage to a depth of about 1 cm over a five year service life at 1200 C in these glasses.

  14. Chromium Activity Measurements in Nickel Based Alloys for Very High Temperature Reactors: Inconel 617, Haynes 230, and Model Alloys

    International Nuclear Information System (INIS)

    The alloys Haynes 230 and Inconel 617 are potential candidates for the intermediate heat exchangers (IHXs) of (very) high temperature reactors ((V)-HTRs). The behavior under corrosion of these alloys by the (V)-HTR coolant (impure helium) is an important selection criterion because it defines the service life of these components. At high temperature, the Haynes 230 is likely to develop a chromium oxide on the surface. This layer protects from the exchanges with the surrounding medium and thus confers certain passivity on metal. At very high temperature, the initial microstructure made up of austenitic grains and coarse intra- and intergranular M6C carbide grains rich in W will evolve. The M6C carbides remain and some M23C6 richer in Cr appear. Then, carbon can reduce the protective oxide layer. The alloy loses its protective coating and can corrode quickly. Experimental investigations were performed on these nickel based alloys under an impure helium flow (Rouillard, F., 2007, 'Mecanismes de formation et de destruction de la couche d'oxyde sur un alliage chrominoformeur en milieu HTR, Ph.D. thesis, Ecole des Mines de Saint-Etienne, France). To predict the surface reactivity of chromium under impure helium, it is necessary to determine its chemical activity in a temperature range close to the operating conditions of the heat exchangers (T approximate to 1273 K). For that, high temperature mass spectrometry measurements coupled to multiple effusion Knudsen cells are carried out on several samples: Haynes 230, Inconel 617, and model alloys 1178, 1181, and 1201. This coupling makes it possible for the thermodynamic equilibrium to be obtained between the vapor phase and the condensed phase of the sample. The measurement of the chromium ionic intensity (I) of the molecular beam resulting from a cell containing an alloy provides the values of partial pressure according to the temperature. This value is compared with that of the pure substance (Cr) at the same temperature

  15. Modification of Johnson-Cook Model for Hot Deformation Behavior of Inconel 625 Alloy%Inconel625合金Johnson-Cook本构模型的一种改进

    Institute of Scientific and Technical Information of China (English)

    俞秋景; 刘军和; 张伟红; 于连旭; 刘芳; 孙文儒; 胡壮麒

    2013-01-01

    The hot deformation behavior of Inconel 625 alloy was investigated by compression tests.The results show that the slope of the true stress-true strain curve increases with the drop of the temperature and the rise of strain rate,indicating a complex interactive influence of temperature,strain and strain rate on the strain hardening and recrystallization.However,the constitutive equation built by Johnson-Cook model fails to predict precisely the stress-strain relation of Inconel 625 alloy due to the ignorance of the interaction.Accordingly,the JC model was modified by taking into account of the interactive effects of temperature,strain and strain rate.The comparison between the experimental data and the predicting value shows that the modified JC model fits accurately.%通过热压缩试验对Incone1625合金的热变形行为进行了测试.结果显示真应力-真应变曲线的斜率随着温度的降低和应变速率的升高而增大.这表明温度,应变和应变速率之间通过一种复杂的交互作用共同对应变硬化和再结晶产生影响.用Johnson-Cook模型建立的本构方程由于忽略了这个交互作用而不能很好地预测此合金的应力-应变关系.为此对Johnson-Cook模型做了改进.新的模型考虑了温度,应变和应变速率的交互作用.对比结果表明:修改的Johnson-Cook模型的预测值和实验值符合得很好.

  16. Gamma Prime Precipitation, Dislocation Densities, and TiN in Creep-Exposed Inconel 617 Alloy

    Science.gov (United States)

    Krishna, Ram; Atkinson, Helen V.; Hainsworth, Sarah V.; Gill, Simon P.

    2016-01-01

    Inconel 617 is a solid-solution-strengthened Ni-based superalloy with a small amount of gamma prime (γ') present. Here, samples are examined in the as-received condition and after creep exposure at 923 K (650 °C) for 574 hours and 45,000 hours and at 973 K (700 °C) for 4000 hours. The stress levels are intermediate (estimated, respectively, as of the order of 350, 275, and 200 MPa) and at levels of interest for the future operation of power plant. The hardness of the specimens has been measured in the gage length and the head. TEM thin foils have been obtained to quantify dislocation densities (3.5 × 1013 for the as-received, 5.0 × 1014, 5.9 × 1014, and 3.5 × 1014 lines/m2 for the creep-exposed specimens, respectively). There are no previous data in the literature for dislocation densities in this alloy after creep exposure. There is some evidence from the dislocation densities that for the creep-exposed samples, the higher hardness in the gage length in comparison with the creep test specimen head is due to work hardening rather than any other effect. Carbon replicas have been used to extract gamma prime precipitates. The morphology of γ' precipitates in the `as-received' condition was spheroidal with an average diameter of 18 nm. The morphology of these particles does not change with creep exposure but the size increases to 30 nm after 574 hours at 923 K (650 °C) but with little coarsening in 45,000 hours. At 973 K (700 °C) 4000 hours, the average gamma prime size is 32 nm. In the TEM images of the replicas, the particles overlap, and therefore, a methodology has been developed to estimate the volume fraction of gamma prime in the alloy given the carbon replica film thickness. The results are 5.8 vol pct in the as-received and then 2.9, 3.2, and 3.4 vol pct, respectively, for the creep-exposed specimens. The results are compared with predictions from thermodynamic analysis given the alloy compositions. Thermodynamic prediction shows that nitrogen

  17. Influence of sulfur on the passivity of inconel 600 in aqueous environment at 3000C. Relationship with stress corrosion

    International Nuclear Information System (INIS)

    Dissolution kinetics and repassivation of inconel 600 in simulated primary coolant circuits of PWR is studied by fast traction experiment under potentiostatic control. The notion of elementary electrochemical transient is introduced. The model of anodic dissolution - film rupture allows the calculation of crack growth in constant deformation rate tests. When sulfur concentration is smaller than 100 micrograms/g the current is low, above the current is high. Calculation of crack growth from high level current are consistent with experimental data. Influence of pH, temperature, solution composition are determined. A Comparative study with nickel, incoloy 690 and a 19% chromium alloy was carried out to understand fast traction phenomena. Chromium plays an important part without pollution a protecting chromium oxide is formed. In polluted environment sulfur prevent nucleation of this compound and chromium hydroxides are precipitated on the surface. With pure nickel there is no passivity in presence of sulfur

  18. Stress corrosion cracking of Inconel 600 tubing: Influence of thermal treatment, NaOH concentration and temperature

    International Nuclear Information System (INIS)

    A study has been performed concerning the role of thermal treatments on the SCC behaviour of Inconel 600 tubing in NaOH solutions in the temperature range 315-3600C. An additional investigation was undertaken to establish the effect of the NaOH concentration built-up under magnetite deposits. The changes in the microstructural variables in the four metallurgical conditions studied were identified by transmission electron microscopy (TEM). C-ring and slow strain rate tests (10-6 s-1) yielded identical results. SEM fractographs were additionally taken to reveal the cracking mode. It has been found that thermal treatment improves the SCC resistance in hot caustic solutions; particularly annealing at 6500C for 50 h appeared to impart the maximum improvement of SCC resistance. (orig.)

  19. Influence of temperature, environment, and thermal aging on the continuous cycle fatigue behavior of Hastelloy X and Inconel 617

    International Nuclear Information System (INIS)

    Results are presented for strain-controlled fatigue and tensile tests for two nickel-base, solution-hardened reference structural alloys for use in several High-Temperature Gas-Cooled Reactor (HTGR) concepts. These alloys, Hastelloy X and Inconel 617, were tested from room temperature to 8710C in air and impure helium. Materials were tested in both the solution-annealed and the preaged conditios, in which aging consisted of isothermal exposure at one of several temperatures for periods of up to 20,000 h. Comparisons are given between the strain-controlled fatigue lives of these and several other commonly used alloys, all tested at 5380C. An analysis is also presented of the continuous cycle fatigue data obtained from room temperature to 4270C for Hastelloy G, Hastelloy X, Hastelloy C-276, and Hastelloy C-4, an effort undertaken in support of ASME code development

  20. Stress corrosion cracking of Inconel 600 tubing: Influence of thermal treatment, NaOH concentration and temperature

    Energy Technology Data Exchange (ETDEWEB)

    Borello, A.; Masci, D.; Mignone, A.

    1988-09-01

    A study has been performed concerning the role of thermal treatments on the SCC behaviour of Inconel 600 tubing in NaOH solutions in the temperature range 315-360/sup 0/C. An additional investigation was undertaken to establish the effect of the NaOH concentration built-up under magnetite deposits. The changes in the microstructural variables in the four metallurgical conditions studied were identified by transmission electron microscopy (TEM). C-ring and slow strain rate tests (10/sup -6/ s/sup -1/) yielded identical results. SEM fractographs were additionally taken to reveal the cracking mode. It has been found that thermal treatment improves the SCC resistance in hot caustic solutions; particularly annealing at 650/sup 0/C for 50 h appeared to impart the maximum improvement of SCC resistance.

  1. The effect of grain size on the corrosion behaviour of Inconel 600 in high-temperature steam

    International Nuclear Information System (INIS)

    The effect of grain size on the corrosion behaviour of Inconel 600 has been studied in steam of 40 atm pressure at 8000C. A protective Cr2O3-rich scale is formed initially. After this introductory stage, nodular oxides nucleate at the positions where cracks have occurred in the Cr2O3-rich scale. The weight gain due to steam corrosion has a tendency to decrease with increasing grain size in the stage where the Cr2O3-rich scale is formed. This tendency is reversed in the nodular oxide-forming stage, where the weight gain increases with increasing grain size. The effect of grain size on the corrosion behaviour in the two stages is discussed. (author)

  2. TEM, HRTEM, electron holography and electron tomography studies of gamma' and gamma'' nanoparticles in Inconel 718 superalloy.

    Science.gov (United States)

    Dubiel, B; Kruk, A; Stepniowska, E; Cempura, G; Geiger, D; Formanek, P; Hernandez, J; Midgley, P; Czyrska-Filemonowicz, A

    2009-11-01

    The aim of the study was the identification of gamma' and gamma'' strengthening precipitates in a commercial nickel-base superalloy Inconel 718 (Ni-19Fe-18Cr-5Nb-3Mo-1Ti-0.5Al-0.04C, wt %) using TEM dark-field, HRTEM, electron holography and electron tomography imaging. To identify gamma' and gamma'' nanoparticles unambiguously, a systematic analysis of experimental and theoretical diffraction patterns were performed. Using HRTEM method it was possible to analyse small areas of precipitates appearance. Electron holography and electron tomography techniques show new possibilities of visualization of gamma' and gamma'' nanoparticles. The analysis by means of different complementary TEM methods showed that gamma'' particles exhibit a shape of thin plates, while gamma' phase precipitates are almost spherical. PMID:19903242

  3. Microstructure and fractal characteristics of the solid-liquid interface forming during directional solidification of Inconel 718

    Directory of Open Access Journals (Sweden)

    WANG Ling

    2007-08-01

    Full Text Available The solidification microstructure and fractal characteristics of the solid-liquid interfaces of Inconel 718, under different cooling rates during directional solidification, were investigated by using SEM. Results showed that 5 μm/s was the cellular-dendrite transient rate. The prime dendrite arm spacing (PDAS was measured by Image Tool and it decreased with the cooling rate increased. The fractal dimension of the interfaces was calculated and it changes from 1.204310 to 1.517265 with the withdrawal rate ranging from 10 to 100 μm/s. The physical significance of the fractal dimension was analyzed by using fractal theory. It was found that the fractal dimension of the dendrites can be used to describe the solidification microstructure and parameters at low cooling rate, but both the fractal dimension and the dendrite arm spacing are needed in order to integrally describe the evaluation of the solidification microstructure completely.

  4. Investigation of surface integrity in high-speed ball end milling of cantilever shaped thin plate of Inconel 718

    Directory of Open Access Journals (Sweden)

    N.N. Bhopale

    2012-12-01

    Full Text Available The paper addresses the effects of cutting speed and feed on the work piece deflection and surface integrity during milling of cantilever shaped Inconel 718 plate under different cutter orientations. The experiments were conducted on a CNC vertical milling machine using 10 mm diameter TiAlN coated solid carbide ball end milling cutter. Surface integrity is assessed in terms of micro hardness beneath the machined surface. The micro-hardness profile shows different patterns at various cutting parameters. It is observed that at large cutting speed as well as feeds, thicker work piece with larger work piece inclination shows higher micro hardness as compared to the other machining conditions.

  5. Microstructural evolution during transient liquid phase bonding of Inconel 617 using Ni-Si-B filler metal

    International Nuclear Information System (INIS)

    The influence of process parameters on microstructural characteristics of transient liquid phase (TLP) bonded Inconel 617 alloy was investigated. Experiments were carried out at 1065 deg. C using nickel based filler metal (Ni-4.5% Si-3% B) with B as the melting point depressant (MPD) element. Two different thickness of interlayer and various holding times were employed. The influence of these processing parameters on the characteristics of the joint area particularly size, morphology and composition of precipitates was investigated. The presence of MoB, Mo2B, M23C6, TiC, M23(B, C)6 and Ni3B precipitates in the diffusion layer and Ni3B, Ni3Si and Ni5Si2 precipitates in the interlayer at the interface between the base metal and interlayer were demonstrated using electron back scattered diffraction (EBSD), energy dispersive spectrometry (EDS) and TEM

  6. Stability of machining induced residual stresses in Inconel 718 under quasi-static loading at room temperature

    International Nuclear Information System (INIS)

    Tensile residual stresses are very often generated on the surface when machining nickel alloys. In order to determine their influence on the final mechanical behaviour of the component residual stress stability should be considered. In the present work the evolution of surface residual stresses induced by machining in Inconel 718 under static loading at room temperature was studied experimentally and numerically. An Inconel 718 disc was face turned employing industrial working conditions and specimens for tensile tests were extracted from the disc. Surface residual stresses were measured by X-ray diffraction for initial state and after applying different loads over the material's yield stress. Then, a finite element model based on the surface–core approach was fitted to experimental results and the study was extended to analyse the influence of load level, degree of work-hardening and initial surface conditions. For the studied case, initial tensile surface residual stress (776 MPa) became even more tensile when applying loads higher than the material yield stress, but a shift was observed at the highest applied load (1350 MPa) and initial residual stress was relaxed about 170 MPa. This particular behaviour is associated to the modified stress–strain properties of the machined affected surface layer which was strongly work-hardened. Moreover, if the work-hardened properties are not considered in the finite element model results differ substantially from experiments. Surface residual stress stability also depends on the initial surface residual stress, but the degree of work-hardening induced by the machining process must be considered as well. If the difference between the yield stress of the surface and the yield stress of the core is lower than the initial surface residual stress, the surface begins yielding first and consequently the surface residual stress is decreased. In contrast, if the difference between the yield stress of the surface and the

  7. Study of liquid phase formation kinetics due to solid/solid chemical interaction and its model. Application to the Zircaloy/Inconel

    International Nuclear Information System (INIS)

    A description is made of the chemical interaction between Inconel spacing grids and the Zircaloy of the sheaths. Experiments performed at 1000, 1100 and 1200 deg C with base Zircaloy and with a previously formed layer of ZrO2, show that the kinetics is parabolic. The difference between both types of experiments is that the oxide layer delays the initiation of the Inconel-Zry interaction. A model is presented, for the description of the solid/solid interaction, which leads to the formation of eutectic that is liquid at the experiment temperature. Also a model, which represents the oxide layer dissolution and predicts the instant in which it disappears completely, is presented. (Author)

  8. Time-Dependent Fatigue Crack Propagation Behavior of Two Solid-Solution-Strengthened Ni-Based Superalloys—INCONEL 617 and HAYNES 230

    Science.gov (United States)

    Ma, Longzhou; Roy, Shawoon K.; Hasan, Muhammad H.; Pal, Joydeep; Chatterjee, Sudin

    2012-02-01

    The fatigue crack propagation (FCP) as well as the sustained loading crack growth (SLCG) behavior of two solid-solution-strengthened Ni-based superalloys, INCONEL 617 (Special Metals Corporation Family of Companies) and HAYNES 230 (Haynes International, Inc., Kokomo, IN), were studied at increased temperatures in laboratory air under a constant stress-intensity-factor ( K) condition. The crack propagation tests were conducted using a baseline cyclic triangular waveform with a frequency of 1/3 Hz. Various hold times were imposed at the maximum load of a fatigue cycle to study the hold time effect. The results show that a linear elastic fracture mechanics (LEFM) parameter, stress intensity factor ( K), is sufficient to describe the FCP and SLCG behavior at the testing temperatures ranging from 873 K to 1073 K (600 °C to 800 °C). As observed in the precipitation-strengthened superalloys, both INCONEL 617 and HAYNES 230 exhibited the time-dependent FCP, steady SLCG behavior, and existence of a damage zone ahead of crack tip. A thermodynamic equation was adapted to correlate the SLCG rates to determine thermal activation energy. The fracture modes associated with crack propagation behavior were discussed, and the mechanism of time-dependent FCP as well as SLCG was identified. Compared with INCONEL 617, the lower crack propagation rates of HAYNES 230 under the time-dependent condition were ascribed to the different fracture mode and the presence of numerous W-rich M6C-type and Cr-rich M23C6-type carbides. Toward the end, a phenomenological model was employed to correlate the FCP rates at cycle/time-dependent FCP domain. All the results suggest that an environmental factor, the stress assisted grain boundary oxygen embrittlement (SAGBOE) mechanism, is mainly responsible for the accelerated time-dependent FCP rates of INCONEL 617 and HAYNES 230.

  9. Study on laser beam welding/superplastic forming technology of multi-sheet cylinder sandwich structure for Inconel718 superalloy with ultra-fine grains

    International Nuclear Information System (INIS)

    Highlights: ► In this study, we design the inner diameter variation of fixture for the structure. ► The welding problem of structure is solved by changing the diameter of the fixture. ► The multi-sheet cylinder sandwich structure is manufactured by LBW/SPF technology. ► Through SPF process, most Laves precipitated phase turns into δ precipitated phase. ► Nb concentration in the dendritics was improved greatly. -- Abstract: Multi-sheet cylinder sandwich structure of Inconel718 superalloy will be widely used in aerospace as heat resisting and heat shielding structure due to its lightweight, high strength and stiffness. Superplasticity of Inconel718 superalloy was investigated. Under T = 950 °C and initial strain rate with ε.=1.6×10-4s-1, the elongation of Inconel718 superalloy is 483.6%. The perfect superplastic forming temperature for Inconel718 superalloy is at 950 °C. The laser penetration welding parameters are as follows: power 1200 W, welding speed 1200 mm/min, defocusing amount −1 mm, shield gas flow 0.6 L/min, and the parameters for superplastic forming are as follows: temperature Tf = 950 °C, pressure Pf = 4.2 MPa, time tf = 130 min. The multi-sheet cylinder sandwich structure manufactured by laser beam welding/superplastic forming (LBW/SPF) technology has good shape, uniform wall thickness distribution, high symmetry in internal structure. Laves phase, harmful to the materials, translates to the δ phase which will help improve the performance of the material after SPF process. The hardness of laser welding joints is improved from 331.63 HV to 391.74 HV after the SPF process. The tensile strength of base material of multi-sheet cylinder sandwich structure has been increased about 261 MPa after the SPF process.

  10. Research on the applicability of the oxygenated water treatment method to PWR's secondary water. Pt. 2. Effect of dissolved oxygen on the uniform corrosion of metal materials used for heat-transfer tubes and tube-support plates in steam generators

    International Nuclear Information System (INIS)

    We conducted research to confirm the suitability of applying Oxygenated Water Treatment (OWT) to the feedwater of a PWR's secondary side. In this study, under conditions of 0 ppb, 50 ppb and 200 ppb (pH 9.5, 270degC) of dissolved oxygen, we examined uniform corrosion for Inconel alloys 600TT and 690TT, which are used for the heat transfer tube of a Steam Generator (SG). We calculated the surface corrosion amounts (mg/cm2) and corrosion rates (mg/cm2/h) from the data obtained after defilming using an oxidation-reduction method. The results suggest the following: (1) After exposure testing of the alloy 690TT under the condition of 0 ppb, 50 ppb and 200 ppb of dissolved oxygen, we found that the corrosion amount is smallest and the corrosion rate is lowest when the concentration of dissolved oxygen is 50 ppb. Therefore, it can be assumed that 50 ppb of dissolved oxygen should be the optimum concentration for use with the alloy 690TT in Combined Water Treatment (CWT); (2) The corrosion rate on the surface of alloy 690TT is slower than that on 600TT, that is 600TT exhibits poorer anticorrosion characteristics than 690TT under the experimental condition of 50 ppb of dissolved oxygen; (3) Under the condition of 50 ppb and 200 ppb of dissolved oxygen, the corrosion products formed on the surface of the alloy 690TT are mainly constituted of NiFe2O4 and NiCr2O4, and that formed on the surface of the alloy 600TT are mainly constituted of NiFe2O4 and NiO. Under the condition of 0 ppb of dissolved oxygen, the corrosion products formed on the surface of the alloy 690TT are mainly constituted of NiFe2O4. (author)

  11. Crack growth threshold under hold time conditions in DA Inconel 718 – A transition in the crack growth mechanism

    Directory of Open Access Journals (Sweden)

    E. Fessler

    2016-01-01

    Full Text Available Aeroengine manufacturers have to demonstrate that critical components such as turbine disks, made of DA Inconel 718, meet the certification requirements in term of fatigue crack growth. In order to be more representative of the in service loading conditions, crack growth under hold time conditions is studied. Modelling crack growth under these conditions is challenging due to the combined effect of fatigue, creep and environment. Under these conditions, established models are often conservative but the degree of conservatism can be reduced by introducing the crack growth threshold in models. Here, the emphasis is laid on the characterization of crack growth rates in the low ΔK regime under hold time conditions and in particular, on the involved crack growth mechanism. Crack growth tests were carried out at high temperature (550 °C to 650 °C under hold time conditions (up to 1200 s in the low ΔK regime using a K-decreasing procedure. Scanning electron microscopy was used to identify the fracture mode involved in the low ΔK regime. EBSD analyses and BSE imaging were also carried out along the crack path for a more accurate identification of the fracture mode. A transition from intergranular to transgranular fracture was evidenced in the low ΔK regime and slip bands have also been observed at the tip of an arrested crack at low ΔK. Transgranular fracture and slip bands are usually observed under pure fatigue loading conditions. At low ΔK, hold time cycles are believed to act as equivalent pure fatigue cycles. This change in the crack growth mechanism under hold time conditions at low ΔK is discussed regarding results related to intergranular crack tip oxidation and its effect on the crack growth behaviour of Inconel 718 alloy. A concept based on an “effective oxygen partial pressure” at the crack tip is proposed to explain the transition from transgranular to intergranular fracture in the low ΔK regime.

  12. Effects of the aging temperature and stress relaxation conditions on γ′ precipitation in Inconel X-750

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Jeong Won [Department of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); Research and Development Center, KOS Limited, Yangsan 626-230 (Korea, Republic of); Seong, Baek Seok [Neutron Science Division, HANARO Center, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Jeong, Hi Won [Advanced Metallic Materials Division, Korea Institute of Materials Science, Changwon 642-831 (Korea, Republic of); Choi, Yoon Suk [Department of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); Kang, Namhyun, E-mail: nhkang@pusan.ac.kr [Department of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of)

    2015-02-15

    Highlights: • Stress relaxation after aging 620 °C increased carbides and maintained γ′ fraction. • Aging temperature increase to 732 °C raised the γ′ increment after stress relaxation. • Small increase of carbides induced the large increase of γ′ after stress relaxation. • Loading for stress relaxation raised γ′ increment due to dislocation multiplication. - Abstract: Inconel X-750 is a Ni-based precipitation-hardened superalloy typically used in springs designed for high-temperature applications such as the hold-down springs in nuclear power plants. γ′ is a major precipitate in X-750 alloys which affects the strength, creep resistance, and stress relaxation properties of the spring. In this study, a solution-treated X-750 wire coiled into a spring was used that was aged at various temperatures and submitted to stress relaxation tests with and without loading. Small angle neutron scattering was employed to quantify the size and volume fraction of γ′ phase in the springs as a function of the aging temperature and the application of a load during stress relaxation. The volume fraction of γ′ precipitates increased in the specimen aged at 732 °C following stress relaxation at 500 °C for 300 h. However, the mean size of the precipitates in the samples was not affected by stress relaxation. The specimen aged at the lower temperature (620 °C) contained a smaller γ′ volume fraction and gained a smaller fraction of γ′ during stress relaxation compared with the sample aged at the higher temperature (732 °C). The smaller increase in the γ′ volume fraction for the sample aged at 620 °C was associated with a larger increase in the M{sub 23}C{sub 6} secondary carbide content during relaxation. The Cr depletion zone around the secondary carbides raises the solubility of γ′ thereby decreasing the volume fraction of γ′ precipitates in Inconel X-750. In terms of stress relaxation, a larger increase in the γ′ volume fraction was

  13. Estimate of thermal fatigue lifetime for the INCONEL 625lCF plate while exposed to concentrated solar radiation

    Directory of Open Access Journals (Sweden)

    Rojas-Morín, A.

    2011-04-01

    Full Text Available A system for testing the thermal cycling of materials and components has been developed and installed at the DISTAL-I parabolic dish facility located at the Plataforma Solar de Almería (PSA in Spain. This system allows us to perform abrupt heating/cooling tests by exposing central solar receiver materials to concentrated solar radiation. These tests are performed to simulate both the normal and critical operational conditions of the central solar receiver. The thermal fatigue life for the INCONEL 625LCF® plate when subjected to concentrated solar radiation has been estimated with this system. We have also developed a numerical model that evaluates the thermal behavior of the plate material; additionally, the model yields the tensile-compressive stresses on the plate, which allow the estimation of the Stress-Life (S-N fatigue curves. These curves show that the lifetime of the plate is within the High Cycle Fatigue (HCF region at the operational temperatures of both 650 °C and 900 °C.

    En el concentrador solar de disco parabólico DISTAL-I, situado en la Plataforma Solar de Almería (PSA, en España, se ha instalado un sistema para pruebas de ciclado térmico de materiales. Este sistema permite realizar pruebas abruptas de calentamiento y enfriamiento, en materiales para receptores solares de torre central, al exponerlos a radiación solar concentrada. Estas pruebas se realizan para simular las condiciones de operación de un receptor solar, las condiciones críticas y las condiciones normales. Con este sistema se ha estimado el tiempo de vida bajo fatiga térmica, en una placa de INCONEL 626LCF®, cuando es sometida a radiación solar concentrada. Asimismo, hemos desarrollado un modelo numérico que evalúa el desarrollo térmico en el material de la placa: adicionalmente, el modelo obtiene los esfuerzos de tensión-compresión en la placa, los cuales permiten la estimaciónde las curvas de fatiga vidaesfuerzo (S-N. Estas curvas

  14. Corrosion Resistance of Inconel 740H in Simulated Coal-ash/Flue-gas Environments%Inconel 740H合金在模拟煤灰/烟气中的抗腐蚀性研究

    Institute of Scientific and Technical Information of China (English)

    侯世香; 吴正发; 袁晓娜; 刘东雨

    2016-01-01

    针对用于超超临界锅炉过热器管的镍基高温合金Inconel 740H,在750℃及合成烟气的条件下,研究了涂刷合成煤灰试样和无涂刷试样累计3000 h的腐蚀情况.利用XRD、EDS和SEM对试样的表面和截面进行了分析.结果表明,涂刷合成煤灰试样的腐蚀分为两个阶段,开始在表面生成Cr2O3保护膜,随时间的延长氧化膜被硫酸盐溶解,腐蚀程度较重.无涂刷试样的腐蚀为一个阶段,即氧化和硫化腐蚀.

  15. Effect of argon injection on the high Z impurity generation from the poloidal inconel limiter in FTU

    International Nuclear Information System (INIS)

    Argon injection experiment on FTU (Frascati Tokamak Upgrade) plasma has been utilised to clarify the physical mechanism responsible for impurity production. A simple O-D model for the SOL (scrape off layer), coupled with sputtering by the main deuteron flux and self-sputtering can reproduce the variation of impurity concentration, Ni in the case of inconel limiter in FTU, when Argon is puffed into the plasma. The increase of radiation power losses leads to a decrease of the SOL temperature, and therefore to a decrease of the sputtering yield. Since Zeff remains essentially unchanged by Ar puffing, a fraction of high Z impurity is substituted by Ar ions. As a consequence both the line radiation emission profile and the total radiation losses are modified, while all the other plasma parameters (temperature and density profiles, ohmic power and energy confinement time) remain unchanged. Radiation losses increase up to 80% of the input power, at relatively high densities, with a corresponding decrease of the heat load on the limiter surface

  16. Thermal outgassing properties of mechanically polished and of sand- and bead-blasted Inconel 600 surfaces up to 5000C

    International Nuclear Information System (INIS)

    In the present work, two different types of Inconel 600 samples have been investigated. The first one was mechanically polished and chemically cleaned in several steps and had a total hemispherical emissivity at 750C of epsilon1 = 0.146 and a surface roughness of CLA1 = 0.08 μm, while the second sample was sand- and bead-blasted with epsilon2 = 0.382 and CLA2 = 1.2 μm. The experimental studies were composed of the determination of desorption spectra from 200C up to 5500C at different heating rates, the investigation of the decrease of thermal outgassing rates during a longer heating interval at about 5000C and the measurement of equilibrium outgassing rates at higher temperatures of samples which have been heated several days at about 5000C. The total outgassing rates and the partial outgassing rates of the main components H2, H2O, CO and CO2 have been determined in these studies. Activation energies of desorption, rate constants and equilibrium surface coverages have been calculated from the experimental data using the theory of Redhead. (author)

  17. High-temperature-oxidation-induced ordered structure in Inconel 939 superalloy exposed to oxy-combustion environments

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Jingxi; Wise, Adam; Nuhfer, Thomas; Holcomb, Gordon R; Jablonski, Paul D; Sridhar, Seetharaman; Laughlin, David E

    2013-04-20

    In the integrated oxy-fuel combustion and turbine power generation system, turbine alloys are exposed to high temperature and an atmosphere comprised of steam, CO2 and O2. While surface and internal oxidation of the alloy takes place, the microstructure in the subsurface region also changes due to oxidation that results in the loss of the strengthening precipitates. In an earlier study of the oxidation of Inconel 939 Ni-based superalloy exposed to oxy-fuel combustion environment for up to 1000 hours, a high-temperature-oxidation-induced phase transformation in the sub-surface region was noticed and a two-phase region formed at the expense of strengthening γ' phase. While one of the two phases was identified as the Ni-matrix (γ solid solution, face-center-cubic) phase, the other product phase remained unidentified. In this study, the crystal structure of the unknown phase and its orientation relationship with the parent Ni-matrix phase was investigated through electron diffraction and high-resolution transmission electron microscopy. It was determined that the crystal structure of the unknown phase could be modeled as a ternary derivative of the ordered η-Ni3Ti phase (D024) structure with lattice parameters of a = 0.5092 nm and c = 0.8336 nm, α = 90º, β = 90º and γ = 120º.

  18. Cracking in fusion zone and heat affected zone of electron beam welded Inconel-713LC gas turbine blades

    Energy Technology Data Exchange (ETDEWEB)

    Chamanfar, A., E-mail: achamanfar@gmail.com [Département de Génie Mécanique, École de Technologie Supérieure, 1100 rue Notre-Dame Ouest, Montréal, Québec, Canada H3C 1K3 (Canada); Jahazi, M. [Département de Génie Mécanique, École de Technologie Supérieure, 1100 rue Notre-Dame Ouest, Montréal, Québec, Canada H3C 1K3 (Canada); Bonakdar, A.; Morin, E. [Siemens Canada Limited, 9545 Côte-de-Liesse, Dorval, Québec, Canada H9P 1A5 (Canada); Firoozrai, A. [Département de Génie Mécanique, École de Technologie Supérieure, 1100 rue Notre-Dame Ouest, Montréal, Québec, Canada H3C 1K3 (Canada)

    2015-08-26

    Electron beam welding (EBW) of shrouds in Inconel-713LC low pressure gas turbine blades was associated with cracking in fusion zone (FZ) and heat affected zone (HAZ) leading to a high scrap rate in manufacturing of gas turbine blades. In this study, in order to develop a detailed map of cracks and understand the root cause of cracking, a comprehensive microstructural and numerical analysis was performed. The elemental mapping in scanning electron microscope (SEM)-energy dispersive spectral analysis revealed segregation of alloying elements in the cracked area of FZ and HAZ. In other words, one of the cracking mechanisms in FZ and HAZ was found to be segregation induced liquation and subsequent cracking due to thermal and mechanical tensile stresses generated during EBW. Cracking in FZ also occurred because of low strength of the solidifying weld metal as well as solidification contraction. As well, γ′ dissolution and reprecipitation in HAZ leading to decreased ductility and generation of contraction stresses was another mechanism for cracking in HAZ. The numerical model was capable to predict the cracking location as well as cracking orientation with respect to the weld line.

  19. Cracking in fusion zone and heat affected zone of electron beam welded Inconel-713LC gas turbine blades

    International Nuclear Information System (INIS)

    Electron beam welding (EBW) of shrouds in Inconel-713LC low pressure gas turbine blades was associated with cracking in fusion zone (FZ) and heat affected zone (HAZ) leading to a high scrap rate in manufacturing of gas turbine blades. In this study, in order to develop a detailed map of cracks and understand the root cause of cracking, a comprehensive microstructural and numerical analysis was performed. The elemental mapping in scanning electron microscope (SEM)-energy dispersive spectral analysis revealed segregation of alloying elements in the cracked area of FZ and HAZ. In other words, one of the cracking mechanisms in FZ and HAZ was found to be segregation induced liquation and subsequent cracking due to thermal and mechanical tensile stresses generated during EBW. Cracking in FZ also occurred because of low strength of the solidifying weld metal as well as solidification contraction. As well, γ′ dissolution and reprecipitation in HAZ leading to decreased ductility and generation of contraction stresses was another mechanism for cracking in HAZ. The numerical model was capable to predict the cracking location as well as cracking orientation with respect to the weld line

  20. Creep behaviour of as received, aged and cold worked INCONEL 617 at 850 deg. C and 950 deg. C

    International Nuclear Information System (INIS)

    The effect of initial microstructure on alloy 617 creep behaviour has been investigated at 850 deg. C and 950 deg. C. The solution treated material shows non-classical creep behaviour at both temperatures with a strain rate drop at the beginning of the tests followed by a creep rate increase to a plateau before the onset of the tertiary creep. The intragranular secondary carbides which precipitate early at test temperature are responsible of the strong initial hardening effect by pinning the dislocations. This effect is overpassed during the thermo mechanical ageing of the alloy which induces growth of these carbides. Prior 1000 h thermal ageing at the temperature test totally removes the strain rate drop and reduces the lifetime. The intragranular microstructure has evolved thanks to the prior thermal ageing before the creep tests. Microstructural examinations also show the presence of grain boundary migration and recrystallization in the material during creep tests of the as received and aged materials. Preliminary cold work treatment highly reduces the strain rate of Inconel 617 and enhances the lifetime at 850 deg. C while the opposite is observed at 950 deg. C.

  1. Estimate of thermal fatigue lifetime for the INCONEL 625lCF plate while exposed to concentrated solar radiation

    International Nuclear Information System (INIS)

    A system for testing the thermal cycling of materials and components has been developed and installed at the DISTAL-I parabolic dish facility located at the Plataforma Solar de Almeria (PSA) in Spain. This system allows us to perform abrupt heating/cooling tests by exposing central solar receiver materials to concentrated solar radiation. These tests are performed to simulate both the normal and critical operational conditions of the central solar receiver. The thermal fatigue life for the INCONEL 625LCF plate when subjected to concentrated solar radiation has been estimated with this system. We have also developed a numerical model that evaluates the thermal behavior of the plate material; additionally, the model yields the tensile-compressive stresses on the plate, which allow the estimation of the Stress-Life (S-N) fatigue curves. These curves show that the lifetime of the plate is within the High Cycle Fatigue (HCF) region at the operational temperatures of both 650 degree centigrade and 900 degree centigrade. (Author) 20 refs.

  2. Corrosion Characteristics of Inconel-600 at the NP(Cu)-HYBRID Decontamination Demonstration Test with HANARO FTL Specimen

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Jun Young; Park, Sang Yoon; Won, Hui Jun; Kim, Seon Byeong; Choi, Wang Kyu; Moon, Jei Kwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-10-15

    An alkaline permanganate (AP) or nitric permanganate (NP) oxidative phase has been generally used to dissolve the chromium-rich oxide. AP is advantageous for the corrosion resistance, but increases the volume of secondary waste during the decontamination procedure. On the other hand, NP has a high corrosion rate but reduces secondary waste. For the safe use of an oxidative decontamination solution with high corrosive resistance and less amount of secondary waste are required. In this study, we modified NP oxidative decontamination solution by adding Cu{sup 2+} to reduce the corrosion rate. To evaluate the general corrosion characteristics, we measured the weight losses of selected specimens in an NP(Cu) and other solutions. The localized corrosion was observed using an optical microscope (OM). To compare the decontamination performance, we measured the contact dose rate of specimens treated in NP-HYBRID and NP(Cu)-HYBRID systems. The reduced corrosion characteristics of the Inconel-600 specimen in a NP(Cu) oxidative solution was observed in terms of generalized corrosion as well as localized corrosion. Less corrosion characteristics do not affect the performance of the overall decontamination compared to the NP-HYBRID process. Therefore, our results support that the NP(Cu)-HYBRID decontamination process is appropriate for the decontamination of the primary coolant system in a nuclear reactor.

  3. Flank wear and I-kaz 3D correlation in ball end milling process of Inconel 718

    Directory of Open Access Journals (Sweden)

    M.A.S.M. Tahir

    2015-12-01

    Full Text Available Tool wear may deteriorate the machine product quality due to high surface roughness, dimension exceeding tolerance and also to machine tool itself. Tool wear monitoring system is vital to be used in machining process to achieve high quality of the machined product and at the same time improve the productivity. Nowadays, many monitoring system developed using various sensor and statistical technique to analyze the signals being used. In this paper, I-kaz 3D method is used to analyze cutting force signal in milling process of Inconel 718 for monitoring the status of tool wear in milling process. The results from analyzing cutting force show that I-kaz 3D coefficient has a correlation with cutting tool condition. Tool wear will generate high value of I-kaz 3D coefficient than the sharp cutting tool. Furthermore, the three dimension graphical representation of I-kaz 3D for all cutting condition shown that the degree of scattering data increases with tool wear progression.

  4. Research and Improvement on structure stability and corrosion resistance of nickel-base superalloy INCONEL alloy 740

    International Nuclear Information System (INIS)

    INCONEL alloy 740 is a newly developed Ni-Cr-Co-Mo-Nb-Ti-Al superalloy in the application to ultra-supercritical boilers with steam temperatures up to 700 deg. C. By means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), micro-chemical phase analyses, and corrosion-resisting test, this paper investigates the structure stability of the alloy at elevated temperature and concentrates on coal ash corrosion performance of the alloy under the simulated coal ash/flue gas condition. Experimental results show that the most important structure instabilities of the alloy during prolonged aging are γ' coarsening, γ' to η transformation and G phase formation at grain boundary. The performance of corrosion resistance of the alloy would meet the requirement of ultra-supercritical boiler tubes. The phase computation by means of Thermo-Calc has been adopted in chemical composition modification for structure stability improvement. Two suggested new modified alloys in adjustment of the Al and Ti contents and in control of Si level, and also in maintenance of Cr content of the alloy were designed and melted for experimental investigation. These two modified alloys exhibit more stable microstructure during 760 deg. C long time aging

  5. Influence of humidity on high temperature oxidation of Inconel 600 alloy: Oxide layers and residual stress study

    International Nuclear Information System (INIS)

    In order to understand the influence of humidity on high temperature oxidation of Inconel 600 alloy, in this work, water vapour (absolute humidity varying from 0% to 19%) was introduced in the thermal gravimetric analysis (TGA) system under artificial air between 600 °C and 900 °C. The oxides identification and the residual stress in the oxide layers have been studied by X-ray diffraction method in each of two oxide phases, simultaneously. The oxide surface morphology, cross-section microstructure and the chemical composition of the oxide layers were determined by FEG-SEM (Field Emission Gun Scanning Electron Microscope) observation and FEG-SEM EDS (Energy-dispersive X-ray spectroscopy) analysis. Depending on the oxidation temperature, the humidity and the oxidation duration, the oxide layer differed significantly. The residual stress levels in the different oxide layers (NiO-type layer and Cr2O3-type layer) have also been affected by the introduction of the water vapour. According to the analysis results, the residual stresses on oxide mainly came from the growth stress and thermomechanical stress; and the oxide growth stress was especially affected by humidity at high temperature.

  6. Diffusion of Cr, Fe, and Ti ions from Ni-base alloy Inconel-718 into a transition alumina coating

    International Nuclear Information System (INIS)

    Heat treating metals at high temperatures trigger diffusion processes which may lead to the formation of oxide layers. In this work the diffusion of Cr, Fe and Ti into an alumina coating applied to Inconel-718 is being investigated. Mass gain measurements, UV–vis spectroscopy and transmission electron microscopy were applied in order to study the evolution of the diffusion process. It was found that mainly Cr as well as minor amounts of Fe and Ti are being incorporated into the alumina coating upon prolonged heat treatment at 700 °C. It could be shown that alumina coatings being void of Cr have the same oxidation related mass gain as uncoated samples. However, incorporation of Cr into the alumina coating decreased their mass gain below that of uncoated substrates forming a Cr oxide scale only. - Highlights: ► We investigated the diffusion of Cr into alumina coatings applied on IN-718. ► The ingress of Cr led to the formation of mixed alumina/chromium coatings. ► The mass gain of mixed alumina/chromium coatings was compared to uncoated IN-718. ► The mixed alumina/chromium coatings improved the oxidation resistance of IN-718.

  7. Control of interfacial reactions during liquid phase processing of aluminum matrix composites reinforced with INCONEL 601 fibers

    Science.gov (United States)

    Boland, F.; Colin, C.; Delannay, F.

    1998-06-01

    A comprehensive investigation is made of the parameters affecting the extent of interface reactions during squeeze casting of composites consisting of a matrix of either pure Al or alloy AS13 reinforced with fibers of INCONEL 601. The process parameters are the preform thickness and temperature, the fiber volume fraction, the temperature and mass of the liquid metal, and the temperature of the die. Adjustment of these process parameters made possible the full control of reactions. It is found that reactions proceed mainly in the solid state after decomposition of the oxide barrier layer covering the fibers. A simple kinetic model is developed that enlightens the role of this barrier layer. No trace of reaction could be detected in composites processed using preoxidized preforms. Alloying Al with Si also induces a drastic reduction of reactivity. The high ductility of the composites attests to the processing quality. An original procedure is proposed for measuring the activation energy for initiation of reactions by differential thermal analysis.

  8. Aspectos metalúrgicos de revestimentos dissimilares com a superliga à base de níquel inconel 625 Metallurgical aspects of dissimilar weld overlays of inconel 625 nickel based superalloys

    Directory of Open Access Journals (Sweden)

    Cleiton Carvalho Silva

    2012-09-01

    Full Text Available Prolongar a vida útil e aumentar a confiabilidade de equipamentos e tubulações de plantas de produção e processamento de petróleo é uma busca constante no setor de petróleo e gás. Tais aspectos dependem essencialmente do uso de ligas resistentes à corrosão. Neste contexto, a soldagem de revestimento com superligas à base de níquel tem sido uma alternativa interessante, pois confere aos equipamentos uma alta resistência à corrosão com um custo inferior, se comparado à fabricação de componentes ou tubulações maciças com superligas. Assim, o objetivo do presente trabalho foi investigar o comportamento metalúrgico de revestimento de superliga à base de níquel do tipo Inconel 625 depositados pelo processo TIG com alimentação de arame frio. As soldagens foram realizadas em uma bancada robotizada, empregando uma fonte eletrônica de soldagem com sistema de aquisição de dados para o monitoramento dos sinais de corrente e tensão. A caracterização microestrutural foi realizada através das técnicas de microscopia eletrônica de varredura (MEV e transmissão (MET, espectroscopia de energia dispersiva de raios-X (EDS. Os resultados mostraram que a microestrutura do metal de solda foi constituída por uma matriz γ com fases secundárias ricas em Nb. Foi encontrada a formação de precipitados complexos de carbonetos/nitretos de Ti e Nb.To extend the life and reliability of pipes and equipment in oil & gas production and processing settings is a continuous demand. These aspects are essentially dependent on corrosion resistant alloys used. In this context, the weld overlay with Ni-based superalloys is a great interesting alternative, since improve the corrosion resistance without increase the cost of manufacture when compared to massive equipment. Thus, the objective of this study was to evaluate the metallurgical aspects of Inconel 625 weld overlays deposited by GTAW cold wire feed process. The welds were performed using a

  9. Solidificação da zona de fusão na soldagem do AISI 304 com inconel 600 por laser de Nd: YAG Microstructure development in Nd: YAG laser welding of AISI 304 and Inconel 600

    Directory of Open Access Journals (Sweden)

    Maurício David M. das Neves

    2009-06-01

    Full Text Available Neste trabalho estudou-se a morfologia de solidificação da zona de fusão, numa junta formada a partir de materiais dissimilares, composta por aço inoxidável austenítico AISI 304 e por liga de níquel Inconel 600, soldada com laser pulsado de Nd:YAG. Os parâmetros do feixe laser e do sistema óptico foram selecionados, visando obter uma solda com penetração total e bom acabamento superficial. A caracterização microestrutural foi realizada por microscopia ótica, onde se observou uma zona de fusão com penetração total do tipo keyhole, a presença de pequenos poros e a ausência de trincas. As juntas soldadas foram caracterizadas também, por meio de microscopia eletrônica de varredura (MEV. Medidas realizadas por espectrometria de raios X por dispersão de energia na zona de fusão indicaram uma distribuição levemente heterogênea de níquel e ferro. Observou-se que o início de solidificação da zona de fusão ocorreu por meio de crescimento epitaxial. A morfologia de solidificação da ZF foi basicamente dendrítica e celular sendo, influenciada pelo gradiente de temperatura, velocidade de solidificação e composição química. As variações de composição química e da morfologia de solidificação não alteraram significativamente os valores de microdureza Vickers na zona de fusão. Resultados obtidos nos ensaios de tração indicaram valores de eficiência de soldagem adequados.An autogenous laser welding of dissimilar materials involving AISI 304 austenitic stainless steels and Inconel 600 nickel alloy was investigated in this study. Hence, the aim of this investigation was to study the solidification and microstructure of fusion zone when using a pulsed Nd:YAG laser. The laser and optical beam parameters were chosen to achieve a good weld with total penetration. Optical microscopy pictures showed a typical keyhole weld with total penetration, small pores and free of cracks. The x-ray spectrometry by energy dispersion

  10. Study on LBW/SPF Technology of Multi-sheet Cylinder Sandwich Structure for Inconel718 Superalloy%Inconel718合金多层夹芯筒结构LBW/SPF技术研究

    Institute of Scientific and Technical Information of China (English)

    曲凤盛; 卢振; 刑飞; 张凯锋

    2012-01-01

    The high temperature plasticity of the laser butt welding plate and LBW/SPF technology for Inconel718 superalloy with ultrafine grain were investigated. The results showed that when the tensile direction is vertical to laser welding seam, the maximum elonga- tion is 400.6% at temperature of 950 ℃ with initial strain rate of 3.1 ×10 -4 s -1. When the tensile direction is parallel to laser welding seam, the maximum elongation is 164.0% at temperature of 965 ℃ with initial strain rate of 6.2 × 10 -4 s -1. At the temperature of 950 ~ 980 ℃, the laser butt welding plate has good plasticity in free bulging state. The relative bulging height is higher than 1. 0. The laser welding problem of multi-sheet cylinder sandwich structure is settled through clamp apparatus which has internal stay of diametral varia- tion. The laser penetration welding parameters are the power of 1 200 W, welding speed of 1 200 mm/min, defocusing amount of - 1 mm, shield gas flow rate of 0.6 L/min. The parameters for superplastic forming are the temperature of 965 ℃, pressure of 4.2 MPa, time of 130 min. The multi-sheet cylinder sandwich structure by LBW/SPF composite technology has good shape, uniform wall thickness distribution, the high symmetry of internal structure.%研究了超细晶Inconel718合金激光对接板高温塑性及多层夹芯筒结构的LBW/SPF成形技术。结果表明:垂直焊缝拉伸时最大延伸率发生在温度为950℃、应变速率为3.1×10-4s-1条件下,为400.6%,平行焊缝拉伸时最大延伸率发生在温度为965℃,应变速率为6.2×10-4s-1条件下,为164.0%。对接板在950~980℃相对胀形高度均高于1.0。通过设计直径可变的卡具以及采取点焊加固等措施,解决了多层夹芯结构的激光焊接难题。激光穿透焊参数:功率1 200 W,焊速1 200 mm/min,离焦量-1 mm,保护气体流量0.6 L/min,超塑成形参数:温度Tf=965℃,压力Pf=4.2 MPa,时间tf=130 min。采用LBW/SPF技术制造的多层夹

  11. 激光选区熔化Inconel625合金开裂行为及抑制研究%Cracking Behavior and Inhibiting Process of Inconel 625 Alloy Formed by Selective Laser Melting

    Institute of Scientific and Technical Information of China (English)

    张洁; 李帅; 魏青松; 史玉升; 王联凤; 郭立杰

    2015-01-01

    裂纹是激光选区熔化(SLM,selective laser melting)镍基高温合金最严重的缺陷之一,严重削弱了材料的力学性能.采用逐行扫描策略制备了Inconel 625合金试样,利用扫描电子显微镜(SEM)、电子背散射衍射(EBSD)等检测方法研究了裂纹微观形貌、周边元素和晶粒分布等.SEM结果显示在常温下成形件内部形成大量缅小裂纹,裂纹长度约100μm.裂纹形成的内因是在快速凝固的过程中,由于Nb,Mo元素的局部偏析,形成(γ +Laves)共晶凝固.同时在脆性相Laves周围形成应力集中,导致沿着晶界开裂,SLM高凝固速率产生的残余应力是微裂纹产生的直接原因.通过基板加热工艺减小热残余应力,利用X射线测定了不同预热温度(150和300℃)下的残余应力值.结果显示基板预热降低了热残余应力,并最终抑制了裂纹的产生,随着温度的升高,裂纹数量逐渐减少,在预热温度300℃时裂纹数量最少.

  12. Effects of Heat Treatment on the Ballistic Impact Properties of Inconel 718 for Jet Engine Fan Containment Applications

    Science.gov (United States)

    Pereira, J. Michael; Lerch, Bradley A.

    2001-01-01

    The effects of heat treating Inconel 718 on the ballistic impact response and failure mechanisms were studied. Two different annealing conditions and an aged condition were considered. Large differences in the static properties were found between the annealed and the aged material, with the annealed condition having lower strength and hardness and greater elongation than the aged. High strain rate tests show similar results. Correspondingly large differences were found in the velocity required to penetrate material in the two conditions in impact tests involving 12.5 mm diameter, 25.4 mm long cylindrical Ti-6-4 projectiles impacting flat plates at velocities in the range of 150 to 300 m/sec. The annealed material was able to absorb over 25 percent more energy than the aged. This is contrary to results observed for ballistic impact response for higher velocity impacts typically encountered in military applications where it has been shown that there exists a correlation between target hardness and ballistic impact strength. Metallographic examination of impacted plates showed strong indication of failure due to adiabatic shear. In both materials localized bands of large shear deformation were apparent, and microhardness measurements indicated an increase in hardness in these bands compared to the surrounding material. These bands were more localized in the aged material than in the annealed material. In addition the annealed material underwent significantly greater overall deformation before failure. The results indicate that lower elongation and reduced strain hardening behavior lead to a transition from shear to adiabatic shear failure, while high elongation and better strain hardening capabilities reduce the tendency for shear to localize and result in an unstable adiabatic shear failure. This supports empirical containment design methods that relate containment thickness to the static toughness.

  13. Brazing of inconel 600 and SUS304 stainless steel with used of rapidly solidified nickel-base brazing foil

    Energy Technology Data Exchange (ETDEWEB)

    Miyazawa, Yasuyuki; Ariga, Tadashi (Tokai Univ., Tokyo (Japan))

    1992-05-01

    In this study, the clad material which have been brazed with the nickel-base heat resistant alloy; Inconel 600 on AISI304 stainless steel has been produced by the brazing using three types of nickel-base brazing foils. The three types of nickel-base brazing foils are 7Cr(4.5Si-7.0Cr-3.0B-3.0Fe-Ni bal.), 5Cr(4.5Si-5.0Cr-3.0B-3.0Fe-Ni bal.) and 10Cr(4.5Si-10.0Cr-3.0B-3.0Fe-Ni bal.). Brazing was done in an electrical resistant furnace in an argon gas atmosphere. The brazing temperatures employed in this study were 1050, 1100, 1150, 1200 and 1250degC and the brazing times were 10, 30, 60 and 120 min for all types of brazing foils. The property of the joint was estimated by the mechanical properties, microstructures and distributions of the elements which were investigated by SEM and EPMA. The brazed joint was obtained for all of brazing conditions in this study. The shear strength of the specimen increased with increasing brazing time except at 1050degC. At 1050degC, the shear strength of the specimen was not influenced by brazing time. In this case, the break of the specimen during the shear test occurred in the brazed layer. At 1250degC, the value of 450 MPa was obtained as the maximum shear strength in this study; the break of the specimen occurred in the base metal. The shear strength of the specimen increased with increasing brazing temperature. The shear strength of the specimen increased with increasing chromium content in the brazing foil to 7 mass%. (J.P.N.).

  14. Brazing of inconel 600 and SUS304 stainless steel with used of rapidly solidified nickel-base brazing foil

    International Nuclear Information System (INIS)

    In this study, the clad material which have been brazed with the nickel-base heat resistant alloy; Inconel 600 on AISI304 stainless steel has been produced by the brazing using three types of nickel-base brazing foils. The three types of nickel-base brazing foils are 7Cr(4.5Si-7.0Cr-3.0B-3.0Fe-Ni bal.), 5Cr(4.5Si-5.0Cr-3.0B-3.0Fe-Ni bal.) and 10Cr(4.5Si-10.0Cr-3.0B-3.0Fe-Ni bal.). Brazing was done in an electrical resistant furnace in an argon gas atmosphere. The brazing temperatures employed in this study were 1050, 1100, 1150, 1200 and 1250degC and the brazing times were 10, 30, 60 and 120 min for all types of brazing foils. The property of the joint was estimated by the mechanical properties, microstructures and distributions of the elements which were investigated by SEM and EPMA. The brazed joint was obtained for all of brazing conditions in this study. The shear strength of the specimen increased with increasing brazing time except at 1050degC. At 1050degC, the shear strength of the specimen was not influenced by brazing time. In this case, the break of the specimen during the shear test occurred in the brazed layer. At 1250degC, the value of 450 MPa was obtained as the maximum shear strength in this study; the break of the specimen occurred in the base metal. The shear strength of the specimen increased with increasing brazing temperature. The shear strength of the specimen increased with increasing chromium content in the brazing foil to 7 mass%. (J.P.N.)

  15. Understanding the Role of Hot Isostatic Pressing Parameters on the Microstructural Evolution of Ti-6Al-4V and Inconel 718 Fabricated by Electron Beam Melting

    Energy Technology Data Exchange (ETDEWEB)

    Peter, William H [ORNL; Nandwana, Peeyush [ORNL; Kirka, Michael M [ORNL; Dehoff, Ryan R [ORNL; Sames, William [Texas A& M University; ERDMAN III, DONALD L [ORNL; Eklund, Anders [Avure Technologies, Inc.; Howard, Ron [Avure Technologies, Inc.

    2015-04-01

    In this project, Avure and ORNL evaluated the influence of hot isostatic pressing (HIP) and thermal cycling as standalone post processing techniques on the microstructure of electron beam powder bed deposited Ti-6Al-4V and Inconel 718 alloys. Electron beam powder bed deposition is an effective technology for fabricating complex net shape components that cannot be manufactured with conventional processes. However, material deposited by this technology results in columnar grain growth which is detrimental for many applications. For Ti-6Al-4V, it has been found that thermal cycling alone is not sufficient to breakdown the columnar microstructure that is typical of electron beam powder bed technology. HIP, on the other hand, has the potential to be an effective technique to break down the columnar microstructure of Ti-6Al-4V into a more equiaxed and refined β grain structure, and provide a more homogeneous microstructure compared to the thermally cycled samples. Overall, the project showed that hot isostatic pressing reduced/eliminated porosity in both Ti-6Al-4V and Inconel 718 However, based on the unique thermal cycle and the application of pressure in the HIP vessel, Ti-6Al-4V e-beam deposited microstructures were modified from columnar grain growth to equiaxed microstructures; a significant outcome to this collaboration. Inconel 718, on the other hand, shows no change in the macrostructure as a result of the current HIP cycle based on the thermal history, and would require further investigation. Though the results of HIP cycle were very good at changing the microstructure, further development in optimizing the post heat treatments and HIP cycles is required to improve mechanical properties.

  16. 700℃超超临界锅炉过热器管材Inconel 740H合金冷变形行为研究%Cold Deformation Behavior of Inconel 740H Alloy for 700 ℃ Ultra-supercritical Boiler Superheater Tubes

    Institute of Scientific and Technical Information of China (English)

    江河; 董建新; 张麦仓; 姚志浩

    2015-01-01

    Inconel 740H合金荒管进行了不同变形量的冷轧实验,分析了其冷变形特性.通过冷变形后不同制度的退火处理,对Inconel 740H合金组织演变规律进行研究,建立了退火过程中再结晶晶粒长大方程.同时引入不均匀因子Z对组织均匀性进行评定.研究表明,Inconel 740H合金中间退火处理中的静态再结晶过程主要受退火温度和保温时间影响,所构建的再结晶晶粒长大方程与实验值吻合度较好.冷轧变形量为20%,中间退火制度为1100℃/5 min时得到的组织最为均匀.

  17. Influence of the Overlapping Factor and Welding Speed on T-Joint Welding of Ti6Al4V and Inconel 600 Using Low-Power Fiber Laser

    OpenAIRE

    Shamini Janasekaran; Ai Wen Tan; Farazila Yusof; Mohd Hamdi Abdul Shukor

    2016-01-01

    Double-sided laser beam welding of skin-stringer joints is an established method for many applications. However, in certain cases with limited accessibility, single-sided laser beam joining is considered. In the present study, single-sided welding of titanium alloy Ti6Al4V and nickel-based alloy Inconel 600 in a T-joint configuration was carried out using continuous-wave (CW), low-power Ytterbium (Yb)-fiber laser. The influence of the overlapping factor and welding speed of the laser beam on ...

  18. Impact of hydrogen on the high cycle fatigue behaviour of Inconel 718 in asymmetric push-pull mode at room temperature

    OpenAIRE

    Bruchhausen, Matthias; Fischer, Burkhard; Ruiz, A.; Gonzalez Sanchez, Sergio; Hähner, Peter; Soller, Sebastian

    2014-01-01

    The influence of hydrogen on the high cycle fatigue (HCF) behaviour of Inconel 718 has been studied at room temperature in asymmetric push–pull mode using an ultrasonic HCF test rig. Fatigue tests have been carried out in gaseous hydrogen (GH2) and in Ar at a pressure of 30 MPa. Oscillating stresses with amplitudes (σa) up to 450 MPa and mean stresses (σm) up to 600 MPa have been applied. For a given σa and σm, the lifetime in Ar is generally longer than in GH2, which is explained by a hydrog...

  19. Electrochemical impedance spectrometry using 316L steel, hastelloy, maraging, Inconel 600, Elgiloy, carbon steel, TiN and NiCr. Simulation in tritiated water. 2 volumes

    International Nuclear Information System (INIS)

    Polarization and electrochemical impedance spectrometry curves are presented and discussed. These curves make it possible to ascertain the corrosion domains and to compare the slow and fast kinetics (voltammetry) of different stainless steel alloys. These corrosion kinetics, the actual or simulated tritiated water redox potentials, and the corrosion potentials provide a classification of the steels studied here: 316L, Hastelloy, Maraging, Inconel 600, Elgiloy, carbon steel and TiN and NiCr deposits. From the results it can be concluded that Hastelloy and Elgiloy have the best corrosion resistance. (author). 49 refs., 695 figs., tabs

  20. Influence of Hold Times on Fatigue Life and Fracture Behavior of Cast Superalloy INCONEL 713LC at 700°C

    Czech Academy of Sciences Publication Activity Database

    Obrtlík, Karel; Man, Jiří; Petrenec, Martin; Polák, Jaroslav; Podrábský, T.

    Ottawa : NRCan - CANMET, 2009, s. 1-9. ISBN N. [International Conference on Fracture /12./. Ottawa (CA), 12.07.2009-17.07.2009] R&D Projects: GA AV ČR 1QS200410502; GA ČR GA106/08/1631; GA ČR GA106/07/1507 Institutional research plan: CEZ:AV0Z20410507 Keywords : Fatigue life * Hold times * High temperature * Inconel 713LC Subject RIV: JL - Materials Fatigue, Friction Mechanics http://www.icf12.org/

  1. Improvement of Surface Properties of Inconel718 by HVOF Coating with WC-Metal Powder and by Laser Heat Treatment of the Coating

    OpenAIRE

    Hui Gon Chun; Tong Yul Cho; Jae Hong Yoon; Gun Hwan Lee

    2015-01-01

    High-velocity oxygen-fuel (HVOF) thermal spray coating with WC-metal powder was carried out by using optimal coating process on an Inconel718 surface for improvement of the surface properties, friction, wear, and corrosion resistance. Binder metals such as Cr and Ni were completely melted and WC was decomposed partially to W2C and graphite during the high temperature (up to 3500°C) thermal spraying. The melted metals were bonded with WC and other carbides and were formed as WC-metal coating. ...

  2. Comparative Analysis of Properties and Microstructure of the Plastically Deformed Alloy Inconel®718, Manufactured by Plastic Working and Direct Metal Laser Sintering

    Directory of Open Access Journals (Sweden)

    Żaba K.

    2016-03-01

    Full Text Available Nickel superalloys as Inconel® are materials widely used in the aerospace industry among others for diffusers, combustion chamber, shells of gas generators and other. In most cases, manufacturing process of those parts are used metal strips, produced by conventional plastic processing techniques, and thus by hot or cold rolling. An alternative technology allowing for manufacturing components for jet engines is the technique of 3D printing (additive manufacturing, and most of all Direct Metal Laser Sintering, which is one of the latest achievement in field of additive technologies.

  3. Influence of cutting parameters on surface characteristics of cut section in cutting of Inconel 718 sheet using CW Nd:YAG laser

    Institute of Scientific and Technical Information of China (English)

    Dong-Gyu AHN; Kyung-Won BYUN

    2009-01-01

    Recently, laser cutting technologies begin to use for manufacturing mechanical parts of lnconel super-alloy sheet due to difficulties of machining of the Inconel material as a results of its extremely tough nature. The objective of this work is to investigate the influence of cutting parameters on surface characteristics of the cut section in the cutting of Inconel 718 super-alloy sheet using CW Nd:YAG laser through laser cutting experiments. Normal cutting experiments were performed using a laser cutting system with six-axis controlled automatic robot and auto-tracking system of the focal distance. From the results of the experiments, the effects of the cutting parameters on the surface roughness, the striation formation and the microstructure of the cut section were examined. In addition, an optimal cutting condition, at which the surface roughness is minimized and both the delayed cutting phenomenon and the micro-cracking are not initiated, is estimated to improve both the part quality and the cutting efficiency.

  4. Inconel 939 processed by selective laser melting: Effect of microstructure and temperature on the mechanical properties under static and cyclic loading

    International Nuclear Information System (INIS)

    Nickel-based superalloys, such as Inconel 939, are a long-established construction material for high-temperature applications and profound knowledge of the mechanical properties for this alloy produced by conventional techniques exists. However, many applications demand for highly complex geometries, e.g. in order to optimize the cooling capability of thermally loaded parts. Thus, additive manufacturing (AM) techniques have recently attracted substantial interest as they provide for an increased freedom of design. However, the microstructural features after AM processing are different from those after conventional processing. Thus, further research is vital for understanding the microstructure-processing relationship and its impact on the resulting mechanical properties. The aim of the present study was to investigate Inconel 939 processed by selective laser melting (SLM) and to reveal the differences to the conventional cast alloy. Thorough examinations were conducted using electron backscatter diffraction, transmission electron microscopy, optical microscopy and mechanical testing. It is demonstrated that the microstructure of the SLM-material is highly influenced by the heat flux during layer-wise manufacturing and consequently anisotropic microstructural features prevail. An epitaxial grain growth accounts for strong bonding between the single layers resulting in good mechanical properties already in the as-built condition. A heat treatment following SLM leads to microstructural features different to those obtained after the same heat treatment of the cast alloy. Still, the mechanical performance of the latter is met underlining the potential of this technique for producing complex parts for high temperature applications

  5. Analysis and modelling of the chemical interactions between Inconel grid spacers and Zircaloy cladding of LWR fuel rods; formation of liquid phases due to chemical interactions

    International Nuclear Information System (INIS)

    The experimental results show that the interactions obey parabolic rate laws at the examined temperatures of 1000, 1100 and 1200degC, with or without preoxidized Zircaloy. The fundamental difference of the experiments with preoxidized Zircaloy (oxide layer thickness ≤ 100μm) compared to as-received Zircaloy is the time delay of the start of the interaction between Inconel and Zircaloy. Two models will be presented to describe the experimental results: a) the DISOL code, which is able to simulate the oxidation of Zircaloy up to a given oxide layer thickness and then the dissolution of the ZrO2 layer by the Zircaloy, and b) the solid/solid interaction model that is able to describe the kinetics of the Inconel/Zircaloy interaction. The simple relations obtained as a result of this work can be introduced as modules in SFD code systems to describe the behavior of the core with increasing temperature. Comparison between the experimental results and the code predictions shows a good agreement. (orig.)

  6. Friction and wear behavior of Inconel 625 with Ni3Ti, TiN, TiC-CVD coatings in an HTGR environment

    International Nuclear Information System (INIS)

    The following conclusions apply to Inconel 625 with Ni3Ti, TiN, TiC-CVD coatings, tested in an HTGR environment in a temperature range between 500 and 9000C at a contact pressure of 3.45 MPa. The average wear rate is very small varying between 0.0 and 1.7 x 10-4 g/m. The wear rate shows little dependence on temperature and sliding velocity, increasing slightly as the temperature increases or as the sliding velocity decreases. Damage experienced by wear areas is minimal. Stick-slip friction was observed at low sliding velocity, however the friction coefficient is low (maximum 0.63) with an average value of about 0.44. The friction coefficient shows little dependence on temperature and sliding velocity, increasing slightly as the temperature increases, or as the sliding velocity decreases. Ni3Ti, TiN, TiC-CVD coatings, are considered effective in minimizing friction and wear damage of Inconel 625 in an HTGR environment

  7. Galvanic coupling between D6AC steel, 6061-T6 aluminum, Inconel 718 and graphite-epoxy composite material: Corrosion occurrence and prevention

    Science.gov (United States)

    Danford, M. D.; Higgins, R. H.

    1983-01-01

    The effects of galvanic coupling between D6AC steel, 6061-T6 aluminum, Inconel 718, and graphite-epoxy composite material (G/E) in 3.5% NaCl were studied. Measurements of corrosion potentials, galvanic currents and corrosion rates of the bare metals using weight-loss methods served to establish the need for corrosion protection in cases where D6AC steel and 6061-T6 aluminum are galvanically coupled to G/E in salt water while Inconel 718 was shown to be compatible with G/E. Six tests were made to study corrosion protective methods for eliminating galvanic corrosion in the cases of D6AC steel and 6061-T6 aluminum coupled to G/E. These results indicate that, when the G/E is completely coated with paint or a paint/polyurethane resin combination, satisfactory protection of the D6AC steel is achieved with either a coat of zinc-rich primer or a primer/topcoat combination. Likewise, satisfactory corrosion protection of the aluminum is achieved by coating it with an epoxy coating system.

  8. Combined strengthening of multi-phase and graded interface in laser additive manufactured TiC/Inconel 718 composites

    International Nuclear Information System (INIS)

    Laser metal deposition (LMD) additive manufacturing of TiC particle reinforced Inconel 718 composite parts was performed. The influence of laser energy density (LED) on densification, microstructures and wear behaviour of LMD-processed composites was studied. It showed that using a LED of 280 J mm−3 produced ∼5% porosity in LMD-processed composites, caused by the aggregation of reinforcing particles. A further increase in LED above 350 J mm−3 yielded near-full densification. Two categories of reinforcing phases, i.e. the substoichiometric TiCx particles and the in situ (Ti,M)C (M = Mo, Nb and Cr) carbide having 7–10 at% Nb and Mo contents, were formed in the matrix of LMD-processed composites. The TiCx reinforcing particles changed from an irregular poly-angular shape to a smoothened and refined structure as the LED increased. An increase in LED resulted in a larger amount of phase formation and an enhanced degree of crystal growth of the in situ (Ti,M)C reinforcement. The interfacial graded layer with thickness of 0.2–1.2 µm, which was identified as (Ti,M)C (M = Mo, Nb and Cr) carbide with 5–6 at% Mo and Nb contents, was tailored between the TiCx particles and the matrix. At an optimal LED of 420 J mm−3, a considerably low coefficient of friction of 0.38 and resultant low wear rate of 1.8 × 10−4 mm3 N−1 m−1 were obtained in sliding tests, due to the combined strengthening of the interfacial graded layer and the multiple reinforcing phases. The wear resistance decreased at an excessive LED because of the coarsening of reinforcement crystals and the decrease in microstructural uniformity of composites. (paper)

  9. 690合金传热管胀管区质量检测%Examination for Tubing Expansion of Alloy 690 Heat Exchangers

    Institute of Scientific and Technical Information of China (English)

    程仲贺; 王佐森; 鲍兴华

    2012-01-01

    Expansion between tube and tubesheet is a key process during the manufacture of heat exchangers, and the expansion quality affects the use of heat exchangers. The basic principles of expanding technology and the key points of quality control for expansion during the nuclear island heat exchanger manufacturing were introduced, and three methods (eddy current profile curve method, inner diameter variation measurement,dissection measurement) to evaluate the quality of expansion were studied.%胀接是换热器制造中的一道关键工序,胀接区质量影响着换热器的使用.介绍了胀接工艺的基本原理,并分析了核电站换热器胀接过程中的质量控制要点:胀管率和未胀合长度,研究了胀管区质量进行评估的三种方法:涡流轮廓曲线法、内径变化测量法和解剖测量法.

  10. Infrared and x-ray photoelectron spectroscopic studies on sodium borosilicate glass interacted with thermally oxidized aluminides formed on alloy 690

    International Nuclear Information System (INIS)

    Thermally oxidized aluminides formed on Ni-Cr-Fe based superalloy 690 substrates were subjected to interaction with sodium borosilicate melt (used as matrices for immobilization of high-level radioactive liquid waste) at 1248 K for 192 hours. After the interaction, Fourier-transform infrared (FT-IR) spectroscopy analysis of glass samples indicated the incorporation of Al in the glass network. X-ray photoelectron spectroscopy (XPS) of glass specimens revealed modified glass structure. (author)

  11. A study of the release rate of corrosion products for nuclear SG tubing

    International Nuclear Information System (INIS)

    Out-of-core radiation fields mainly are caused by activated corrosion product released from nuclear heat supply system. It is very important to minimize the generation of radioactive corrosion products which become a radiation source, in order to meet the needs of operation and maintenance. A study was conducted on determining the general corrosion rate and metal release rate for Inconel 690 (Japan), Inconel 690 (China), Inconel 600 and Incoloy 800 tubes on the primary water side of nuclear power plant simulation. The results show that the release rates of corrosion products of Alloy 690 on the primary water side is very low and that they decrease with the increase of chromium content in the alloys. (8 refs, 9 figs., 4 tabs.)

  12. 300℃氮气中交变载荷条件下Inconel 690合金的微动磨损特性%Fretting wear behavior of Inconel 690 alloy under alternating load conditions at 300℃ in nitrogen environment

    Institute of Scientific and Technical Information of China (English)

    张晓宇; 任平弟; 蔡振兵; 彭金方; 刘建华; 朱旻昊

    2016-01-01

    The fretting wear mechanisms and kinetic behaviours of Inconel690 alloy were investigated on the improved PLINT fretting rig under alternating loads conditions in high-temperature controlled-atmosphere environments. The results show that the fretting running behaviors are closely related to the normal excitation frequency. In parallelogram shapedFt−D curves, the friction fluctuates periodically, and accordingly the fretting runs in the slip regime (SR). Five stages of friction force curves can be observed at 300℃ in nitrogen environment, including initial stage, ascending stage, peak value stage descending stage and steady stage. The fretting wear behaviors for Inconel 690 alloy strongly depend on the normal load, displacement amplitude, temperature, atmosphere, excitation frequency and other test conditions. The super position effect of fretting wear behavior due to the combined effect of alternating normal force and tangential force is produced, so that delamination phenomenon becomes much more prominent. The abrasive wear and delamination are the major mechanisms of Inconel 690 at 300℃ in nitrogen environment.%采用改进后的PLINT高温可控气氛的微动磨损试验机,研究Inconel 690合金在300℃氮气及法向交变载荷条件下的微动磨损机制和动力学特性。结果表明:微动运行行为与激振频率密切相关,微动的Ft−D曲线呈现摩擦力周期波动的平行四边形型特征,微动运行于滑移区。在300℃氮气环境中,摩擦力的动态变化可以分为5个阶段,即跑合阶段、上升阶段、峰值阶段、下降阶段和稳定阶段。Inconel 690合金的微动损伤行为强烈地依赖于载荷、位移幅值、环境温度、气氛及激振频率等试验条件。从表面损伤形貌看,损伤微结构与试验参数密切相关;由于交变法向力和切向力共同作用,微动产生叠加效应,使剥层现象更加突出。在300℃氮气环境下,Inconel 690合金的损

  13. ASTM 4130自动氩弧焊堆焊 Inconel 625焊接工艺%Procedure of 625 Overlay Weld on ASTM 4130 75K

    Institute of Scientific and Technical Information of China (English)

    郭必永

    2014-01-01

    通过理论分析及试验结合的方法,确认ASTM 413075K调质钢自动氩弧焊堆焊Inconel 625的工艺确认,根据API 6A Ed 20th和ASME IX-2010的要求进行评定,此结果可为生产提供一定的指导。%T hrough the combination of theoretical analysis and test ,the procedure of 625 overlay weld on ASTM 4130 75K which was quenched and tempered steel ,by automatic argon tungsten arc welding ,was evaluated according to API 6A Ed 20th and ASME IX-2010 requirements ,and provides guidance for production .

  14. Electrochemical impedance spectrometry using Inconel 690, zircaloy 4, 316Ti steel, 17-4-PH, UR52N et URSB8. Simulation in tritiated water. Tome 2

    International Nuclear Information System (INIS)

    The redox potential of 3 H2O, as well as the corrosion potentials in this medium are found, abnormally, in the trans-passive region. This is completely different from behavior in the chemical industry or in the water in nuclear powers. With such behavior, there will be breakdowns of the protective oxide layers, and in the presence of chloride there will be immediate pitting. Polarization and electrochemical impedance spectrometry curves are presented and discussed. These curves make it possible to ascertain the corrosion domains and to compare the kinetics of different stainless steel alloys. These corrosion kinetics and the corrosion potentials provide a classification of the steels studied here: Inconel 690, zircaloy 4, 316 Ti steel, 17-4-PH, UR52N et URSB8. From the results it can be concluded that URSB8 has the best corrosion resistance. (author). 13 refs., 522 figs., tabs

  15. Electrochemical impedance spectrometry using Inconel 690, zircaloy 4, 316Ti steel, 17-4-PH, UR52N et URSB8. Simulation in tritiated water. Tome 1

    International Nuclear Information System (INIS)

    The redox potential of 3 H2O, as well as the corrosion potentials in this medium are found, abnormally, in the trans-passive region. This is completely different from the behavior in the chemical industry or in the water in nuclear powers. With such behavior, there will be breakdowns of the protective oxide layers, and in the presence of chloride there will be immediate pitting. Polarization and electrochemical impedance spectrometry curves are presented and discussed. These curves make it possible to ascertain the corrosion domains and to compare the kinetics of different stainless alloys. These corrosion kinetics and the corrosion potentials provide a classification of the steels studied here: Inconel 690, zircaloy 4, 316 Ti steel, 17-4-PH, UR52N et URSB8. From the results it can be concluded that URSB8 has the best corrosion resistance. (author). 279 figs., tabs

  16. Effect of the Fine-Grained Structure on the Fatigue Properties of the Heat-Resistant Nickel-Iron Alloy Inconel 718

    Science.gov (United States)

    Mukhtarov, Sh. Kh.; Shakhov, R. V.

    2015-10-01

    It is well known that ultrafine-grained nickel alloys with average grain sizes d = 0.1-1 μm possess improved hot workability and can be used for superplastic forming or rolling. However, microstructure refinement can worsen some performance characteristics of the alloy, for example, heat-resistant or fatigue properties. In the present work, fatigue characteristics of the fine-grained alloy Inconel 718 are investigated. Ultrafine-grained alloys with average grain sizes d = 0.1-1 μm were manufactured by multiple forging with stage-by-stage deformation temperature decrease. During standard heat treatment of the alloy performed to obtain the desired properties, the γ-grain size was controlled by precipitations of δ-phase particles along the boundaries. Results of low-cycle fatigue tests of the fine-grained alloy at room and elevated temperatures are compared with the properties of the coarse-grained alloy.

  17. Tensile properties of haynes alloy 230 and inconel 617 after long exposures to LiF-22CaF2 and vacuum at 1093 K

    Science.gov (United States)

    Whittenberger, J. D.

    1994-12-01

    As a part of a study of a space-based thermal energy storage system utilizing the latent heat of fusion of the eutectic salt LiF-20CaF2 (mole%), the two wrought Ni-base superalloys Haynes alloy 230 and Inconel 617 were subjected to molten salt, its vapor, and vacuum for periods as long as 10,000 h at 1093 K. Following exposure, the microstructures were characterized, and samples from each superalloy were tensile tested between 77 and 1200 K. Neither the structure nor mechanical properties revealed evidence for additional degradation due to exposures to the salt. Although some loss in tensile properties was noted, particularly at 77 K, this reduction could be ascribed to the influence of simple aging at 1093 K.

  18. A preliminary mechanical property and stress corrosion evaluation of VIM-VAR work strengthened and direct aged Inconel 718 bar material

    Science.gov (United States)

    Montano, J. W.

    1987-01-01

    This report presents a preliminary mechanical property and stress corrosion evaluation of double melted (vacuum induction melted (VIM), and vacuum arc remelted (VAR)), solution treated, work strengthened and direct aged Inconel 718 alloy bar (5.50 in. (13.97 cm) diameter). Two sets of tensile specimens, one direct single aged and the other direct double aged, were tested at ambient temperature in both the longitudinal and transverse directions. Longitudinal tensile and yield strengths in excess of 200 ksi (1378.96 MPa) and 168 ksi (1158.33 MPa), respectively, were realized at ambient temperature, for the direct double aged specimen. No failures occurred in the single or double edged longitudinal and transverse tensile specimens stressed to 75 and 100 percent of their respective yield strengths and exposed to a salt fog environment for 180 days. Tensile tests performed after the stress corrosion test showed no mechanical property degradation.

  19. Chromium activity measurements in nickel based alloys for very high temperature reactors: Inconel 617, haynes 230 and model alloys - HTR2008-58147

    International Nuclear Information System (INIS)

    The alloys Haynes 230 and Inconel 617 are potential candidates for the intermediate heat exchangers (IHX) of (V)-HTR reactors. The behaviour under corrosion of these alloys by the (V)-HTR coolant (impure helium) is an important selection criterion because it defines the service life of these components. At high temperature, the Haynes 230 is likely to develop a chromium oxide on the surface. This layer protects from the exchanges with the surrounding medium and thus confers certain passivity on metal. At very high temperature, the initial microstructure made up of austenitic grains and coarse intra and intergranular M6C carbide grains rich in W will evolve. The M6C carbides remain and some M23C6 richer in Cr appear. Then, carbon can reduce the protective oxide layer Then, the alloy loses its protective coating and can corrode quickly. Experimental investigations were performed on these nickel based alloys under an impure helium flow [1]. To predict the surface reactivity of chromium under impure helium, it is necessary to determine its chemical activity in a temperature range close to the operating conditions of the heat exchangers (T∼1273 K). For that, high temperature mass spectrometry measurements coupled to multiple effusion Knudsen cells are carried out on several samples: Haynes 230, Inconel 617 and model alloys 1178, 1181, 1201. This coupling makes it possible thermodynamic equilibrium to be obtained between the vapour phase and the condensed phase of the sample. The measurement of the chromium ionic intensity (/) of the molecular beam resulting from a cell containing an alloy provides the values of partial pressure according to the temperature. This value is compared to that of the pure substance (Cr) at the same temperature. These calculations provide thermodynamic data characteristic of the chromium behaviour in these alloys. These activity results call into question those previously measured by Hilpert [2], largely used in the literature. (authors)

  20. Inconel740H主要强化元素对热力学平衡相析出行为的影响

    Institute of Scientific and Technical Information of China (English)

    符锐; 林富生; 赵双群; 迟成宇

    2013-01-01

    对700℃等级超超临界电站过热器/再热器管材所用镍基高温合金Inconel740H进行热力学相计算并研究了主要析出强化元素对其平衡析出相析出行为的影响.结果表明:合金中),’相和M:。C。碳化物稳定温度范围较宽;Al、Ti和Nb3种元素对y1目、77相和口相的析出行为影响较大,而co元素对其影响不大,其中Al对7’相和d相的析出和稳定有促进作用,对刀相却有抑制作用,Ti和Nb对7’相、即相和口相均有促进作用;C对M。。c。碳化物析出量的影响显著,而Cr对M2。C。的析出温度影响显著.将Al、Ti、Nb、C和Cr的质量分数控制在一定范围内并适当减小Co的质量分数,可以使Inconel740H合金的成分范围得到一定的优化.

  1. Assessing the kinetics of high temperature oxidation of Inconel 617 in a dedicated HTR impure helium facility coupling thermogravimetry and gas phase chromatography

    International Nuclear Information System (INIS)

    Graphical abstract: Display Omitted -- Highlights: •New facility coupling thermogravimetry (TGA) with gas phase chromatography (GPC). •Dedicated for HT oxidation study in VHTR impure helium containing CO, H2O and H2. •The oxidation kinetics obeys a complete parabolic law due to a mixed kinetic regime. •CO contributes during initial stage of oxidation only for very low H2O partial pressure. •Long-term oxidation of Inconel 617 by H2O is diffusion controlled with constant kp. -- Abstract: A new facility coupling thermogravimetric analysis (TGA) with gas phase chromatography (GPC) has been developed. This facility is dedicated for studying high temperature oxidation of Inconel 617 in impure helium environment containing H2O, H2 and CO at very low partial pressures (in the Pa range), which is representative of the high temperature reactor (HTR) concept developed within the Generation IV Forum. Simultaneous acquisition of mass gain and gas composition has allowed the influence of carbon monoxide and water vapour on the kinetics of oxidation to be studied. GPC measurements of gas consumption have allowed the plotting of individual mass gain curves for oxidation by H2O and CO. During isothermal exposure at 1123 K for 20 h, the oxidation was mainly due to water vapour with a minor contribution of carbon monoxide during the first hours. The contribution of water vapour to the oxidation kinetics was extracted. It was shown to obey a complete parabolic law and to be limited by an interfacial reaction during the first few hours of oxidation and to be controlled by a mixed interfacial and diffusion process, diffusion becoming the rate-determining step for long term oxidation. There was very good agreement between GPC measurements and the experimental TGA results

  2. Assessing the kinetics of high temperature oxidation of Inconel 617 in a dedicated HTR impure helium facility coupling thermogravimetry and gas phase chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Chapovaloff, J., E-mail: chpvlff@aol.com [AREVA NP, Centre Technique, Département Corrosion-Chimie, 30 Bd de l’industrie, 71200 Le Creusot (France); Ecole Nationale Supérieure des Mines, SMS-EMSE, CNRS: UMR5146, LCG, 158 Cours Fauriel, 42023 Saint Etienne (France); Rouillard, F., E-mail: fabien.rouillard@cea.fr [CEA, DEN, DPC, SCCME, Laboratoire d’Etude de la Corrosion Non Aqueuse, 91191 Gif sur Yvette (France); Combrade, P., E-mail: pierre.combrade@orange.fr [AREVA NP, Centre Technique, Département Corrosion-Chimie, 30 Bd de l’industrie, 71200 Le Creusot (France); ACXCOR, 63, chemin de l’Arnica, 42660 Le Bessat (France); Pijolat, M., E-mail: mpijolat@emse.fr [Ecole Nationale Supérieure des Mines, SPIN-EMSE, CNRS: UMR5148, LCG, 158 Cours Fauriel, 42023 Saint Etienne (France); Wolski, K., E-mail: wolski@emse.fr [Ecole Nationale Supérieure des Mines, SMS-EMSE, CNRS: UMR5146, LCG, 158 Cours Fauriel, 42023 Saint Etienne (France)

    2013-10-15

    Graphical abstract: Display Omitted -- Highlights: •New facility coupling thermogravimetry (TGA) with gas phase chromatography (GPC). •Dedicated for HT oxidation study in VHTR impure helium containing CO, H{sub 2}O and H{sub 2}. •The oxidation kinetics obeys a complete parabolic law due to a mixed kinetic regime. •CO contributes during initial stage of oxidation only for very low H{sub 2}O partial pressure. •Long-term oxidation of Inconel 617 by H{sub 2}O is diffusion controlled with constant kp. -- Abstract: A new facility coupling thermogravimetric analysis (TGA) with gas phase chromatography (GPC) has been developed. This facility is dedicated for studying high temperature oxidation of Inconel 617 in impure helium environment containing H{sub 2}O, H{sub 2} and CO at very low partial pressures (in the Pa range), which is representative of the high temperature reactor (HTR) concept developed within the Generation IV Forum. Simultaneous acquisition of mass gain and gas composition has allowed the influence of carbon monoxide and water vapour on the kinetics of oxidation to be studied. GPC measurements of gas consumption have allowed the plotting of individual mass gain curves for oxidation by H{sub 2}O and CO. During isothermal exposure at 1123 K for 20 h, the oxidation was mainly due to water vapour with a minor contribution of carbon monoxide during the first hours. The contribution of water vapour to the oxidation kinetics was extracted. It was shown to obey a complete parabolic law and to be limited by an interfacial reaction during the first few hours of oxidation and to be controlled by a mixed interfacial and diffusion process, diffusion becoming the rate-determining step for long term oxidation. There was very good agreement between GPC measurements and the experimental TGA results.

  3. Study on Selective Laser Melting Additive Manufacturing Process of INCONEL Ni-based Superalloy%INCONEL系镍基高温合金选区激光熔化增材制造工艺研究

    Institute of Scientific and Technical Information of China (English)

    张颖; 顾冬冬; 沈理达; 田宗军

    2014-01-01

    Influence of the process parameters on densification behavior ,microstructure characteristics,microhardness and wear performance of SLM-processed Inconel 718 alloy samples was studied comprehensively. The result shows that at a lower laser linear energy density (η),the balling effect caused a low densification level. At a higher value of laser energy density with reasonable process parameters,nearly full dense Inconel 718 part was obtained. Besides,as laser energy density increased,microstructures of Inconel 718 parts experienced such changes:coarsened columnar dendrites,clustered dendrites,slender and uniformly distributed columnar dendrites. Samples manufactured at optimized process parameters exhibited high microhardness of 397.8 HV0.2,low mean COF value of 0.40 and low wear rate of 4.78 ×10-4 mm3/Nm. The formation of fine microstructure and the protective tribolayer gave the sample good wear performance.%研究了激光加工工艺参数对选区激光熔化工艺成形的Inconel 718合金试样的致密化行为、显微组织特征、硬度及摩擦磨损性能的影响。结果表明:当激光线能量密度(η)较低时,球化效应的出现使试样的致密度水平较低;在较高的线能量密度与合适的加工参数下,可获得接近完全致密的Inconel 718合金试样。同时,随着激光线能量密度的增加,SLM成形Inconel 718合金试样的显微组织经历了粗大的柱状树枝晶、聚集的枝晶、细长而均匀分布的柱状枝晶等变化过程。在优化工艺参数下,成形试样的显微硬度高达397.8 HV0.2;摩擦系数和磨损率较低,分别为0.40和4.78×10-4 mm3/Nm;且试样内部显微组织均匀细小,摩擦试样的表面形成摩擦保护层,使试样的摩擦磨损性能较好。

  4. DESGASTE POR ABRASIÓN DEL ACERO API 5L X65 REVESTIDO CON NIOBIO POR ASPERSIÓN TÉRMICA A PLASMA Y CON INCONEL 625 POR SOLDADURA

    Directory of Open Access Journals (Sweden)

    JOSE MATOS

    2012-01-01

    Full Text Available El objetivo de este trabajo fue evaluar y caracterizar el comportamiento mecánico en desgaste del acero API 5L X65, revestido con niobio en comparación al desempeño del revestimiento de la aleación de inconel 625 empleados en la industria de petróleo y gas. El revestimiento de niobio fue obtenido por el proceso de aspersión térmica a plasma de arco no transferido y el revestimiento inconel 625 por soldadura con electrodo revestido. La resistencia al desgaste por abrasión fue evaluada según la norma Petrobras N-2568, en un tribómetro CTER, la rugosidad y el volumen de material desgastado se determinó a través de perfilometría y la dureza de los revestimientos por microscopia Vickers. Los revestimientos obtenidos fueron caracterizados respecto a su morfología por microscopia electrónica de barrido (MEB y microscopía óptica (MO. La mayor dureza del revestimiento con niobio obtenido puede haber contribuido a reducir la tasa de desgaste en comparación con el revestimiento de inconel 625.

  5. Inconel 740H主要强化元素对热力学平衡相析出行为的影响

    Institute of Scientific and Technical Information of China (English)

    符锐; 林富生; 赵双群; 迟成宇

    2013-01-01

    针对700℃先进超超临界电站过热器/4g热器管用镍基高温合金Inconel 740H,通过热力学相计算研究了主要析出强化元素对其平衡析出相析出行为的影响.结果表明:合金中7’相和M23C6碳化物稳定温度范围宽,稳定性好;A1、Ti和Nb3种合金成分对y相、叩相和dr相的析出和稳定性影响大,而Co的影响不大,其中A1对’,’相和d相的析出和稳定起促进作用,对7/相起抑制作用,Ti和Nb对y’相、∞相和口相均起促进作用;C显著影响M23C6碳化物的析出量,Cr显著影响M23C6碳化物的析出温度.Al、Ti和Nb的质量分数分别控制在1.2V0~1.4%、1%~1.5%和1%~1.6%为宜;同时,c的质量分数保持在0.05%左右,Cr的质量分数也应保持25%左右,Co的质量分数有所减小,不会影响y’相和M:。c。碳化物等强化相的析出量,从而对Inconel 740H合金的成分范围进行了一定的优化.

  6. Influence of the Overlapping Factor and Welding Speed on T-Joint Welding of Ti6Al4V and Inconel 600 Using Low-Power Fiber Laser

    Directory of Open Access Journals (Sweden)

    Shamini Janasekaran

    2016-06-01

    Full Text Available Double-sided laser beam welding of skin-stringer joints is an established method for many applications. However, in certain cases with limited accessibility, single-sided laser beam joining is considered. In the present study, single-sided welding of titanium alloy Ti6Al4V and nickel-based alloy Inconel 600 in a T-joint configuration was carried out using continuous-wave (CW, low-power Ytterbium (Yb-fiber laser. The influence of the overlapping factor and welding speed of the laser beam on weld morphology and properties was investigated using scanning electron microscopy (SEM and X-ray diffraction (XRD, respectively. XRD analysis revealed the presence of intermetallic layers containing NiTi and NiTi2 at the skin-stringer joint. The strength of the joints was evaluated using pull testing, while the hardness of the joints was analyzed using Vickers hardness measurement at the base metal (BM, fusion zone (FZ and heat-affected zone (HAZ. The results showed that the highest force needed to break the samples apart was approximately 150 N at a laser welding power of 250 W, welding speed of 40 mm/s and overlapping factor of 50%. During low-power single-sided laser welding, the properties of the T-joints were affected by the overlapping factor and laser welding speed.

  7. In-situ heat treatment and polythionic acid testing of Inconel 600 Row 1 steam-generator U-bends. Final report. [PWR

    Energy Technology Data Exchange (ETDEWEB)

    Gilkison, J.M.

    1983-04-01

    U-bend leakage in Row 1 steam generator tubes has been reported at some operating plants. The leakage in these U-bends has been attributed to stress corrosion cracking that initiated at the ID surface of the tubes. The objective of Project S191-3 is to demonstrate the feasibility of heating the U-bends from the bore of the tube to a temperature that will reduce the residual stresses at the U-bend and thereby provide added resistance to stress corrosion. A number of U-bends fabricated from 3/4-inch and 7/8-inch O.D. mill annealed Inconel Alloy 600 tubing were heated to 788/sup 0/C (1450/sup 0/F) for 15 minutes using specially designed electrical resistance heaters. The results of these tests showed that the resistance heaters were capable of heating the U-bends to the desired temperatures and thus cause a significant reduction in the residual stresses. However, a desired improvement in microstructure was not detected. No significant distortion in the U-bends was detected, but the tube support plate was heated sufficiently to possibly cause unacceptable local thermally induced stresses.

  8. In-situ heat treatment and polythionic acid testing of Inconel 600 Row 1 steam-generator U-bends. Final report

    International Nuclear Information System (INIS)

    U-bend leakage in Row 1 steam generator tubes has been reported at some operating plants. The leakage in these U-bends has been attributed to stress corrosion cracking that initiated at the ID surface of the tubes. The objective of Project S191-3 is to demonstrate the feasibility of heating the U-bends from the bore of the tube to a temperature that will reduce the residual stresses at the U-bend and thereby provide added resistance to stress corrosion. A number of U-bends fabricated from 3/4-inch and 7/8-inch O.D. mill annealed Inconel Alloy 600 tubing were heated to 7880C (14500F) for 15 minutes using specially designed electrical resistance heaters. The results of these tests showed that the resistance heaters were capable of heating the U-bends to the desired temperatures and thus cause a significant reduction in the residual stresses. However, a desired improvement in microstructure was not detected. No significant distortion in the U-bends was detected, but the tube support plate was heated sufficiently to possibly cause unacceptable local thermally induced stresses

  9. Improvement of Surface Properties of Inconel718 by HVOF Coating with WC-Metal Powder and by Laser Heat Treatment of the Coating

    Directory of Open Access Journals (Sweden)

    Hui Gon Chun

    2015-01-01

    Full Text Available High-velocity oxygen-fuel (HVOF thermal spray coating with WC-metal powder was carried out by using optimal coating process on an Inconel718 surface for improvement of the surface properties, friction, wear, and corrosion resistance. Binder metals such as Cr and Ni were completely melted and WC was decomposed partially to W2C and graphite during the high temperature (up to 3500°C thermal spraying. The melted metals were bonded with WC and other carbides and were formed as WC-metal coating. The graphite and excessively sprayed oxygen formed carbon oxide gases, and these gases formed porous coating by evolution of the gases. The surface properties were improved by HVOF coating and were improved further by CO2 laser heat treatment (LH. Wear resistance of In718 surface was improved by coating and LH at 25°C and an elevated temperature of 450°C, resulting in reduction of wear trace traces, and was further improved by LH of the coating in reducing wear depth. Corrosion resistance due to coating in sea water was improved by LH. HVOF coating of WC-metal powder on a metal surface and a LH of the coating were highly recommended for the improvement of In718 surface properties, the friction behavior, and wear resistance.

  10. A mechanical property and stress corrosion evaluation of VIM-ESR-VAR work strengthened and direct double aged Inconel 718 bar material

    Science.gov (United States)

    Montano, J. W.

    1986-01-01

    Presented are the mechanical properties and the stress corrosion resistance of triple melted vacuum induction melted (VIM), electro-slag remelted (ESR), and vacuum arc remelted (VAR), solution treated, work strengthened and direct double aged Inconel 718 alloy bars 4.00 in. (10.16) and 5.75 in. (14.60 cm) diameter. Tensile, charpy v-notched impact, and compact tension specimens were tested at ambient temperature in both the longitudinal and transverse directions. Longitudinal tensile and yield strengths in excess of 220 ksi (1516.85 MPa) and 200 ksi (1378.00 MPa) respectively, were realized at ambient temperature. Additional charpy impact and compact tension tests were performed at -100 F (-73 C). Longitudinal charpy impact strength equalled or exceeded 12.0 ft-lbs (16.3 Joules) at ambient and at -100 F(-73 C) while longitudinal compact (LC) tension fracture toughness strength remained above 79 ksi (86.80 MPa) at ambient and at -100 F(-73 C) temperatures. No failures occurred in the longitudinal or transverse tensile specimens stressed to 75 and 100 percent of their respective yield strengths and exposed to a salt fog environment for 180 days. Tensile tests performed after the stress corrosion test indicated no mechanical property degradation.

  11. Imaging and characterization of γ′ and γ″ nanoparticles in Inconel 718 by EDX elemental mapping and FIB–SEM tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kulawik, K., E-mail: kulawik@agh.edu.pl [AGH University of Science and Technology, International Centre of Electron Microscopy for Materials Science, Faculty of Metals Engineering and Industrial Computer Science, Al. A. Mickiewicza 30, 30-059 Kraków (Poland); Buffat, P.A., E-mail: philippe.buffat@epfl.ch [AGH University of Science and Technology, International Centre of Electron Microscopy for Materials Science, Faculty of Metals Engineering and Industrial Computer Science, Al. A. Mickiewicza 30, 30-059 Kraków (Poland); Ecole Polytechnique Fédérale de Lausanne, CIME, Station 12, CH-1015 Lausanne Switzerland (Switzerland); Kruk, A., E-mail: kruczek@uci.agh.edu.pl [AGH University of Science and Technology, International Centre of Electron Microscopy for Materials Science, Faculty of Metals Engineering and Industrial Computer Science, Al. A. Mickiewicza 30, 30-059 Kraków (Poland); Wusatowska-Sarnek, A.M., E-mail: agnieszka.wusatowska-sarnek@pw.utc.com [Pratt & Whitney, 400 Main Street, East Hartford, CT 06108 (United States); Czyrska-Filemonowicz, A., E-mail: czyrska@agh.edu.pl [AGH University of Science and Technology, International Centre of Electron Microscopy for Materials Science, Faculty of Metals Engineering and Industrial Computer Science, Al. A. Mickiewicza 30, 30-059 Kraków (Poland)

    2015-02-15

    Microstructural characterization of Inconel 718 superalloy after three different heat treatment variants was performed by electron microscopy and electron tomography techniques, taking advantage of recent development in quantitative electron microscopy. Distribution maps of the chemical elements, collected by ChemiSTEM™ EDX system, offer a clear contrast between γ′, γ″, and the γ matrix. It was found that the γ′ phase contains mainly Ni, Al, and Ti, while the γ″ phase contains Ni, Nb, and Ti. Thus application of the Al and Nb STEM–EDX elemental maps enables identification and size measurements of γ′ and γ″ nanoparticles. 3D morphology of γ′ and γ″ precipitates was examined by electron microscopy and FIB–SEM tomography. Employed methods revealed that in all three heat treatment variants the γ′ particles are almost spheroidal while the γ″ precipitates are mainly elongated-disc shaped. However, the precipitate sizes differed for each variant contributing to differences in the yield strength. Tomographic images were used for estimation of the volume fraction of the both strengthening phases. - Highlights: • ChemiSTEM™ EDX elemental maps bring a fast mean to differentiate γ′ and γ″ particles. • Such maps enable for the explicit size measurements of γ′ and γ″ nanoparticles. • Explicit γ′ and γ″ phases total volume fraction was measured employing FIB–SEM. • γ′/γ″ co-precipitates and sandwich-like γ′/γ″/γ′ particles were present. • HRSTEM-HAADF imaging revealed atomic columns of the γ′/γ″ co-precipitates.

  12. Imaging and characterization of γ′ and γ″ nanoparticles in Inconel 718 by EDX elemental mapping and FIB–SEM tomography

    International Nuclear Information System (INIS)

    Microstructural characterization of Inconel 718 superalloy after three different heat treatment variants was performed by electron microscopy and electron tomography techniques, taking advantage of recent development in quantitative electron microscopy. Distribution maps of the chemical elements, collected by ChemiSTEM™ EDX system, offer a clear contrast between γ′, γ″, and the γ matrix. It was found that the γ′ phase contains mainly Ni, Al, and Ti, while the γ″ phase contains Ni, Nb, and Ti. Thus application of the Al and Nb STEM–EDX elemental maps enables identification and size measurements of γ′ and γ″ nanoparticles. 3D morphology of γ′ and γ″ precipitates was examined by electron microscopy and FIB–SEM tomography. Employed methods revealed that in all three heat treatment variants the γ′ particles are almost spheroidal while the γ″ precipitates are mainly elongated-disc shaped. However, the precipitate sizes differed for each variant contributing to differences in the yield strength. Tomographic images were used for estimation of the volume fraction of the both strengthening phases. - Highlights: • ChemiSTEM™ EDX elemental maps bring a fast mean to differentiate γ′ and γ″ particles. • Such maps enable for the explicit size measurements of γ′ and γ″ nanoparticles. • Explicit γ′ and γ″ phases total volume fraction was measured employing FIB–SEM. • γ′/γ″ co-precipitates and sandwich-like γ′/γ″/γ′ particles were present. • HRSTEM-HAADF imaging revealed atomic columns of the γ′/γ″ co-precipitates

  13. Surface state of Inconel 718 ultrasonic shot peened: Effect of processing time, material and quantity of shot balls and distance from radiating surface to sample

    International Nuclear Information System (INIS)

    Research highlights: → As USP processing time increases more compressive surface stresses are induced until a saturation level is reached. → The distance between part and radiating surface notably influences the surface state. → A greater number of shot balls leads to less impacts of lower energy on the part surface. → Surface nanocrystallization can only be achieved with large impacting energies of the balls. -- Abstract: Plates of Inconel 718 in precipitated state have been subjected to ultrasonic shot peening (USP), varying the distance from the radiating surface of the booster to the sample, the processing time and the material (WC/Co and steel) and number of shot balls, in order to study the effect of these parameters on the final state generated by the USP process. A change to more compressive residual stresses at the surface of the treated parts has been measured in all cases. For higher USP processing times and/or lower booster-sample distances, the degree of plastic deformation in the treated material increases, leading to a change to more compressive surface stresses and a higher density of impact marks in the treated surface. The same occurs when WC/Co balls are used instead of steel balls. The tendency to more compressive stresses reaches a saturation level after a certain processing time, when the system is not able to force the material to continue with more plastic deformation. If a higher quantity of balls is used, there will be less impacts of the shots with the surface and their energy will be lower (due to losses of energy after inelastic collisions). This diminishes the effect of the impacts in introducing compressive stresses and leads to less and shallower impact marks in the treated surface.

  14. The corrosion behaviour (stress corrosion and intergranular corrosion) of the tube materials inconel 600 and incoloy 800 for nuclear steam generators in treated secondary cycle water during tube burst tests in the temperature range from 270 to 3500C

    International Nuclear Information System (INIS)

    Surface removal, intergranular corrosion and stress corrosion of the materials No. 2.4640 (Inconel 600) and No. 1.4558 (Incoloy 800) were investigated in solutions of NaOH, Na2HPO4 and Na3PO4 whose concentrations were about 10,000 higher than those given in the guidelines. The test parameters varied were the alkalising agent and the pH value and, in addition, temperature (270, 310 and 3500C); the possible influence of low temperature sensitation (for 1000 and 10,000 hours) was also investigated. (orig.)

  15. Research on Mechanical Properties and Corrosion Behavior of Welded Joints of X65/316L and AISI4130/Inconel625 Clad Pipe%X65/316L与AISI4130/Inconel625复合管焊接接头力学性能及腐蚀行为研究

    Institute of Scientific and Technical Information of China (English)

    吴星东; 谢树军

    2014-01-01

    X65/316L and AISI4130/Inconel625 clad pipe were successfully welded with ERNiCrMo-3 filler metal, and the mechanical properties and corrosion behavior of the welded joints were studied in this paper. Tensile test, all-weld metal tensile test, impact test, as well as hardness test were performed to characterize the mechanical properties of the joints. The CO2 stress corrosion test and electrochemical corrosion test were conducted on clad pipe joints according to the corresponding standards of ASTM G39 and ASTM G5. The results showed that tensile strength of the joint achieved 583 MPa and crack propagated along X65/316L base metal; however, the yield strength, tensile strength and elongation of the weld metal reached to 441.4 MPa, 725.9 MPa, 37.67%, respectively. The absorbed impact energy of the weld metal at-10℃was 157 J, and the hardness value of joint presented gradient transition. After CO2 stress corrosion test, the weightlessness of clad pipe welded sample reached the standard, and no crack was observed in base metal and weld; the corrosion resistance of weld and HAZ is was equal to that of base metal after electrochemical corrosion test.%采用ERNiCrMo-3焊丝成功焊接X65/316L与AISI4130/Inconel625复合管,研究了复合管焊接接头的力学性能和腐蚀行为。采用拉伸试验、全焊缝拉伸试验、冲击试验、硬度测试表征了焊接接头的力学性能。参照ASTM G39和ASTM G5的相应标准对复合管焊接接头进行了CO2应力腐蚀和电化学腐蚀性能测试。结果表明,复合管焊接接头的抗拉强度达到583 MPa,断裂发生在 X65/316L 母材处;焊缝屈服强度为441.4 MPa,抗拉强度为725.9 MPa,延伸率达到37.67%;在-10℃试验条件下,焊缝的冲击吸收功为157 J,接头硬度值呈现梯度过渡。复合管焊接试样经过CO2应力腐蚀试验后失重达标,在母材和焊缝处没有观察到裂纹;电化学腐蚀试验后焊缝和热影响区的耐蚀性与母材相当。

  16. Materials corrosion and mitigation strategies for APT, end of FY `97 report: Inconel 718 in-beam corrosion rates from the `97 A6 irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Lillard, R.S.; Pile, D.L.; Butt, D.P.

    1998-08-01

    This report summarizes the results from the 1997 irradiation of the corrosion insert at the LANSCE A6 Target Station. It addresses the corrosion measurements made on the in-beam Inconel 718 probe only. To simulate the environment that materials may be exposed to in a spallation neutron target/blanket cooling loops, samples were irradiated by the proton beam at the A6 Target Station of the Los Alamos Neutron Scattering Center (LANSCE). EIS measurements have demonstrated that the polarization resistance of IN718 decreases from approximately 3 x 10{sup 5} ohms prior to irradiation to approximately 1,000 ohms during irradiation at a proton beam current of 400 {micro}A. From the polarization resistance measurements, corrosion rate as a function of beam current was calculated for several different scenarios of beam/sample interaction. As the beam spot was small relative to the size of the IN718 corrosion probe (2{sigma} = 3 cm vs. 1.3 cm diam. x 15.9 cm length respectively), The first method for calculating corrosion rate used beam profile as a criterion for the area of highest damage. The beam spot intensity profile at LANSCE has been characterized and found to be a Gaussian distribution rotated about a central axis. From this relationship, and R{sub p} as a function of beam current, corrosion rate as a function of radial distance from the center of the beam was calculated for each beam current. Physical evidence from change in thickness measurements made on tungsten rods irradiated at 1 mA during the FY 96 irradiation period suggest that this Gaussian damage profile is an accurate depiction of beam/sample interaction. From this method the corrosion rate of IN718 during irradiation at a beam current of 1.0 mA is calculated to be approximately 0.002 inches per yr (2 mpy). The second method assumed that the predominant contributor to the corrosion current comes from an area defined by 2{sigma}. Further, the method assumed that the corrosion rate was uniform over this area

  17. The Study Of The Impact Of Surface Preparation Methods Of Inconel 625 And 718 Nickel-Base Alloys On Wettability By BNi-2 And BNi-3 Brazing Filler Metals

    Directory of Open Access Journals (Sweden)

    Lankiewicz K.

    2015-06-01

    Full Text Available The article discusses the impact of surface preparation method of Inconel 625 and 718 nickel-base alloys in the form of sheets on wettability of the surface. The results of the investigations of surface preparation method (such as nicro-blasting, nickel plating, etching, degreasing, abrasive blasting with grit 120 and 220 and manually grinding with grit 120 and 240 on spreading of BNi-2 and BNi-3 brazing filler metals, widely used in the aerospace industry in high temperature vacuum brazing processes, are presented. Technological parameters of vacuum brazing process are shown. The macro- and microscopic analysis have shown that nicro-blasting does not bring any benefits of wettability of the alloys investigated.

  18. Interactions in Zircaloy/UO2 fuel rod bundles with Inconel spacers at temperatures above 1200deg C (posttest results of severe fuel damage experiments CORA-2 and CORA-3)

    International Nuclear Information System (INIS)

    In the CORA experiments test bundles of usually 16 electrically heated fuel rod simulators and nine unheated rods are subjected to temperature transients of a slow heatup rate in a steam environment. Thus, an accident sequence is simulated, which may develop from a small-break loss-of-coolant accident of an LWR. An aim of CORA-2, as a first test of its kind, was also to gain experience in the test conduct and posttest handling of UO2 specimens. CORA-3 was performed as a high-temperature test. The transient phases of CORA-2 and CORA-3 were initiated with a temperature ramp rate of 1 K/s. The temperature escalation due to the exothermal zircaloy(Zry)-steam reaction started at about 1000deg C, leading the bundles to maximum temperatures of 2000deg C and 2400deg C for tests CORA-2 and CORA-3, respectively. The test bundles resulted in severe oxidation and partial melting of the cladding, fuel dissolution by Zry/UO2 interaction, complete Inconel spacer destruction, and relocation of melts and fragments to lower elevations in the bundle, where extended blockages have formed. In both tests the fuel rod destruction set in together with the formation of initial melts from the Inconel/Zry interaction. The lower Zry spacer acted as a catcher for relocated material. In test CORA-2 the UO2 pellets partially disintegrated into fine particles. This powdering occurred during cooldown. There was no physical disintegration of fuel in test CORA-3. (orig./MM)

  19. Probabilistic and microstructural aspects of fatigue cracks initiation in Inconel 718; Aspects probabilistes et microstructuraux de l'amorcage des fissures de fatigue dans l'alliage INCO 718

    Energy Technology Data Exchange (ETDEWEB)

    Alexandre, F

    2004-03-15

    Thermomechanical treatments have been recently developed to produce Inconel 718DA (Direct Aged). This alloy optimisation leads to an increase of the fatigue life but also the scatter. The aim of this study is on the one hand the understanding of the fatigue crack initiation mechanisms and on the other hand the modelling of the fatigue life and the scatter. An experimental study showed that the fatigue cracks were initiated from carbide particles in fine grain alloy. Interrupted tensile tests show that the particles cracking occurred at the first quarter of the fatigue cycle. Fatigue behaviour tests were also performed on various grain size 718 alloys. The last experimental part was devoted to measurements of the low cycle fatigue crack growth rates using a high focal distance microscope. For these tests, EDM micro-defects were used for the fatigue crack initiation sites. This method was also used to observe the small fatigue crack coalescence. A fatigue life model is proposed. It is based on the three fatigue crack initiation mechanisms competition: particle crack initiation on the surface, internal particle crack initiation and Stade I crack initiation. The particle fatigue crack initiation is supposed instantaneous at a critical stress level. The Tanaka and Mura model is used for analysing the Stage I crack initiation number of cycles. The fatigue crack growth rate was analysed using the Tomkins model identified on the small fatigue crack growth rate measurements. The proposed fatigue life model decomposed in three levels: a deterministic one and two probabilistic with and without crack coalescence. (author)

  20. Development of safety evaluation technique of steam generator tubes for the next generation

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Hyuk Sang; Kim, I. S.; Ann, Se Jin; Lee, S. J.; Seo, M. S.; Lee, Y. H.; Kim, J. H.; Hong, J. G. [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)

    2000-02-15

    Subject 1 - a technique for predicting the SCC susceptibility of steam generator tube material based on the repassivation kinetics was developed and the effects of Pb in the repassivation rate and SCC susceptibility rate of tube material was investigated with this technique. An alloy with a higher slope value of log i(t) vs. q(t) plot based on the current transient curve obtained by scratch test and a lower slope value log i(t) vs. l/q(t) plot (cBV) is repassivated faster with a more protective passive film and it can be predicted that it will show higher resistance to SCC. With PbO addition in all solution studied (pH 4, pH 10, Cl- containing pH 4), alloy 690TT showed decreased repassivation rate. So it can be predict that PbO addition lower the resistance of SCC of steam generator tune material. Subject 2 - SG wear testing of tube and support materials has been conducted at various load and sliding amplitude in air environment. The results showed effect of normal load and sliding amplitude on SG tube wear damage. It was also shown that, for predominantly sliding motion, the SG wear coefficient of work-rate model is lower for Inconel 690TT compared with inconel 600MA. SG tube wear data show that, for work-rates ranging from 4 to 25mW, average tube wear coefficient of 43.76{approx}54.05 X 10{sup 15} Pa{sup -1} for Inconel 600MA and 26.88{approx}33.94 X 10{sup -15} Pa{sup 1} for Inconel 690TT against 405 and 409 stainless steels.

  1. Development of safety evaluation technique of steam generator tubes for the next generation

    International Nuclear Information System (INIS)

    Subject 1 - a technique for predicting the SCC susceptibility of steam generator tube material based on the repassivation kinetics was developed and the effects of Pb in the repassivation rate and SCC susceptibility rate of tube material was investigated with this technique. An alloy with a higher slope value of log i(t) vs. q(t) plot based on the current transient curve obtained by scratch test and a lower slope value log i(t) vs. l/q(t) plot (cBV) is repassivated faster with a more protective passive film and it can be predicted that it will show higher resistance to SCC. With PbO addition in all solution studied (pH 4, pH 10, Cl- containing pH 4), alloy 690TT showed decreased repassivation rate. So it can be predict that PbO addition lower the resistance of SCC of steam generator tune material. Subject 2 - SG wear testing of tube and support materials has been conducted at various load and sliding amplitude in air environment. The results showed effect of normal load and sliding amplitude on SG tube wear damage. It was also shown that, for predominantly sliding motion, the SG wear coefficient of work-rate model is lower for Inconel 690TT compared with inconel 600MA. SG tube wear data show that, for work-rates ranging from 4 to 25mW, average tube wear coefficient of 43.76∼54.05 X 1015 Pa-1 for Inconel 600MA and 26.88∼33.94 X 10-15 Pa1 for Inconel 690TT against 405 and 409 stainless steels

  2. Operation experiences of the steam generator repair technique by means of weldless sleeves

    International Nuclear Information System (INIS)

    Field performances of the weldless PLUSS sleeve up to these days establishes it as a reliable technique for use as tube-in-tube repair of damaged tubing of steam generators customarily served by nuclear reactors. For the functioning of the weldless PLUSS Sleeve the proper combination of tube and sleeve material is decisive. It turned out that for steam generator tubing of Inconel Alloy 600 and Inconel Alloy 690 the sleeve out of Incoloy Alloy 800 serves this purpose perfectly. Via hydraulic expansion the weldless sleeve of Incoloy Alloy 800 is permanently fixed against the parent tube of Inconel Alloys 600/690. Upon relieving the exerted hydraulic pressure, the tube springs back more than the sleeve does, the net effect being that there materializes an interference at the interface between sleeve and tube. The PLUSS sleeve, while spanning the defective zone of the tube, takes the advantage of this phenomenon to secure the sleeve within the tube at ambient temperature. Emergence of the unique expansion joint of the PLUSS sleeve is the result. At higher operating temperatures associated with higher system pressures the expansion joint gets even tighter as the interference between the joint members increases owing to the fact that Inconel Alloys 600/690 and Incoloy Alloy 800 possess different coefficients of thermal expansion. The weldless sleeving technique with favourable stress situation and reduced installation steps compared to other kind of sleeving techniques offers a significant improvement in the field application. At present it is probably the most efficient and cost-effective repair technique of all. The paper discusses the working principle of the product and its successful installation in various nuclear power plants worldwide. It further discusses the field application with respect to a particular utility and operational experiences gained so far. Furthermore, the plant performance is dealt with briefly. (author)

  3. Microstructure and precipitation effects in inconel alloy 600.

    OpenAIRE

    Gane, Peter James

    1992-01-01

    The main objectives of the project were to investigate the interactions of carbon, titanium and aluminium contents, grain size and cold working, with precipitation reactions which occur during heat treatments similar to those experienced as a consequence of commercial PWR Steam Generator (SG) tube processing. In order to carry out this investigation commercial material was supplemented by a range of experimental casts. The selected casts allowed the investigation of the following comp...

  4. Composite spacer with inconel grid and zircaloy band

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, E.B.; Matzner, B.; Latter, G.M.

    1992-02-18

    This patent describes a spacer for use in a nuclear fuel bundle having a plurality of fuel rods. It includes spring metal spacer cells, each cell having: at least one spring leg, the spring leg inwardly deflected at the medial portion thereof for spring contact with a fuel rod within the spacer cell; at least two rod encircling arms affixed at remote ends of the spring legs; each rod encircling arm defining stops for abutting a fuel rod whereby the spring leg can bias an encircled fuel rod within the cells into the stops; the rod encircling arms having differential length including a first portion of the arms having a relatively longer length and a second portion of the arms having a relatively shorter length; the cells confronted into cell pairs with the spring legs remote from one another.

  5. Real structure of milled inconel 738LC turbine blades

    Czech Academy of Sciences Publication Activity Database

    Pala, Z.; Kolařík, K.; Beránek, L.; Čapek, J.; Kyncl, J.; Mušálek, Radek; Ganev, N.

    Vol. 996. Zürich: Trans Tech Publications, 2014 - (François, M.; Montay, G.; Panicaud, B.; Retraint, D.; Rouhaud, E.), s. 646-651. (996). ISSN 1662-8985. [European Conference on Residual Stresses, ECRS 2014/9./. Troyes (FR), 07.07.2014-10.07.2014] Institutional support: RVO:61389021 Keywords : Milling * Nickel super-alloys * Turbine blades Subject RIV: JK - Corrosion ; Surface Treatment of Materials http://www.scientific.net/AMR.996.646

  6. Influences of Alloying Element and Annealing on the Microstructure and Corrosion Resistance of Steam Generator Tubing Materials of Nuclear Power Plant (I)

    International Nuclear Information System (INIS)

    Influences of alloying elements and annealing heat treatments on Alloy 690 and Alloy 600 for steam generator tubing materials of nuclear power plants were studied. OM, SEM, TEM, and XRD analyses were used to study the microstructural changes of the alloys. Mechanical properties were investigated by means of tension tests and Rockwell hardness tests, and corrosion resistance was evaluated using the anodic polarization tests and the 65% boiling nitric acid immersion tests. Increasing the carbon content of Alloy 690, the hardness and tensile strength were increased, but the elongation and grain size were decreased. However, increasing the annealing temperature, the tensile strength and hardness were decreased, but the elongation and grain size were increased. Increasing the carbon content of Alloy 690, the results of the anodic polarization tests and the nitric acid immersion tests showed that the annealing temperature to reveal a minimum corrosion rate was increased. This behavior seemed to be due to the combination of the solid solution of carbon in the matrix and grain growth with annealing. In this work, the corrosion properties of Alloy 690 were better than that of Alloy 600, and the range of the optimum annealing temperature of Alloy 690 was from 1100 .deg. C to 1150 .deg. C

  7. Positron annihilation study of ageing and creep on inconel X750

    International Nuclear Information System (INIS)

    The correlation of positron annihilation characteristics with microstructrual changes occurring in a Ni-base alloy is experimentally studied using lifetime and angular-correlation methods. The samples are examined at room temperature after various ageing phases and after creep rupture; their structure is also investigated by differential chemical analysis, by electron microscopy and by small-angle neutron scattering. The comparison of the results obtained with the various techniques shows the field of applicability of the positron annihilation technique for material testing in cases of technological interest. (author)

  8. Influence of composition on precipitation behavior and stress rupture properties in INCONEL RTM740 series superalloys

    Science.gov (United States)

    Casias, Andrea M.

    Increasing demands for energy efficiency and reduction in CO2 emissions have led to the development of advanced ultra-supercritical (AUSC) boilers. These boilers operate at temperatures of 760 °C and pressures of 35 MPa, providing efficiencies close to 50 pct. However, austenitic stainless steels typically used in boiler applications do not have sufficient creep or oxidation resistance. For this reason, nickel (Ni)-based superalloys, such as IN740, have been identified as potential materials for AUSC boiler tube components. However, IN740 is susceptible to heat-affected-zone liquation cracking in the base metal of heavy section weldments. To improve weldability, IN740H was developed. However, IN740H has lower stress rupture ductility compared to IN740. For this reason, two IN740H modifications have been produced by lowering carbon content and increasing boron content. In this study, IN740, IN740H, and the two modified IN740H alloys (modified 1 and 2) were produced with equiaxed grain sizes of 90 ìm (alloys IN740, IN740H, and IN740H modified 1 alloys) and 112 µm (IN740H modified 2 alloy). An aging study was performed at 800 °C on all alloys for 1, 3, 10, and 30 hours to assess precipitation behavior. Stress rupture tests were performed at 760 °C with the goal of attaining stress levels that would yield rupture at 1000 hours. The percent reduction in area was measured after failure as a measure of creep ductility. Light optical, scanning electron, and transmission electron microscopy were used in conjunction with X-ray diffraction to examine precipitation behavior of annealed, aged, and stress rupture tested samples. The amount and type of precipitation that occurred during aging prior to stress rupture testing or in-situ during stress rupture testing influenced damage development, stress rupture life, and ductility. In terms of stress rupture life, IN740H modified 2 performed the best followed by IN740H modified 1 and IN740, which performed similarly, and IN740H. In terms of stress rupture ductility, IN740H modified 1 performed the best, followed by IN740H modified 2, IN740, and IN740H. G-phase, η, M23C 6, and MX precipitated in IN740 during stress rupture testing. IN740H and the two modified alloys displayed M23C6 precipitates that were often in lamellar form and blocky MX precipitates. However, IN740H displayed more extensive formation of lamellar precipitates along grain boundaries after both aging and during stress rupture testing, which negatively influenced stress rupture life and ductility. Grain size was also shown to influence stress rupture life and ductility; a larger grain size increased stress rupture life, but decreased ductility as shown by the IN740H modified 1 and 2 alloy results. Transmission electron microscopy analysis was performed to assess the lamellar precipitation in IN740H. These precipitates were identified to be Cr-rich M23C6 that form by discontinuous cellular precipitation (DCP). The M23C6 precipitates were found to adopt different {111} habit planes based on the conditions of DCP boundary migration. Discontinuous precipitation of lamellar M23C6 is harmful to stress rupture life and ductility.

  9. Effect of Temperature on cyclic stress components of Inconel 738LC superalloy

    Czech Academy of Sciences Publication Activity Database

    Petrenec, Martin; Šmíd, Miroslav; Obrtlík, Karel; Polák, Jaroslav

    Brno: VUTIUM Brno, 2008 - (Pokluda, J.; Lukáš, P.; Šandera, P.; Dlouhý, I.), s. 1358-1365 ISBN 978-80-214-3692-3. [ECF17 - European Conference on Fracture /17./. Brno (CZ), 02.09.2008-05.09.2008] R&D Projects: GA ČR GA106/08/1631; GA ČR GA106/07/1507; GA AV ČR IAA100480704 Institutional research plan: CEZ:AV0Z20410507 Keywords : Low cycle fatigue * High temperatrures * superalloy * internal and effective stresses Subject RIV: JL - Materials Fatigue, Friction Mechanics

  10. Oxidation assisted intergranular cracking under loading at dynamic strain aging temperatures in Inconel 718 superalloy

    International Nuclear Information System (INIS)

    Highlights: • Mechanical properties are controlled by DSA, precipitation hardening and OAIC. • Between 600 and 700 °C the critical strain for serrations increases with temperature. • This is related to the consumption of matrix elements (especially Nb: for γ′ and γ″). • A reduction in ductility occurs (related to the OAIC) when the DSA is no longer effective. • This reduction is accompanied by an increase in intergranular brittle fracture. - Abstract: It is well established that 718 superalloy exhibits brittle intergranular cracking when deformed under tension at temperatures above 600 °C. This embrittlement effect is related with grain boundary penetration by oxygen (Oxygen Assisted Intergranular Cracking – OAIC). Simultaneously, impacting on its mechanical properties, the precipitation of coherent γ′ and γ″ phases occur above 650 °C and Dynamic Strain Aging (DSA) occurs in the temperature range between 200 and 800 °C. Although literature indicates that OAIC is the mechanism that controls mechanical properties at high temperatures, its interactions with DSA and precipitation are still under discussion. The objective of this work is to investigate the interactions between the embrittlement phenomena (OAIC and DSA) and the hardening mechanism of γ′ and γ″ precipitation on the mechanical properties of an annealed 718 superalloy. Tensile tests were performed at a strain rate of 3.2 × 10−4 s−1 under secondary vacuum, in temperatures ranging from 200 to 800 °C. Fracture surfaces were observed by scanning electron microscopy (SEM) and precipitation by transmission electron microscopy (TEM). The effect of DSA and precipitation on the strength and of OAIC on the ductility was verified

  11. A study on the deformation mechanism of inconel alloys for steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Hong, S. H.; Kim, H. Y.; Ahn, Y. C.; Lee, H. S.; Sohn, W. H.; Cha, S. I.; Bae, Y. H. [Korea Advanced Institute of Science and Technology, Taejeon (Korea)

    2001-04-01

    The microstructure and the mechanical properties of lnconel 600 and 690 steam generator tube were investigated to develop the lnconel steam generator tube for nuclear power plant. The grain size and shape of lnconel 690 alloy were dependent on Mill Annealing temperature. It is shown that the smaller grain and the more serrated grain boundary, the higher tensile strength and creep resistance. The carbides were analyzed by using SEM and TEM after Thermal Treatment. Also, the quantitative analysis of carbide precipitation with Thermal Treatment was conducted by SPEED method. Thermal Treatment temperature was 705 deg C for lnconel 600 alloy and 720 deg C for lnconel 690 alloy. It is observed by XRD that the M{sub 23}C{sub 6} type and M{sub 7}C{sub 3}-type carbides were simultaneously precipitated in lnconel 600 alloy and only M{sub 23}C{sub 6}-type carbides were precipitated in lnconel 690 alloy. While the carbide length and thickness increased with increasing Thermal Treatment time, the growth rate of carbide length was higher than that of carbide thickness. The distance between carbides decreased for the first 15 hour Thermal Treatment for lnconel 600 alloy and 10 hour for lnconel 690 alloy, respectively, and then increased again. The distance between carbides decreased until the carbide precipitation reached at 90% of maximum precipitation because the carbides were precipitated and grown simultaneously. After 90% precipitation time, the precipitation ceased and only growth of the carbides took place, so the distance between carbides decreased. The serrations in stress-strain curves of in lnconel 690 could be interpreted in the temperature range from 200 deg C to 600 deg C. The phenomena and controlling mechanism of serrations were analyzed by investigating the critical strains for the onset of the serrations. The controlling mechanism for A1 serration was generation of vacancy by deformation, and those for A2 serration and B serrations were diffusion of substitutional alloying element, lattice diffusion of carbons, respectively. Besides, the C serration was formed above the temperature of 5OO deg C with irregular periods. It was shown through the creep test for lnconel 690 alloy that stress exponent, n, was 5, and activation energy for creep was about 265 k]/mol. An activation energy value for creep was similar to that for self diffusion of Ni, which is 250 k]/mol. It perhaps indicates that the controlled mechanism for high temperature deformation of lnconel 690 alloy was dislocation climb. 65 refs., 51 figs., 10 tabs. (Author)

  12. Development and Characterization of a Metal Injection Molding Bio Sourced Inconel 718 Feedstock Based on Polyhydroxyalkanoates

    OpenAIRE

    Alexandre Royer; Thierry Barrière; Jean-Claude Gelin

    2016-01-01

    The binder plays the most important role in the metal injection molding (MIM) process. It provides fluidity of the feedstock mixture and adhesion of the powder to keep the molded shape during injection molding. The binder must provide strength and cohesion for the molded part and must be easy to remove from the molded part. Moreover, it must be recyclable, environmentally friendly and economical. Also, the miscibility between polymers affects the homogeneity of the injected parts. The goal of...

  13. Laser deposition of Inconel 625/tungsten carbide composite coatings by powder and wire feedstock

    OpenAIRE

    Abioye, Taiwo E.

    2014-01-01

    There is an increasing global demand to extend the life span of down-hole drilling tools in order to improve operation effectiveness and efficiency of oil and gas production. Laser cladding of tungsten carbide/Ni-based alloy metal matrix composite (MMC) coatings is currently being utilised for this purpose. However, the effect of tungsten carbide dissolution on the corrosion performance of the MMC coatings has not been completely understood. In this work, a study was carried out in which lase...

  14. The influence of testing conditions on burst pressure assessment for inconel tubing

    International Nuclear Information System (INIS)

    Because at the lack of normalization for burst testing of tubes with TWD flaws, large divergences are observed between laboratory results. This could result in either unsafe or unduly penalizing consequences. Testing flawed tubes under representative conditions (high leak rate without any sealing provision) yielded results matching previous laboratory data that were obtained with a locally reinforced bladder. This should not be construed to validate any similar laboratory technique, as the particular combination of materials (plastic and metal) strength and thickness, together with other testing details (such as load rate) may affect the results. (author)

  15. Characterization of Machine Variability and Progressive Heat Treatment in Selective Laser Melting of Inconel 718

    Science.gov (United States)

    Prater, T.; Tilson, W.; Jones, Z.

    2015-01-01

    The absence of an economy of scale in spaceflight hardware makes additive manufacturing an immensely attractive option for propulsion components. As additive manufacturing techniques are increasingly adopted by government and industry to produce propulsion hardware in human-rated systems, significant development efforts are needed to establish these methods as reliable alternatives to conventional subtractive manufacturing. One of the critical challenges facing powder bed fusion techniques in this application is variability between machines used to perform builds. Even with implementation of robust process controls, it is possible for two machines operating at identical parameters with equivalent base materials to produce specimens with slightly different material properties. The machine variability study presented here evaluates 60 specimens of identical geometry built using the same parameters. 30 samples were produced on machine 1 (M1) and the other 30 samples were built on machine 2 (M2). Each of the 30-sample sets were further subdivided into three subsets (with 10 specimens in each subset) to assess the effect of progressive heat treatment on machine variability. The three categories for post-processing were: stress relief, stress relief followed by hot isostatic press (HIP), and stress relief followed by HIP followed by heat treatment per AMS 5664. Each specimen (a round, smooth tensile) was mechanically tested per ASTM E8. Two formal statistical techniques, hypothesis testing for equivalency of means and one-way analysis of variance (ANOVA), were applied to characterize the impact of machine variability and heat treatment on six material properties: tensile stress, yield stress, modulus of elasticity, fracture elongation, and reduction of area. This work represents the type of development effort that is critical as NASA, academia, and the industrial base work collaboratively to establish a path to certification for additively manufactured parts. For future flight programs, NASA and its commercial partners will procure parts from vendors who will use a diverse range of machines to produce parts and, as such, it is essential that the AM community develop a sound understanding of the degree to which machine variability impacts material properties.

  16. Microstructural response to heat affected zone cracking of prewelding heat-treated Inconel 939 superalloy

    International Nuclear Information System (INIS)

    The microstructural response to cracking in the heat-affected zone (HAZ) of a nickel-based IN 939 superalloy after prewelding heat treatments (PWHT) was investigated. The PWHT specimens showed two different microstructures: 1) spherical ordered γ′ precipitates (357–442 nm), with blocky MC and discreet M23C6 carbides dispersed within the coarse dendrites and in the interdendritic regions; and 2) ordered γ′ precipitates in “ogdoadically” diced cube shapes and coarse MC carbides within the dendrites and in the interdendritic regions. After being tungsten inert gas welded (TIG) applying low heat input, welding speed and using a more ductile filler alloy, specimens with microstructures consisting of spherical γ′ precipitate particles and dispersed discreet MC carbides along the grain boundaries, displayed a considerably improved weldability due to a strong reduction of the intergranular HAZ cracking associated with the liquation microfissuring phenomena. - Highlights: ► Homogeneous microstructures of γ′ spheroids and discreet MC carbides of Ni base superalloys through preweld heat treatments. ► γ′ spheroids and discreet MC carbides reduce the intergranular HAZ liquation and microfissuring of Nickel base superalloys. ► Microstructure γ′ spheroids and discreet blocky type MC carbides, capable to relax the stress generated during weld cooling. ► Low welding heat input welding speeds and ductile filler alloys reduce the HAZ cracking susceptibility.

  17. Inducement of IGA/SCC in Inconel 600 steam generator tubing during unit outages

    International Nuclear Information System (INIS)

    The degradation of Unit 4 SG tubing by IGA/SCC has limited both the operating period and end of life predictions for Unit 4 since restart in late 2003. The circumferential IGA/SCC has been most significant in SG4 with substantial increases in both initiation and growth rates from 2005 through the spring of 2007. A detailed review of the occurrence of circumferential OD IGA/SCC at the RTZ in the HL TTS region of Bruce 4 steam generator tubes has led a conclusion that it is probable that the IGA/SCC has been the result of attack by partially reduced sulfur species such as tetrathionates and thiosulfates during periods of low temperature exposure. It is believed that attack of this type has mostly likely occurred during startup evolutions following outages as the result the development of aggressive reduced sulfur species in the TTS region during periods when the boilers were fully drained for maintenance activities. The modification of outage practices to limit secondary side oxygen ingress in the spring of 2007 has apparently arrested the degradation and has had significant affects on the allowable operating interval and end of life predictions for the entire unit. (author)

  18. Microstructural response to heat affected zone cracking of prewelding heat-treated Inconel 939 superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, M.A., E-mail: mgonzalez@comimsa.com.mx [Facultad de Ingenieria Mecanica y Electrica (FIME-UANL), Av. Universidad s/n. Ciudad Universitaria, C.P.66451 San Nicolas de los Garza, N.L. (Mexico); Martinez, D.I., E-mail: dorairma@yahoo.com [Facultad de Ingenieria Mecanica y Electrica (FIME-UANL), Av. Universidad s/n. Ciudad Universitaria, C.P.66451 San Nicolas de los Garza, N.L. (Mexico); Perez, A., E-mail: betinperez@hotmail.com [Facultad de Ingenieria Mecanica y Electrica (FIME-UANL), Av. Universidad s/n. Ciudad Universitaria, C.P.66451 San Nicolas de los Garza, N.L. (Mexico); Guajardo, H., E-mail: hguajardo@frisa.com [FRISA Aerospace, S.A. de C.V., Valentin G. Rivero No. 200, Col. Los Trevino, C.P. 66150, Santa Caterina N.L. (Mexico); Garza, A., E-mail: agarza@comimsa.com [Corporacion Mexicana de Investigacion en Materiales S.A. de C.V. (COMIMSA), Ciencia y Tecnologia No.790, Saltillo 400, C.P. 25295 Saltillo Coah. (Mexico)

    2011-12-15

    The microstructural response to cracking in the heat-affected zone (HAZ) of a nickel-based IN 939 superalloy after prewelding heat treatments (PWHT) was investigated. The PWHT specimens showed two different microstructures: 1) spherical ordered {gamma} Prime precipitates (357-442 nm), with blocky MC and discreet M{sub 23}C{sub 6} carbides dispersed within the coarse dendrites and in the interdendritic regions; and 2) ordered {gamma} Prime precipitates in 'ogdoadically' diced cube shapes and coarse MC carbides within the dendrites and in the interdendritic regions. After being tungsten inert gas welded (TIG) applying low heat input, welding speed and using a more ductile filler alloy, specimens with microstructures consisting of spherical {gamma} Prime precipitate particles and dispersed discreet MC carbides along the grain boundaries, displayed a considerably improved weldability due to a strong reduction of the intergranular HAZ cracking associated with the liquation microfissuring phenomena. - Highlights: Black-Right-Pointing-Pointer Homogeneous microstructures of {gamma} Prime spheroids and discreet MC carbides of Ni base superalloys through preweld heat treatments. Black-Right-Pointing-Pointer {gamma} Prime spheroids and discreet MC carbides reduce the intergranular HAZ liquation and microfissuring of Nickel base superalloys. Black-Right-Pointing-Pointer Microstructure {gamma} Prime spheroids and discreet blocky type MC carbides, capable to relax the stress generated during weld cooling. Black-Right-Pointing-Pointer Low welding heat input welding speeds and ductile filler alloys reduce the HAZ cracking susceptibility.

  19. Microstructural study and wear behavior of ductile iron surface alloyed by Inconel 617

    International Nuclear Information System (INIS)

    Highlights: • The Ni-base alloy was deposited on the surface of ductile iron by TIG welding process. • Microstructure of alloyed layer consisted of carbides embedded in Ni-rich dendrite. • Hardness and wear resistance of coated sample greatly improved. • The formation of oxide layer and delamination were dominant mechanisms of wear. - Abstract: In this research, microstructure and wear behavior of Ni-based alloy is discussed in detail. Using tungsten inert gas welding process, coating of nearly 1–2 mm thickness was deposited on ductile iron. Optical and scanning electron microscopy, as well as X-ray diffraction analysis and electron probe microanalysis were used to characterize the microstructure of the surface alloyed layer. Micro-hardness and wear resistance of the alloyed layer was also studied. Results showed that the microstructure of the alloyed layer consisted of M23C6 carbides embedded in Ni-rich solid solution dendrites. The partial melted zone (PMZ) had eutectic ledeburit plus martensite microstructure, while the heat affected zone (HAZ) had only a martensite structure. It was also noticed that hardness and wear resistance of the alloyed layer was considerably higher than that of the substrate. Improvement of wear resistance is attributed to the solution strengthening effect of alloying elements and also the presence of hard carbides such as M23C6. Based on worn surface analysis, the dominant wear mechanisms of alloyed layer were found to be oxidation and delamination

  20. Grinding performance evaluation of porous composite-bonded CBN wheels for Inconel 718

    Directory of Open Access Journals (Sweden)

    Chen Zhenzhen

    2014-08-01

    Full Text Available For high-efficiency grinding of difficult-to-cut materials such as titanium and nickel alloys, a high porosity is expected and also a sufficient mechanical strength to satisfy the function. However, the porosity increase is a disadvantage to the mechanical strength. As a promising pore forming agent, alumina bubbles are firstly induced into the abrasive layer to fabricate porous cubic boron nitride (CBN wheels. When the wheel porosity reaches 45%, the bending strength is still high up to 50 MPa with modified orderly pore distribution. A porous CBN wheel was fabricated with a total porosity around 30%. The grinding performance of the porous composite-bonded CBN wheel was evaluated in terms of specific force, specific grinding energy, and grinding temperature, which were better than those of the vitrified one under the same grinding conditions. Compared to the vitrified CBN wheel, clear straight cutting grooves and less chip adhesion are observed on the ground surface and there is also no extensive loading on the wheel surface after grinding.

  1. High-cycle fatigue of Ni-base superalloy Inconel 713LC

    Czech Academy of Sciences Publication Activity Database

    Kunz, Ludvík; Lukáš, Petr; Konečná, R.

    2010-01-01

    Roč. 32, č. 6 (2010), s. 908-913. ISSN 0142-1123 R&D Projects: GA MPO FT-TA4/023; GA MŠk MEB080812 Institutional research plan: CEZ:AV0Z20410507 Keywords : IN 713LC * High-cycle fatigue * Effect of mean stress * Fractography * Casting defetcts * Extreme value statistics Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 1.799, year: 2010

  2. Microstructural Evolution and Creep Rupture Behavior of INCONEL RTM Alloy 740H Fusion Welds

    Science.gov (United States)

    Bechetti, Daniel H., Jr.

    Electron microscopy techniques were used to investigate the causes of reduced creep-rupture life in INCONEL® alloy 740H ® fusion welds with a specific focus on understanding the formation and evolution of γ'-free zones along grain boundaries. Investigation of creep-rupture specimens revealed four operational factors that influence the formation of these precipitate-free zones, and the identity of large second phase particles typically found within them has been determined. A stress-free aging has demonstrated the influence of stress on the formation of the precipitate-free regions and has illustrated what appear to be the initial stages of their development. It is concluded that the mechanism of precipitate-free zone formation in alloy 740H is moderate discontinuous precipitation accompanied by significant discontinuous growth of the γ' phase. These discontinuous reactions are likely exacerbated by microsegregation within the welded microstructure and by the mechanical deformation associated with grain boundary sliding during creep. Thermodynamic and kinetic modeling were used to determine appropriate heat treatment schedules for homogenization and second phase dissolution of welds in alloy 740H. Following these simulations, a two-step heat treatment process was applied to specimens from a single pass gas tungsten arc weld (GTAW). Scanning electron microscopy (SEM) has been used to assess the changes in the distribution of alloying elements as well as changes in the fraction of second phase particles within the fusion zone. Experimental results demonstrate that homogenization of alloy 740H weld metal can be achieved by an 1100°C/4hr treatment. Complete dissolution of second phase particles could not be completely achieved, even at exposure to temperatures near the alloy's solidus temperature. These results are in good agreement with thermodynamic and kinetic predictions.

  3. Optimizing the Machining Parameters of Micro-EDM for Inconel 718

    OpenAIRE

    Venkatesan, R; Manikandan, R.

    2012-01-01

    This paper aims to study on the feasibility of micron size hole manufacturing using micro Electric Discharge Machining (Micro-EDM). Main and auxiliary unit of the micro-EDM machine tool and their functions are described in some detail. The technological and electrical parameters that are effective in Micro-EDM are stated explicitly. Geometry of the machined micro-holes and resolidified material around the hole entrance are observed. Several descriptive pictures, obtained by Scanning Ele...

  4. Grinding performance evaluation of porous composite-bonded CBN wheels for Inconel 718

    Institute of Scientific and Technical Information of China (English)

    Chen Zhenzhen; Xu Jiuhua; Ding Wenfeng; Ma Changyu

    2014-01-01

    For high-efficiency grinding of difficult-to-cut materials such as titanium and nickel alloys, a high porosity is expected and also a sufficient mechanical strength to satisfy the function. However, the porosity increase is a disadvantage to the mechanical strength. As a promising pore forming agent, alumina bubbles are firstly induced into the abrasive layer to fabricate porous cubic boron nitride (CBN) wheels. When the wheel porosity reaches 45%, the bending strength is still high up to 50 MPa with modified orderly pore distribution. A porous CBN wheel was fabricated with a total porosity around 30%. The grinding performance of the porous composite-bonded CBN wheel was evaluated in terms of specific force, specific grinding energy, and grinding temper-ature, which were better than those of the vitrified one under the same grinding conditions. Com-pared to the vitrified CBN wheel, clear straight cutting grooves and less chip adhesion are observed on the ground surface and there is also no extensive loading on the wheel surface after grinding.

  5. Micromechanisms of fatigue crack growth in a forged Inconel 718 nickel-based superalloy

    International Nuclear Information System (INIS)

    The micromechanisms of fatigue crack propagation in a forged, polycrystalline IN 718 nickel-based superalloy are evaluated. Fracture modes under cyclic loading were established by scanning electron microscopy analysis. The results of the fractographic analysis are presented on a fracture mechanism map that shows the dependence of fracture modes on the maximum stress intensity factor, Kmax, and the stress intensity factor range, ΔK. Plastic deformation associated with fatigue crack growth was studied using transmission electron microscopy. The effects of ΔK and Kmax on the mechanisms of fatigue crack growth in this alloy are discussed within the context of a two-parameter crack growth law. Possible extensions to the Paris law are also proposed for crack growth in the near-threshold and high ΔK regimes. (orig.)

  6. Nickel super alloy INCONEL 713LC - structural characteristics after heat treatment

    Directory of Open Access Journals (Sweden)

    A. Hernas

    2007-06-01

    Full Text Available Purpose: Nickel super alloy’s products are mainly using for construction parts of jet engines, gas turbines and turbo-blowers.Design/methodology/approach: Super alloy was commercially produced and was investigated by using the light microscopy (OLYMPUS IX 71 and local chemical microanalysis and by the scanning electron microscopy (JEOL JSM 50AFindings: We found a mode of optimum heat treatment. On the basis of obtained results it is possible to recommend a following regime of heat treatment: heating and dwell at the temperature exceeding 1240 °C (min. 1260 °C, so that precipitates at the grain boundaries dissolve completely, with subsequent slow cooling down to the temperature of approx. 940-950 °C, so that there occurs intensive intra-granular precipitation of intermetallic phase γ’.Research limitations/implications: The experiment was limited by occurrence a void in cast alloys.Practical implications: Nickel super alloy’s products are mainly using for construction parts of jet engines, gas turbines and turbo-blowers.Originality/value: Mode of optimum heat treatment was proposed. On the basis of obtained results it is possible to recommend the most suitable heat treatment, which produce intensive intra-granular precipitation of inter-metallic phase γ’. It was received a new know-how in this field.

  7. Velocity of crack growing of Inconel-600, sensitized, contaminated with sulphur in PWR type reactors

    International Nuclear Information System (INIS)

    The origin of the vessel head penetration cracking of Jose Cabrera NPP has been attributed to an IGA/SCC process in a highly sensitized Alloy 600 assisted by sulphur species, as both acid sulphates and reduced species originated by the thermal breakdown of the cationic resins present in the primary coolant. The thermal degradation of the cationic resins leads sulphonic acid group scission and sulphates. Under the operating conditions the reduction of sulphates to sulphides is produced. The sulphides formed from the reduction of sulphate can precipitate with metallic cations and be incorporated into the oxide layers of the materials, preferably into nickel alloys. Others components at Jose Cabrera NPP are fabricated from sensitized alloy 600, as bottom vessel penetrations. In order to determine the influence of sulphur incorporated to the oxide layers of bottom vessel penetration alloy 600, an experimental work has been performed to obtained crack growth rate data under PWR primary conditions on sensitized alloy 600. (Author) 5 refs

  8. Study of Material Consolidation at Higher Throughput Parameters in Selective Laser Melting of Inconel 718

    Science.gov (United States)

    Prater, Tracie

    2016-01-01

    Selective Laser Melting (SLM) is a powder bed fusion additive manufacturing process used increasingly in the aerospace industry to reduce the cost, weight, and fabrication time for complex propulsion components. SLM stands poised to revolutionize propulsion manufacturing, but there are a number of technical questions that must be addressed in order to achieve rapid, efficient fabrication and ensure adequate performance of parts manufactured using this process in safety-critical flight applications. Previous optimization studies for SLM using the Concept Laser M1 and M2 machines at NASA Marshall Space Flight Center have centered on machine default parameters. The objective of this work is to characterize the impact of higher throughput parameters (a previously unexplored region of the manufacturing operating envelope for this application) on material consolidation. In phase I of this work, density blocks were analyzed to explore the relationship between build parameters (laser power, scan speed, hatch spacing, and layer thickness) and material consolidation (assessed in terms of as-built density and porosity). Phase II additionally considers the impact of post-processing, specifically hot isostatic pressing and heat treatment, as well as deposition pattern on material consolidation in the same higher energy parameter regime considered in the phase I work. Density and microstructure represent the "first-gate" metrics for determining the adequacy of the SLM process in this parameter range and, as a critical initial indicator of material quality, will factor into a follow-on DOE that assesses the impact of these parameters on mechanical properties. This work will contribute to creating a knowledge base (understanding material behavior in all ranges of the AM equipment operating envelope) that is critical to transitioning AM from the custom low rate production sphere it currently occupies to the world of mass high rate production, where parts are fabricated at a rapid rate with confidence that they will meet or exceed all stringent functional requirements for spaceflight hardware. These studies will also provide important data on the sensitivity of material consolidation to process parameters that will inform the design and development of future flight articles using SLM.

  9. A Study on the High Temperature Oxidation Behavior of Hastelloy X and Inconel 713C

    International Nuclear Information System (INIS)

    In order to preserve surface stability and mechanical properties of the substrate materials, coatings are applied to the alloy surfaces for the high temperature applications. Even with the application of coating, the substrate materials must also have its own resistance to the high temperature oxidation because the substrate may be catastrophically degraded when coatings are failed. In this research, Ni-base superalloys, IN 713C and Hastelloy X for the substrate materials of coatings, were examined by the isothermal and cyclic oxidation experiments. In the isothermal oxidation experiments, the dominant protective oxide scale of Hastelloy X was Cr2O3 and that of IN 713C was the Al-rich oxide scale. Both alloys formed protective oxide scales, and showed good isothermal oxidation resistance but IN 713C showed better oxidation resistance than Hastelloy X owing to the formation of Al-rich oxide scales. Also for cyclic oxidation experiments, due to the favorable adhesion between the substrate and oxide scales, IN 713C having thin Al-rich oxide scales showed better oxidation resistance than Hastelloy X throughout the temperature ranges tested. Comparing these two alloys IN 713C had better oxidation resistance but both alloys showed good oxidation resistance up to 1000 .deg. C

  10. Analysis of material response to ultrasonic vibration loading in turning Inconel 718

    International Nuclear Information System (INIS)

    The paper is focused on the analysis of the surface layer formed on a workpiece treated with ultrasonically assisted turning (UAT) in comparison to conventional turning (CT). Various experimental methods are used to study the difference between the two machining techniques: nanoindentation, light microscopy and scanning electron microscopy (SEM). The experimental part of the paper studies the material response to CT and UAT in terms of material's hardness, residual stresses, and changes in the microstructure. The difference in the distribution of residual stresses in the machined surface layer is further studied by means of numerical (finite element) simulations. A three-dimensional thermomechanically coupled finite element (FE) model of both UAT and CT is used to study temperature distributions in the process zone and thermally induced stresses. Numerical results are compared with the obtained experimental data

  11. Analysis of Effective and Internal Cyclic Stress Components in the Inconel Superalloy Fatigued at Elevated Temperature

    Czech Academy of Sciences Publication Activity Database

    Šmíd, Miroslav; Petrenec, Martin; Polák, Jaroslav; Obrtlík, Karel; Chlupová, Alice

    2011-01-01

    Roč. 278, 4 July (2011), s. 393-398. ISSN 1022-6680. [European Symposium on Superalloys and their Application. Wildbad Kreuth, 25.5.2010-28.5.2010] R&D Projects: GA ČR GA106/08/1631 Institutional research plan: CEZ:AV0Z20410507 Keywords : low cycle fatigue * superalloys * high temperature * hysteresis loop * effective and internal stresses Subject RIV: JL - Materials Fatigue, Friction Mechanics; JL - Materials Fatigue, Friction Mechanics (UFM-A)

  12. Influence of lead on the SCC-behaviour of SG tubing materials

    International Nuclear Information System (INIS)

    All Siemens/KWU designed PWRs use Alloy 800 mod. as SG tubing material. Till now, no IGA/IGSCC has been observed in these plants. Replacement SGs offered by Siemens/KWU in Europe for plants of other NSSS-vendors may use Alloy 690 TT as SG tubing material. Specific questions of PWR operators induced test series on the corrosion behaviour of Alloy 800 mod. and Alloy 690 TT under highly faulted chemistry conditions. One of the test series was performed in order to clarify the influence of lead contamination on the SCC-behaviour of Alloy 800 mod. and Alloy 690 TT. The objective of the test run was to determine the thresholds of lead concentration, stresses and potential in caustic and acidic sulfate solutions of the SCC-behaviour of Alloy 800 mod. and Alloy 690 TT. Therefore three types of examinations has been carried out in caustic solutions as well as in acidic sulfate solutions both contaminated with lead of different concentrations: to determine the influence of lead on the electrochemical behaviour current density-potential-curves has been done at 300 degree centigree. To determine the influence of potential as well as the influence of lead concentration exposure of C-rings under potentiostatic control were performed at 300 degree centigree. To determine the influence of stress and lead concentration exposure of C-rings in capsules at free corrosion potential were carried out at 315 degree centigree

  13. Improvement factors for steam generator tubing alloys

    International Nuclear Information System (INIS)

    Predictions of reliability gains associated with the use of advanced alloys have been made in the past through the use of improvement factors. Improvement factors for thermally treated Alloy 600 (Alloy 600TT) and thermally treated Alloy 690 (Alloy 690TT) steam generator tubing were previously developed and have been used in the most recent revision of the EPRI Secondary Water Chemistry Guidelines. However, due to the long expected failure times relative to field experience, field-experience-based estimates of these improvement factors continue to be overly conservative (as shown by the absence of wide spread in-service cracking of these materials). A recent study updated the previously developed improvement factors associated with the use of advanced alloys. This paper will discuss the development of relative improvement factors for Alloy 600TT, Alloy 690TT, and Alloy 800 nuclear grade (Alloy 800NG) with respect to mill annealed Alloy 600 (Alloy 600MA) steam generator tubing. The various uses which are appropriate for these improvement factors will be discussed. This presentation focuses on primary side tube degradation (PWSCC), although this project also addressed secondary side tube degradation (ODSCC). The following four techniques were used to assess the performance of the Alloy 600TT, Alloy 690TT, and Alloy 800NG relative to that of Alloy 600MA: Field data on tube degradation were evaluated using statistical techniques, based on plant population Weibull/Weibayes analyses, similar to those employed in the past and reviewed by industry experts as part of the EPRI guidelines revision process. This paper presents updated improvement factors based on further accumulation of operating experience with Alloy 600TT, Alloy 800NG, and Alloy 690TT; Field data on tube degradation were evaluated using alternative statistical techniques which are not as overly conservative as those used in the past; Field data on tube plug cracking were evaluated to compare the performance

  14. Effect of applied potential on stress corrosion cracking of steam generator tubings

    International Nuclear Information System (INIS)

    Effects of applied potential on stress corrosion cracking(SCC) of alloy 600 and alloy 690 used as steam generator tubing materials have been studied in deaerated 40% NaOH at 315 deg C using C-ring specimen. Corrosion oxides formed at the potentials where SCC tests had been performed were analyzed with X-ray diffraction. Current transient at various potential and polarization curves of alloy 600, alloy 690 and Pure Ni were obtained. Polarization curves on alloy 600 and alloy 690 showed second peak at 270mV above OCP, while polarization curve on pure Ni had no second peak at that potential. X-ray diffraction patterns of corrosion oxides of alloy 600 which had been formed at 150 and 200mV above OCP coincided with NiO, while those formed at 250mV and 330mV showed slight shift in 2 of NiO, meaning change in lattice parameter of NiO. Corrosion oxide of alloy 690 which had been formed at 150mV above OCP were NiO while those at 200, 250 and 330mV above OCP were mixed oxides of NiO and spinel structure(M3O4) of Ni, Cr and Ni. Almost through wall cracks were observed for alloy 600 held at 150 and 200mV above OCP while no cracks were observed for alloy 600 held at 250 and 330mV. These results imply that SCC of alloy 600 might proceed in the range of potential from passivation potential to second peak where NiO were produced. Alloy 690 were more resistant to SCC than alloy 600

  15. The mode of stress corrosion cracking in Ni-base alloys in high temperature water containing lead

    International Nuclear Information System (INIS)

    The mode of stress corrosion cracking (SCC) in Ni-base alloys in high temperature aqueous solutions containing lead was studied using C-rings and slow strain rate testing (SSRT). The lead concentration, pH and the heat treatment condition of the materials were varied. TEM work was carried out to observe the dislocation behavior in thermally treated (TT) and mill annealed (MA) materials. As a result of the C-ring test in 1M NaOH+5000 ppm lead solution, intergranular stress corrosion cracking (IGSCC) was found in Alloy 600MA, whereas transgranular stress corrosion cracking (TGSCC) was found in Alloy 600TT and Alloy 690TT. In most solutions used, the SCC resistance increased in the sequence Alloy 600MA, Alloy 600TT and Alloy 690TT. The number of cracks that was observed in alloy 690TT was less than in Alloy 600TT. However, the maximum crack length in Alloy 690TT was much longer than in Alloy 600TT. As a result of the SSRT, at a nominal strain rate of 1 x 10-7/s, it was found that 100 ppm lead accelerated the SCC in Alloy 600MA (0.01%C) in pH 10 at 340 C. IGSCC was found in a 100 ppm lead condition, and some TGSCC was detected on the fracture surface of Alloy 600MA cracked in the 10000 ppm lead solution. The mode of cracking for Alloy 600 and Alloy 690 changed from IGSCC to TGSCC with increasing grain boundary carbide content in the material and lead concentration in the solution. IGSCC seemed to be retarded by stress relaxation around the grain boundaries, and TGSCC in the TT materials seemed to be a result of the crack blunting at grain boundary carbides and the enhanced Ni dissolution with an increase of the lead concentration. (orig.)

  16. Low cycle fatigue with hold times of cast superalloy Inconel 792-5A at 800 °C

    Czech Academy of Sciences Publication Activity Database

    Šmíd, Miroslav; Obrtlík, Karel; Petrenec, Martin; Polák, Jaroslav

    Žilina: Žilinská univerzita, 2012, s. 65-68. ISBN 978-80-554-0477-6. [International of PhD. students´ seminar SEMDOK 2012 /17./. Terchová (SK), 25.01.2012-27.01.2012] R&D Projects: GA ČR(CZ) GAP204/11/1453; GA ČR(CZ) GAP107/11/2065 Keywords : low cycle fatigue * superalloy * hold time * high temperatures * surface relief Subject RIV: JL - Materials Fatigue, Friction Mechanics

  17. Dwell effect on low cycle fatigue behaviour of cast superalloy Inconel 792-5A at 800 °C

    Czech Academy of Sciences Publication Activity Database

    Šmíd, Miroslav; Obrtlík, Karel; Polák, Jaroslav

    Berlín: DMV, 2013, s. 113-118. ISBN 978-3-9814516-2-7. [LCF7 - International Conference on Low Cycle Fatigue /7./. Aachen (DE), 09.09.2013-11.09.2013] R&D Projects: GA ČR(CZ) GAP204/11/1453; GA ČR(CZ) GAP107/11/2065; GA MPO FR-TI4/030 Institutional support: RVO:68081723 Keywords : nickel base superalloy * low cycle fatigue * dwell * high temperature fatigue * surface relief * dislocation structure Subject RIV: JL - Materials Fatigue, Friction Mechanics

  18. Multiaxial creep of tubes from Incoloy 800 H and Inconel 617 under static and cyclic loading conditions

    International Nuclear Information System (INIS)

    At temperatures above 8000C the material behaviour under mechanical load is determined by creep. The service of heat exchanging components leads to multiaxial loading conditions. For design and inelastic analysis of the component behaviour time dependent design values and suitable constitutive equations are necessary. The present report gives a survey of the approaches to describing creep under multiaxial loading. Norton's law and v. Mises' theory are applied. The load combinations of internal pressure, tensile and torsional stress are studied more closely, cyclic stress superposition in the tensile-pulsating range is discussed and cases of partial relaxation are examined. Experimental results are presented for the loading conditions discussed, and satisfactory agreement between theory and experiment has been found up to now for these results. Regarding lifetime determination under multiaxial creep load, a more precise analysis of creep damage is presented suggesting a suitable deviatoric stress for evaluation in the long-time range. (orig.)

  19. Determination of Yield and Flow Surfaces for Inconel 718 Under Axial-Torsional Loading at Temperatures Up to 649 C

    Science.gov (United States)

    Gil, Christopher M.

    1998-01-01

    An experimental program to determine flow surfaces has been established and implemented for solution annealed and aged IN718. The procedure involved subjecting tubular specimens to various ratios of axial-torsional stress at temperatures between 23 and 649 C and measuring strain with a biaxial extensometer. Each stress probe corresponds to a different direction in stress space, and unloading occurs when a 30 microstrain (1 micro eplison = 10(exp -6) mm/mm) offset is detected. This technique was used to map out yield loci in axial-torsional stress space. Flow surfaces were determined by post-processing the experimental data to determine the inelastic strain rate components. Surfaces of constant inelastic strain rate (SCISRS) and surfaces of constant inelastic power (SCIPS) were mapped out in the axial-shear stress plane. The von Mises yield criterion appeared to closely fit the initial loci for solutioned IN718 at 23 C. However, the initial loci for solutioned IN718 at 371 and 454 C, and all of the initial loci for aged IN718 were offset in the compression direction. Subsequent loci showed translation, distortion, and for the case of solutioned IN718, a slight cross effect. Aged IN718 showed significantly more hardening behavior than solutioned IN718.

  20. Modelling of fatigue crack growth in Inconel 718 under hold time conditions - application to a flight spectrum

    OpenAIRE

    Lundström, Erik; Simonsson, Kjell; Månsson, Tomas; Gustafsson, David

    2014-01-01

    Gas turbine operating cycles at high temperatures often consist of load reversals mixed with hold times; the latter occurring either as cruise for aero engines or at continuous power output for land based turbines, but also at low frequency loading conditions, e.g. slow “ramp up” of engine thrust. The hold time conditions cause the crack to grow by intergranular fracture due to material damage near the crack tip, thus rapidly increasing the crack growth rate. Since the damaged zone will affec...

  1. Effect of grit blasting surface treatment on high temperature low cycle fatigue life of Inconel 713LC

    Czech Academy of Sciences Publication Activity Database

    Šulák, Ivo; Obrtlík, Karel; Čelko, L.; Gejdoš, P.

    Brno: Brno University of Technology, 2015 - (Dlouhý, I.; Jan, V.; Maca, K.; Válka, L.), s. 139-144 ISBN 978-80-214-5146-9. [Multi Scale Design of Advanced Materials. Velké Bílovice (CZ), 28.05.2015-29.05.2015] R&D Projects: GA MŠk(CZ) EE2.3.20.0214; GA ČR(CZ) GA15-20991S Institutional support: RVO:68081723 Keywords : Grit blasting * Surface relief * Surface microhardnes * High temperature fatigue life * Inocel 713LC Subject RIV: JL - Materials Fatigue, Friction Mechanics

  2. Multi-objective optimization of surface roughness, cutting forces, productivity and Power consumption when turning of Inconel 718

    Directory of Open Access Journals (Sweden)

    Hamid Tebassi

    2016-01-01

    Full Text Available Nickel based super alloys are excellent for several applications and mainly in structural components submitted to high temperatures owing to their high strength to weight ratio, good corrosion resistance and metallurgical stability such as in cases of jet engine and gas turbine components. The current work presents the experimental investigations of the cutting parameters effects (cutting speed, depth of cut and feed rate on the surface roughness, cutting force components, productivity and power consumption during dry conditions in straight turning using coated carbide tool. The mathematical models for output parameters have been developed using Box-Behnken design with 15 runs and Box-Cox transformation was used for improving normality. The results of the analysis have shown that the surface finish was statistically sensitive to the feed rate and cutting speed with the contribution of 43.58% and 23.85% respectively, while depth of cut had the greatest effect on the evolution of cutting force components with the contribution of 79.87% for feed force, 66.92% for radial force and 66.26% for tangential force. Multi-objective optimization procedure allowed minimizing roughness Ra, cutting forces and power consumption and maximizing material removal rate using desirability approach.

  3. Estimate of thermal fatigue lifetime for the INCONEL 625lCF plate while exposed to concentrated solar radiation

    OpenAIRE

    Rojas-Morín, A.; Fernández-Reche, J.

    2011-01-01

    A system for testing the thermal cycling of materials and components has been developed and installed at the DISTAL-I parabolic dish facility located at the Plataforma Solar de Almería (PSA) in Spain. This system allows us to perform abrupt heating/cooling tests by exposing central solar receiver materials to concentrated solar radiation. These tests are performed to simulate both the normal and critical operational conditions of the central solar receiver. The thermal fatigue life for the IN...

  4. Preliminary stress corrosion cracking modeling study of a dissimilar material weld of alloy (INCONEL) 182 with Stainless Steel 316

    International Nuclear Information System (INIS)

    Dissimilar welds (DW) are normally used in many components junctions in structural project of PWR (Pressurized Water Reactors) in Nuclear Plants. One had been departed of a DW of a nozzle located at a Reactor Pressure Vessel (RPV) of a PWR reactor, that joins the structural vessel material with an A316 stainless steel safe end. This weld is basically done with Alloy 182 with a weld buttering of Alloy 82. It had been prepared some axial cylindrical specimens retired from the Alloy 182/A316 weld end to be tested in the slow strain rate test machine located at CDTN laboratory. Based in these stress corrosion susceptibility results, it was done a preliminary semi-empirical modeling application to study the failure initiation time evolution of these specimens. The used model is composed by a deterministic part, and a probabilistic part according to the Weibull distribution. It had been constructed a specific Microsoft Excel worksheet to do the model application of input data. The obtained results had been discussed according with literature and also the model application limits. (author)

  5. Gas-turbine HTGR materials screening test program. Quarterly progress report, July 1, 1976--September 30, 1976. [IN 100; IN 713; MM004; M21; IN 738; RENE 100; MoTZM; Hastelloy X; Inconel 617; MA 753; IN 519, Inconel 706; Inconel 718; A286; 316 SS; Incoloy 800

    Energy Technology Data Exchange (ETDEWEB)

    Rosenwasser, S.N.; Johnson, W.R.

    1976-09-30

    The duration of controlled-impurity creep-screening tests and unstressed aging tests has reached 10,000 hr. Creep and weight change data from testing up to 9,000 hr and results from post-test metallurgical evaluations of several recently returned 3,000-hr specimens, including alloys IN519 and MoTZM, are presented. Preliminary materials requirements for key GT-HTGR 850/sup 0/C (1562/sup 0/F) reactor outlet temperature reference design components are documented.

  6. Steam generator replacement as a part of a general problem management process

    International Nuclear Information System (INIS)

    effective strategy. The integrated Belgian approach to SG defect management results in a global optimization of the plant operation in terms of safety, reliability and economy. Applying this approach to the particular problem of PWSCC required a number of original developments -in such fields as non destructive testing and, probabilistic modelling of SG behaviour. It allowed after performance of a long term study to conclude that the most cost-effective strategy for Doel 3 was the immediate replacement of the SG combined with an up-rating of the plant. This study included a thorough comparison of the 2 candidate alloys for the tube material of the new SG: Inconel alloy 690 and Incoloy alloy 800. Finally the latter was selected in the peened condition because of its larger service experience and of favourable economic arguments

  7. Development of a scratch electrode system in high temperature high pressure water

    International Nuclear Information System (INIS)

    Highlights: • A rapid scratch electrode system in high temperature water has been built. • Repassivation kinetics of Alloy 690 was studied in high temperature water. • The slope of log i(t) vs. 1/Q(t) shows stress corrosion cracking susceptibility. - Abstract: The scratch electrode system in high temperature high pressure (HTHP) water has been built. The design temperature and design pressure of this system are 350 °C and 20 MPa respectively, and the maximum scratch speed is 3.3 m/s. By using this scratch electrode system, the repassivation kinetics of Alloy 690 in high temperature pressurized water with different dissolved hydrogen (DH) at 300 °C is studied. The research results justify that the scratch electrode system is valid and the scratch technique in HTHP water is a new effective and reliable method to study the SCC susceptibility of nuclear materials

  8. Repair technology for steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seung Ho; Jung, Hyun Kyu; Jung, Seung Ho; Kim, Chang Hoi; Jung, Young Moo; Seo, Yong Chil; Kim, Jung Su; Seo, Moo Hong

    2001-02-01

    The most commonly used sleeving materials are thermally treated Alloy 600 and thermally treated Alloy 690 Alloy. Currently, thermally treated Alloy 690 and Alloy 800 are being offered although Alloy 800 has not been licensed in the US. To install sleeve, joint strength, leak tightness, PWSCC resistance, evaluation on process parameter range and the effect of equipments and procedures on repair plan and radiation damage have to be investigated before sleeving. ABB CE provides three type of leak tight Alloy 690 TIG welded and PLUSS sleeve. Currently, Direct Tube Repair technique using Nd:YAG laser has been developed by ABB CE and Westinghouse. FTI has brazed and kinetic sleeve designs for recirculating steam generator and hydraulic and rolled sleeve designs for one-through steam generators. Westinghouse provides HEJ, brazed and laser welded sleeve design. When sleeve is installed in order to repair the damaged S/G tubes, it is certain that defects can be occurred due to the plastic induced stress and thermal stress. Therefore it is important to minimize the residual stress. FTI provides the electrosleeve technique as a future repair candidate using electroplating.

  9. Repair technology for steam generator tubes

    International Nuclear Information System (INIS)

    The most commonly used sleeving materials are thermally treated Alloy 600 and thermally treated Alloy 690 Alloy. Currently, thermally treated Alloy 690 and Alloy 800 are being offered although Alloy 800 has not been licensed in the US. To install sleeve, joint strength, leak tightness, PWSCC resistance, evaluation on process parameter range and the effect of equipments and procedures on repair plan and radiation damage have to be investigated before sleeving. ABB CE provides three type of leak tight Alloy 690 TIG welded and PLUSS sleeve. Currently, Direct Tube Repair technique using Nd:YAG laser has been developed by ABB CE and Westinghouse. FTI has brazed and kinetic sleeve designs for recirculating steam generator and hydraulic and rolled sleeve designs for one-through steam generators. Westinghouse provides HEJ, brazed and laser welded sleeve design. When sleeve is installed in order to repair the damaged S/G tubes, it is certain that defects can be occurred due to the plastic induced stress and thermal stress. Therefore it is important to minimize the residual stress. FTI provides the electrosleeve technique as a future repair candidate using electroplating

  10. Application Feasibility of PRE 50 grade Super Austenitic Stainless Steel as a Steam Generator Tubing

    Energy Technology Data Exchange (ETDEWEB)

    Park, Yong Soo [Yonsei University, Seoul (Korea, Republic of); Kim, Young sik [Andong National University, Andong (Korea, Republic of); Kim, Taek Jun; Kim, Sun Tae; Park, Hui Sang [Yonsei University, Seoul (Korea, Republic of)

    1997-07-01

    The aim of this study is to evaluate the properties of the super austenitic stainless steel, SR-50A for application as steam generator tubing material. The microstructure, mechanical properties, corrosion properties, were analyzed and the results were compared between super austenitic stainless steel and Alloy 600 and Alloy 690. Super austenitic stainless steel, SR-50A is superior to Alloy 600, Alloy 690 and Alloy 800 in the mechanical properties(tensile strength, yield strength, and elongation). It was investigated that thermal conductivity of SR-50A was higher than Alloy 600. As a result of thermal treatment on super stainless steel, SR-50A, caustic SCC resistance was increased and its resistance was as much as Alloy 600TT and Alloy 690TT. In this study, optimum thermal treatment condition to improve the caustic corrosion properties was considered as 650 deg C or 550 deg C 15 hours. However, it is necessary to verify the corrosion mechanism and to prove the above results in the various corrosive environments. 27 refs., 6 tabs., 59 figs. (author)

  11. Studies on nickel base superalloys for nuclear high level waste storage application

    International Nuclear Information System (INIS)

    Traditional austenitic stainless steels like 304L are widely used in the nuclear industries for waste storage but they are susceptible to sensitization in the welded zones and also suffer from pitting corrosion in chloride containing medium. In order to minimize these problems austenitic nickel base alloys stand as an alternative due to its better corrosion resistance thermal conductivity and good metallurgical properties. In the present investigation, the corrosion behavior and surface investigation of three nickel based superalloys (Alloy 600, Alloy 690 and Alloy 693) are carried out in as-received and heat treated condition, in simulated nuclear high level waste medium. Electrochemical studies were carried out in 3M HNO3 containing simulated high level waste, using potentiodynamic anodic polarization and electrochemical impedance spectroscopy technique. In order to investigate the passive film formed under simulated high level waste medium, X-ray photoelectron spectroscopy (XPS) study was carried out. The passive film was found to consist of a mixed oxide of Ni-Cr-Fe, for the Alloy 690 and Alloy 693 in simulated high level waste whereas for Alloy 600 it was only oxides of Cr. In all the conditions, Alloy 690 was found to possess superior corrosion resistance compared to Alloy, followed by Alloy 600 in simulated high level waste medium. (author)

  12. Advances in production of realistic cracks to NDT development and qualification purposes of steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Virkkunen, I.; Kemppainen, M. [Truflaw Ltd., Espoo (Finland); Tchilian, J.-M. [AREVA Nuclear Power Plant Sector, Saskatoon, Saskatchewan (Canada); Martens, J. [AREVA NP Intercontrole (France)

    2009-07-01

    Realistic defects are needed for steam generator tube inspections when developing new NDT methods or assessing the performance and reliability of methods and procedures used. Furthermore, realistic defects give the most reliable results in assessing service-related reliability of steam generator tubes by, for example, burst or leak tests. It is crucial to have representative defects as the defect characteristics has marked effect on the results both in NDE, burst and leak tests. Representativeness should be to the actual service-induced defects, and the evaluation should be based on the essential defect characteristics. In this paper real world application cases are presented about crack production to steam generator tubes. Crack production technique used is based on controlled thermal fatigue process creating natural cracks. Such cracks have been produced in Alloy 690 and austenitic stainless steel steam generator tubes. These cracks have been used, for example, for advanced NDT qualification purposes of a new build nuclear power plant. Paper presents results of the destructive tests performed after validation tests of the crack manufacturing in the Alloy 690 and austenitic stainless steel. These results are shown for both of the materials with measured essential crack characteristics. In addition to metallographic analysis, the paper presents the results of performed NDT inspections for the Alloy 690. Results have been obtained with an advanced inspection technique developed and used for today's inspections of steam generator tubes in nuclear power plants. (author)

  13. New Technology for Corrosion Mitigation of Steam Generator Tubesheet in Secondary Side Environments

    International Nuclear Information System (INIS)

    Denting has been mitigated by a modification of the design and material of the tube support structures, it has been an inevitable problem in the crevice region of the top of the tubesheet(TTS). Denting at the TTS has been a significant concern regardless of the tube materials. This is because it is a mechanical process resulted from a volume expansion of corrosion products of the tubesheet materials. It should be noted that the corrosion rate of low alloy tubesheet materials is accelerated due to the presence of corrosion products accumulated at the top of the tubesheet. Therefore a reduction of the corrosion rate of the tubesheet material should be a key strategy to prevent tube denting at the TTS as well as an improvement of the secondary water chemistry. This paper provides a new technology to prevent denting by cladding the secondary side surface of the tubesheet with a corrosion resistant material. In this study, Alloy 690 material on the surface of the SA508 tubesheet was cladded to a thickness of about 9mm. The corrosion rates of the SA508 original tubesheet and Alloy 690 clad material were measured in acidic and caustic simulated environments. Denting has been a precursor of stress corrosion cracking in nuclear steam generator tubing, although it may be mitigated by a design and material modification of the tube support structures and secondary water chemistry control. Corrosion resistant Alloy 690 tubing is not an exception because denting at the TTS is due to corrosion of the tubesheet material. In this paper, a new technology was suggested to prevent denting at the TTS by cladding the secondary side surface of the tubesheet with a corrosion resistant material. It was verified that the corrosion rates of a tubesheet with an Alloy 690 clad layer drastically decreased in both acidic and alkaline environments, even inside the magnetite sludge pile. Because the cladding processes of Alloy 690 have already been applied to the primary side surface of a

  14. Pacific Northwest National Laboratory Investigation of the Stress Corrosion Cracking in Nickel-Base Alloys, Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    Bruemmer, Stephen M.; Toloczko, Mychailo B.; Olszta, Matthew J.

    2012-03-01

    The objective of this program is to evaluate the primary water stress corrosion cracking (PWSCC) susceptibility of high chromium alloy 690 and its weld metals, establish quantitative measurements of crack-growth rates and determine relationships among cracking susceptibility, environmental conditions and metallurgical characteristics. Stress-corrosion, crack-growth rates have been determined for 12 alloy 690 specimens, 11 alloy 152/52/52M weld metal specimens, 4 alloy 52M/182 overlay specimens and 2 alloy 52M/82 inlay specimens in simulated PWR primary water environments. The alloy 690 test materials included three different heats of extruded control-rod-drive mechanism (CRDM) tubing with variations in the initial material condition and degree of cold work for one heat. Two cold-rolled (CR) alloy 690 plate heats were also obtained and evaluated enabling comparisons to the CR CRDM materials. Weld metal, overlay and inlay specimens were machined from industry mock ups to provide plant-representative materials for testing. Specimens have been tested for one alloy 152 weld, two alloy 52 welds and three alloy 52M welds. The overlay and inlay specimens were prepared to propagate stress-corrosion cracks from the alloy 182 or 82 material into the more resistant alloy 52M. In all cases, crack extension was monitored in situ by direct current potential drop (DCPD) with length resolution of about +1 µm making it possible to measure extremely low growth rates approaching 5x10-10 mm/s. Most SCC tests were performed at 325-360°C with hydrogen concentrations from 11-29 cc/kg; however, environmental conditions were modified during a few experiments to evaluate the influence of temperature, water chemistry or electrochemical potential on propagation rates. In addition, low-temperature (~50°C) cracking behavior was examined for selected alloy 690 and weld metal specimens. Extensive characterizations have been performed on material microstructures and stress-corrosion cracks by

  15. Effect of tensile dwell on low cycle fatigue of cast superalloy Inconel 792-5A at 800°C

    Czech Academy of Sciences Publication Activity Database

    Šmíd, Miroslav; Obrtlík, Karel; Petrenec, Martin; Polák, Jaroslav

    488-489, - (2012) s. 735-738. ISSN 1013-9826 R&D Projects: GA ČR(CZ) GAP107/11/2065; GA ČR(CZ) GAP204/11/1453 Institutional research plan: CEZ:AV0Z20410507 Keywords : nickle base superalloy * elevated temperatures * low cycle fatigue * dwells Subject RIV: JL - Materials Fatigue, Friction Mechanics

  16. The application of photoelectron spectroscopy in the study of corrosion and oxidation mechanisms of alloys: Inconel 182, Fe/Cu(100 and U-Zr-Nb

    International Nuclear Information System (INIS)

    In. this work a study of the oxidation/corrosion process of three systems of metallic materials by Photoemission Spectroscopy is presented. In the first system, it was investigated the corrosion of Ineonel 182 at simulated Pressurized Water Reactor (PWR) environment. Samples with and without surface chemical treatment were exposed to the simulated environment for until 18 weeks. The oxide layer formed on the surfaces of the samples at different conditions was characterized by Scanning Electron Microscopy and XPS coupled with argon ion sputtering. The comparison between the oxide films grown on the samples showed that the oxide layer formed on the chemically treated sample is thinner and relatively Cr-rich. In second system it was studied the initial oxidation at room temperature of epitaxial films of Fe evapored on Cu (100). The films were deposited with two different thicknesses in order to get tbe fcc Fe (100) and bcc Fe (110) surfaces. The results, obtained by photoemission spectroscopy at the TEMPO beamline of the Synchrotron Soleil, showed the formation of distinct oxides films. The surfaces also presented different kinetics of oxidation and the (110) Fe-bcc showed highest reactivity. The analysis of the data indicated the Fe1-xO formation on fcc Fe (100) and suggested the Fe1-xO and FC304 formation on (110) Fe-bcc surface. In the last system, it was investigated the initial oxidation of U-Zr-Nb alloys at room temperature. For this experiment, the alloys were exposed to oxygen in ultra high vacuum. The analysis of the U 4f peak showed the fast formation of U)2 on the surfaces and similar kinetics of oxidation between the U and the U-Zr-Nb alloy. The alloying elements showed slower oxidation. The Zr 3d peak suggested the zr02 formation while the Nb 3d peak showed a remarkable enlargement that became necessary a deconvolution which indicated the formation ofNhO, Nb02 and N205. (author)

  17. Stress corrosion cracking of pressurized boundary materials of 600 MW nuclear power plant. The critical potential for SCC of SG tubing alloy inconel-690 in simulated secondary water

    International Nuclear Information System (INIS)

    The experimental method of slow strain rate tests (SSRTs) with constant applied electrochemical potential (ECP) was applied first time on steam generator (SG) tubing alloy In-690 to investigate the relations between stress corrosion cracking (SCC) behavior and ECP in simulated secondary water chemistry condition: 260 degree C, 1 x 10-6 Cl- un-deaerated water. The critical potentials (Ec) for SCC have been determined finally. SSRTs with constant ECP experiments were performed on SERT-5000 dP 9H tension tester, in all tests the nominal strain rate was 4.2 x 10-6/s. Anodic polarization was conducted on high temperature electrochemistry testing autoclave with a model 350A corrosion measurement system, with potential scanning rate 0.3 mV/s. The experimental materials were alloy In-690 provided by Sumitomo of Japan and Vallurac of France

  18. Probabilistic Material Strength Degradation Model for Inconel 718 Components Subjected to High Temperature, High-Cycle and Low-Cycle Mechanical Fatigue, Creep and Thermal Fatigue Effects

    Science.gov (United States)

    Bast, Callie C.; Boyce, Lola

    1995-01-01

    The development of methodology for a probabilistic material strength degradation is described. The probabilistic model, in the form of a postulated randomized multifactor equation, provides for quantification of uncertainty in the lifetime material strength of aerospace propulsion system components subjected to a number of diverse random effects. This model is embodied in the computer program entitled PROMISS, which can include up to eighteen different effects. Presently, the model includes five effects that typically reduce lifetime strength: high temperature, high-cycle mechanical fatigue, low-cycle mechanical fatigue, creep and thermal fatigue. Results, in the form of cumulative distribution functions, illustrated the sensitivity of lifetime strength to any current value of an effect. In addition, verification studies comparing predictions of high-cycle mechanical fatigue and high temperature effects with experiments are presented. Results from this limited verification study strongly supported that material degradation can be represented by randomized multifactor interaction models.

  19. Effect of Al-Si Pack Cementation Diffusion Coating on High-Temperature Low-Cycle Fatigue Behavior of Inconel 713LC

    Science.gov (United States)

    Mansuri, Mohammadreza; Hadavi, Seyed Mohammad Mehdi; Zare, Esmail

    2016-01-01

    In this research, an Al-Si protective coating was applied on the surface of an IN713LC specimen using pack cementation method. Surface-treated and untreated specimens were exposed to low-cycle fatigue by tension-tension loading under total strain control at 1173 K (900 °C) in air. Based on the obtained results, the hardening/softening, cyclic stress-strain, and fatigue life curves were plotted and analyzed. The results showed that both the single-stage and two-stage coatings improved the fatigue life of the substrate. However, owing to more silicon content of single-stage coating compared to that of two-stage coating, the effect of single-stage coating was superior. The stress response of the treated material was lower compared with the untreated one. Observations of the specimen section and fracture surface examinations were used to analyze fatigue behavior of both coated and uncoated materials.

  20. High spatial resolution, high energy synchrotron x-ray diffraction characterization of residual strains and stresses in laser shock peened Inconel 718SPF alloy

    Science.gov (United States)

    Gill, Amrinder S.; Zhou, Zhong; Lienert, Ulrich; Almer, Jonathan; Lahrman, David F.; Mannava, S. R.; Qian, Dong; Vasudevan, Vijay K.

    2012-04-01

    Laser shock peening (LSP) is an advanced surface enhancement technique used to enhance the fatigue strength of metal parts by imparting deep compressive residual stresses. In the present study, LSP was performed on IN718 SPF alloy, a fine grained nickel-based superalloy, with three different power densities and depth resolved residual strain and stress characterization was conducted using high energy synchrotron x-ray diffraction in beam line 1-ID-C at the Advanced Photon Source at the Argonne National laboratory. A fine probe size and conical slits were used to non-destructively obtain data from specific gauge volumes in the samples, allowing for high-resolution strain measurements. The results show that LSP introduces deep compressive residual stresses and the magnitude and depth of these stresses depend on the energy density of the laser. The LSP induced residual stresses were also simulated using three-dimensional nonlinear finite element analysis, with employment of the Johnson-Cook model for describing the nonlinear materials constitutive behavior. Good agreement between the experimental and simulated data was obtained. These various results are presented and discussed.

  1. Seal welding of PWSCC at J-weld of reactor vessel head penetration nozzle

    International Nuclear Information System (INIS)

    The penetration nozzles of reactor vessel head, which are made of alloy 600, have sensitivity to Stress Corrosion Cracking in PWR primary water environment (PWSCC). To preparing the countermeasure in case of cracks observed during the inspection activity, a dedicated seal welding method has been developed, where alloy 690 is used for welding metal to isolate the cracking from the environment. This method was applied to an actual plant effectively, when a leakage at the penetration due to wall-through crack was observed at the domestic plant in 2004. (author)

  2. Steam generators: learning from experience

    International Nuclear Information System (INIS)

    The North Anna power plant in Virginia, USA, comprises two PWR units. Each employs three Westinghouse series 51 steam generators. New lower steam generator assemblies, with 3592 tubes made of thermally treated Alloy 690, were installed in 1993, replacing the original assemblies which contained 3388 tubes of mild annealed Alloy 600. Since then, the operators have been engaged in planning a similar replacement for unit 2. This article examines how lessons learned in the unit 1 replacement are being taken into account. It is hoped to improve performance by 30% in the unit 2 replacement which is scheduled to start in September 1996. (UK)

  3. STRESS CORROSION CRACKING OF NICKEL BASE SUPERALLOYS IN AERATED SUPERCRITICAL WATER

    OpenAIRE

    Fournier, L.; Delafosse, David; Bosch, C.; Magnin, Thierry

    2001-01-01

    The stress corrosion cracking behaviour of two nickel base superalloys (A718 and A690) is investigated in aerated supercritical water by means of constant extension rate tensile (CERT) tests at 400°C and 25 MPa. Alloy 718 is observed to be extremely sensitive to intergranular stress corrosion cracking (IGSCC) while alloy 690 is found to be immune to IGSCC. CERT tests are also carried out in air and under vacuum on both alloys at 600°C, i.e. in a temperature domain where nickel base superalloy...

  4. Effects of zinc injection from hot functional test at Tomari Unit 3

    International Nuclear Information System (INIS)

    At Tomari Nuclear Power Station unit 3 (hereafter Tomari unit 3, PWR, commercial operation from December 2009), the zinc injection for dose-rate reduction was started as early as at the Hot Functional Test (hereafter HFT) stage, for the first time in the world. The results of the Steam Generator (hereafter SG) insert plate analysis and the ambient dose-rate measurement till the end of the test operation reported heretofore, show the formation of the robust oxide film on the primary material surfaces and the associated corrosion suppression effect, and a considerable dose-rate reduction of about 40 to 60% lower than a reference plant. (*: Asian Water Chemistry Symposium in Nagoya on 2009 and NPC2010 in Canada). The material of SG tube is Alloy 690TT in Tomari unit 3. Generally, the dose-rates of the plants with Alloy 690TT SG are the highest at the 1. or 2. refueling outage (hereafter RFO), due to the effects of the Ni dissolution from the initial corrosion of Alloy 690TT. Therefore, the dose-rate of Tomari unit 3 at the 1. RFO is compared with those of the other Japanese PWR plants at their 1. RFO. As the result, the dose-rates inside the main components such as SG, Main Coolant Pipe (hereafter MCP) and Reactor Vessel (hereafter RV) are about 50% lower at the 1. RFO of Tomari unit 3 than those of a reference plant (a 3-Loop PWR plant in Japan). Therefore, an additional dose-rate reduction effects is expected by the Ni release rate reduction from Alloy 690TT and the effect of zinc injection. In this report, the actual dose-rates at the primary main components, the trends of the water chemistry and dose rates reduction effect with the zinc injection at the 1. RFO (offline in January 2011) of Tomari unit 3 are introduced. Also, a part of the experiences at the 2. RFO (offline in May 2012) is introduced. (authors)

  5. Stress corrosion crack tip microstructure in nickel-based alloys

    International Nuclear Information System (INIS)

    Stress corrosion cracking behavior of several nickel-base alloys in high temperature caustic environments has been evaluated. The crack tip and fracture surfaces were examined using Auger/ESCA and Analytical Electron Microscopy (AEM) to determine the near crack tip microstructure and microchemistry. Results showed formation of chromium-rich oxides at or near the crack tip and nickel-rich de-alloying layers away from the crack tip. The stress corrosion resistance of different nickel-base alloys in caustic may be explained by the preferential oxidation and dissolution of different alloying elements at the crack tip. Alloy 600 (UNS N06600) shows good general corrosion and intergranular attack resistance in caustic because of its high nickel content. Thermally treated Alloy 690 (UNS N06690) and Alloy 600 provide good stress corrosion cracking resistance because of high chromium contents along grain boundaries. Alloy 625 (UNS N06625) does not show as good stress corrosion cracking resistance as Alloy 690 or Alloy 600 because of its high molybdenum content

  6. Development of modified alloy 52 filler metal for weldability

    International Nuclear Information System (INIS)

    Alloy 690 was developed to improve resistance to Primary Water Stress Corrosion Cracking (PWSCC) compared with conventional Alloy 600. Alloy 690 weld metal (Alloy 52 filler metal) is also used in PWR nuclear power plants for welding of dissimilar-metal joints, such as safe-end welds of reactor vessels. Alloy 52, however, tends to be inferior to Alloy 600 weld metal (Alloy 82 filler metal) in terms of weldability due to its large amount of oxide scale generation on the weld bead surfaces. In this study, the effects of alloying elements on hot-cracking susceptibility and oxide scale generation were investigated in Alloy 52 filler metals. By means of cracking tests and cladding tests, investigation results were obtained as follows; 1) Increase of Nb and S contents increase hot-cracking susceptibility, although Ta dose not influence hot-cracking susceptibility. 2) Al and Ti contents influences amount of oxide scale generation. Modified Alloy 52 filler metal, which was developed based on the investigation results, showed improvements in suppression of oxide scale generation and hot cracking susceptibility. (author)

  7. Atomic scale study of grain boundary segregation before carbide nucleation in Ni–Cr–Fe Alloys

    International Nuclear Information System (INIS)

    Highlights: • Impurities segregated at grain boundaries were observed by atom probe tomography. • The comparison of segregation features in two Ni–Cr–Fe alloys was studied by APT. • C and Cr atoms co-segregated at grain boundaries before carbide precipitation. -- Abstract: Three dimensional chemical information concerning grain boundary segregation before carbide nucleation was characterized by atom probe tomography in two Ni–Cr–Fe alloys which were aged at 500 °C for 0.5 h after homogenizing treatment. B, C and Si atoms segregation at grain boundary in Alloy 690 was observed. B, C, N and P atoms segregation at grain boundary in 304 austenitic stainless steel was observed. C atoms co-segregation with Cr atoms at the grain boundaries both in Alloy 690 and 304 austenitic stainless steel was found, and its effect on the carbide nucleation was discussed. The amount of each segregated element at grain boundaries in the two Ni–Cr–Fe alloys were analyzed quantitatively. Comparison of the grain boundary segregation features of the two Ni–Cr–Fe alloys were carried out based on the experimental results

  8. Straining electrode behavior and corrosion resistance of nickel base alloys in high temperature acidic solution

    International Nuclear Information System (INIS)

    Repassivation behavior and IGA resistance of nickel base alloys containing 0∼30 wt% chromium was investigated in high temperature acid sulfate solution. (1) The repassivation rate was increased with increasing chromium content. And so the amounts of charge caused by the metal dissolution were decreased with increasing chromium content. (2) Mill-annealed Alloy 600 suffered IGA at low pH environment below about 3.5 at the fixed potentials above the corrosion potential in 10%Na2SO4+H2SO4 solution at 598K. On the other hand, thermally-treated Alloy 690 was hard to occur IGA at low pH environments which mill-annealed Alloy 600 occurred IGA. (3) It was considered that the reason, why nickel base alloys containing high chromium content such as Alloy 690 (60%Ni-30%Cr-10%Fe) had high IGA/SCC resistance in high temperature acidic solution containing sulfate ion, is due to both the promotion of the repassivation and the suppression of the film dissolution by the formation of the dense chromium oxide film

  9. Fatigue and creep cracking of nickel alloys for 700 C steam turbines

    International Nuclear Information System (INIS)

    Four materials of the types Inconel 706 (two heat treatment states), Inconel 617, and Waspaloy were tested as shaft materials for 700 to 720 C steam turbines. At an extrapolation time ratio of 10, Waspaloy was expected to have the highest creep strength (about 270 MPa at 700 C), with values of about 140 MPa at 700 C for Inconel 617. A preliminary evaluation of the 700 C creep rupture tests showed the highest creep rupture resistance for Inconel 617, followed by Waspaloy and Inconel 706

  10. The use of finite element analysis and notch tensile testing to determine the cryogenic fracture toughness of thick section weldment in forged CSUS-JN1 plate with Inconel 625 type filler metals

    International Nuclear Information System (INIS)

    The use of the notch tensile test to estimate the elastic-plastic fracture toughness (JIC) of structural alloys and weldments for superconducting magnets in fusion energy systems was studied. Notch tensile tests were performed with small round bar specimens containing an electro discharge machined (EDM) notch at liquid helium temperature (4 K) using crosshead rates of 3.3 x 10-3 and 20 mm/s. Notch tensile test specimens were 5 mm in diameter with a 30-mm reduced section. In the mid section of the specimen a 1 mm deep EDM notch of 0.2 mm width was machined around the girth, thus maintaining a starting diameter of 3 mm. Correlations between notch tensile strength, failure energy absorption, and JIC were assessed. A finite element analysis was also performed to compute directly the J-values. Comparisons of the predicted JIC with results obtained from conventional JIS Z 2284 standard tests were made. (author)

  11. The electrochemical corrosion behavior of austenitic alloys, cobalt or nickel based super alloys, structurally hardened martensitic, Inconel, zircaloy, super austenitic, duplex and of Ni-Cr or NTi deposits in tritiated water. 3 volumes

    International Nuclear Information System (INIS)

    The redox potential of 3 H2O, as well as the corrosion potentials in this medium are found, abnormally, in the trans-passive region. This is completely different from the behavior in the chemical industry or in the water in nuclear powers. With such behavior, there will be breakdowns of the protective oxide layers, and in the presence of chloride there will be immediate pitting. The steels that are most resistant to this behavior are the super austenitic and super Duplex. To avoid corrosion, another solution is to decompose the radiolytic products by imposing a slight reducing potential. Corrosion inhibitors, which are stable in tritiated water, can be used. (author). 69 refs., 421 figs., tabs

  12. The electrochemical corrosion behavior of austenitic alloys, cobalt or nickel based super alloys, structurally hardened martensitic, Inconel, zircaloy, super austenitic, duplex and of Ni-Cr or NTi deposits in tritiated water. 3 volumes; Comportement electrochimique a la corrosion d`alliages austenitiques, superalliages base cobalt ou nickel, martensitiques a durcissement structural, inconel, zircaloy, superaustenitiques et duplex, de depots Ni-Cr et NTi en eau tritiee. 3 volumes

    Energy Technology Data Exchange (ETDEWEB)

    Bellanger, G.

    1994-12-31

    The redox potential of {sup 3} H{sub 2}O, as well as the corrosion potentials in this medium are found, abnormally, in the trans-passive region. This is completely different from the behavior in the chemical industry or in the water in nuclear powers. With such behavior, there will be breakdowns of the protective oxide layers, and in the presence of chloride there will be immediate pitting. The steels that are most resistant to this behavior are the super austenitic and super Duplex. To avoid corrosion, another solution is to decompose the radiolytic products by imposing a slight reducing potential. Corrosion inhibitors, which are stable in tritiated water, can be used. (author). 69 refs., 421 figs., tabs.

  13. Creep behavior of plasma sprayed NiCr and NiCrAl coating-based systems

    Institute of Scientific and Technical Information of China (English)

    Xiancheng ZHANG; Changjun LIU; Fuzhen XUAN; Zhengdong WANG; Shan-Tung TU

    2011-01-01

    The creep behavior of the plasma sprayed NiCr and NiCrAl coating/Nickel alloy 690substrate systems at 1033 K was investigated. Results showed that there was almost no difference in the creep lives between the NiCr and NiCrAl coated specimens at a given stress level, since the contents of Cr used in the NiCr and NiCrAl powders are almost same. The relationship between the minimum creep rate and the applied stress followed the well-known Norton's power law, εmin=Aσn, with the values of A=2.66× 10-16 Mpa-n.h-1 and n=6.48. The relation between the applied stress and time to rupture of the coated specimens can be estimated by using Larson-Miller equation. The θ projection method can be used to accurately characterize the creep behavior of the coated specimens.

  14. Materials Reliability Program Low-Temperature Cracking of Nickel-Based Alloys and Weld Metals (MRP-108)

    International Nuclear Information System (INIS)

    OAK-B135 A rising load test in low-temperature (50-100 degree C) pH 10 water containing a high concentration of dissolved hydrogen (150 cc/kg) has demonstrated that Alloy 690 as well as weld metals 82 and 52 exhibit a marked loss of ductility. A similar loss of ductility has been shown to occur in widely used weld metal 182 under replica test conditions and simulated PWR primary water containing 100 cc/kg of hydrogen. The objective of this report was to confirm the Bettis test results for weld metal 82 and determine whether weld metal 182 is susceptible to the same reductions in toughness. This report documents the first industry effort to reckon with the low temperature crack propagation (LTCP) issue

  15. The susceptibility of Candu steam generator tubing alloys to IGA/IGSCC in acid sulphate environments

    International Nuclear Information System (INIS)

    Constant extension rate tests (CERT) were carried out to assess the susceptibility of CANDU steam generator (SG) tube materials to intergranular stress corrosion cracking (IGSCC) in acidified sulphate solutions calculated to exist in SG crevices following sulphuric acid and Lake Huron water ingress. The results indicate significant susceptibility of Alloy 600 tubing (i.e. Bruce A) to IGSCC following sulphuric acid ingress and some susceptibility to intergranular attack (IGA) following Lake Huron water ingress. Alloy 800 was slightly susceptible to IGA in sulphuric acid ingress crevice chemistries but not at all to Lake Huron water ingress crevice chemistry. Alloy 690 was not susceptible to IGSCC or IGA in any of the chemistries tested. Preliminary results suggest that lead contamination of 1000 ppm does not increase the susceptibility of any of the Alloys tested to IGSCC following sulphuric acid ingress. (authors). 3 figs., 2 tabs., 6 refs

  16. Oxidation and reduction of copper and iron species in steam generator deposits - Effects of hydrazine, carbohydrazide and catalyzed hydrazine

    International Nuclear Information System (INIS)

    It has long been suspected that oxidation and reduction of secondary side deposits in PWR steam generators have a significant influence on the onset of intergranular attack and stress corrosion cracking (IGA/SCC) of mill annealed Alloy 600 steam generator tubes. It is believed that these same processes could affect the possible future occurrence of IGA/SCC of thermally treated Alloy 600 and Alloy 690 tubes that are in newer steam generators. The working hypothesis for describing the influence of oxides on accelerated tube degradation is that deposits formed during normal operation are oxidized during lay-up. During subsequent operation, these oxidized species accelerate tube degradation by raising the electrochemical potential. (authors)

  17. Internal oxidation as a mechanism for steam generator tube degradation

    International Nuclear Information System (INIS)

    Internal oxidation has been proposed as a plausible mechanism for intergranular stress corrosion cracking (IGSCC) of alloy 600 steam generator tubing. This theory can reconcile the main thermodynamic and kinetic characteristics of the observed cracking in hydrogenated primary water. Although secondary side IG attack or IGSCC is commonly attributed to the presence of strong caustic or acidic solutions, more recent evidence suggests that this degradation takes place in a near-neutral environment, possibly dry polluted steam. As a result, internal oxidation is also a feasible mechanism for secondary side degradation. The present paper reviews experimental work carried out in an attempt to determine the validity of this mechanism. The consequences for the expected behaviour of alloys 690 and 800 replacement materials are also described. (author)

  18. Study of the IGA/SCC behavior of Alloy 600 and 690 in high temperature solutions

    International Nuclear Information System (INIS)

    IGA/SCC of Alloy 600 steam generator (SG) tubes in the secondary side has been recognized as a matter of great concern for PWRs. IGA/SCC behavior of Alloy 600 and 690 in high temperature solutions were studied using CERT method under potentiostatic conditions. The IGA/SCC susceptible regions were investigated as the function of pH and electrode potential. To understand the cause of IGA/SCC, the electrochemical measurements and surface film analysis were also performed in acidic and alkaline solutions. To verify the results of CERT test, the long term model boiler tests were also carried out. Thermally treated Alloy 690 showed higher IGA/SCC resistance than Alloy 600 under both acid and alkaline conditions

  19. Wear behavior of steam generator tubes in nuclear power plant operating condition

    International Nuclear Information System (INIS)

    Reciprocating sliding wear tests were performed on steam generator tubes materials at steam generator operating temperature. The material surfaces react with oxygen to form oxides. The oxide properties such as formation rate and mechanical properties are varied with the test temperature and alloy composition. So, it is important to investigate the wear properties of each steam generator tube materials in steam generator operating condition. The tests results indicated that the wear coefficient in work rate model of alloy 690 was faster than that of alloy 800. From the scanning electron microscopy observation, the wear scars were similar each other and worn surfaces were covered with oxide layers. It seemed that the oxide layers were formed by wear debris sintering or cold welding and these layer properties affected the wear rate of steam generator tube materials. (author)

  20. Zinc injection during hot functional test (HFT) in Tomari unit 3

    International Nuclear Information System (INIS)

    Zinc injection is performed to reduce radiation exposure around the world, and its effect is confirmed. In Japanese PWRs, the actual effect is also confirmed. Therefore, number of Japanese PWR plans, where zinc is injected, increase. Also, further effect of the zinc injection will be expected, when the zinc injection will be done early stage by its principle. Also, it is confirmed that zinc injection reduces corrosion amount of alloy 690TT in laboratory test. As mentioned above, authors estimate that zinc injection is effective for reducing radiation exposure, when zinc injection is performed during high corrosion rate, when RCS is firstly heated up in plant test operation. Actual results of water chemistry and zinc injection are reported, when zinc injection is started from Hot Functional Test (HFT) in Tomari Unit 3 (PWR, commercial operation to be planed in December 2009) of HOKKAIDO ELECTRIC POWER CO., INC. This zinc injection is first trial in the world. (author)

  1. The addition of zinc to primary reactor coolant for enhanced PWSCC resistance

    International Nuclear Information System (INIS)

    The effect of zinc borate additions on the primary water stress corrosion cracking (PWSCC) of specimens exposed to simulated pressurized water reactor (PWR) primary coolant was evaluated in the laboratory. Highly stressed reverse U-bend (RUB) specimens of Alloy 600MA, Alloy 600TT, and Alloy 690TT, were exposed under simulated PWR conditions of chemistry, temperature and pressure. Statistically significant reductions in the initiation and extent of observed cracking of the RUB's were observed as a function of zinc additions versus controlled experiments in the absence of zinc additives. Coupons of other primary side materials of interest showed that both overall corrosion and metal release to solution were reduced in the presence of zinc. Additional qualification work, considering all aspects of system performance, is presently ongoing

  2. 78 FR 42584 - Bureau of International Security and Nonproliferation: Report to Congress Pursuant to Section...

    Science.gov (United States)

    2013-07-16

    ... infiltrated tungsten; copper- beryllium; graphite; hastelloy; inconel; magnesium; molybdenum; nickel; niobium...); titanium; titanium diboride; tungsten; tungsten carbide; and zirconium. Dated: July 1, 2013. Thomas...

  3. Fracture assessment of a BWR pump nozzle

    International Nuclear Information System (INIS)

    Fracture mechanics calculations are performed to support the non-destructive testing (NDT) qualification programs for pump nozzle investigations of boiling water reactor (BWR) nozzles of reactor pressure vessels (RPVs), with the aim of the determination of qualification defects, which are located in the Inconel 182 weld of the pump nozzle at the bottom of the RPV. The ferritic nozzle and housing have an Inconel buttering and each part is cladded with Inconel 182 before it is mounted. All theses weldments are heat treated after welding; only the connecting weldment between pump housing and nozzle, which is also an Inconel 182 weld, performed on site, is in the as welded condition. (author)

  4. PWSCC Preventive Maintenance Activities for Alloy 600 in Japanese PWR Plants

    International Nuclear Information System (INIS)

    Because many nuclear plants have been in operation for ages, the importance of preventive maintenance technologies is getting higher. One conspicuous problem found in pressurized water reactor (PWR) plants is the primary water stress corrosion cracking (PWSCC) observed in Alloy 600 (a kind of high nickel based alloy) parts. Alloy 600 was used for butt welds between low alloy steel and stainless steel of nozzles of Reactor Vessel (RV), Steam Generator (SG), and Pressurizer (Pz). As PWSCC occurred at these parts may cause Loss of Coolant Accident (LOCA), preventive maintenance is necessary. PWSCC is considered to be caused by a mixture of three elements: high residual tensile stress on surface, material (Alloy 600) and environment. PWSCC can be prevented by improving one of the elements. MHI has been developing stress improvement methods, for example, Water Jet Peening (WJP), Shot Peening by Ultrasonic vibration (USP), and Laser Stress Improvement Process (L-SIP). According to the situation, appropriate method is applied for each part. WJP has been applied for RV nozzles of a lot of plants in Japan. However PWSCC was observed in RV nozzles during the inspection before WJP in recent years, MHI developed the Advanced INLAY system to improve the material from Alloy 600 to Alloy 690. Alloy 600 on the inner surface of the nozzles is removed and welding with Alloy 690 is performed. In addition, heat treatments for the nozzles are difficult for its structural situation, so ambient temperature temper bead welding technique for RV nozzles was developed to make the heat treatments unnecessary. This paper describes countermeasures against PWSCC and introduces the maintenance activities performed in Japan. (author)

  5. Kinetics of corrosion products release from nickel-base alloys corroding in primary water conditions. A new modeling of release

    International Nuclear Information System (INIS)

    The radioactivity in the primary circuit arises mainly from the activation of corrosion products in the core of pressurised water reactors; corrosion products dissolve from the oxide scales developed on steam generator tubes of alloy 690. The controlling and modelling of this process require a detailed knowledge of the microstructure and chemical composition of oxide scales as well as the kinetics of their corrosion and dissolution. Alloy 690 was studied as tubes and sheets, with three various surface states (as-received, cold-worked, electropolished). Corrosion tests were performed at 325 C and 155 bar in primary water conditions (B/Li - 1000/2 ppm, [H2] 30 cm3.kg-1 TPN, [O2] < 5 ppb); test durations ranged between 24 and 2160 hours. Corrosion tests in the TITANE loop provided mainly corrosion and oxidation kinetics, and tests in the BOREAL loop yielded release kinetics. This study revealed asymptotic type kinetics. Characterisation of the oxide scales grown in representative conditions of the primary circuit was performed by several techniques (SEM, TEM, SIMS, XPS, GIXRD). These analyses revealed the essential role of the fine grained cold-worked scale present on as-received and cold-worked materials. This scale controls the corrosion and release phenomena. The kinetic study and the characterisation of the oxide scales contributed to the modelling of the corrosion/release process. A growth/dissolution model was proposed for corrosion product scales grown in non-saturated dynamic fluid. This model provided the temporal evolution of oxide scales and release kinetics for different species (Fe, Ni, Cr). The model was validated for several surface states and several alloys. (authors)

  6. Relationship between Microstructure and Ductility Dip Cracking resistance of Alloy 600/690 weld metals

    International Nuclear Information System (INIS)

    Ni-Cr-Fe alloys are used extensively in nuclear power systems for their resistance to general corrosion, localized corrosion, and environmentally assisted cracking. However, concerns with stress corrosion cracking of moderate chromium (14.22 wt-%) alloys such as Alloy 600 and its filler metals(FMs) (E-182 and EN82) have driven the application of higher chromium (28.30 wt-%) alloys like Alloy 690. While Alloy 690 and its FMs show outstanding resistance to environmentally assisted cracking in most water-reactor environments, these alloys are prone to welding defects, most notably to ductility dip cracking(DDC). The DDC occurs at temperatures between 0.5 and 0.8 of their melting temperature. This ductility drop may result in intergranular elevated temperature cracking often referred to as DDC. The DDC may occur during the high temperature processing of these alloys or during welding if the imposed strain exhausts the available ductility within this temperature range. Several alloy systems including Ni-base alloys, Ni.Cu alloys, Cu alloys, stainless steels and steels, have been reported to be susceptible to DDC. A complete understanding of the DDC mechanism does not exist, which makes DDC control in actual production conditions a very difficult task. In this study, the DDC resistance was evaluated with different FMs which have different chemical composition. The microstructural features of FMs such as precipitation behavior and grain boundaries morphology were observed, and it were correlated with the DDC susceptibility. The hot ductility test and strainto- fracture test was used to evaluate the DDC susceptibility at high temperature

  7. Design and performance of BWC replacement steam generators for PWR systems

    International Nuclear Information System (INIS)

    In recent years, Babcock and Wilcox Canada (BWC) has provided a number of PWR Replacement Steam Generators (RSGS) to replace units that had experienced extensive Alloy 600 tube degradation. BWC RSG units are in operation at Northeast Utilities' Millstone Unit 2, Rochester Gas and Electric's Ginna Station, Duke Energy's Catawba Unit 1, McGuire Unit 1 and 2, Florida Power and Light's St. Lucie Unit 1 and Commonwealth Edison's Byron 1 Station. Extensive start-up performance characteristics have been obtained for Millstone 2, Ginna, McGuire 1, and Catawba 1 RSGS. The Millstone 2, Ginna and Catawba 1 RSGs have also undergone extensive inspections following their first cycle of operation. The design and start-up performance characteristics of these RSGs are presented. The BWC Replacement Steam generators were designed to fit the existing envelope of pressure boundary dimensions to ensure licensability and integration into the Nuclear Steam Supply System. The RSGs were provided with a tube bundle of Alloy 690TT tubing, sized to match or exceed the original steam generator (OSG) thermal performance including provision for the reduced thermal conductivity of Alloy 690 relative to Alloy 600. The RSG tube bundle configurations provide a higher circulation design relative to the OSG, and feature corrosion resistant lattice grid and U-bend tube supports which provide effective anti-vibration support. The tube bundle supports accommodate relatively unobstructed flow and allow unrestrained structural interactions during thermal transients. Efficient steam separators assure low moisture carryover as well as high circulation. Performance measurements obtained during start-up verify that the BWC RSGs meet or exceed the specified thermal and moisture carryover performance requirements. RSG water level stability results at nor-mal operation and during plant transients have been excellent. Visual and ECT inspections have confirmed minimal deposition and 100% tube integrity following

  8. Niobium-3-tin internally cooled cabled superconductor (ICCS) technology I

    International Nuclear Information System (INIS)

    Recent work, using tantalum and Incoloy 903 sheathing has demonstrated that internally cooled, cabled superconductors (ICCS) can be compacted without current degradation. This paper compares Inconel 617 sheathing to previous results. Inconel 617 is a practical engineering material with a thermal contraction lying between stainless steel and Incoloy 903

  9. NIOBIUM-3-TIN INTERNALLY COOLED CABLED SUPERCONDUCTOR (ICCS) TECHNOLOGY I

    OpenAIRE

    Hoenig, M.; Steeves, M.; Cyders, C.

    1984-01-01

    Recent work, using tantalum and Incoloy 903 sheathing has demonstrated that internally cooled, cabled superconductors (ICCS) can be compacted without current degradation. This paper compares Inconel 617 sheathing to previous results. Inconel 617 is a practical engineering material with a thermal contraction lying between stainless steel and Incoloy 903.

  10. Abrasive blasting technology for decontamination of the inner surface of steam generator tubes

    International Nuclear Information System (INIS)

    The inner surfaces of bundled inconel tubes from steam generators in South Korean nuclear power plants are contaminated with cobalt and abrasive blasting equipment has been developed to efficiently remove the cobalt. The principal parameters related to the efficient removal using this equipment are the type of abrasive, the distance from the nozzle, and the blasting time. Preliminary tests were performed using oxidized inconel samples which enabled the simulation of cobalt removal from the radioactive inconel samples. The oxygen in the oxidized samples and the cobalt in the radioactive inconel were removed more effectively using the blasting distance, blasting time, and a silicon carbide abrasive. Using the developed abrasive blasting equipment, the optimum decontamination conditions for radioactive inconel samples were blasting for more than 6 minutes using silicon carbides under 5 atmospheric pressures

  11. Predictive methodology to address PWSCC of Alloy 600 locations in PWRS

    International Nuclear Information System (INIS)

    Contributing factors to primary water stress corrosion cracking (PWSCC) are susceptible microstructure, temperature, and residual and applied stresses. In order to predict PWSCC of Inconel 600 components in PWR type reactors, a number of steps were taken. All Inconel 600 components were located, fabrication history, weld procedures and material properties were identified. Service temperatures and approximate stresses were determined. Precise service stress evaluations of Inconel 600 locations by Finite Element and other analytical evaluations were made. Using data analysis, relative PWSCC susceptibility evaluations of Inconel 600 locations were made on the basis of the Westinghouse RSI model. Finally, a prioritized inspection plan for Inconel 600 locations was developed and recommendations provided. 11 figs., 2 tabs

  12. Thick-section weldments in 21-6-9 and 316LN stainless steel for fusion energy applications

    International Nuclear Information System (INIS)

    The mechanical properties of several weldments in 21-6-9 and 316LN stainless steel metals have been measured at 77 K and room temperature. Filler metals for the 211-6-9 included Nitronic 35W and 40W, 21-6-9, Inconel 82, 182, 625, and 625 PLUS. For the 316LN base metal, 316L, 316L-T3, 316L-4K-O, and Inconel 82 filler metals were used. At room temperature all of the filler metals had yield strengths that exceeded those of the base metals. At 77K only the Nitronics and the 21-6-9 filler metals exceeded those of the base metals, and the Inconel filler metals were significantly weaker. The impact properties of the weld metals were very good at room temperature, with the exception of Inconel 625. At 77 K the impact toughness was greatly reduced for all of the filler metals, with the dramatic exception of Inconel 82. The 316L-4K-O filler metal showed higher impact energies than the other ferrite-containing filler metals, although the levels were still much lower than for the Inconel filler metals. The Inconel 82 filler had excellent fracture toughness at both temperatures

  13. Subcritical crack growth in the ligament between the instrumentation rods of the BBR pressure vessel bottom

    International Nuclear Information System (INIS)

    A fracture mechanics fatigue analysis is made for an assumed crack emanating from the bore of an instrumentation rod. This assumed crack has partially penetrated the Inconel buttering of the 22 Ni Mo Cr 37 on which the structural Inconel welds are laid. Our analysis shows that the assumed crack could only penetrate 26% of the remaining ligament of the Inconel structural weld as a result of the fatigue crack growth during the entire operating life of the pressure vessel. Therefore a leak caused by a flaw missed during pre-service and in-service non-destructive testing can be excluded. (author)

  14. Corrosion aspects of compatible alloys in molten salt (FLiNaK) medium for Indian MSR program in the temperature range of 550-750 °C using electrochemical techniques

    International Nuclear Information System (INIS)

    Corrosion behaviours of different alloys were evaluated in fluoride eutectic FLiNaK in the temperature range of 550-750 °C under static and dynamic conditions. Electrochemical polarization and impedance techniques were used to estimate corrosion rate. The results showed that the corrosion process was controlled by activation and in some cases by formation of passive layer. In static mode, the corrosion rates followed the order : Inconel 625 > Inconel 617 > Inconel 600 > Incoloy 800 > Ni 220 > Hastelloy N > Incoloy 800HT. In dynamic mode, Hastelloy N and Incoloy 800HT showed better corrosion resistance in comparison to other alloys. (author)

  15. Mechanism study of c.f.c Fe-Ni-Cr alloy corrosion in supercritical water

    International Nuclear Information System (INIS)

    Supercritical water can be use as a high pressure coolant in order to improve the thermodynamic efficiency of power plants. For nuclear concept, lifetime is an important safety parameter for materials. Thus materials selection criteria concern high temperature yield stress, creep resistance, resistance to irradiation embrittlement and also to both uniform corrosion and stress corrosion cracking.This study aims for supplying a new insight on uniform corrosion mechanism of Fe-Ni-Cr f.c.c. alloys in deaerated supercritical water at 600 C and 25 MPa. Corrosion tests were performed on 316L and 690 alloys as sample autoclaves taking into account the effect of surface finishes. Morphologies, compositions and crystallographic structure of the oxides were determined using FEG scanning electron microscopy, glow discharge spectroscopy and X-ray diffraction. If supercritical water is expected to have a gas-like behaviour in the test conditions, the results show a significant dissolution of the alloy species. Thus the corrosion in supercritical water can be considered similar to corrosion in under-critical water assuming the higher temperature and its effect on the solid state diffusion. For alloy 690, the protective oxide layer formed on polished surface consists of a chromia film topped with an iron and nickel mixed chromite or spinel. The double oxide layer formed on 316L steel seems less protective with an outer porous layer of magnetite and an inhomogeneous Cr-rich inner layer. For each alloy, the study of the inner protective scale growth mechanisms by marker or tracer experiments reveals that diffusion in the oxide scale is governed by an anionic process. However, surface finishes impact deeply the growth mechanisms. Comparisons between the results for the steel suggest that there is a competition between the oxidation of iron and chromium in supercritical water. Sufficient available chromium is required in order to form a thin oxide layer. Highly deformed or ultra fine

  16. Electron beam welding and laser welding of FRAGEMA fuel assembly components

    International Nuclear Information System (INIS)

    Neutron balance and activity of the primary coolant circuit are improved in PWR if inconel 718 is replaced by a zirconium alloy for fuel element grids. This paper examines laser welding and EB welding of these zirconium alloy grids

  17. Long range plan for flexible joint development program

    International Nuclear Information System (INIS)

    Objective is to develop bellows expansion joints into CDS and subsequent LMFBR and liquid metal applications. An assessment was performed on the use of Incoloy 800H and Inconel 718 as bellows materials

  18. Thermoelectric materials evaluation program spring design to minimize load relaxation

    Energy Technology Data Exchange (ETDEWEB)

    Grimm, F.R.

    1980-03-31

    The recommended spring material for use in thermoelectric modules is either Inconel x or Elgiloy based on their excellent performance and availability. The stress level for generator applications is 75,000 psi. (FS)

  19. Assessment of high-strength stainless steel weldments for fusion energy applications

    International Nuclear Information System (INIS)

    Primary design considerations for the Compact Ignition Tokomak fusion reactor magnet cases are yield strength and toughness in the temperature range from liquid nitrogen to room temperature (77 to 300K). Type 21-6-9 stainless steel, also known as Nitronic 40, is the proposed alloy for this application. This study documented the mechanical properties, including tensile yield strength and Charpy V-notch impact toughness, at 77K and room temperature, of weldments made using seven different filler metals. Six welds were made with filler metal added as cold filler wire using the argon-shielded gas tungsten arc welding process. Filler metals included Nitronic 35W and 40W, 21-6-9, ERNiCr-3 (Inconel 82), ERNiCrMo-3 (Inconel 625), and Inconel 625 PLUS. All welds were prepared with a double-groove butt-weld geometry. At room temperature, all of the filler metals had yield strengths which exceeded the base metal. However, at 77K only the Nitronics and the 21-6-9 filler metals exceeded the base metals, and the Inconel filler metals were significantly weaker. The impact properties of the weld metals were very good at room temperature, with the exception of Inconel 625. At 77K, impact toughness was greatly reduced for all of the filler metals with the exception of Inconel 82. This alloy had excellent toughness at both temperatures. The severe drop in the impact toughness of the Nitronic and 21-6-9 filler metals was attributed to the amount of ferrite present in these welds. At 77K, fracture occurred by a cleavage mechanism in the ferrite regions which allowed the crack to grow readily. The fully austenitic Inconel 82 material fractured by a microvoid coalescence mode at either test temperature. These results indicate that the Inconel 82 filler metal is the preferred material for welding 21-6-o stainless steel for this application

  20. Methodology to evaluate the crack growth rate by stress corrosion cracking in dissimilar metals weld in simulated environment of PWR nuclear reactor

    International Nuclear Information System (INIS)

    Inconel alloys weld metal is widely used to join dissimilar metals in nuclear reactors applications. It was recently observed failures of weld components in plants, which have triggered an international effort to determine reliable data on the stress corrosion cracking behavior of this material in reactor environment. The objective of this work is to develop a methodology to determine the crack growth rate caused by stress corrosion in Inconel alloy 182, using the specimen (Compact Tensile) in simulated PWR environment. (author)

  1. Fatigue crack growth experiments and analyses - from small scale to large scale yielding at constant and variable amplitude loading

    OpenAIRE

    Ljustell, Pär

    2013-01-01

    This thesis is on fatigue crack growth experiments and assessments of fatigue crack growth rates. Both constant and variable amplitude loads in two different materials are considered; a nickel based super-alloy Inconel 718 and a stainless steel 316L. The considered load levels extend from small scale yielding (SSY) to large scale yielding (LSY) for both materials. The effect of different load schemes on the fatigue crack growth rates is investigated on Inconel 718 and compact tension specimen...

  2. Oxidization and stress corrosion cracking initiation of austenitic alloys in supercritical water

    International Nuclear Information System (INIS)

    This study determined the stress corrosion cracking behaviour of austenitic alloys in pure supercritical water. Austenitic stainless steels 310S, 316L, and Inconel 625 were tested as static capsule samples at 500oC for up to 5000 h. After that period, crack initiations were readily observed in all samples, signifying susceptibility to stress corrosion cracking. The microcracks in 316L stainless steel and Inconel 625 were almost intergranular, whereas transgranular microcrack initiation was observed in 310S stainless steel. (author)

  3. Bimetallic sleeve for repairing a heat exchanger tube locally damaged and repairing process of a such tube with this sleeve

    International Nuclear Information System (INIS)

    A tubular sleeve comprising two end sections made of the same metal as the heat exchanger tube and connected by a ring of an alloy suitable for welding is inserted into the tube and welded in place from the inside. The tube and end sections may be of Incoloy 800 while the ring is in Ni-Cr Alloy, Inconel 600 or Inconel 690. 3 figs

  4. Non-destructive evaluation of RbCl and Rb targets in Sr-82 production

    OpenAIRE

    Bach, H T; Hunter, H. T.; Summa, D. A.; Stull, C. J.; Olivas, E. R.; Connors, M A; Reass, D. A.; Moddrell, C.; Nortier, F. M.; John, K. D.

    2015-01-01

    Introduction Sr-82 is produced for PET cardiac imaging at the Isotope Production Facility (IPF) with 100-MeV proton beams. During irradiation, the target material (RbCl, Rb) and Inconel capsule are ex-posed for extended periods to intense radiation, thermally and mechanically induced stresses, and chemicals. The structural integrity of the Inconel capsules is of crucial importance to containing the target starting materials and produced Sr-82. Unexpected failure capsules severely affects t...

  5. Fatigue-crack propagation response of two nickel-base alloys in a liquid sodium environment

    International Nuclear Information System (INIS)

    The elevated temperature fatigue-crack propagation response of Inconel 600 and Inconel 718 was characterized within a linear-elastic fracture mechanics framework in air and low-oxygen liquid sodium environments. The crack growth rates of both nickel-base alloys tested in liquid sodium were found to be considerably lower than those obtained in air. This enhanced fatigue resistance in sodium was attributed to the very low oxygen content in the inert sodium environment. Electron fractographic examination of the Inconel 600 and Inconel 718 fatigue fracture surfaces revealed that operative crack growth mechanisms were dependent on the prevailing stress intensity level. Under low growth rate conditions, Inconel 600 and Inconel 718 fracture surfaces exhibited a faceted, crystallographic morphology in both air and sodium environments. In the higher growth rate regime, fatigue striations were observed; however, striations formed in sodium were rather ill-defined. These indistinct striations were attributed to the absence of oxygen in the liquid sodium environment. Striation spacing measurements were found to be in excellent agreement with macroscopic growth rates in both environments

  6. Microstructural studies on friction surfaced coatings of Ni-based alloys; Gefuegeuntersuchungen an reibgeschweissten Beschichtungen von Ni-Basislegierungen

    Energy Technology Data Exchange (ETDEWEB)

    Akram, Javed; Puli, Ramesh; Kalvala, Prasad Rao; Misra, Mano [Utah Univ., Salt Lake City, UT (United States). Dept. of Metallurgical Engineering

    2015-07-01

    Inconel 625, Inconel 600, Inconel 800H were friction surfaced on steel and Inconel substrates. The interface between steel and Ni-based alloys showed intermixing of two alloys while the interface between two Ni-based alloys showed no such intermixing. The XRD results confirmed that this intermixed zone consisted of mechanical mix two separate metals and no intermetallics were noticed. Friction surfaced Inconel coatings were metallurgically bonded to steel and Inconel substrates with out any physical defects such as voids or cracks. Friction surfaced coatings showed equiaxed fine grained microstructures (4-18 μm) compared with their consumable rod counterparts (12 - 85 μm). Scanning electron microscope electron backscattered diffraction results showed that the coatings consisted of mainly high angle grain boundaries indicative of dynamic recrystallization mechanism. The temperatures recorded using Infra Red camera showed that the temperature attained at the interface between rod and the substrate is about 1100 C. The grain size of the consumable rod was relatively fine near the coating/substrate interface and relatively coarser away from interface indicating the change in strain and temperature the rod experienced at or away from the interface.

  7. Microstructural studies on friction surfaced coatings of Ni-based alloys

    International Nuclear Information System (INIS)

    Inconel 625, Inconel 600, Inconel 800H were friction surfaced on steel and Inconel substrates. The interface between steel and Ni-based alloys showed intermixing of two alloys while the interface between two Ni-based alloys showed no such intermixing. The XRD results confirmed that this intermixed zone consisted of mechanical mix two separate metals and no intermetallics were noticed. Friction surfaced Inconel coatings were metallurgically bonded to steel and Inconel substrates with out any physical defects such as voids or cracks. Friction surfaced coatings showed equiaxed fine grained microstructures (4-18 μm) compared with their consumable rod counterparts (12 - 85 μm). Scanning electron microscope electron backscattered diffraction results showed that the coatings consisted of mainly high angle grain boundaries indicative of dynamic recrystallization mechanism. The temperatures recorded using Infra Red camera showed that the temperature attained at the interface between rod and the substrate is about 1100 C. The grain size of the consumable rod was relatively fine near the coating/substrate interface and relatively coarser away from interface indicating the change in strain and temperature the rod experienced at or away from the interface.

  8. Effects of thermal aging on the microstructure of Type-II boundaries in dissimilar metal weld joints

    Science.gov (United States)

    Yoo, Seung Chang; Choi, Kyoung Joon; Bahn, Chi Bum; Kim, Si Hoon; Kim, Ju Young; Kim, Ji Hyun

    2015-04-01

    In order to investigate the effects of long-term thermal aging on the microstructural evolution of Type-II boundary regions in the weld metal of Alloy 152, a representative dissimilar metal weld was fabricated from Alloy 690, Alloy 152, and A533 Gr.B. This mock-up was thermally aged at 450 °C to accelerate the effects of thermal aging in a nuclear power plant operation condition (320 °C). The microstructure of the Type-II boundary region of the weld root, which is parallel to and within 100 μm of the fusion boundary and known to be more susceptible to material degradation, was then characterized after different aging times using a scanning electron microscope equipped with an energy dispersive X-ray spectroscope for micro-compositional analysis, electron backscattered diffraction detector for grain and grain boundary orientation analysis, and a nanoindenter for measurement of mechanical properties. Through this, it was found that a steep compositional gradient and high grain average misorientation is created in the narrow zone between the Type-II and fusion boundaries, while the concentration of chromium and number of low-angle grain boundaries increases with aging time. A high average hardness was also observed in the same region of the dissimilar metal welds, with hardness peaking with thermal aging simulating an operational time of 15 years.

  9. Zinc injection during Hot Functional Test (HFT) in Tomari Unit 3

    Energy Technology Data Exchange (ETDEWEB)

    Hayakawa, H.; Mino, Y.; Nakahama, S.; Aizawa, Y. [Hokkaido Electric Power Co., Tomari-mura, Furuu-gun, Hokkaido (Japan); Nishimura, T.; Umehara, R.; Shimuz, Y.; Kogawa, N.; Ojima, Z. [Mitsubishi Heavy Industries, Ltd., Wadasaki-cho, Hyogo-ku, Kobe-shi, Hyogo-ken (Japan)

    2010-07-01

    Zinc injection is performed to reduce radiation exposure around the world, and its effect is confirmed. In Japanese PWRs, the actual effect is also confirmed. Therefore, number of Japanese PWR plans, where zinc is injected, increase. We conclude that zinc injection from Hot Function Test (HFT), when RCS temperature and corrosion rate of material of primary components are increased firstly, is more effective for reducing radiation exposure, because oxide layer with zinc is more stable than with other metals such as cobalt and it is confirmed that zinc injection reduces corrosion amount of alloy 690TT in laboratory test. Therefore in Tomari Unit 3 (PWR, commercial operation from December 2009) of HOKKAIDO ELECTRIC POWER CO., INC, zinc injection was started from first Heat-up during trial operation. During HFT, zinc consumption coincides with assumed plan and Ni concentration is lower than in reference plant. Therefore we conclude that stable and fine oxide layer including zinc is formed. We hope that radiation exposure reduces because of these results. (We published at Asia Water Chemistry Symposium 2009 in NAGOYA.) Results of analysis of oxide layer on SG insert plate, removed after HFT, will be reported. Also Actual results of water chemistry and zinc injection after HFT will be reported. (author)

  10. Solid-state Diffusion Bonding of Candidate Fe-base and Ni-base Alloys for the Application of S-CO2 Cycle Heat Exchanger

    International Nuclear Information System (INIS)

    To achieve efficient heat transfer, compact type heat exchangers, such as printed circuit or plate fin type heat exchanger, are considered for intermediate heat exchangers (IHXs). Solid-state diffusion bonding (DB) is one of key issues for joining the thin metal sheets with flow passages that are either machined or photo-chemically etched. In this study, diffusion bonding was performed for the candidate Fe-base and Ni-base alloys. Tensile properties of the as-bonded were compared with the as-received and characteristics of the aged in high temperature S-CO2 environment were discussed. Studies on diffusion bonding of candidate alloys for the application of super-critical CO2 cycle were carried out. Strength ratios were close to 1 for Fe-base alloys (F91, SS 316H, and SS 347H), while those of Ni-base alloys (Alloy 600, Alloy 690) and Fe-Ni-Cr alloy (Incoloy 800HT) were somewhat decreased to about 0.8 due to the planar grain boundary and precipitates formed along the bond-line. After exposure in high temperature S-CO2 environment for 1000 h, mechanical properties were not changed substantially and the location of the failure was still in the gauge section away from the bond-line for most alloys. Thus, bond-line which plays a role as grain boundary is thought to have superior corrosion and carburization resistance comparable to that of parent matrix

  11. Wear performance and activity reduction effect of Co-free valves in PWR environment

    International Nuclear Information System (INIS)

    Co-based hardfacing alloys exposed to PWR primary coolant may be replaced with Co-free alloys to lower occupational radiation exposure. To evaluate the viability of Co-free hardfacing alloys, we conducted hot-water tests for gate valves hardfaced with NOREMTM 02 (Fe-base), DeloroTM 50 (Ni-base), and StelliteTM 6 (Co-base). Using a high flow test loop, on-off cycling tests were conducted in 280 deg. C water. It was observed that NOREM 02 exhibited galling and excessive leak after 1000 cycle test whereas no leakage was developed with Deloro 50 after 2000 cycles. To estimate the activity reduction effect of Co-free hardfacing alloys, an existing activity transport model was modified. It is found that the main contributor of Co activity buildup is the corrosion of steam generator (SG) tubing. The Korean Next Generation Reactor (APR-1400) tubed with alloy 690 having a reduced cobalt impurity allowance is expected to have 73% lower Co activity on SG surface compared with the case of alloy 600 tubing. The complete replacement of Stellite 6 with Co-free hardfacing alloys is expected to cut additional 5% of activity which may be too small to justify the risk of galling and leakage development as revealed by the hot-water test

  12. Aging management of major light water reactor components

    International Nuclear Information System (INIS)

    Review of technical literature and field experience has identified stress corrosion cracking as one of the major degradation mechanisms for the major light water reactor components. Three of the stress corrosion cracking mechanisms of current concern are (a) primary water stress corrosion cracking (PWSCC) in pressurized water reactors, and (b) intergranular stress corrosion cracking (IGSCC) and (c) irradiation-assisted stress corrosion cracking (IASCC) in boiling water reactors. Effective aging management of stress corrosion cracking mechanisms includes evaluation of interactions between design, materials, stressors, and environment; identification and ranking of susceptible sites; reliable inspection of any damage; assessment of damage rate; mitigation of damage; and repair and replacement using corrosion-resistant materials. Management of PWSCC includes use of lower operating temperatures, reduction in residual tensile stresses, development of reliable inspection techniques, and use of Alloy 690 as replacement material. Management of IGSCC of nozzle and attachment welds includes use of Alloy 82 as weld material, and potential use of hydrogen water chemistry. Management of IASCC also includes potential use of hydrogen water chemistry

  13. Corrosion and Rupture of Steam Generator Tubings in PWRs

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Seong Sik; Kim, Hong Pyo

    2007-08-15

    This report is intended to provide corrosion engineers in the filed of nuclear energy with information on the corrosion and rupture behavior of steam generator tubing in PWRs. Various types of corrosion in PWR steam generator tubing have been reported all around the world, and countermeasures such as the addition of corrosion inhibitors, a water chemistry control, a tube plugging and sleeving have been applied. Steam generators equipped with alloy 600 tubing, which are not so resistant to a stress corrosion cracking (SCC), have generally been replaced with new steam generators made of alloy 690 TT (Thermally treated). Pull tube examination results which were performed of KAERI are summarized. The tubes were affected by a pitting, SCC, and a denting. Nondestructive examination method for the tubes and repair techniques are also reviewed. In addition, the regulatory guidance of some countries are reviewed. As a part of a tube integrity project in Korea, some results on a tube rupture and leak behaviors for axial cracks are also mentioned.

  14. Nuclear power supply (Japan Nuclear Safety Institute)

    International Nuclear Information System (INIS)

    After experienced nuclear disaster occurred on March 11, 2011, role of nuclear power in future energy share in Japan became uncertain because most public seemed to prefer nuclear power phase out to energy security or costs. Whether nuclear power plants were safe shutdown or operational, technologies were requisite for maintaining their equipment by refurbishment, partly replacement or pressure proof function recovery works, all of which were basically performed by welding. Nuclear power plants consisted of tanks, piping and pumps, and considered as giant welded structures welding was mostly used. Reactor pressure vessel subject to high temperature and high pressure was around 200mm thick and made of low-alloy steels (A533B), stainless steels (308, 316) and nickel base alloys (Alloy 600, 690). Kinds of welding at site were mostly shielded-metal arc welding and TIG welding, and sometimes laser welding. Radiation effects on welding of materials were limited although radiation protection was needed for welding works under radiation environment. New welding technologies had been applied after their technical validation by experiments applicable to required regulation standards. Latest developed welding technologies were seal welding to prevent SCC propagation and temper-bead welding for cladding after removal of cracks. Detailed procedures of repair welding of Alloy 600 at the reactor outlet pipe at Oi Nuclear Power Plants unit 3 due to PWSCC were described as an example of crack removal and water jet peening, and then overlay by temper-bead welding using Alloy 600 and clad welding using Alloy 690. (T. Tanaka)

  15. Stress corrosion cracking experience with existing and potential safe-end materials

    International Nuclear Information System (INIS)

    Cracking in austenitic stainless steel safe-ends has generally been associated with furnace-sensitized microstructures. This type of cracking was observed as early as 1969 when intergranular stress corrosion cracking (IGSCC) was determined to be the cause of a leak in a sensitized Type 304 stainless steel safe-end in the LaCross boiling water reactor (BWR). The problem has been observed in other BWR's and has generally been addressed as part of the much larger pipe cracking problem that has plagued BWR's over the past 20 years. This paper will not address IGSCC of sensitized stainless steel but will focus on the IGSCC behavior of safe-end weldments and, in particular, weld metals associated with these joints. This paper describes the results of a study to evaluate the IGSCC behavior of alloy 600, I-182 and I-82, and of the potential replacement alloy 690 and its' compatible weld metals, under conditions simulating present operating BWR's. The emphasis of the program was a determination of the relative IGSCC susceptibilities of alloys 600 and 690, and a better definition of the conditions under which nickel-base alloys are susceptible to IGSCC

  16. Laboratory studies of lead stress corrosion of alloy 600

    International Nuclear Information System (INIS)

    Lead stress corrosion cracking of Alloy 600 was first reported in the open literature by Copson and Dean. Since then, other laboratory studies were performed and documented either in the open literature or various company reports. The Electric Power Research Institute conducted three projects to determine the possible extent of a lead stress corrosion cracking problem in nuclear power plants. The first study was a comprehensive review of the information available either in the open literature or various company reports. The second study was a water chemistry analysis program to investigate lead contamination in operating nuclear plants. The third study, a laboratory investigation, is the subject here. The primary objective of this laboratory project was to investigate the stress corrosion cracking behavior of nuclear grade Alloy 600 and Alloy 690 tubing materials in lead contaminated environments at an elevated temperature (3240C). Variables of importance included material heat treatment, lead species, specimen location (liquid or vapor), and solution pH regime. A secondary objective was to correlate any observed cracking with the test variables and calculated high temperature lead chemistries

  17. STRESS CORROSION CRACK GROWTH RESPONSE FOR ALLOY 152/52 DISSIMILAR METAL WELDS IN PWR PRIMARY WATER

    Energy Technology Data Exchange (ETDEWEB)

    Toloczko, Mychailo B.; Olszta, Matthew J.; Overman, Nicole R.; Bruemmer, Stephen M.

    2015-08-15

    As part of ongoing research into primary water stress corrosion cracking (PWSCC) susceptibility of alloy 690 and its welds, SCC tests have been conducted on alloy 152/52 dissimilar metal (DM) welds with cracks positioned with the goal to assess weld dilution and fusion line effects on SCC susceptibility. No increased crack growth rate was found when evaluating a 20% Cr dilution zone in alloy 152M joined to carbon steel (CS) that had not undergone a post-weld heat treatment (PWHT). However, high SCC crack growth rates were observed when the crack reached the fusion line of that material where it propagated both on the fusion line and in the heat affected zone (HAZ) of the carbon steel. Crack surface and crack profile examinations of the specimen revealed that cracking in the weld region was transgranular (TG) with weld grain boundaries not aligned with the geometric crack growth plane of the specimen. The application of a typical pressure vessel PWHT on a second set of alloy 152/52 – carbon steel DM weld specimens was found to eliminate the high SCC susceptibility in the fusion line and carbon steel HAZ regions. PWSCC tests were also performed on alloy 152-304SS DM weld specimens. Constant K crack growth rates did not exceed 5x10-9 mm/s in this material with post-test examinations revealing cracking primarily on the fusion line and slightly into the 304SS HAZ.

  18. Effect of chemical composition and cooling conditions on solidification hot cracking of Ni-based alloys

    International Nuclear Information System (INIS)

    Ni-based alloys 690 present solidification hot cracks during welding of vapour generators. Hot cracks are qualitatively known to be due to the formation of inter-dendritic liquid films and of secondary phases down to low temperatures. This study aims at establishing the link between thermodynamics, solidification and hot cracking. Experimental solidification paths of high purity alloys (with varying Nb and Si contents) are obtained from quenching during directional solidification and TIG-welding experiments. They are compared to Thermo-Calc computations, assuming no diffusion in the solid. From directional solidification samples, good agreement between computed and experimental solidification paths is shown in the quenched liquid. Secondary arms of dendrites are affected by solid state diffusion of Nb. Combined effect of diffusion and solute build-up in the liquid phase modifies micro-segregation in the solid region. Solidification paths from welding specimens are similar to those of the solid region of quenched samples. Nb solid state diffusion is negligible but undercooling compensates the effect of solid state diffusion in directional solidification. Evolution of liquid fraction at the end of the solidification is in accordance with the hot cracking classification of the alloys. Nb favours formation of inter-dendritic liquid films and eutectic-like phases down to low temperature. (author)

  19. Zinc injection during Hot Functional Test (HFT) in Tomari Unit 3

    International Nuclear Information System (INIS)

    Zinc injection is performed to reduce radiation exposure around the world, and its effect is confirmed. In Japanese PWRs, the actual effect is also confirmed. Therefore, number of Japanese PWR plans, where zinc is injected, increase. We conclude that zinc injection from Hot Function Test (HFT), when RCS temperature and corrosion rate of material of primary components are increased firstly, is more effective for reducing radiation exposure, because oxide layer with zinc is more stable than with other metals such as cobalt and it is confirmed that zinc injection reduces corrosion amount of alloy 690TT in laboratory test. Therefore in Tomari Unit 3 (PWR, commercial operation from December 2009) of HOKKAIDO ELECTRIC POWER CO., INC, zinc injection was started from first Heat-up during trial operation. During HFT, zinc consumption coincides with assumed plan and Ni concentration is lower than in reference plant. Therefore we conclude that stable and fine oxide layer including zinc is formed. We hope that radiation exposure reduces because of these results. (We published at Asia Water Chemistry Symposium 2009 in NAGOYA.) Results of analysis of oxide layer on SG insert plate, removed after HFT, will be reported. Also Actual results of water chemistry and zinc injection after HFT will be reported. (author)

  20. French nuclear power plants life management - reactor pressure vessel assessment and steam generators life management strategy

    Energy Technology Data Exchange (ETDEWEB)

    Bezdikian, G. [Electricite de France - Nuclear Generation Div., SAINT-DENIS (France)

    2007-07-01

    The approach used by the French utility, concerning the Aging Management system of the Steam Generators (SG) and Reactor Pressure Vessel, applied on 58 PWR NPPs, involves the verification of the integrity of the component and the Life Management of each plant to guarantee in the first step the design life management and in the second step to prepare long term life time in operation, taking into account the degradation of Alloy 600 material and the replacement of these materials by components made with Alloy 690. The financial stakes associated with maintaining the lifetime of nuclear power stations are very high; thus, if their lifetime is shortened by about ten years, dismantling and renewal would be brought forward which would increase their costs by several tens of billions of Euros. The main objectives are: to maintain current operating performances (safety, availability, costs, security, environment) in the long term, and possibly improve on some aspects; wherever possible, to operate the units throughout their design lifetime, 40 years, and even more if possible. This paper shows the program to follow the aging evaluation with application on Steam Generators replacement and Reactor Pressure Vessel Integrity assessment. (orig.)

  1. A study on fatigue crack propagation considering crack tip plasticity

    International Nuclear Information System (INIS)

    Fatigue crack propagation of materials considering crack tip plasticity was studied. For this, fatigue tests were performed with compact tension (CT) specimens of Inconel 690, Inconel 600, Inconel 718 and Type 304 stainless steel at room temperature. Fatigue test on Inconel 600 was performed to be used as a reference data of Inconel 690. Inconel 718 specimen, which has very high yield strength, was selected to simulate different plasticity at the crack tip in comparison with 304 stainless steel. The effect of specimen thickness on fatigue crack propagation was studied with 304 stainless steel of 3mm-, 6mm- and 25mm-thick specimens. Inconel 690 has been proposed as a substitute material for Inconel 600 in pressurized water reactor (PWR) steam generator tube application. This alloy was developed to improve the stress corrosion cracking resistance of Inconel 600. Now, it is known that Inconel 690 has better intergranular stress corrosion cracking (IGSCC) property than Inconel 600. But, more data of Inconel 690 about mechanical properties are needed in steam generator design. To investigate the effects of heat treatment on yield strength and fatigue crack propagation of Inconel 690, tensile tests and fatigue tests were performed on heat-treated specimen. From the test results, it is believed that chromium carbide precipitates at the grain boundaries reduce fatigue crack growth rate (FCGR) of Inconel 690 by crack tip blunting as far as the fatigue cracking is intergranular fracture mode. To investigate the effect of residual stress on fatigue crack propagation, residual stresses were introduced by induction-heat treatment. And, the distribution of residual stresses was measured with 3mm-thick 304 stainless steel by X-ray diffraction (XRD) measurement. From the tests, it was found that FCGR was increased in tensile residual stress region and decreased in compressive region. From the fatigue tests on 304 stainless steel, it was found that FCGR of thick specimen was faster

  2. Creep crack growth behavior of several structural alloys

    Science.gov (United States)

    Sadananda, K.; Shahinian, P.

    1983-07-01

    Creep crack growth behavior of several high temperature alloys, Inconel 600, Inconel 625, Inconel X-750, Hastelloy X, Nimonic PE-16, Incoloy 800, and Haynes 25 (HS-25) was examined at 540, 650, 760, and 870 °C. Crack growth rates were analyzed in terms of both linear elastic stress intensity factor and J*-integral parameter. Among the alloys Inconel 600 and Hastelloy X did not show any observable crack growth. Instead, they deformed at a rapid rate resulting in severe blunting of the crack tip. The other alloys, Inconel 625, Inconel X-750, Incoloy 800, HS-25, and PE-16 showed crack growth at one or two temperatures and deformed continuously at other temperatures. Crack growth rates of the above alloys in terms ofJ* parameter were compared with the growth rates of other alloys published in the literature. Alloys such as Inconel X-750, Alloy 718, and IN-100 show very high growth rates as a result of their sensitivity to an air environment. Based on detailed fracture surface analysis, it is proposed that creep crack growth occurs by the nucleation and growth of wedge-type cracks at triple point junctions due to grain boundary sliding or by the formation and growth of cavities at the boundaries. Crack growth in the above alloys occurs only in some critical range of strain rates or temperatures. Since the service conditions for these alloys usually fall within this critical range, knowledge and understanding of creep crack growth behavior of the structural alloys are important.

  3. Microstructural and Mechanical Evaluation of a Cu-Based Active Braze Alloy to Join Silicon Nitride Ceramics

    Science.gov (United States)

    Singh, M.; Asthana, Rajiv; Varela, F. M.; Martinez-Fernandez, J.

    2010-01-01

    Self-joining of St. Gobain Si3N4 (NT-154) using a ductile Cu-Al-Si-Ti active braze (Cu-ABA) was demonstrated. A reaction zone approx.2.5-3.5 microns thick) developed at the interface after 30 min brazing at 1317 K. The interface was enriched in Ti and Si. The room temperature compressive shear strengths of Si3N4/Si3N4 and Inconel/Inconel joints (the latter created to access baseline data for use with the proposed Si3N4/Inconel joints) were 140+/-49MPa and 207+/-12MPa, respectively. High-temperature shear tests were performed at 1023K and 1073 K, and the strength of the Si3N4/Si3N4 and Inconel/Inconel joints were determined. The joints were metallurgically well-bonded for temperatures above 2/3 of the braze solidus. Scanning and transmission electron microscopy studies revealed a fine grain microstructure in the reaction layer, and large grains in the inner part of the joint with interfaces being crack-free. The observed formation of Ti5Si3 and AlN at the joint interface during brazing is discussed.

  4. System studies of compact ignition tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Galambos, J.D.; Blackfield, D.T.; Peng, Y.K.M.; Reid, R.L.; Strickler, D.J.; Selcow, E.

    1987-08-01

    The new Tokamak Systems Code, used to investigate Compact Ignition Tokamaks (CITs), can simultaneously vary many parameters, satisfy many constraints, and minimize or maximize a figure of merit. It is useful in comparing different CIT design configurations over wide regions of parameter space and determining a desired design point for more detailed physics and engineering analysis, as well as for performing sensitivity studies for physics or engineering issues. Operational windows in major radius (R) and toroidal field (B) space for fixed ignition margin are calculated for the Ignifed and Inconel candidate CITs. The minimum R bounds are predominantly physics limited, and the maximum R portions of the windows are engineering limited. For a modified Kaye-Goldston plasma-energy-confinement scaling, the minimum size is 1.15 m for the Ignifed device and 1.25 m for the Inconel device. With the Ignition Technical Oversight Committee (ITOC) physics guidance of B/sup 2/a/q and I/sub p/ >10 MA, the Ignifed and Base-line Inconel devices have a minimum size of 1.2 and 1.25 m and a toroidal field of 11 and 10.4 T, respectively. Sensitivity studies show Ignifed to be more sensitive to coil temperature changes than the Inconel device, whereas the Inconel device is more sensitive to stress perturbations.

  5. Maintenance technologies for SCC of PWR

    International Nuclear Information System (INIS)

    The recent technologies of test, relaxation of deterioration, repairing and change of materials are explained for safe and stable operation of pressurized water reactor (PWR). Stress corrosion cracking (SCC) is originated by three factors such as materials, stress and environment. The eddy current test (ECT) method for the stream generator pipe and the ultrasonic test method for welding part of pipe were developed as the test technologies. Primary water stress corrosion cracking (PWSCC) of Inconel 600 in the welding part is explained. The shot peening of instrument in the gas, the water jet peening of it in water, and laser irradiation on the surface are illustrated as some examples of improvement technology of stress. The cladding of Inconel 690 on Inconel 600 is carried out under the condition of environmental cut. Total or some parts of the upper part of reactor, stream generator and structure in the reactor are changed by the improvement technologies. Changing Inconel 600 joint in the exit pipe of reactor with Inconel 690 is illustrated. (S.Y.)

  6. The effect of dissolved zinc on the transport of corrosion products in PWRs

    International Nuclear Information System (INIS)

    This report describes an experimental program designed to evaluate the effects of dissolved zinc in the μg/kg-1 range in PWR coolant on activity transport. The program consisted of two phases. The first measured corrosion product releases from Inconel-600 with and without zinc in the coolant, and monitored the corresponding growth of oxide films. The second measured the pick-up of Co-60 by type 304 stainless steel and Inconel-600 with and without zinc in the coolant, and again monitored the corresponding growth of oxide films. Zinc in the range 10--40 μg/kg-1 lowered Co-60 pick-up by both materials by factors of 8--10, and generally led to thinner oxide films. A result showing that zinc led to a thicker film on Inconel, and a result that it had no significant effect on corrosion release from Inconel, were deemed to be anomalous. The mechanisms by which Co-60 pick-up was reduced by zinc were the inhibition of the growth of oxide films and the reduced incorporation of cobalt within the growing oxide. The latter dominated on stainless steel, and both were important on Inconel. A mathematical model of activation by Co-60 was adapted to the conditions of the experiment, and fitted to the data for stainless steel. Good fits to the data were obtained when logarithmic kinetics for film growth were assumed. 18 refs., 31 figs., 10 tabs

  7. Creep-rupture behaviour of four high temperature alloy weldments at 850 and 950 deg C

    International Nuclear Information System (INIS)

    Creep tests were conducted on weldments made with Hastelloy X (matching filler), Nimonic 86 (Inconel 112 filler), Inconel 617 (Inconel 112 filler) and Alloy 800H (Thermanit 21/33 filler) at 850 and 950 deg C in air and in controlled impurity helium. Plain and notched samples were used, the notch being in the weld metal. At 850 deg C, the welds achieved rupture strengths close to those expected for the parent materials. At 950 deg C, however, shortfalls in expected strength were found for the Hastelloy X and Inconel 617 welds. In Hastelloy X, welding reduced the rupture strength of the parent material but in the Inconel 617 weld, failure reflected inadequate strength of the filler. Various failure types were noted but failure often occurred near a structural or strength transition. In particular, a heat affected zone type of failure was promoted by a combination of strong filler and weaker parent. Notched samples achieved or exceeded rupture lives of their companion plain samples. Environmental effects were small, producing no consistent effect on rupture life although oxidation rates and surface crack nucleation were greater in air. Oxidation resistance of Thermanit 21/33 in air at 950 deg C was poor. (author)

  8. System studies of compact ignition tokamaks

    International Nuclear Information System (INIS)

    The new Tokamak Systems Code, used to investigate Compact Ignition Tokamaks (CITs), can simultaneously vary many parameters, satisfy many constraints, and minimize or maximize a figure of merit. It is useful in comparing different CIT design configurations over wide regions of parameter space and determining a desired design point for more detailed physics and engineering analysis, as well as for performing sensitivity studies for physics or engineering issues. Operational windows in major radius (R) and toroidal field (B) space for fixed ignition margin are calculated for the Ignifed and Inconel candidate CITs. The minimum R bounds are predominantly physics limited, and the maximum R portions of the windows are engineering limited. For a modified Kaye-Goldston plasma-energy-confinement scaling, the minimum size is 1.15 m for the Ignifed device and 1.25 m for the Inconel device. With the Ignition Technical Oversight Committee (ITOC) physics guidance of B2a/q and I/sub p/ >10 MA, the Ignifed and Base-line Inconel devices have a minimum size of 1.2 and 1.25 m and a toroidal field of 11 and 10.4 T, respectively. Sensitivity studies show Ignifed to be more sensitive to coil temperature changes than the Inconel device, whereas the Inconel device is more sensitive to stress perturbations

  9. Inspection of tubing defects with ultrasonic guided waves

    International Nuclear Information System (INIS)

    The purpose of this study is to show the utility of ultrasonic guided waves in 439 stainless steel heat exchanger and Inconel steam generator tubing inspection. Phase velocity and group velocity dispersion curves for the longitudinal and flexural modes of a sample Inconel steam generator tube were presented. In experimental studies, ultrasonic guided wave applications were demonstrated for man made flaws. For the detection of EDM wears under a tube support plate in the heater exchanger tubing, a bore probe generated axisymmetric longitudinal guided wave modes in the tubing. For the detection and sizing of circumferential Laser notches in Inconel steam generator tubes, a variable angle beam transducer set up was used. Excellent detection results were demonstrated for EDM wears and Laser Notches with various modes and L(0,1) modes, respectively. Circumferential sizing of Laser notches was achieved with L(0,1) mode at 3.5 MHz.

  10. "Flat-Fish" Vacuum Chamber

    CERN Multimedia

    1978-01-01

    The picture shows a "Flat-Fish" vacuum chamber being prepared in the ISR workshop for testing prior to installation in the Split Field Magnet (SFM) at intersection I4. The two shells of each part were hydroformed from 0.15 mm thick inconel 718 sheet (with end parts in inconel 600 for easier manual welding to the arms) and welded toghether with two strips which were attached by means of thin stainless steel sheets to the Split Field Magnet poles in order to take the vertical component of the atmospheric pressure force. This was the thinnest vacuum chamber ever made for the ISR. Inconel material was chosen for its high elastic modulus and strenght at chamber bake-out temperature. In this picture the thin sheets transferring the vertical component of the atmosferic pressure force are attached to a support frame for testing. See also 7712182, 7712179.

  11. Second generation "Flat-Fish" vacuum chamber for an ISR intersection

    CERN Multimedia

    1977-01-01

    The picture shows the part of the "Flat-Fish" chamber covering one side of the beam intersection region. The other side is covered by an equal part and both are welded toghether at their small end. The two shells of each part were hydroformed from 0.15 mm thick inconel 718 sheet (with end parts in inconel 600 for easier manual welding to the arms) and welded toghether with two strips which were attached by means of stainless steel strings to the Split Field Magnet poles in order to take the atmospheric pressure forces. This was the thinnest vacuum chamber made for the ISR. Inconel material was chosen for its high elastic modulus and strenght at chamber bake-out temperature.

  12. Effect of Surface Precipitate on the Crevice Corrosion in HYBRID and Oxalic Acid Solution

    International Nuclear Information System (INIS)

    In this study, we investigated the characteristics of the crevice corrosion for Inconel-600 and 304SS in OA solution according to the change in pH. The evaluation of the crevice corrosion with the chemical thermodynamic analysis identified the effect of the residual chemicals such as iron-oxalate and nickeloxalate to the crevice corrosion behavior. Test results were compared with those of HYBRID (HYdrizine Base Reductive metal Ion Decontamination). The crevice corrosion properties of 304 SS and Inconel-600 in HYBRID and oxalic acid solution were evaluated. In case of oxalic acid solution, the corrosion rate on 304SS was rapidly increased with a pH decrease of around 2, but there was no increase in the corrosion rate on Inconel-600

  13. Evaluation on mechanical and corrosion properties of steam generator tubing materials

    International Nuclear Information System (INIS)

    Steam generator is one of the major components of nuclear reactor pressure boundary. It's main function os transferring heat which generated in the reactor to turbine generator through steam generator tube. In these days, steam generator tubing materials of operating plant are used Inconel 600 alloys. But according to the operation time, there are many degradation phenomena which included mechanical damage due to flow induced vibration and corrosion damage due to PWSCC, IGA/SCC and pitting etc. Recently Inconel 690 alloys are selected as new and replacement steam generator tubes for domestic nuclear power plant. But there are few study about mechanical and corrosion properties of Inconel 600 and 690. The objectives of this study is to evaluate and compare mechanical and corrosion propertied of steam generator tube materials

  14. Effect of Surface Precipitate on the Crevice Corrosion in HYBRID and Oxalic Acid Solution

    Energy Technology Data Exchange (ETDEWEB)

    Park, S. Y.; Jung, J. Y.; Won, H. J.; Kim, S. B.; Choi, W. K.; Moon, J. K. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Park, S. J. [Chungnam National Univ., Daejeon (Korea, Republic of)

    2015-05-15

    In this study, we investigated the characteristics of the crevice corrosion for Inconel-600 and 304SS in OA solution according to the change in pH. The evaluation of the crevice corrosion with the chemical thermodynamic analysis identified the effect of the residual chemicals such as iron-oxalate and nickeloxalate to the crevice corrosion behavior. Test results were compared with those of HYBRID (HYdrizine Base Reductive metal Ion Decontamination). The crevice corrosion properties of 304 SS and Inconel-600 in HYBRID and oxalic acid solution were evaluated. In case of oxalic acid solution, the corrosion rate on 304SS was rapidly increased with a pH decrease of around 2, but there was no increase in the corrosion rate on Inconel-600.

  15. Detector response in a CANDU low void reactivity core

    International Nuclear Information System (INIS)

    The response of the in-core flux detectors to the CANFLEX Low-Void-Reactivity Fuel (LVRF) [1] bundles for use in the CANDU reactor at Bruce nuclear generation station has been studied. The study was based on 2 detector types - platinum (Pt)-clad Inconel and pure Inconel detectors, and 2 fuel types - LVRF bundles and natural-uranium (NU) bundles. Both detectors show a decrease of thermal-neutron-flux to total-photon-flux ratio when NU fuel bundles are replaced by LVRF bundles in the reactor core (7% for Inconel and 9% for Pt-clad detectors). The ratio of the prompt component of the net electron current to the total net electron current (PFe) of the detectors however shows a different response. The use of LVRF bundles in place of NU fuel bundles in the reactor core did not change the PFe of the Pt-clad Inconel detector but increased the PFe of the pure Inconel detector by less than 2%. The study shows that the Inconel detector has a larger prompt-detector response than that of the platinum-clad detector; it reacts to the change of fluxes in the reactor core more readily. On the other hand, the Pt-clad detector is less sensitive to perturbations of the neutron-to-gamma ratio. Nevertheless the changes in an absolute sense are minimal; one does not anticipate a change of the flux-monitoring system if the NU fuel bundles are replaced with the CANFLEX LVRF bundles in the core of the Bruce nuclear generating station. (authors)

  16. Sonic Infrared (IR) Imaging and Fluorescent Penetrant Inspection Probability of Detection (POD) Comparison

    International Nuclear Information System (INIS)

    Sandia National Laboratories Airworthiness Assurance Nondestructive Inspection Validation Center (AANC) implemented two crack probability of detection (POD) experiments to compare in a quantitative manner the ability of Sonic Infrared (IR) Imaging and fluorescent penetrant inspection (FPI) to reliably detect cracks. Blind Sonic IR and FPI inspections were performed on titanium and Inconel registered specimens having statistically relevant flaw profiles. Inspector hit/miss data was collected and POD curves for each technique were generated and compared. In addition, the crack lengths for a number of titanium and Inconel registered reference standards were measured before and after repeated Sonic IR inspections to determine if crack growth occurred

  17. Evaluation of candidate Stirling engine heater tube alloys after 3500 hours exposure to high pressure doped hydrogen or helium. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Misencik, J.A.; Titran, R.H.

    1984-10-01

    Sixteen commercial tubing alloys were endurance tested at 820/sup 0/ C, 15 MPa in a diesel-fuel fired Stirling engine simulator materials test rig: iron-base N-155, A-286, Incoloy 800, 19-9DL, CG-27, W-545, 12RN72, 253MA, Sanicro 31H and Sanicro 32; nickel-base Inconel 601, Inconel 625, Inconel 718, Inconel 750 and Pyromet 901; and cobalt-base HS-188. The iron-nickel alloys CG-27 and Pyromet 901 exhibited superior oxidation/corrosion resistance to the diesel-fuel combustion products and surpassed the design criterias' 3500 h creep-rupture endurance life. Three other alloys, Inconel 625, W-545, and 12RN72, had creep-rupture failures after 2856, 2777, and 1598 h, respectively. Hydrogen permeability coefficients determined after 250 h of rig exposure show that Pyromet 901 had the lowest Phi value, 0.064x10/sup -6/ cm/sup 2//s MPa/sup 1///sup 2/. The next five hairpin tubes, CG-27, Inconel 601, Inconel 718(wd), Inconel 750, and 12RN72(cw) all had Phi values below 0.2x10/sup -6/ more than a decade lower than the design criteria. Based upon its measured high strength and low hydrogen permeation, CG-27 was selected for 3500 h endurance testing at 21 MPa gas pressure and 820/sup 0/C. Results of the high pressure, 21 MPa, CG-27 endurance test demonstrated that the 1.0 vol % C0/sub 2/ dopant is an effective deterrent to hydrogen permeation. The 21 MPa hydrogen gas pressure apparent permeability coefficient at 820/sup 0/C approached 0.1x10/sup -6/ cm/sup 2/sec MPa/sup 1///sup 2/ after 500 hr, the same as the 15 MPa test. Even at this higher gas pressure and comparable permeation rate, CG-27 passed the 3500 hr endurance test without creep-rupture failures. It is concluded that the CG-27 alloy, in the form of thin wall tubing is suitable for Stirling engine applications at 820/sup 0/C and gas pressures up to 21 MPa.

  18. Examples of expert methodology. B : met cases in nuclear power plants

    International Nuclear Information System (INIS)

    In spite of especially severe quality controls of materials, stress corrosion is the most important problem met during PWR type reactors operating. Examples of corrosion (except stress corrosion) are presented. Intergranular corrosion is illustrated by stainless steel 18-10 family (fuels assemblies, heat exchanger of a breeder reactor) and by Inconel 600 (vapor generator J tubes), electrochemical corrosion by low alloy Mn-Ni-Mo steel coated with an austenitic steel (pressure vessel pipes), pitting corrosion by Inconel 600 (vapor generator) and by stainless steel 304L (raw water circuits), erosion/corrosion by carbon steels (PWR secondary circuits). (A.B.). 13 refs., 9 figs

  19. Influence of hydrogen oxidation kinetics on hydrogen environment embrittlement

    Science.gov (United States)

    Walter, R. J.; Kendig, M. W.; Meisels, A. P.

    1992-01-01

    Results are presented from experiments performed to determine the roles of hydrogen absorption and hydrogen electron transfer on the susceptibility of Fe- and Ni-base alloys to ambient-temperature hydroen embrittlement. An apparent independence is noted between hydrogen environment embrittlement and internal hydrogen embrittlement. The experiments were performed on Inconel 718, Incoloy 903, and A286. The electrochemical results obtained indicate that Inconel 718 either adsorbs hydrogen more rapidly and/or the electrochemical oxidation of the adsorbed hydrogen occurred more rapidly than in the other two materials.

  20. Hydrogen gas embrittlement and the disc pressure test

    Science.gov (United States)

    Bachelet, E. J.; Troiano, A. R.

    1973-01-01

    A disc pressure test has been used to study the influenced of a hydrogen gas environment on the mechanical properties of three high strength superalloys, Inconel 718, L-605 and A-286, in static and dynamic conditions. The influence of the hydrogen pressure, loading rate, temperature, mechanical and thermal fatigue has investigated. The permeation characteristics of Inconel 718 have been determined in collaboration with the French AEC. The results complemented by a fractographic study are consistent either with a stress-sorption or with an internal embrittlement type of mechanism.