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Sample records for caustic stress corrosion

  1. Caustic stress corrosion cracking

    International Nuclear Information System (INIS)

    Liquid Metal Fast Breeder Reactors (LMFBRs) use sodium as a coolant for transfer of heat from the core to the steam generators. Maintenance and examination of the system require removal of sodium from components of the system. One process for removal reacts the sodium with water vapor and removes the residual sodium hydroxide from the components by rinsing with liquid water. This process exposes components such as pumps, heat exchangers, valves, and fuel-handling machines to contact with aqueous NaOH solutions in various concentrations over a range of temperatures and times. Since stress can be present in these components, as generated by fabrication, structural loads, deformation in service, and possible wedging action by corrosion products, conditions are potentially available for the mechanism of caustic stress corrosion cracking (CSCC). Since LMFBR components are fabricated from Types 304 and 316 stainless steels which have been found to be susceptible to CSCC, it was therefore considered necessary to establish the threshold of CSCC so that the components could be processed under conditions avoiding CSCC. The materials used in the testing program included heats of Types 304 and 316 stainless steel, Inconel 600 and 718, hardfacing deposits of Stellite 6 and 156, and three special wear-resistant, carbide-type materials. The analysis of these materials is tabulated

  2. Caustic stress corrosion cracking of austenitic stainless steels with thermal treatment(TT)

    International Nuclear Information System (INIS)

    This paper dealt with the effects of TT(Thermal Treatment) and nitrogen content on caustic stress corrosion cracking of austenitic stainless steels. Nitrogen content and grain size had affected on the caustic SCC resistance. Increasing nitrogen content, SCC resistance was increased due to the enhanced repassivation rate, but at high nitrogen content, the resistance was decreased because of the dual effects between mechanical and repassivation behavior. Regardless of nitrogen content, TT improved the caustic SCC resistance and this behavior was reviewed on the points of residual stress, grain size, and dislocation array

  3. Effect of Heat Treatment on Corrosion and Stress Corrosion Cracking of S32205 Duplex Stainless Steel in Caustic Solution

    Science.gov (United States)

    Bhattacharya, Ananya; Singh, Preet M.

    2009-06-01

    Duplex stainless steels (DSSs) have generally performed very well in caustic environments. However, some corrosion and stress corrosion cracking (SCC) of DSSs have been reported in different pulp mill environments employing caustic solutions. Studies have shown that the corrosion and SCC susceptibility of DSSs depend on the alloy composition and microstructure of the steel. In this study, the effect of a sulfide-containing caustic environment (pulping liquor) and material properties (DSS alloy composition and microstructure) on the corrosion and SCC of DSSs was evaluated. During metal fabrication processes, localized areas of DSSs may be exposed to different temperatures and cooling rates, which may lead to changes in the microstructure in these regions. This change in microstructure, in turn, may affect the general and localized corrosion or SCC susceptibility of the affected area as compared to the rest of the metal. Hence, the effect of different annealing and aging temperatures as well as cooling rates on the microstructure and corrosion behavior of S32205 DSSs in caustic environment was evaluated. The results showed that changes in the microstructure of S32205 DSSs due to selected heat treatments did not have a significant effect on the general corrosion susceptibility of the steel in caustic environment, but its SCC susceptibility varied with changes in microstructures.

  4. Effect of caustic environment on intergranular attack and stress corrosion cracking of alloy 600

    International Nuclear Information System (INIS)

    Intergranular corrosion of alloy 600 tubes in PWR steam generators has been a continuing mode of degradation at many sites. The Steam Generator Owners Group has funded a program addressing the intergranular corrosion of commercial tubing materials for the past 6 years. In April 1987, the Mechanistic and Environmental Effects Program was reviewed at a contractors' workshop. Intergranular corrosion (IGC) of alloy 600 can occur in caustic, acid and neutral waters. This paper summarizes the work of EPRI contractors on caustic IGC and integrates different viewpoints and experimental techniques. The paper explores the postulated mechanisms of corrosion including: segregation of alloy impurities, formation of nickel sulfide, dealloying at grain boundaries, and the role of chromium oxide. The paper also focuses on the role of environment, microstructure, electrochemical potential and stress on the incidence and rate of intergranular corrosion

  5. Inhibition of caustic induced stress corrosion cracking of Alloy 600 by inhibitors

    International Nuclear Information System (INIS)

    The effect of inhibitors on the electrochemical behavior and the stress corrosion cracking resistance of Alloy 600 was evaluated in 10% sodium hydroxide solution at 315.deg.C. The C-ring specimens for stress corrosion cracking test were polarized at 150 mV above the corrosion potential for 120 hours with and without inhibitors such as titanium oxide, titanium boride and cerium boride. The chemical compositions of the films formed on the crack tip in the C-ring specimens were analyzed using scanning Auger electron spectroscopy. The cerium boride, the most effective inhibitor, was observed to decrease the crack propagation rate by more than a factor of three compared with that obtained in a no inhibitor solution. It was found that the changes of the active-passive transition potentials and the film compositions were related to the resistance to stress corrosion cracking in high temperature caustic solutions

  6. 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

  7. Cyclic stress effect on stress corrosion cracking of duplex stainless steel in chloride and caustic solutions

    Science.gov (United States)

    Yang, Di

    Duplex stainless steel (DSS) is a dual-phase material with approximately equal volume amount of austenite and ferrite. It has both great mechanical properties (good ductility and high tensile/fatigue strength) and excellent corrosion resistance due to the mixture of the two phases. Cyclic loadings with high stress level and low frequency are experienced by many structures. However, the existing study on corrosion fatigue (CF) study of various metallic materials has mainly concentrated on relatively high frequency range. No systematic study has been done to understand the ultra-low frequency (˜10-5 Hz) cyclic loading effect on stress corrosion cracking (SCC) of DSSs. In this study, the ultra-low frequency cyclic loading effect on SCC of DSS 2205 was studied in acidified sodium chloride and caustic white liquor (WL) solutions. The research work focused on the environmental effect on SCC of DSS 2205, the cyclic stress effect on strain accumulation behavior of DSS 2205, and the combined environmental and cyclic stress effect on the stress corrosion crack initiation of DSS 2205 in the above environments. Potentiodynamic polarization tests were performed to investigate the electrochemical behavior of DSS 2205 in acidic NaCl solution. Series of slow strain rate tests (SSRTs) at different applied potential values were conducted to reveal the optimum applied potential value for SCC to happen. Room temperature static and cyclic creep tests were performed in air to illustrate the strain accumulation effect of cyclic stresses. Test results showed that cyclic loading could enhance strain accumulation in DSS 2205 compared to static loading. Moreover, the strain accumulation behavior of DSS 2205 was found to be controlled by the two phases of DSS 2205 with different crystal structures. The B.C.C. ferrite phase enhanced strain accumulation due to extensive cross-slips of the dislocations, whereas the F.C.C. austenite phase resisted strain accumulation due to cyclic strain

  8. Stress corrosion cracking behaviour of alloys 600 and 690 in water and caustic solutions

    International Nuclear Information System (INIS)

    For many industries, corrosion damages and particularly those due to Stress Corrosion Cracking (SCC) remain one of the most difficult problems to fight as well as to understand for the researcher. The Nuclear Energy Industry is no exception to that rule and the Commissariat a l'Energie Atomique has been studying the stress corrosion cracking phenomenon of nuclear alloys for more than 30 years, phenomenon which is still the subject of a great number of studies among the Nuclear Industrialists. The aim of the following paper is to briefly summarize some results obtained in a study of the SCC behaviour of Alloys 600 and 690 in mediums such as primary water and caustic solution (simulating local conditions of the secondary side) involving, in the case of the Constant Elongation Rate Tests in primary medium, the influence of the temperature, surface state, thermal treatment and strain rate

  9. 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)

  10. Electrochemical studies on stress corrosion cracking of incoloy-800 in caustic solution. Part II: Precracking samples

    Directory of Open Access Journals (Sweden)

    Dinu Alice

    2006-01-01

    Full Text Available Stress corrosion cracking (SCC in a caustic medium may affect the secondary circuit tubing of a CANDU NPP cooled with river water, due to an accidental formation of a concentrated alkaline environment in the areas with restricted circulation, as a result of a leakage of cooling water from the condenser. To evaluate the susceptibility of Incoloy-800 (used to manufacture steam generator tubes for CANDU NPP to SCC, some accelerated corrosion tests were conducted in an alkaline solution (10% NaOH, pH = 13. These experiments were performed at ambient temperature and 85 °C. We used the potentiodynamic method and the potentiostatic method, simultaneously monitoring the variation of the open circuit potential during a time period (E corr/time curve. The C-ring method was used to stress the samples. In order to create stress concentrations, mechanical precracks with a depth of 100 or 250 μm were made on the outer side of the C-rings. Experimental results showed that the stressed samples were more susceptible to SCC than the unstressed samples whereas the increase in temperature and crack depth lead to an increase in SCC susceptibility. Incipient micro cracks of a depth of 30 μm were detected in the area of the highest peak of the mechanical precrack.

  11. Effects of Pb on the Stress Corrosion Cracking of Alloy 600 in Weak Caustic Water

    International Nuclear Information System (INIS)

    The effects of lead on the stress corrosion cracking of Alloy 600 were investigated in weak caustic water at high temperature by Slow Strain Rate Test (SSRT). The extent and morphology of cracking were analyzed by Scanning Electron Microscope (SEM). The chemical compositions on the fracture surface were analyzed by Wavelength Dispersive X-ray spectroscopy (WDX). Alloy 600 was cracked severely under the condition of 100 ppm Pb, 1 x 10-7sec-1. PbO acted as a role of oxidizer on the surface of Alloy 600, and IGA and SCC occurred at a low concentration of PbO, while SCC only occurred at a high concentration of PbO. The strain rate is a critical factor in this SCC test, no SCC occurred in the solution containing 1000 ppm Pb at strain rates of 5x10-7 and 1 x 10-6sec-1. The transgranular stress corrosion cracking of Alloy 600 in lead doped water may be closely associated with the carbide morphology at a grain boundary, the lead concentration and the strain rate. And the transgranular cracking mechanism of Alloy 600 was interpreted on the base of the anodic dissolution followed by active slip step dissolution

  12. Influence of microstructure on stress corrosion cracking of mild steel in synthetic caustic-nitrate nuclear waste solution

    International Nuclear Information System (INIS)

    The influence of alloy microstructure on stress corrosion cracking of mild steel in caustic-nitrate synthetic nuclear waste solutions was studied. An evaluation was made of the effect of heat treatment on a representative material (ASTM A 516 Grade 70) used in the construction of high activity radioactive waste storage tanks at Savannah River Plant. Several different microstructures were tested for susceptibility to stress corrosion cracking. Precracked fracture specimens loaded in either constant load or constant crack opening displacement were exposed to a variety of caustic-nitrate and nitrate solutions. Results were correlated with the mechanical and corrosion properties of the microstructures. Crack velocity and crack arrest stress intensity were found to be related to the yield strength of the steel microstructures. Fractographic evidence indicated pH depletion and corrosive crack tip chemistry conditions even in highly caustic solutions. Experimental results were compatible with crack growth by a strain-assisted anodic dissolution mechanism; however, hydrogen embrittlement also was considered possible

  13. POTENTIAL FOR STRESS CORROSION CRACKING OF A537 CARBON STEEL NUCLEAR WASTE TANKS CONTAINING HIGHLY CAUSTIC SOLUTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Lam, P.; Stripling, C.; Fisher, D.; Elder, J.

    2010-04-26

    The evaporator recycle streams of nuclear waste tanks may contain waste in a chemistry and temperature regime that exceeds the current corrosion control program, which imposes temperature limits to mitigate caustic stress corrosion cracking (CSCC). A review of the recent service history found that two of these A537 carbon steel tanks were operated in highly concentrated hydroxide solution at high temperature. Visual inspections, experimental testing, and a review of the tank service history have shown that CSCC has occurred in uncooled/un-stress relieved tanks of similar construction. Therefore, it appears that the efficacy of stress relief of welding residual stress is the primary corrosion-limiting mechanism. The objective of this experimental program is to test A537 carbon steel small scale welded U-bend specimens and large welded plates (30.48 x 30.38 x 2.54 cm) in a caustic solution with upper bound chemistry (12 M hydroxide and 1 M each of nitrate, nitrite, and aluminate) and temperature (125 C). These conditions simulate worst-case situations in these nuclear waste tanks. Both as-welded and stress-relieved specimens have been tested. No evidence of stress corrosion cracking was found in the U-bend specimens after 21 days of testing. The large plate test was completed after 12 weeks of immersion in a similar solution at 125 C except that the aluminate concentration was reduced to 0.3 M. Visual inspection of the plate revealed that stress corrosion cracking had not initiated from the machined crack tips in the weld or in the heat affected zone. NDE ultrasonic testing also confirmed subsurface cracking did not occur. Based on these results, it can be concluded that the environmental condition of these tests was unable to develop stress corrosion cracking within the test periods for the small welded U-bends and for the large plates, which were welded with an identical procedure as used in the construction of the actual nuclear waste tanks in the 1960s. The

  14. INVESTIGATION OF THE POTENTIAL FOR CAUSTIC STRESS CORROSION CRACKING OF A537 CARBON STEEL NUCLEAR WASTE TANKS

    Energy Technology Data Exchange (ETDEWEB)

    Lam, P.

    2009-10-15

    The evaporator recycle streams contain waste in a chemistry and temperature regime that may be outside of the current waste tank corrosion control program, which imposes temperature limits to mitigate caustic stress corrosion cracking (CSCC). A review of the recent service history (1998-2008) of Tanks 30 and 32 showed that these tanks were operated in highly concentrated hydroxide solution at high temperature. Visual inspections, experimental testing, and a review of the tank service history have shown that CSCC has occurred in uncooled/un-stress relieved F-Area tanks. Therefore, for the Type III/IIIA waste tanks the efficacy of the stress relief of welding residual stress is the only corrosion-limiting mechanism. The objective of this experimental program is to test carbon steel small scale welded U-bend specimens and large welded plates (12 x 12 x 1 in.) in a caustic solution with upper bound chemistry (12 M hydroxide and 1 M each of nitrate, nitrite, and aluminate) and temperature (125 C). These conditions simulate worst-case situations in Tanks 30 and 32. Both as-welded and stress-relieved specimens have been tested. No evidence of stress corrosion cracking was found in the U-bend specimens after 21 days of testing. The large plate test is currently in progress, but no cracking has been observed after 9 weeks of immersion. Based on the preliminary results, it appears that the environmental conditions of the tests are unable to develop stress corrosion cracking within the duration of these tests.

  15. Electro chemical studies on stress corrosion cracking of Incoloy-800 in caustic solution, part I: As received samples

    Directory of Open Access Journals (Sweden)

    Dinu Alice

    2005-01-01

    Full Text Available Many non-volatile impurities accidentally introduced into the steam generator tend to Concentrate on its surface in restricted flow areas. In this way these impurities can lead to stress corrosion cracking (SCC on stressed tubes of the steam generator. Such impurities can be strong alkaline or acid solutions. To evaluate the effect of alkaline concentrated environments on SCC of steam generator tubes, the tests were con ducted on stressed samples of Incoloy-800 in 10% NaOH solution. To accelerate the SCC process, stressed specimens were anodically polarised in a caustic solution in an electro chemical cell. The method of stressing of Incoloy-800 tubes used in our experiments was the C-ring. Using the cathodic zone of the potentiodynamic curves it was possible to calculate the most important electrochemical parameters: the corrosion current, the corrosion rate, and the polarization resistance. We found that the value of the corrosion potential to initiate the SCC microcracks was -100 mV. The tested samples were examined using the metallographic method. The main experimental results showed that the in crease of the stress state promoted the in crease of the SCC susceptibility of Incoloy-800 samples tested under the same conditions, and that the length of the SCC-type microcracks in creased with the growth of the stress value.

  16. Electrochemical studies on stress corrosion cracking of Incoloy-800 in caustic solution Part I: As received samples

    International Nuclear Information System (INIS)

    Many non-volatile impurities accidentally introduced into the steam generator tend to concentrate on its surface in restricted flow areas. In this way these impurities can lead to stress corrosion cracking (SCC) on stressed tubes of the steam generator. Such impurities can be strong alkaline or acid solutions. To evaluate the effect of alkaline concentrated environments on SCC of steam generator tubes, the tests were conducted on stressed samples of Incoloy-800 in 10% NaOH solution. To accelerate the SCC process, stressed specimens were anodically polarised in a caustic solution in an electrochemical cell. The method of stressing of Incoloy-800 tubes used in our experiments was the C-ring. Using the cathodic zone of the potentiodynamic curves it was possible to calculate the most important electrochemical parameters: the corrosion current, the corrosion rate, and the polarisation resistance. We found that the value of the corrosion potential to initiate the SCC microcracks was -100 mV. The tested samples were examined using the metallographic method. The main experimental results showed that the increase of the stress state promoted the increase of the SCC susceptibility of Incoloy-800 samples tested under the same conditions, and that the length of the SCC-type microcracks increased with the growth of the stress value. (author)

  17. Stress corrosion cracking behavior of two Ni-Cr-Mo-V steels in caustic solutions and pure oxygenated water

    Energy Technology Data Exchange (ETDEWEB)

    Maday, M.F.; Mignone, A.; Borello, A. (ENEA, Rome (Italy))

    1989-04-01

    The purpose of this work is to evaluate the stress corrosion cracking (SCC) of two Ni-Cr-Mo-V Italian-made alloys that are materials used for low-pressure (LP) turbine discs in light water reactor (LWR) nuclear plants. All the tests reported in this investigation have been performed using the slow strain rate technique (SSRT). The first set of experiments was conducted in pure deaerated caustic solutions in a static Ni autoclave system in order to determine the effects of temperature on NaOH concentration on the SCC behavior of these materials. In the second set of tests, the influence of dissolved oxygen on cracking in water was studied. Results showed that the minimum value of oxygen to promote SCC was lower for the heat with the higher Ni content and the larger grain size.

  18. Stress corrosion cracking behavior of two Ni-Cr-Mo-V steels in caustic solutions and pure oxygenated water

    International Nuclear Information System (INIS)

    The purpose of this work is to evaluate the stress corrosion cracking (SCC) of two Ni-Cr-Mo-V Italian-made alloys that are materials used for low-pressure (LP) turbine discs in light water reactor (LWR) nuclear plants. All the tests reported in this investigation have been performed using the slow strain rate technique (SSRT). The first set of experiments was conducted in pure deaerated caustic solutions in a static Ni autoclave system in order to determine the effects of temperature on NaOH concentration on the SCC behavior of these materials. In the second set of tests, the influence of dissolved oxygen on cracking in water was studied. Results showed that the minimum value of oxygen to promote SCC was lower for the heat with the higher Ni content and the larger grain size

  19. Stress corrosion cracking behaviour of two Ni-Cr-Mo-V steels in caustic solutions and pure oxygenated water

    Energy Technology Data Exchange (ETDEWEB)

    Maday, M.F.; Mignone, A.; Borello, A.

    1987-01-01

    The purpose of this work is to evaluate the stress corrosion cracking (SCC) behaviour of two NiCrMoV alloys of Italian production, that are materials used for low pressure (LP) turbine discs in LWR nuclear plants. All the tests reported in this investigation have been performed using the slow strain rate technique (SSRT). A first set of experiments has been conducted in pure deaerated caustic solutions in a static NI autoclave system, in order to determine the effects of temperature and NaOH concentration on the SCC behaviour of these materials. In a second set of tests, the influence of the oxygen content on cracking was studied; for this purpose, specimens were strained to fracture at 200/sup 0/C in pure water with various amounts of oxygen; a refreshed autoclave system was used to permit a continuous monitoring of the chemical parameters. Both alloys showed a decreasing SCC susceptibility as NaOH concentration and temperature decreased. The alloy with lower Ni content seemed to behave slightly better in caustic solutions and somewhat worse in pure oxygenated water.

  20. Stress corrosion cracking behaviour of two Ni-Cr-Mo-V steels in caustic solutions and pure oxygenated water

    International Nuclear Information System (INIS)

    The purpose of this work is to evaluate the stress corrosion cracking (SCC) behaviour of two NiCrMoV alloys of Italian production, that are materials used for low pressure (LP) turbine discs in LWR nuclear plants. All the tests reported in this investigation have been performed using the slow strain rate technique (SSRT). A first set of experiments has been conducted in pure deaerated caustic solutions in a static NI autoclave system, in order to determine the effects of temperature and NaOH concentration on the SCC behaviour of these materials. In a second set of tests, the influence of the oxygen content on cracking was studied; for this purpose, specimens were strained to fracture at 2000C in pure water with various amounts of oxygen; a refreshed autoclave system was used to permit a continuous monitoring of the chemical parameters. Both alloys showed a decreasing SCC susceptibility as NaOH concentration and temperature decreased. The alloy with lower Ni content seemed to behave slightly better in caustic solutions and somewhat worse in pure oxygenated water

  1. Caustic stress corrosion cracking of NiCrMoV rotor steels—The effects of impurity segregation and variation in alloy composition

    Science.gov (United States)

    Bandyopadhyay, N.; Briant, C. L.

    1983-10-01

    This paper reports a study of the effects of phosphorus, tin, and molybdenum on the caustic stress corrosion cracking susceptibility of NiCrMoV rotor steels. Constant load tests were performed on these steels in 9M NaOH at 98 ± 1 °C at a controlled potential of either -800 mVHg/Hgo or -400 mVHg/Hgo. Times to failure were measured. The results show that at a potential of -400 mVHg/Hgo the segregation of phosphorus to grain boundaries lowers the resistance of these steels to caustic stress corrosion cracking. When molybdenum is removed from a steel that has phosphorus segregated to the grain boundaries, the steel’s resistance to stress corrosion cracking is improved. High purity alloys, both with and without molybdenum, show very good resistance to caustic cracking at this potential. At-800 mVHg/Hgo segregated phophorus has no effect; only molybdenum additions lower the resistance of the steel to caustic stress corrosion cracking. Segregated tin has little effect at either potential. Metallographic examination shows that one explanation for these results is that molybdenum and phosphorus, probably as anions precipitated from solution, aid in passivating the sides of the crack and thus help keep the crack tip sharp. This sharpness will increase the speed with which the crack will propagate through the sample. Furthermore, removal of molybdenum greatly increases the number of cracks which nucleate. This higher crack density would increase the relative area of the anode to the cathode and thus act to decrease the crack growth rate.

  2. The effect of microstructural changes on the caustic stress corrosion cracking resistance of a NiCrMoV rotor steel

    Science.gov (United States)

    Bandyopadhyay, N.; Briant, C. L.; Hall, E. L.

    1985-07-01

    This paper presents a study of the effects of microstructural changes on the caustic stress corrosion cracking resistance of a NiCrMoV rotor steel. All tests were run in 9 M NaOH at 98 °C and at an electrochemical potential of -400 mVHg/Hgo. Different microstructures were obtained by tempering martensitic samples for different times at 600 °C or by using a slow controlled cool from the austenite to produce a bainitic structure. The results show that heat treatments which produced large, chromiumrich carbides are beneficial. These carbides are preferentially corroded and cause pits to form at the crack tip. We propose that these pits cause crack tip blunting and slow crack propagation. It is further shown that, although changes in microstructure can produce improvements in the susceptibility to stress corrosion cracking, these changes cannot compensate for the detrimental effects of phosphorus segregation to grain boundaries.

  3. Effect of thermal treatment on caustic stress corrosion cracking an chloride SCC of super austenitic stainless steel-S32050

    International Nuclear Information System (INIS)

    This paper focused on the caustic SCC and chloride SCC of super austenitic stainless stee S32050. Thermal treatment (550 .deg. C 15hrs) and high temperature mill annealing (HTMA, 1,250 .deg. C 5min.) did enhance the SCC resistance than mill annealed specimen. It is considered that dislocation array is the most important factor on SCC resistance among some variables such as repassivation rate, residual stress, grain size, yield strength etc. Substituted Mn didn't affec the anodic polarization behavior of Mn-modified S32050, but cold working to the alloys reduced the SCC resistance because of the embrittlement by cold working

  4. Effect of thermal treatment on caustic stress corrosion cracking an chloride SCC of super austenitic stainless steel-S32050

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S. K.; Park, Y. S. [Yonsei Univ., Seoul (Korea, Republic of); Kim, Y. S. [Andong Univ., Andong (Korea, Republic of); Ryu, W. S. [KAERI, Taejon (Korea, Republic of)

    2000-10-01

    This paper focused on the caustic SCC and chloride SCC of super austenitic stainless stee S32050. Thermal treatment (550 .deg. C 15hrs) and high temperature mill annealing (HTMA, 1,250 .deg. C 5min.) did enhance the SCC resistance than mill annealed specimen. It is considered that dislocation array is the most important factor on SCC resistance among some variables such as repassivation rate, residual stress, grain size, yield strength etc. Substituted Mn didn't affec the anodic polarization behavior of Mn-modified S32050, but cold working to the alloys reduced the SCC resistance because of the embrittlement by cold working.

  5. Stress corrosion cracking and vibration corrosion cracking

    International Nuclear Information System (INIS)

    Under certain conditions of stress practically all metallic materials are subject to such cracking corrosion processes. They are much feared because as a rule they are not recognized until the damage - leakage of a container, fracture of a component part-occurs. They may belong to the category of either stress corrosion cracking or vibration corrosion cracking, depending on the different mechanisms of the damage process. As the denominations indicate, one constitutes the interaction between local corrosion attack and mainly static tensile stress (load stress and/or non-load stress) and the other a combination of varying mechanical stress over time and corrosion. Hydrogen-induced cracking is a special form of stress corrosion cracking characterized by trapping of atomic hydrogen in material and subsequent cracking owing to the interaction with mechanical stress. (orig./HP)

  6. Superclean steel development: Stress corrosion cracking characteristics

    Energy Technology Data Exchange (ETDEWEB)

    1990-07-01

    Stress corrosion tests (SCC initiation and propagation) were carried out on a high purity version of the 3.5% NiCrMoV low pressure rotor steel in comparison to similar steels of conventional cleanness. In the constant load tests in 30% sodium hydroxide solution the clean steel showed longer times to crack initiation than the conventional steels with comparable strength levels. The amount of scatter makes it difficult to quantify the improvement, which lay at or above 5% in stress level. Neither in pure water (aerated and deaerated) nor in a concentrated caustic solution were differences in the stress corrosion crack velocities detected. Neither the clean steel nor the conventional steel tested in this programme showed any increase in SCC susceptibility after aging at 350 or 450{degree}C for 10,000 hours. 19 refs., 17 figs., 3 tabs.

  7. 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

  8. Alloy SCR-3 resistant to stress corrosion cracking

    International Nuclear Information System (INIS)

    Austenitic stainless steel is used widely because the corrosion resistance, workability and weldability are excellent, but the main fault is the occurrence of stress corrosion cracking in the environment containing chlorides. Inconel 600, most resistant to stress corrosion cracking, is not necessarily safe under some severe condition. In the heat-affected zone of SUS 304 tubes for BWRs, the cases of stress corrosion cracking have occurred. The conventional testing method of stress corrosion cracking using boiling magnesium chloride solution has been problematical because it is widely different from actual environment. The effects of alloying elements on stress corrosion cracking are remarkably different according to the environment. These effects were investigated systematically in high temperature, high pressure water, and as the result, Alloy SCR-3 with excellent stress corrosion cracking resistance was found. The physical constants and the mechanical properties of the SCR-3 are shown. The states of stress corrosion cracking in high temperature, high pressure water containing chlorides and pure water, polythionic acid, sodium phosphate solution and caustic soda of the SCR-3, SUS 304, Inconel 600 and Incoloy 800 are compared and reported. (Kako, I.)

  9. Caustic cracking of 2 1/4 CrMo steel

    International Nuclear Information System (INIS)

    Stress corrosion cracking tests performed on the 21/4 Cr Mo ferritic steel are described. The principal environments studied were strong, aqueous caustic soda, molten anhydrous caustic soda, and caustic soda with an addition of sodium. Emphasis has been placed on material in the quenched-hardened condition. (author)

  10. Intergranular stress corrosion cracking

    International Nuclear Information System (INIS)

    An austenitic stainless steel pipe weldment, which had been in operation in the Ringhals 1 reactor was characterized by using an electrochemical sensitization testing method (EPR) as well as with transmission electron microscopy. Specimens were cut from the studied pipe far from the weld and heat treated. A Nordic EPR ''round robin'' test was performed to measure the degree of sensitization of the material. Critical stress corrosion potential for the heat affected zone was determined in high temperature pure water by using slow strain rate testing. (author)

  11. Stress corrosion in gaseous environment

    International Nuclear Information System (INIS)

    The combined influences of a stress and a gaseous environment on materials can lead to brittleness and to unexpected delayed failure by stress corrosion cracking, fatigue cracking and creep. The most important parameters affering the material, the environment, the chemical reaction and the stress are emphasized and experimental works are described. Some trends for further research are given

  12. Complex stress intensity factors at cracks in birefringent plates by the method of reflected caustics

    International Nuclear Information System (INIS)

    The optical method of reflected caustics was used for evaluating the stress intensity factors in cracked plates made of birefringent materials in the general case when the crack is submitted to a combined mode I and mode II deformations. It has been already shown that the reflected rays from the rear face of the transparent optically active material form a double caustic due to this optical anisotropy of the material and, on the other hand, it is also known that when a crack in an optically inert material is submitted to a combined mode I and mode II deformation the respective caustic is angularly displaced. In this paper the combined effect of the optical anisotropy of the material together with the general case of loading of the cracked plate defined by the ratio μ = Ksub(II)/Ksub(I), where Ksub(I,II) are the respective SIF's for either mode of deformation was studied. Nomograms for the exact evaluation of the respective stress intensity factors Ksub(I) and Ksub(II) from the geometric characteristics of both branches of the caustic for a series of birefringent materials and for different values of μ are given. A series of experiments with cracked birefringent plates made of polycarbonate with a coefficient of anisotropy xi sub(r) = 0.153 for different orientations of the crack have shown that the determination of Ksub(I) and Ksub(II) by these nomograms is accurate since there is a coincidence between theory and experiments. (orig.)

  13. Stress corrosion and hydrogen embrittlement

    Science.gov (United States)

    Blackburn, M. J.; Smyrl, W. H.

    1973-01-01

    Service experience applications, experimental data generation, and the development of satisfactory quantitative theories relevant to the suppression and control of stress corrosion cracking in titanium are discussed. The impact of stress corrosion cracking (SCC) on the use of titanium alloys is considered, with emphasis on utilization in the aerospace field. Recent data on hot salt SCC, crack growth in hydrogen gas, and crack growth in liquid environments containing halide ions are reviewed. The status of the understanding of crack growth processes in these environments is also examined.

  14. Stress corrosion cracking susceptibility of steam generator tubing on secondary side in restricted flow areas

    International Nuclear Information System (INIS)

    Nuclear steam generator tubes operate in high temperature water and on the secondary side in restricted flow areas many nonvolatile impurities accidentally introduced into circuit tend to concentrate. The concentration process leads to the formation of highly aggressive alkaline or acid solutions in crevices, and these solutions can cause stress corrosion cracking (SCC) on stressed tube materials. Even though alloy 800 has shown to be highly resistant to general corrosion in high temperature water, it has been found that the steam generator tubes may crack during service from the primary and/or secondary side. Stress corrosion cracking is still a serious problem occurring on outside tubes in operating steam generators. The purpose of this study was to evaluate the environmental factors affecting the stress corrosion cracking of steam generators tubing. The main test method was the exposure for 1000 hours into static autoclaves of plastically stressed C-rings of Incoloy 800 in caustic solutions (10% NaOH) and acidic chloride solutions because such environments may sometimes form accidentally in crevices on secondary side of tubes. Because the kinetics of corrosion of metals is indicated by anodic polarization curves, in this study, some stressed specimens were anodically polarized in caustic solutions in electrochemical cell, and other in chloride acidic solutions. The results presented as micrographs, potentiokinetic curves, and electrochemical parameters have been compared to establish the SCC behavior of Incoloy 800 in such concentrated environments. (authors)

  15. Stress corrosion cracking of 3.5 NiCrMoV turbine steels

    International Nuclear Information System (INIS)

    This paper describes a research program conducted to determine susceptibility of steels used in low-pressure (LP) turbine rotors of power plants to stress corrosion cracking (SCC) in LP turbine environments. Results indicate cracking occurs under specific conditions of temperature and electrode potential. Transgranular cracking occurred in chloride solutions and in oxygenated water. Cracking in dilute caustic-chloride solutions was both transgranular and intergranular. Results of constant-load tests were found to depend upon procedures followed in establishing test conditions

  16. Stress corrosion cracking of nickel-base alloy weldments

    International Nuclear Information System (INIS)

    Stress corrosion cracking (SCC) of weldments occurs in media such as chloride, hydrofluoric acid, polythionic acid, caustic soda and molten metals. Nickel-base alloys on account of their low SCC are preferred for weldments in the above media. However, the choice of a particular nickel-base alloy depends upon the condition in which they are used. Studies on this aspect are reviewed. In reprocessing plants, Ni-Cr-Mo alloy No6625 and No6455 are found suitable. The Ni-Cr alloy No6600 failed in BWR type reactor due intergranular SCC. The alloy No6690 which has a higher chromium content is immune to intergranular SCC. Reduction of free carbon in the matrix of the weld metal makes it resistant to intergranular SCC. (M.G.B.)

  17. Stress-corrosion cracking in metals

    Science.gov (United States)

    1971-01-01

    Criteria and recommended practices for preventing stress-corrosion cracking from impairing the structural integrity and flightworthiness of space vehicles are presented. The important variables affecting stress-corrosion cracking are considered to be the environment, including time and temperature; metal composition, and structure; and sustained tensile stress. For designing spacecraft structures that are free of stress-corrosion cracking for the service life of the vehicle the following rules apply: (1) identification and control of the environments to which the structure will be exposed during construction, storage, transportation, and use; (2) selection of alloy compositions and tempers which are resistant to stress-corrosion cracking in the identified environment; (3) control of fabrication and other processes which may introduce residual tensile stresses or damage the material; (4) limitation of the combined residual and applied tensile stresses to below the threshold stress level for the onset of cracking throughout the service life of the vehicle; and (5) establishment of a thorough inspection program.

  18. Stress corrosion of alloy 600: mechanism problems

    International Nuclear Information System (INIS)

    To understand better stress corrosion of alloy 600, we experimentally studied: the simultaneous action of atmosphere and stress, the continuous or discontinuous propagation, the part of the formed oxide, the characteristics and peculiar properties in conditions where the material is sensitive. The results show that the beginning of cracking by stress corrosion may be explained by a limited brittleness of grains boundary (a preferential penetration of this grains boundary by a brittle oxide under a traction stress). 8 refs., 1 fig., 1 tab

  19. Nuclear fuel stress corrosion prevention

    International Nuclear Information System (INIS)

    In the operation of nuclear reactors employing sintered fuel tablets sheathed in zirconium alloy sheaths it has been found that, during irradiation, cadmium is released from the fuel and migrates outwardly to the inner surface of the sheath, where it can create an embrittlement phenomenon, resulting in sheath failure due to stress corrosion cracking. In accordance with the present disclosure copper is provided as a barrier or partial barrier between the fuel and the sheath inner surface, to facilitate the formation of a stable copper-cadmium alloy during the irradiation life of the fuel, to thereby impede the formation of a concentration of cadmium or active compounds thereof on the sheath inner surface. (auth)

  20. Review on stress corrosion and corrosion fatigue failure of centrifugal compressor impeller

    Science.gov (United States)

    Sun, Jiao; Chen, Songying; Qu, Yanpeng; Li, Jianfeng

    2015-03-01

    Corrosion failure, especially stress corrosion cracking and corrosion fatigue, is the main cause of centrifugal compressor impeller failure. And it is concealed and destructive. This paper summarizes the main theories of stress corrosion cracking and corrosion fatigue and its latest developments, and it also points out that existing stress corrosion cracking theories can be reduced to the anodic dissolution (AD), the hydrogen-induced cracking (HIC), and the combined AD and HIC mechanisms. The corrosion behavior and the mechanism of corrosion fatigue in the crack propagation stage are similar to stress corrosion cracking. The effects of stress ratio, loading frequency, and corrosive medium on the corrosion fatigue crack propagation rate are analyzed and summarized. The corrosion behavior and the mechanism of stress corrosion cracking and corrosion fatigue in corrosive environments, which contain sulfide, chlorides, and carbonate, are analyzed. The working environments of the centrifugal compressor impeller show the behavior and the mechanism of stress corrosion cracking and corrosion fatigue in different corrosive environments. The current research methods for centrifugal compressor impeller corrosion failure are analyzed. Physical analysis, numerical simulation, and the fluid-structure interaction method play an increasingly important role in the research on impeller deformation and stress distribution caused by the joint action of aerodynamic load and centrifugal load.

  1. Review on Stress Corrosion and Corrosion Fatigue Failure of Centrifugal Compressor Impeller

    Institute of Scientific and Technical Information of China (English)

    SUN Jiao; CHEN Songying; QU Yanpeng; LI Jianfeng

    2015-01-01

    Corrosion failure, especially stress corrosion cracking and corrosion fatigue, is the main cause of centrifugal compressor impeller failure. And it is concealed and destructive. This paper summarizes the main theories of stress corrosion cracking and corrosion fatigue and its latest developments, and it also points out that existing stress corrosion cracking theories can be reduced to the anodic dissolution (AD), the hydrogen-induced cracking (HIC), and the combined AD and HIC mechanisms. The corrosion behavior and the mechanism of corrosion fatigue in the crack propagation stage are similar to stress corrosion cracking. The effects of stress ratio, loading frequency, and corrosive medium on the corrosion fatigue crack propagation rate are analyzed and summarized. The corrosion behavior and the mechanism of stress corrosion cracking and corrosion fatigue in corrosive environments, which contain sulfide, chlorides, and carbonate, are analyzed. The working environments of the centrifugal compressor impeller show the behavior and the mechanism of stress corrosion cracking and corrosion fatigue in different corrosive environments. The current research methods for centrifugal compressor impeller corrosion failure are analyzed. Physical analysis, numerical simulation, and the fluid-structure interaction method play an increasingly important role in the research on impeller deformation and stress distribution caused by the joint action of aerodynamic load and centrifugal load.

  2. 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

  3. State of the art review of degradation processes in LMFBR materials. Volume I. Mechanical properties. Volume II. Corrosion behavior. Revision 1

    International Nuclear Information System (INIS)

    A revision to Volume I and Volume II of the LMFBR materials degradation summary is presented. Information is included on NaOH corrosive effects, effects of metal cleaning procedures, and caustic stress corrosion cracking of reactor materials. (JRD)

  4. Stress corrosion characterization of turbine rotor materials. Phase 2. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1986-06-01

    This report describes the second phase of a research program to identify the conditions of temperature, solution composition and stress sufficient to cause stress corrosion cracking of quenched and tempered 3.5 NiCrMoV steels used in low-pressure (LP) rotors of power plants. Slow-strain-rate tests were conducted on samples from two 3.5 NiCrMoV forgings over a temperature range of 93 to 157/sup 0/C (200 to 315/sup 0/F) in three potential LP turbine environments - water, NaCl solutions, and dilute caustic-chloride solutions. The effect of oxygen also was investigated. A limited number of constant-load tests were conducted in 10% NaOH solutions and in a dilute caustic-chloride solution. Results indicate cracking occurs under specific conditions of temperature and potential. Transgranular cracking occurred in chloride solutions and in oxygenated water. Cracking in dilute caustic-chloride solutions was both transgranular and intergranular. Results of constant-load tests were found to depend upon procedures followed in establishing tests conditions. An evaluation of the slow strain rate results in terms of potential-pH diagrams was performed.

  5. Industrial Experience on the Caustic Cracking of Stainless Steels and Nickel Alloys - A Review

    Energy Technology Data Exchange (ETDEWEB)

    Rebak, R B

    2005-10-09

    Caustic environments are present in several industries, from nuclear power generation to the fabrication of alkalis and alumina. The most common material of construction is carbon steel but its application is limited to a maximum temperature of approximately 80 C. The use of Nickel (Ni) alloys is recommended at higher temperatures. Commercially pure Ni is the most resistant material for caustic applications both from the general corrosion and the stress corrosion cracking (SCC) perspectives. Nickel rich alloys also offer a good performance. The most important alloying elements are Ni and chromium (Cr). Molybdenum (Mo) is not a beneficial alloying element and it dissolves preferentially from the alloy in presence of caustic environments. Austenitic stainless steels such as type 304 and 316 seem less resistant to caustic conditions than even plain carbon steel. Experimental evidence shows that the most likely mechanism for SCC is anodic dissolution.

  6. Stress corrosion of very high purity stainless steels in alkaline media

    International Nuclear Information System (INIS)

    This research thesis reports the study of stress corrosion resistance of stainless steels in caustic environments. It notably concerns the electronuclear industrial sector, the production of soda by electrolysis, and the preparation of hydrogen as energy vector. After a presentation of the experimental conditions, the author highlights the influence of purity on stress corrosion cracking of 20Cr-25Ni-type austenitic alloys. The specific action of a high number of addition metallic and non-metallic elements has been studied. Stress corrosion tests have been also performed in autoclave on austeno-ferritic (21 to 25 pc Cr - 6 to 10 pc Ni) as well as ferritic (26 pc Cr) grades. The author reports the study of electrochemical properties of stainless steel in soda by means of potentiostatic techniques with an application of Pourbaix thermodynamic equilibrium diagrams, and the study of the chemical composition of passivation thin layers by Auger spectroscopy. He more particularly studies the influence of electrode potential and of some addition elements on the chemical characteristics of oxides developed at the surface of austenite. Then, the author tries to establish correlations between strain hardening microstructure of the various steels and their sensitivity to stress corrosion

  7. Kinetic studies of stress-corrosion cracking

    Science.gov (United States)

    Noronha, P. J.

    1977-01-01

    Use of time-to-failure curves for stress-corrosion cracking processes may lead to incorrect estimates of structural life, if material is strongly dependent upon prestress levels. Technique characterizes kinetics of crackgrowth rates and intermediate arrest times by load-level changes.

  8. Stress Corrosion Cracking of Pipeline Steels

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This paper provides a review of the differences between high pH and near-neutral pH stress corrosion cracking ofpipeline steels, influencing factors, and mechanisms. The characteristics and historical information on both forms ofSCC are discussed. The prospect for research in the future is also presented.

  9. Stress corrosion cracking mechanisms of Fe-based alloys in hydrogenated hot water

    International Nuclear Information System (INIS)

    It is generally accepted that carbon steel resists Stress Corrosion Cracking (SCC) in hot water provided the oxygen content is low enough; however, isolated cracking events have occurred, apparently in fully reducing conditions, and these may or may not be true SCC. There are also occasional reports of SCC of austenitic stainless steel in reducing conditions where cold work may play a critical role. SCC though originally seen in sensitized material at oxidizing potentials persists to low potentials and in cold-worked but unsensitized material. We suspect from the literature that alloying with Ni introduces a susceptibility to SCC in reducing hot water as well as in caustic solution. Our hypothesis is that Ni causes SCC, and Cr retards it; so stainless steel has just enough Cr to protect against SCC under most conditions. We are examining this using model Fe-based materials and environments designed to separate the effects of different parameters. Early results suggest that Fe-Ni alloys and austenitic SS both undergo de-alloying and SCC in reducing caustic solutions. It is hypothesised that if these alloys are indeed susceptible to dealloying (and hence to SCC) in this environment then we can reasonably project that their behaviour in reducing, hot pure water may be similar. This is pertinent to understanding recent failures in high temperature, high pressure aqueous systems. As a first step we have investigated the surface reactions that occur in caustic solutions and in hot water. (author)

  10. Corrosion and stress corrosion cracking in coal liquefaction processes

    Energy Technology Data Exchange (ETDEWEB)

    Baylor, V. B.; Keiser, J. R.

    1980-01-01

    The liquefaction of coal to produce clean-burning synthetic fuels has been demonstrated at the pilot plant level. However, some significant materials problems must be solved before scale-up to commercial levels of production can be completed. Failures due to inadequate materials performance have been reported in many plant areas: in particular, stress corrosion cracking has been found in austenitic stainless steels in the reaction and separation areas and several corrosion has been observed in fractionation components. In order to screen candidate materials of construction, racks of U-bend specimens in welded and as-wrought conditions and unstressed surveillance coupons were exposed in pilot plant vessels and evaluated. Failed components were analyzed on-site and by subsequent laboratory work. Laboratory tests were also performed. From these studies alloys have been identified that are suitable for critical plant locations. 19 figures, 7 tables.

  11. TESTING OF FLOW THROUGH STRESS CORROSION CRACKS

    International Nuclear Information System (INIS)

    One aspect of licensing the high-level nuclear waste repository to be located at Yucca Mountain, Nevada, is the determination of the inclusion of the effects of features, events, and processes (FEPs) on the performance of the repository. Among the FEPs evaluated are the advection of solids and liquids through stress corrosion cracks in waste packages and drip shields. The presence of one or more cracks or other small openings of sufficient size in a waste package or drip shield may provide a pathway for the advective flow of water (e.g., thin films or droplets) or solid material through a waste package or drip shield. The resulting flux may affect drip shield performance and/or subsequent dripping onto or into the waste packages. The objective of this set of tests involved the detection/non-detection of advective water flow through stress cracks similar to those that may occur in the drip shield or waste package. If sufficient flow volume was present then attempts were made to quantify the volume of water flow through a stress crack. Literature was reviewed to identify previous studies and models that may be relevant to the current study of flow through stress corrosion cracks in a drip shield or waste package. Although no studies could be found that were directly applicable to our current problem, studies were identified that investigated portions of the overall problem. The papers that were reviewed were organized into the following categories: (1) maximum static head in a crack; (2) liquid impingement on surfaces [1]; (3) leakage through stress cracks [2]; and (4) dripping from cracks and fractures [3]. Because of the unique configuration and processes associated with the current problem of flow through stress corrosion cracks in drip shields and waste packages, experimental studies are needed to better understand whether flow can occur in stress cracks from impinging water droplets

  12. Stress corrosion testing of irradiated cladding tubes

    International Nuclear Information System (INIS)

    Samples from two fuel rods with different cladding have been stress corrosion tested by closed-end argon-iodine pressurization at 3200C. The fuel rods with stress relieved and recrystallized Zircaloy-2 had received burnups of 10.000 and 20.000 MWd/ton UO2, respectively. It was found that the SCC failure stress was unchanged or slightly higher for the irradiated than for the unirradiated control tubes. The tubes failed consistently in the end with the lowest irradiation dose. The diameter increase of the irradiated cladding during the test was 1.1% for the stress-relieved samples and 0.24% for the recrystallized samples. SEM examination revealed no major differences between irradiated and unirradiated cladding. A ''semi-ductile'' fracture zone in recrystallized material is described in some detail. (author)

  13. Stress corrosion cracking of a Kori 1 retired steam generator tube

    International Nuclear Information System (INIS)

    The present work addressed the evolution trends of the Kori 1 retired steam generators tube degradation such as pitting, primary water stress corrosion cracking (PWSCC), and outer diameter stress corrosion cracking (ODSCC) using the Weibull distribution based on the repair of the tubing and introduced a failure analysis of the pulled out tubes from the Kori 1. A material and condenser replacement in the secondary side and a chemical cleaning of the steam generator changed the Weibull distribution for the pitting. An ingress of sea water through the condenser into the steam generator and an accumulation of chloride in the steam generator induced the pitting. A mechanism of a copper band formation within the corrosion product in a pit is proposed. Pitting seemed to have occurred in an acidic and oxidizing environment between 1978 and early 1990. The Weibull characteristic time and slope for a PWSCC is 25 year and 4.5, respectively. Axial PWSCC was only observed in the R16C35 tube and circumferential PWSCC was only observed in the R11C45 tube at the roll expansion transition. Some tubes that experienced extensive ODSCC rather than PWSCC in the roll transition seemed to be due to the impurities concentrated in the crevice which induce ODSCC, even though the stress in the roll transition of the primary side was higher than that in the secondary side. ODSCC seemed to have occurred in a caustic and slightly oxidizing environment from early 1990 to 1998. (authors)

  14. Stress corrosion cracking susceptibility of steam generator tube materials in AVT chemistry contaminated with lead

    International Nuclear Information System (INIS)

    The existence of lead is steam generator detected during analysis of deposits in the damaged areas of tube and in the fracture surfaces of existing cracks, bears out the hypothesis that lead may contribute to the secondary stress corrosion problems of steam generator tubes. The lead present in a steam generator which comes from the turbine, pump seals, valve packing, liners, etc. may form concentration from 0.02% to 0.2% in the sludge (1). The ubiquity of the major sources of lead limits the scope for controlling this contaminant and make difficult to remove it from steam generator. Taking this fact into account, it seems necessary to count on lead being present in new steam generator and to consider the influence of this contaminant on the behaviour of the materials considered as substitutes for Inconel 600. An extensive experimental work has been carried out in order to determine the stress corrosion crackings susceptibility of Inconel 690 TT, Incoloy 800 and Inconel 600 MA and TT in caustic and acidic environments contaminated with lead oxide. The results from this work, in particular for Incoloy 800, raised some concerns about the effect of minor amount of lead oxide in AVT environment. This paper presents the experimental work conducted with a view to determine the influence of lead oxide concentration in AVT conditions on the stress corrosion resistance of nickel alloys used in the fabrication of steam generator tubing. (authors). 3 tabs., 6 refs

  15. A stress corrosion cracking experience

    Energy Technology Data Exchange (ETDEWEB)

    Dicic, Z.

    1999-07-01

    Severe cracking was found on two discs when a steam turbine was inspected during the outage to replace the last stage blades (LSB). The cracks were on the inlet side in the form of star burst around balance holes, and in the form of long circumferential cracks in the region of the fillet radius between the disc and the shaft. In order to return the turbine to service, the turbine was modified by removing the disc that was damaged more severely, and by machining of the other to remove the cracks. The basis for the modifications was established after having performed metallurgical and deposit examination, and reviews of stress calculations and design features. Additional modifications were performed in order to improve the internal environment at location where the cracking had occurred. The turbine is a non-reheat, 3,600 RPM, single shaft, monoblock unit used in a combined cycle plant. The steam cycle is a two pressure system; The high pressure (HP) steam parameters are: 1,450 psig, and 950 F, and the low pressure (LP) induction steam: 60 psig, saturated. The first eight stages are action type. The induction steam inlet is followed by five reaction stages. There are no extractions. The source of steam is a two pressure, unfired Heat Recovery Steam Generator (HRSG). The boiler feed water is treated with phosphates.

  16. Stress-Assisted Corrosion in Boiler Tubes

    Energy Technology Data Exchange (ETDEWEB)

    Preet M Singh; Steven J Pawel

    2006-05-27

    A number of industrial boilers, including in the pulp and paper industry, needed to replace their lower furnace tubes or decommission many recovery boilers due to stress-assisted corrosion (SAC) on the waterside of boiler tubes. More than half of the power and recovery boilers that have been inspected reveal SAC damage, which portends significant energy and economic impacts. The goal of this project was to clarify the mechanism of stress-assisted corrosion (SAC) of boiler tubes for the purpose of determining key parameters in its mitigation and control. To accomplish this in-situ strain measurements on boiler tubes were made. Boiler water environment was simulated in the laboratory and effects of water chemistry on SAC initiation and growth were evaluated in terms of industrial operations. Results from this project have shown that the dissolved oxygen is single most important factor in SAC initiation on carbon steel samples. Control of dissolved oxygen can be used to mitigate SAC in industrial boilers. Results have also shown that sharp corrosion fatigue and bulbous SAC cracks have similar mechanism but the morphology is different due to availability of oxygen during boiler shutdown conditions. Results are described in the final technical report.

  17. Stress corrosion cracking of stainless steel used in drill collars

    International Nuclear Information System (INIS)

    The present work, studies the stress corrosion cracking behavior in austenitic Fe-Cr-Mn-N stainless steel, in as received, solubilized and sensitized conditions, submitted to several chlorides environments. To evaluate the stress corrosion cracking susceptibility, double cantilever beam specimens, fatigue precracked, side grooved and wedge loaded were used. The environments employed were boiling solution of 45wt.% of MgCl2 at 154 deg. C and synthetic marine environment at ambient and boiling temperature. The susceptibility to stress corrosion cracking has been evaluated in terms of the corrosion stress intensity limit factor, KISCC, applying the fracture-mechanics concept. The results showed that only the specimens in the as received and sensitized conditions, were susceptible to the stress corrosion cracking effect in the boiling solution of 45wt.% of MgCl2 at 154 deg. C, and mean values of the stress corrosion intensity limit factor, KISCC, of 15MPam and 7.8MPam, respectively

  18. Stress corrosion cracking of steam turbine rotors

    International Nuclear Information System (INIS)

    In the wake of the catastrophic failure of a low-pressure (LP) turbine disk at the Hinkley Point Nuclear Station in 1969, considerable research and development has been devoted to the problem of stress corrosion cracking (SCC) in steam turbine rotors. Principle factors affecting the susceptibility of rotors to SCC have been identified as disk yield strength, applied stress level, and surface film/crevice chemistry. Microstructure and cleanliness of the steel have been found to have relatively little effect. Advances in steel making and forging over the last 20 years have provided manufacturers with additional design and material options to mitigate the problem. Increases in forging size capabilities of steel companies and the welded construction of rotors now permit designing with integral and partial integral rotors that use materials with lower yield strength (more SCC resistant) as well as eliminating the SCC problem in bores and keyways. However, a recent survey of US utilities has shown that SCC in the blade attachment legion of LP rotors is an increasing concern. This problem has led to development of repair and refurbishment methods for rim attachments, especially weld buildup of rims with corrosion-resistant alloys. Life prediction of rotors under SCC conditions currently involves estimating crack growth time from assumed defects to critical size. Factors that govern the location and time of crack initiation are not understood adequately. 50 refs., 23 figs., 1 tab

  19. An overview of materials degradation by stress corrosion in PWRs

    International Nuclear Information System (INIS)

    The aging of water cooled and moderated nuclear steam supply systems has given rise to many material corrosion problems of which stress corrosion cracking has proved to be one of the most serious. The aim of this paper is to review some examples of corrosion and particularly stress corrosion problems from the author's experience of interpreting and modelling these phenomena in PWR systems. Examples of stress corrosion cracking in PWR systems described include the major issue of Alloy 600 intergranular cracking in primary PWR coolants, for which it is generally perceived that both adequate life prediction models and remedial measures now exist. Intergranular corrosion and stress corrosion cracking of Alloy 600 steam generator tubes that occur in occluded superheated crevices on the secondary side of steam generators due to hide-out and concentration of water borne impurities are also addressed. Rather less extensive or well known examples are discussed such as the stress corrosion cracking of carbon and low alloy steels and of stainless steels in occluded dead-leg situations where it is sometimes difficult to guarantee adequate control of water chemistry, particularly at plant start-up. Reference is also be made to the use of high strength fastener materials in PWR systems as well as to the emerging issue of the effect of high neutron doses on the stress corrosion resistance of core structural components fabricated from austenitic stainless steels. (authors)

  20. Relationship among Parameters Evaluating Stress Corrosion Cracking

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@The threshold stress, σc, for sulfide stress corrosion cracking (SCC) of seven pipeline steels and five other steels, the critical stress, SC, for seven pipeline steels and two drill rod steels with various strengths and the susceptibility to SCC, IRA or σf(SCC)/σf, for four pipeline steels, two drill rod steels and five other steels were measured. The results showed that there are no definite elationships among σc, SC and IRA or σf(SCC)/σf. The threshold stress for hydrogen induced cracking (HIC) during charging with loading in the H2SO4 solution, σc(H), decreased linearly with logarithm of the concentration of diffusible hydrogen c0, i.e., σC(H)=A-B Inc0 for four pipeline steels. σc(H) obtained with a special cathodic current ic, which was corresponding to the diffusible hydrogen concentration during immersing in the H2S solution, were consistent with σc for sulfide SCC for four pipeline steels.Therefore, σc for sulfide SCC can be measured using dynamically charging in the H2SO4 solution with the special cathodic current ic.

  1. Stress corrosion crack growth rates and general corrosion rates at crack tips of steels in high temperature water

    International Nuclear Information System (INIS)

    The maximum stress corrosion crack growth rates for a number of structural materials (steels and nickel alloys) have been measured in 288 C water. Also, the general corrosion rates of these materials have been determined from weight loss experiments in simulated stress corrosion crack tip electrolytes at 288 C. It is shown that the stress corrosion crack growth rates are typically twenty times faster than the general corrosion rates. This correlation holds over five orders of magnitude. It is concluded that strategies to prevent stress corrosion cracking in high temperature aqueous environments might include alloys of higher general corrosion resistance

  2. Stress corrosion cracking of Zircaloys. Final report

    International Nuclear Information System (INIS)

    The overall aim has been to develop an improved understanding of the stress corrosion cracking (SCC) mechanism considered to be responsible for pellet-cladding interaction (PCI) failures of nuclear fuel rods. The objective of the present phase of the project was to investigate the potential for improving the resistance of Zircaloy to iodine-induced SCC by modifying the manufacturing techniques used in the commercial production of fuel cladding. Several aspects of iodine SCC behavior of potential relevance to cladding performance were experimentally investigated. It was found that the SCC susceptibility of Zircaloy tubing is sensitive to crystallographic texture, surface condition, and residual stress distribution and that current specifications for Zircaloy tubing provide no assurance of an optimum resistance to SCC. Additional evidence was found that iodine-induced cracks initiate at local chemical inhomogeneities in the Zircaloy surface, but laser melting to produce a homogenized surface layer did not improve the SCC resistance. Several results were obtained that should be considered in models of PCI failure. The ratio of axial to hoop stress and the temperature were both shown to affect the SCC resistance whereas the difference in composition between Zircaloy-2 and Zircaloy-4 had no detectable effect. Damage accumulation during iodine SCC was found to be nonlinear: generally, a given life fraction at low stress was more damaging than the same life fraction at higher stress. Studies of the thermochemistry of the zirconium-iodine system (performed under US Department of Energy sponsorship) revealed many errors in the literature and provided important new insights into the mechanism of iodine SCC of Zircaloys

  3. Causticizing process

    Energy Technology Data Exchange (ETDEWEB)

    Engdal, H.

    1987-03-10

    This invention seeks to provide a method in which the soda lye obtained as a result of cellulose cooking process and unslaked lime are used for producing white liquor which can be re-used in the cooking process. In this method, the heat released by the slaking of lime with soda lye is recovered by a high pressure slaking process wherein the heat is transferred, either to the steam separating from the lye, which steam is then led to the desired application, or to some other medium to be heated. The invention is characterized in that the soda lye to be causticized is divided into two parts, one of which is used for the slaking of lime by adding to it all the unslaked lime needed for the causticizing process, and that, following slaking, the two volumes are brought together for the actual causticizing reaction involving the total amount of lye needed. This invention provides the advantage that the amount of lye needed is smaller, and so the temperature can be increased.

  4. Experimental Study on Wing Crack Behaviours in Dynamic-Static Superimposed Stress Field Using Caustics and High-Speed Photography

    Directory of Open Access Journals (Sweden)

    L.Y. Yang

    2014-07-01

    Full Text Available During the drill-and-blast progress in rock tunnel excavation of great deep mine, rock fracture is evaluated by both blasting load and pre-exiting earth stress (pre-compression. Many pre-existing flaws in the rock mass, like micro-crack, also seriously affect the rock fracture pattern. Under blasting load with pre-compression, micro-cracks initiate, propagate and grow to be wing cracks. With an autonomous design of static-dynamic loading system, dynamic and static loads were applied on some PMMA plate specimen with pre-existing crack, and the behaviour of the wing crack was tested by caustics corroding with a high-speed photography. Four programs with different static loading modes that generate different pre-compression fields were executed, and the length, velocity of the blasting wing crack and dynamic stress intensity factor (SIF at the wing crack tip were analyzed and discussed. It is found that the behaviour of blasting-induced wing crack is affected obviously by blasting and pre-compression. And pre-compression, which is vertical to the direction of the wing crack propagation, hinders the crack propagation. Furthermore, the boundary constraint condition plays an important role on the behaviour of blasting induced crack during the experiment.

  5. Crack growth and rupture characteristics of stress corrosion cracks

    International Nuclear Information System (INIS)

    The contribution describes rupture-mechanical studies on stress-corrosion cracks which occurred at components during use. The tests are complemented by test specimens with stress-corrosion cracks which were induced in the laboratory. The tests show that the stress-corrosion cracks of the tested higher-tensile heat-treatable steels have an intercrystalline crack development, crack branchings and multiple cracks with differing linear and depth expansions. With the same external stress and fracture toughness, the load on stress-corrosion cracks must be at least 1.4 times higher in order to initiate the fracture. The critical crack sizes are at least two times bigger than the result of a fracture-mechanical evaluation based on clean and unbranched cracks. (orig./RHM)

  6. Predicting stress corrosion crackig in welded steel based on residual stress measurements

    International Nuclear Information System (INIS)

    Residual stress measurements were made on a welded HP-9-4-20 steel test coupon to determine the potential of residual stress for producing stress corrosion cracking. X-ray diffraction and strain gauge rosettes were used to make the measurements. The results indicated that, under the conditions specified, the stress intensity produced by residual stress was one-fourth that required to produce stress corrosion cracking

  7. Corrosion Study of Super Ferritic Stainless Steel UNS S44660 (26Cr-3Ni-3Mo) and Several Other Stainless Steel Grades (UNS S31603, S32101, and S32205) in Caustic Solution Containing Sodium Sulfide

    Science.gov (United States)

    Chasse, Kevin R.; Singh, Preet M.

    2013-11-01

    Electrochemical techniques, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) were used in this study to show how the corrosion mechanism of several commercial grades of stainless steel in hot caustic solution is strongly influenced by the presence of sodium sulfide. Experimental results from super ferritic stainless steel UNS S44660 (26Cr-3Ni-3Mo) were compared to austenitic stainless steel UNS S31603, lean duplex stainless steel (DSS) UNS S32101, and standard DSS UNS S32205 in caustic solution, with and without sodium sulfide, at 443 K (170 °C). Weight loss measurements indicated that corrosion rates of UNS44660 were much lower than the other grades of stainless steel in the presence of the sodium sulfide. Potentiodynamic polarization and linear polarization resistance measurements showed that the electrochemical behavior was altered by the adhesion of sulfur species, which reduced the polarization resistances and increased the anodic current densities. SEM and XPS results imply that the surface films that formed in caustic solution containing sodium sulfide were defective due to the adsorption of sulfide, which destabilized the passive film and led to the formation of insoluble metal sulfide compounds.

  8. Results of u-bend stress-corrosion-cracking specimen exposures in coal-liquefaction pilot plants

    Energy Technology Data Exchange (ETDEWEB)

    Baylor, V.B.; Keiser, J.R.; Allen, M.D.; Howell, M.; Newsome, J.F.

    1982-04-01

    Pilot plants with capacities of up to 600 tons/d are currently demonstrating the engineering feasibility of several coal liquefaction processes including Solvent Refined Coal (SRC), Exxon Donor Solvent (EDS), and H-Coal. These plants are the first step toward commercial production of synthetic fuels. Among other factors, development of the technology depends on reliable materials performance. A concern is the application of those austenitic stainless steels necessary for general corrosion resistance, because they are susceptible to stress corrosion cracking. This cracking results from tensile stresses in combination with offensive agents such as polythionic acids, chlorides, and caustics. To screen candidate construction materials for resistance to stress corrosion cracking, we exposed racks of stressed U-bend specimens in welded and as-wrought conditions at four coal liquefaction pilot plants. Results from exposures through June 1980 were described in a previous report for exposures in the SRC plants. This report summarizes the on-site test results from June 1980 through October 1981 for the two SRC pilot plants and the H-Coal and Exxon coal liquefaction pilot plants.

  9. Corrosion under stress of AISI 304 steel in thiocyanate solutions

    International Nuclear Information System (INIS)

    Corrosion susceptibility under stress of AISI 304 steel sensitized in a sodium thiocyanate solution has been studied and results were compared with those obtained with solutions of thiosulfate and tetrathionate. Sensitized steel type 304 is highly susceptible to corrosion when under intergranular stress (IGSCC) in thiocyanate solutions but the aggressiveness of this anion is less than that of the other sulphur anions studied (thiosulfate and tetrathionate). This work has been partly carried out in the Chemistry Department. (Author)

  10. Fundamental approaches to predicting stress corrosion: 'Quantitative micro-nano' (QMN) approach to predicting stress corrosion cracking in water cooled nuclear plants

    International Nuclear Information System (INIS)

    This paper describes the modeling and experimental studies of stress corrosion cracking with full disciplinary set at the atomic level. Its objective is to develop an intellectual structure for quantitative prediction of stress corrosion cracking in water cooled reactors.

  11. The Effect of Cu on the Intergranular Stress Corrosion Cracking of Alloy 600 MA

    International Nuclear Information System (INIS)

    During the unscheduled outage to repair steam generator(S/G) tube leakage in 1994, a defective S/G tube was removed from Kori Unit 1 for a detailed examination. The results of destructive examinations confirmed the presence of Outside Diameter Stress Corrosion Cracking(ODSCC) at locations indicated by in-service Eddy Current Testing(ECT). The maximum depth of any of defects was 95% of the wall thickness, as determined by metallography. Defects were located primarily in the sludge pile and appeared to be associated with crevice regions formed at Top of Tube Sheet(TTS) sludge pile. Caustic environment could be obtained through crevice boiling process. During crevice boiling process, cations such as sodium could be accumulated, and anion species could be evaporated. These resulted in a high molar ratio of [Na+/Cl-] and high pH. Corrosion potential could also be elevated due to Cu oxide formation from the metallic copper deposit on tubing. The pure Cu deposited on tube surface might be oxidized by dissolved oxygen during start-up

  12. The effect of Cu on the intergranular stress corrosion cracking of alloy 600 MA

    International Nuclear Information System (INIS)

    During the unscheduled outage to repair steam generator(S/G) tube leakage in 1994, a defective S/G tube was removed from Kori unit 1 for a detailed examination. The results of destructive examination confirmed the presence of Outside Diameter Stress Corrosion Cracking(ODSCC) at locations indicated by in-service Eddy Current Testing(ECT). The maximum depth of any of defects was 95% of the wall thickness, as determined by metallography. Defects were located primarily in the sludge pile and appeared to be associated with crevice regions formed at Top of Tube Sheet(TTS) sludge pile. Caustic environment could be obtained through crevice boiling process. During crevice boiling process, cations such as sodium could be accumulated, and anion species could be evaporated. These resulted in a high molar ratio of [Na+/Cl-] and high pH. Corrosion potential could also be elevated due to Cu oxide formation from the metallic copper deposit on tubing. The pure Cu deposited on tube surface might be oxidized by dissolved oxygen during start-up. (author)

  13. Influence of thermal treatment on the caustic SCC of super austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Y.R.; Park, Y.B.; Chung, T.J.; Kim, Y.S. [School of Advanced Materials Engineering, Andong National Univ. (Korea); Chang, H.Y. [Korea Power Engineering Co. (Korea); Park, Y.S. [Dept. of Metallurgical Engineering, Yonsei Univ. (Korea)

    2005-07-01

    In general, thermal treatment at 500 C {proportional_to} 900 C ranges depending upon alloy composition of stainless steels can sensitize the steels and promote the intergranular cracking, and their intergranular corrosion resistance is decreased. These behaviors seem to be related to the change of microstructures. So, heat treatment at that temperature range should be avoided in fabrication, especially welding of stainless steels. In this work, it is focused on the effect of thermal treatment on caustic stress corrosion cracking of super austenitic stainless steel - S32050 The low temperature thermal treatment increased greatly the resistance to caustic SCC than those of annealed specimen. This enhancement might be closely related to the reduction of residual stress and slightly large grain, but its resistance was not affected by the anodic polarization behavior. (orig.)

  14. Stress corrosion cracking of copper canisters

    Energy Technology Data Exchange (ETDEWEB)

    King, Fraser (Integrity Corrosion Consulting Limited (Canada)); Newman, Roger (Univ. of Toronto (Canada))

    2010-12-15

    A critical review is presented of the possibility of stress corrosion cracking (SCC) of copper canisters in a deep geological repository in the Fennoscandian Shield. Each of the four main mechanisms proposed for the SCC of pure copper are reviewed and the required conditions for cracking compared with the expected environmental and mechanical loading conditions within the repository. Other possible mechanisms are also considered, as are recent studies specifically directed towards the SCC of copper canisters. The aim of the review is to determine if and when during the evolution of the repository environment copper canisters might be susceptible to SCC. Mechanisms that require a degree of oxidation or dissolution are only possible whilst oxidant is present in the repository and then only if other environmental and mechanical loading conditions are satisfied. These constraints are found to limit the period during which the canisters could be susceptible to cracking via film rupture (slip dissolution) or tarnish rupture mechanisms to the first few years after deposition of the canisters, at which time there will be insufficient SCC agent (ammonia, acetate, or nitrite) to support cracking. During the anaerobic phase, the supply of sulphide ions to the free surface will be transport limited by diffusion through the highly compacted bentonite. Therefore, no HS. will enter the crack and cracking by either of these mechanisms during the long term anaerobic phase is not feasible. Cracking via the film-induced cleavage mechanism requires a surface film of specific properties, most often associated with a nano porous structure. Slow rates of dissolution characteristic of processes in the repository will tend to coarsen any nano porous layer. Under some circumstances, a cuprous oxide film could support film-induced cleavage, but there is no evidence that this mechanism would operate in the presence of sulphide during the long-term anaerobic period because copper sulphide

  15. Stress corrosion cracking of copper canisters

    International Nuclear Information System (INIS)

    A critical review is presented of the possibility of stress corrosion cracking (SCC) of copper canisters in a deep geological repository in the Fennoscandian Shield. Each of the four main mechanisms proposed for the SCC of pure copper are reviewed and the required conditions for cracking compared with the expected environmental and mechanical loading conditions within the repository. Other possible mechanisms are also considered, as are recent studies specifically directed towards the SCC of copper canisters. The aim of the review is to determine if and when during the evolution of the repository environment copper canisters might be susceptible to SCC. Mechanisms that require a degree of oxidation or dissolution are only possible whilst oxidant is present in the repository and then only if other environmental and mechanical loading conditions are satisfied. These constraints are found to limit the period during which the canisters could be susceptible to cracking via film rupture (slip dissolution) or tarnish rupture mechanisms to the first few years after deposition of the canisters, at which time there will be insufficient SCC agent (ammonia, acetate, or nitrite) to support cracking. During the anaerobic phase, the supply of sulphide ions to the free surface will be transport limited by diffusion through the highly compacted bentonite. Therefore, no HS. will enter the crack and cracking by either of these mechanisms during the long term anaerobic phase is not feasible. Cracking via the film-induced cleavage mechanism requires a surface film of specific properties, most often associated with a nano porous structure. Slow rates of dissolution characteristic of processes in the repository will tend to coarsen any nano porous layer. Under some circumstances, a cuprous oxide film could support film-induced cleavage, but there is no evidence that this mechanism would operate in the presence of sulphide during the long-term anaerobic period because copper sulphide

  16. Pitting corrosion and stress corrosion of Zircaloy 4 in neutral chloride environment

    International Nuclear Information System (INIS)

    In a first part, this research thesis describes the electrochemical methods which are generally used to characterize sensitivity to pitting corrosion of metallic materials, presents the method used for the statistical analysis of pitting initiation as well as results obtained in the case of Zircaloy 4 in a neutral chloride environment. This reveals that passivity film thickness is a critical parameter for the understanding of observed behaviours, and therefore required the study of passivity film formation kinetics. Thus established passivity rules are then used to study the influence of passive film evolution on behaviour in terms of pitting corrosion. Experimental results are then compared with published results. The second part addresses the determination of sensitivity to stress corrosion of the same alloy in the same environment. It aims at trying to identify correlations between sensitivity to this type of corrosion and sensitivity to pitting corrosion

  17. Size effects of TiO2 on stress corrosion cracking resistance of steam generator tube materials

    International Nuclear Information System (INIS)

    In nuclear power plants, steam generator (SG) tubes have certain characteristic features in their design to endure a severe problem, a stress corrosion cracking (SCC) - thin boundary wall of a high temperature and pressure, a heat transition through a wall thickness, a contact with a steam phase, the formation of a sludge pile and a crevice etc. Most SCCs have occurred near the top of a sludge pile on a tubesheet and within a tube support plate crevice in which it is thought to be concentrated by ion impurities such as sodium which might cause a caustic and corrosive environment. Many inhibitors have been studied to reduce these SCC problems for SG tube materials. Several chemicals were also studied to suppress the damage due to a stress corrosion cracking (SCC) of the steam generator (SG) tubes in nuclear power plants. In this study SCC tests were carried out to investigate both the effect of corrosion inhibitor (TiO2) and the size effect of the TiO2 particle on several types of SG tube materials. The SCC tests were conducted by using an m-RUB specimen in a 10% NaOH solution at a temperature of 315o. In order to enhance the corrosion resistance on the SCC of SG materials the size of the TiO2 particles were reduced to nano-sized ranges by applying a sonochemical technique. From the SCC tests with the RUB specimen and penetration test with crevice chemistry and analyzing system, the SG tube materials showed the higher resistance in corrosion cracking with the addition of nano-TiO2. (author)

  18. Study on mitigation of stress corrosion cracking by peening

    International Nuclear Information System (INIS)

    In order to verify stability of residual stress improvement effect of peeing for mitigation of stress corrosion cracking in components of PWR plant, relaxation behavior of residual stress induced by water jet peening (WJP) and ultrasonic shot peening (USP) on surface of alloy 600 and its weld metal was investigated under various thermal aging and stress condition considered for actual plant operation. In the case of thermal aging at 320-380degC, surface residual stress relaxation was observed at the early stage of thermal aging, but no significant stress relaxation was observed after that. Applied stress below yield stress does not significantly affect stress relaxation behavior of surface residual stress. Furthermore, it was confirmed that cyclic stress does not accelerate stress relaxation. (author)

  19. Axial stress corrosion cracking forming method to metal tube

    International Nuclear Information System (INIS)

    Generally, it is more difficult in a metal tube, to intentionally cause a stress corrosion cracking in axial direction than in circumferential direction. In the present invention, a bevel is formed on a metal tube and welding is conducted in circumferential direction along the bevel, and welding is conducted in axial direction partially to the portion welded in circumferential direction. Namely, a bevel is formed in circumferential direction to an abutting portion of thick-walled metal tubes with each other, welding is conducted in circumferential direction along the bevel, and welding is conducted in axial direction partially to a portion welded in circumferential direction. With such procedures, since tensile stress in the circumferential direction is increased partially at a portion welded in axial direction, stress corrosion cracking is caused in axial direction at the portion. Then, stress corrosion cracking in axial direction can thus be formed on the thick-walled metal tube. (N.H.)

  20. Application of Fracture Mechanics to Stress Corrosion Cracking

    Czech Academy of Sciences Publication Activity Database

    Gajdoš, Lubomír

    Poreč : Danubia, 1997 - (Jecič, M.), s. 66-67 [Danubia-Adria Symposium /14./. Poreč (HR), 10.09.1997-12.09.1997] R&D Projects: GA ČR GA103/95/1320 Keywords : stress corrosion, stress intensity factor Subject RIV: JL - Materials Fatigue, Friction Mechanics

  1. 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)

  2. The effect of deformation on stress corrosion of brass

    OpenAIRE

    A. Kadłuczka; Mazur, M.

    2010-01-01

    Brass are some of the most common copper alloys, both due to its characteristics and utility technology. Corrosion fracture after stress corrosion are the most common form of destruction of brass.This is particularly dangerous because of the lack of early, visible signal of decohesion of the material. It is therefore important to know exactly this phenomenon to design and manufacture heavy loaded industrial constructions exposed to aggressive environments, as wellas minimize the danger of des...

  3. Crack bridging in stress corrosion cracking of duplex stainless steels

    International Nuclear Information System (INIS)

    Wedge open loaded (WOL) specimens of age hardened Zeron 100 duplex stainless steel were tested in 3.5 wt % NaCl solution with cathodic polarizes applied at-900m V/SCE to investigate stress corrosion cracking mechanism in duplex stainless steel. The interaction between microstructure and mechanism of stress corrosion cracking was studied. Fracture mechanism was studied by using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). The material was found cracked by ferrite cleavage, austenite tearing and austenite dissolution by environment. The ferrite cleavage took place along [100] planes and [112] twin habit planes. The austenite grains appear to act as crack bridging and crack arrester and failed by tearing and stress corrosion cracking. (author)

  4. Stress corrosion cracking susceptibility of 7A52 aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    ZHAO Jun-jun; WANG Wei-xin; CAI Zhi-hai; ZHANG Ping

    2006-01-01

    The stress corrosion sensitivity of 7A52 aluminum alloy was investigated in the artificial sea water through slow stain rate test(SSRT). The stress corrosion cracking(SCC) susceptibility was estimated with the loss of elongation and stress corrosion sensitivity index. The results show that the susceptibility of 7A52 aluminum alloy is always high when the strain rate is in the range of 10-5-10-7s-1. It reaches the maximum at the strain rate of 8.7×10-7s-1, and the sensitivity index reaches 0.346. The characteristics of stress corrosion can be observed clearly on the fracture of tensile specimen. The process of SCC is depicted according to the fracture morphology. The SCC initiates at the edge of the specimen. Then the SCC grows rapidly because of the anode dissolving and stress concentration. When the area of specimen cannot support the tensile stress, it ruptures suddenly. The secondary cracks and quasi-cleavage surface can be found on the fracture morphology.susceptibility

  5. Three-dimensional characterization of stress corrosion cracks

    DEFF Research Database (Denmark)

    Lozano-Perez, S.; Rodrigo, P.; Gontard, Lionel Cervera

    2011-01-01

    offers the best spatial resolution. To illustrate the power of these techniques, different parts of dominant stress corrosion cracks in Ni-alloys and stainless steels have been reconstructed in 3D. All relevant microstructural features can now be studied in detail and its relative orientation respect to......Understanding crack propagation and initiation is fundamental if stress corrosion cracking (SCC) mechanisms are to be understood. However, cracking is a three-dimensional (3D) phenomenon and most characterization techniques are restricted to two-dimensional (2D) observations. In order to overcome...

  6. Corrosion and Stress Corrosion Behaviors of Low and Medium Carbon Steels in Agro-Fluid Media

    Directory of Open Access Journals (Sweden)

    Ayo Samuel AFOLABI

    2007-01-01

    Full Text Available Investigations were carried out to study critically the corrosion behaviour and Stress Corrosion Cracking (SCC of low and medium carbon steels in cassava and cocoa extracts by weight loss measurement and constant extension to fracture method respectively. The results obtained showed that medium carbon steel is more susceptible to corrosion than low carbon steel in both media. SCC is also more in medium carbon steel than low carbon steel in the two media under study. These deductions are due to higher carbon content in medium carbon steel coupled with various aggressive corrosion constituents contained in these media. Hydrogen embrittlement, as well as carbon cracking, is responsible for SCC of these materials in the agro-fluid media.

  7. The effects of radiolysis on the corrosion and stress corrosion behavior of 316 stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Duquette, D.J.; Steiner, D.

    1993-09-01

    This program is focused on the corrosion, stress corrosion and corrosion fatigue behavior of Type 316 stainless steel (316SS) at 50, 90, and 130 C in high-purity water. Irradiated solution tests are performed using high-energy photon radiation. Purpose of this work is to determine the effects of radiolysis products on the environmental stability of 316SS in support of the ITER first wall/shield/blanket design. Preliminary results suggest that irradiation of pure water at 50 C results in a shift in the electrochemical potential for 316SS of approximately 100mV in the active direction and nearly an order of magnitude increase in the passive current density as compared to non-irradiated conditions. This proposal outlines a three-year program to develop corrosion design criteria for the use of 316SS in an ITER environment.

  8. Corrosion and stress corrosion cracking of bolting materials in light water reactors

    International Nuclear Information System (INIS)

    The primary coolant of a pressurized water reactor contains dissolved boric acid added as a soluble neutron absorber. Corrosion and stress corrosion cracking of bolts on pumps and on primary system manways have occurred where gaskets leak this boric acid onto the low alloy steel bolting material. Laboratory experiments have shown that the concentration of the boric acid to a moist paste at approximately the boiling point of water can produce corrosion rates of the order of several tenths of an inch per year on bolting and piping materials, which values are consistent with service experience. Frequently molybdenum disulfide is used as a lubricant for tightening bolts on massive flanges. Laboratory experience has shown that when the primary coolant leaks through a gasket the molybdenum disulfide can react with the leaking steam to produce hydrogen sulfide and subsequent stress corrosion cracking of the bolts. Additionally, contaminants concentrating over significant time periods have caused stress corrosion cracking failures of reactor coolant pump internals. Failure analysis of cracked bolts from service and the results of laboratory tests that demonstrate these mechanisms of bolt cracking are presented

  9. Compressive residual stresses as a preventive measure against stress corrosion cracking on turbine components

    International Nuclear Information System (INIS)

    Disk type low pressure turbine rotors have been designed for a large variety of power plant applications. Developing disk type rotors required a concerted effort to design a shaft/disk shrink fit with a minimum of tensile stress concentrations in order to aim for the lowest possible susceptibility to corrosive attack, i.e. stress corrosion cracking. As a result of stresses, the regions of greatest concern are the shrink fit boundaries and the keyways of turbine disks. These stresses are caused by service loading, i.e. centrifugal and shrinkage stresses and by manufacturing procedure, i.e. residual stresses. The compressive residual stresses partly compensate the tensile service stresses so that an increase of compressive residual stresses decreases the whole stress state of the component. Special manufacturing procedures, e.g. accelerated cooling after tempering can induce compressive residual stresses up to about 400 MPa in the hub bore region of turbine disk

  10. Effect of hydrogen on stress corrosion cracking of copper

    Institute of Scientific and Technical Information of China (English)

    Li-jie QIAO

    2008-01-01

    The effects of hydrogen on electrochemical behavior and susceptibility of stress corrosion cracking (SCC) of pure copper were studied. SCC susceptibility of pure copper in a 1 M NaNO2 solution was increased by pre-charged hydrogen. The effect of hydrogen on the sus-ceptibility is more obvious in the low stress region due to the longer fracture time, which resulted in a longer time for more hydrogen to diffuse toward the crack tip. Synergistic effects of hydrogen and stress on corrosion and SCC pro-cesses were discussed. The results showed that an inter-action between stress and hydrogen at the crack tip could increase the anodic dissolution rate remarkably.

  11. Stress corrosion cracking of steam generator tubing materials in lead containing solution

    International Nuclear Information System (INIS)

    Stress corrosion cracking (SCC) in lead (Pb) containing environments has been one of key issues in the nuclear power industry since Pb had been identified as a cause of the SCC of steam generator (SG) tubing materials in some power plants. To mitigate or prevent degradation of SG tubing materials, a mechanistic understanding of SCC in Pb containing environment is needed, along with an understanding of the source and transport behaviors of Pb species in the secondary circuit. In this work, SCC behaviors of Alloy 600 in Pb containing environments were studied. Influences of microstructures of Alloy 600 and the inhibitive additives were investigated using the C-ring and the slow strain rate tests in caustic solution and demineralized water at 315oC. Microstructures of Alloy 600 were varied by heat treatment at different temperatures. The additives examined were nickel boride (NiB) and cerium boride (CeB6). The surface films were analyzed using Auger Electron Spectroscopy (AES) and Energy Dispersive X-ray Spectroscopy (EDS). The SCC mode varied with microstructure. Effectiveness of the additives in Pb containing environments is discussed. (author)

  12. Ambient temperature stress-corrosion cracking of sensitized stainless steels

    International Nuclear Information System (INIS)

    Stress-corrosion cracking of sensitized Type 304 steel in low temperature borated water has been observed. The probable role of low levels of chloride ions or sulfur-containing ions is described, including the relationship of the phenomenon to polythionic acid cracking. The mechanism of the sulfur-induced cracking and its usefulness as a test for sensitization are outlined

  13. Proving test on stress corrosion cracking of pipings

    International Nuclear Information System (INIS)

    In September, 1974, stress corrosion cracking was discovered around the welded joints of stainless steel pipings in the recirculating system in the Dresden No. 2 BWR. The similar occurrence of stress corrosion cracking has been reported in a number of nuclear power stations in the US and Japan since then, and their operation was stopped for the inspection, repair and remodeling. In order to eliminate the anxiety of public on nuclear power generation, the Ministry of International Trade and Industry planned the proving test on the stress corrosion cracking of pipings, in other words, the proving test on the reliability of the heat-affected zones of welded parts. Using the test facility simulating the actual plant, the effectiveness of various measures against stress corrosion cracking was examined, and it was attempted to demonstrate the reliability of the actual stainless steel pipings and to confirm the safety. Also, the soundness of the equipments in reactors after the long time operation was investigated. The test plan, general simulation test, accelerated SCC test, cracking behavior confirmation test, and the state of progress of these tests as of the end of December, 1981, are reported. (Kako, I.)

  14. Performance demonstration tests for detection of intergranular stress corrosion cracking

    International Nuclear Information System (INIS)

    This report evaluates detection tests of inservice inspectors (ISI), procedures and equipment that are employed to find intergranular stress corrosion cracks in nuclear power plant piping. Performance is described by two fundamental parameters: false call probability and probability of detection. Acceptable inspection performance and detection tests are therefore defined in terms of these two parameters. 14 refs., 25 figs

  15. Role of secondary austenite on corrosion and stress corrosion cracking of sensitized duplex stainless steel weldments

    International Nuclear Information System (INIS)

    The role of secondary austenite on corrosion and stress corrosion cracking in high temperature water for sensitized duplex stainless steel weldment was investigated using transmission electron microscopy and fractography. Pitting potential measurements, 10% oxalic acid tests (ASTM A262A), Strauss tests (ASTM A262E) and Huey tests (ASTM A262C) were carried out for the corrosion assessment. For stress corrosion cracking, the slow strain rate testing (SSRT) was carried out at 562K with 8 ppm dissolved oxygen under 8 MPa at a strain rate of 4.17x10-6s-1. Volume fraction of γphase decreased with increasing peak temperature and the grain size of the γphase increased with increasing peak temperature. The amount of precipitation of Cr2N at the grain boundary and in the grain increased with increasing peak temperature. The region around Cr2N showed intergranular corrosion. For the sensitization at 923K for 72ks, σphase precipitated and secondary γphases (named γ* phase) appeared between primary γphase and σphase. The γ* phases were predominantly corroded and the pitting potentials were low. Stress corrosion cracking in high temperature water hardly occurred for the solution-treated specimen. The reduction in area of the specimen sensitized at 923K for 72ks was much lower than that of the solution-treated specimens and decreased with decreasing peak temperature, because the γ* phases near the M23C6 and σphase were predominantly corroded and dissolved. (author)

  16. EXPERT PANEL OVERSIGHT COMMITTEE ASSESSMENT OF FY2008 CORROSION AND STRESS CORROSION CRACKING SIMULANT TESTING PROGRAM

    Energy Technology Data Exchange (ETDEWEB)

    BOOMER KD

    2009-01-08

    The Expert Panel Oversight Committee (EPOC) has been overseeing the implementation of selected parts of Recommendation III of the final report, Expert Panel workshop for Hanford Site Double-Shell Tank Waste Chemistry Optimization, RPP-RPT-22126. Recommendation III provided four specific requirements necessary for Panel approval of a proposal to revise the chemistry control limits for the Double-Shell Tanks (DSTs). One of the more significant requirements was successful performance of an accelerated stress corrosion cracking (SCC) experimental program. This testing program has evaluated the optimization of the chemistry controls to prevent corrosion in the interstitial liquid and supernatant regions of the DSTs.

  17. Alkaline stress corrosion of iron-nickel-chromium austenitic alloys

    International Nuclear Information System (INIS)

    This research thesis reports the study of the behaviour in stress corrosion of austenitic iron-nickel-chromium alloys by means of tensile tests at imposed strain rate, in a soda solution at 50 pc in water and 350 degrees C. The author shows that the mechanical-chemical model allows the experimental curves to be found again, provided the adjustment of characteristic parameters, on the one hand, of corrosion kinetics, and on the other hand, of deformation kinetics. A classification of the studied alloys is proposed

  18. Hydrogen-increased dezincification layer-induced stress and susceptibility to stress corrosion cracking of brass

    Institute of Scientific and Technical Information of China (English)

    李会录; 高克玮; 褚武扬; 刘亚萍; 乔利杰

    2003-01-01

    Dezincification layer formed during corrosion or stress corrosion cracking (SCC) of brass in an ammonia solution could induce an additive stress. The effect of hydrogen on the dezincification layer-induced stress and the susceptibility to SCC were studied. The dezincification layer-induced stress was measured using the deflection method and the flowing stress differential method, respectively. The latter measures the difference between the flowing stress of a specimen before unloading and the yield stress of the same specimen after unloading and forming a dezincification layer. The susceptibility to SCC was measured using slow strain rate test. Results show that both the dezincification layer-induced stress and the susceptibility to SCC increase with increasing hydrogen concentration in a specimen. This implies that hydrogen-enhanced dezincification layer-induced stress is consistence with the hydrogen-increased susceptibility to SCC of brass in the ammonia solution.

  19. Stress corrosion cracking experience in steam generators at Bruce NGS

    International Nuclear Information System (INIS)

    In late 1990 and through 1991, units 1 and 2 at the Bruce A Nuclear Generating Station (BNGS-A) experienced a number of steam generator tube leaks. Tube failures were identified by eddy current to be circumferential cracks at U-bend supports on the hot-leg side of the boilers. In late 1991, tubes were removed from these units for failure characterization. Two active failure modes were found: corrosion fatigue in both units 1 and 2 and stress corrosion cracking (SCC) in unit 2. In unit 2, lead was found in deposits, on tubes, and in cracks, and the cracking was mixed-mode: transgranular and intergranular. This convincingly indicated the involvement of lead in the stress corrosion cracking failures. A program of inspection and tube removals was carried out to investigate more fully the extent of the problem. This program found significant cracking only in lead-affected boilers in unit 2, and also revealed a limited extent of non-lead-related intergranular stress corrosion cracking in other boilers and units. Various aspects of the failures and tube examinations are presented in this paper. Included is discussion of the cracking morphology, measured crack size distributions, and chemical analysis of tube surfaces, crack faces, and deposits -- with particular emphasis on lead

  20. Preventative measures to limit stress corrosion cracking in prestressed concrete

    Science.gov (United States)

    Oneil, E. F.

    1983-09-01

    In the past decade, the most significant advances in the area of protection of prestressing steel from stress corrosion cracking have come in the fields of metallurgy and concrete materials. These efforts have developed from a more precise understanding of the mechanisms that cause stress corrosion cracking in prestressing steel, and development of concreting materials that provide greater protection for these steels. This report deals with two aspects of steel protection. First, with respect to the steel itself, new insights into the structure of the prestressing steels have shown metallurgists the conditions under which stress cracks form and advance, as well as ways in which to modify the physical properties of the steel to minimize the possibility of crack formation and advancement. Secondly, in the field of concrete materials, the emphasis on prevention of corrosion to steel has been in the area of durability of the concrete that protects the steel. Lower water-cement ratios and concretes with lower permeability exclude deleterious materials from the surface of the steel. New materials and procedures are discussed that have been designed to limit the penetration of corrosive elements that may attack the steel at the grain boundaries and initiate brittle failure.

  1. Laboratory stress corrosion cracking studies in polythionic acid

    Energy Technology Data Exchange (ETDEWEB)

    Baylor, V.B.; Newsome, J.F.

    1984-08-01

    Stress corrosion cracking caused by polythionic acid and/or chlorides is a problem in coal liquefaction pilot plants. This problem is also common in refineries and has been the subject of extensive research. This study examines (1) the relationship of the ASTM standard ferric sulfate-sulfuric acid test for determining sensitization to resistance to polythionic stress corrosion cracking, (2) the cracking resistance of higher-alloy Fe-Ni-Cr materials in addition to the common austenitic stainless steels, and (3) the effect of chloride concentrations up to 1% in polythionic acid solutions on cracking behavior. We found that the ferric sulfate-sulfuric acid test can be used as an acceptance test for materials resistant to polythionic acid stress corrosion cracking because of its severity. The more highly alloyed materials were more resistant to sensitization than most of the austenitic stainless steels and were virtually unattacked in polythionic acid solutions containing up to 1% chloride. Chloride increased the corrosion rate and caused localized pitting, but it did not affect significantly the number of failures or the failure mode.

  2. Effect of Wall Shear Stress on Corrosion Inhibitor Film Performance

    Science.gov (United States)

    Canto Maya, Christian M.

    In oil and gas production, internal corrosion of pipelines causes the highest incidence of recurring failures. Ensuring the integrity of ageing pipeline infrastructure is an increasingly important requirement. One of the most widely applied methods to reduce internal corrosion rates is the continuous injection of chemicals in very small quantities, called corrosion inhibitors. These chemical substances form thin films at the pipeline internal surface that reduce the magnitude of the cathodic and/or anodic reactions. However, the efficacy of such corrosion inhibitor films can be reduced by different factors such as multiphase flow, due to enhanced shear stress and mass transfer effects, loss of inhibitor due to adsorption on other interfaces such as solid particles, bubbles and droplets entrained by the bulk phase, and due to chemical interaction with other incompatible substances present in the stream. The first part of the present project investigated the electrochemical behavior of two organic corrosion inhibitors (a TOFA/DETA imidazolinium, and an alkylbenzyl dimethyl ammonium chloride), with and without an inorganic salt (sodium thiosulfate), and the resulting enhancement. The second part of the work explored the performance of corrosion inhibitor under multiphase (gas/liquid, solid/liquid) flow. The effect of gas/liquid multiphase flow was investigated using small and large scale apparatus. The small scale tests were conducted using a glass cell and a submersed jet impingement attachment with three different hydrodynamic patterns (water jet, CO 2 bubbles impact, and water vapor cavitation). The large scale experiments were conducted applying different flow loops (hilly terrain and standing slug systems). Measurements of weight loss, linear polarization resistance (LPR), and adsorption mass (using an electrochemical quartz crystal microbalance, EQCM) were used to quantify the effect of wall shear stress on the performance and integrity of corrosion inhibitor

  3. Fuel element failures caused by iodine stress corrosion

    International Nuclear Information System (INIS)

    Sections of unirradiated cladding tubes were plugged in both ends by mechanical seals and internally pressurized with argon containing iodine. The time to failure and the strain at failure as a function of stress was determined for tubing with different heat treatments. Fully annealed tubes suffer cracking at the lowest stress but exhibit the largest strains at failure. Elementary iodine is not necessary for stress corrosion: small amounts of iodides of zirconium, iron and aluminium can also give cracking. Moisture, however, was found to act as an inhibitor. A deformation threshold exists below which stress corrosion failure does not occur regardless of the exposure time. This deformation limit is lower the harder the tube. The deformation at failure is dependent on the deformation rate and has a minimum at 0.1%/hr. At higher deformation rates the failure deformation increases, but only slightly for hard tubes. Fuel was over-power tested at ramp rates varying between 0.26 to 30 W/cm min. For one series of fuel pins the failure deformations of 0.8% at high ramp rates were in good agreement with predictions based on stress corrosion experiments. For another series of experiments the failure deformation was surprisingly low, about 0.2%. (author)

  4. Electrochemical study of stress corrosion cracking of copper alloys

    International Nuclear Information System (INIS)

    This work deals with the electrochemical study of stress corrosion of copper alloys in aqueous environment. Selective dissolution and electrochemical oxidation are two key-points of the stress corrosion of these alloys. The first part of this thesis treats of these aspects applied to Cu-Au alloys. Measurements have been performed using classical electrochemical techniques (in potentio-dynamic, potentio-static and galvano-static modes). The conditions of occurrence of an electrochemical noise is analysed using signal processing techniques. The impact on the behavior of Cu3Au are discussed. In the second part, the stress corrosion problem is addressed in the case of surface oxide film formation, in particular for Cu-Zn alloys. We have found useful to extend this study to mechanical stress oxidation mechanisms in the presence of an oscillating potential electrochemical system. The aim is to examine the influence of these new electrochemical conditions (galvano-static mode) on the behavior of stressed brass. Finally, the potential distribution at crack tip is calculated in order to compare the different observations

  5. Stress corrosion cracking and dealloying of copper-gold alloy in iodine vapor

    International Nuclear Information System (INIS)

    The susceptibility to stress corrosion cracking of copper-gold alloy in iodine vapor was studied and the results were analyzed under the scope of the surface mobility stress corrosion cracking mechanism. The copper-gold alloy undergoes stress corrosion cracking in iodine. Copper iodide was responsible of that behavior. The copper-gold alloy shows two processes in parallel: stress corrosion cracking and dealloying. As was predicted by the surface mobility stress corrosion cracking mechanism, the increase in strain rate induces an increase in the crack propagation rate. (Author)

  6. Mechanistic Understanding Of Caustic Cracking Of Carbon Steels

    International Nuclear Information System (INIS)

    Liquid waste generated by the PUREX process for separation of nuclear materials is concentrated and stored in Type IV single-shell carbon steel tanks at the Savannah River Site (SRS). The Type IV tanks for this waste do not have cooling coils and have not undergone heat treatment to stress-relieve the tanks. After the waste is concentrated by evaporation, it becomes very alkaline and can cause stress corrosion cracking (SCC) and pitting corrosion of the tank materials. SRS has experienced leakage from non-stress-relieved waste tanks constructed of A285 carbon steel and pitting of A212 carbon steel tanks in the vapor space. An investigation of tank materials has been undertaken at SRS to develop a basic understanding of caustic SCC of A285 and A212 grade carbon steels exposed to aqueous solutions, primarily containing sodium hydroxide (NaOH), sodium nitrate (NaNO3), and sodium nitrite (NaNO2) at temperatures relevant to the operating conditions of both the F and H area plants. This report presents the results of this corrosion testing program. Electrochemical tests were designed using unstressed coupons in a simulated tank environment. The purpose of this testing was to determine the corrosion susceptibility of the tank materials as a function of chemical concentration, pH, and temperature. A285 and A516 (simulates A212 carbon steel) coupons were used to investigate differences in the corrosion of these carbon steels. Electrochemical testing included measurement of the corrosion potential and polarization resistance as well as cyclic potentiodynamic polarization (CPP) testing of coupons. From the CPP experiments, corrosion characteristics were determined including: corrosion potential (Ecorr), pitting or breakdown potential (Epit), and repassivation potential (Eprot). CPP results showed no indications of localized corrosion, such as pitting, and all samples showed the formation of a stable passive layer as evidenced by the positive hysteresis during the scan

  7. Stress corrosion cracking susceptibility of dissimilar stainless steels welded joints

    Directory of Open Access Journals (Sweden)

    J. Łabanowski

    2007-01-01

    Full Text Available Purpose: The aim of the current study is to reveal the influence of welding conditions on structure and stresscorrosion cracking resistance of dissimilar stainless steels butt welded joints.Design/methodology/approach: Butt joints between duplex 2205 and austenitic 316L steels were performedwith the use of submerged arc welding (SAW method. The plates 15 mm in thickness were welded with heatinput in the range of 1.15 – 3.2 kJ/mm using duplex steel filler metal. Microstructure examinations and corrosiontests were carried out. Slow strain rate tests (SSRT were performed in inert (glycerin and aggressive (boiling35% MgCl2 solution environments.Findings: It was shown that place of the lowest resistance to stress corrosion cracking is heat affected zone atduplex steel side of dissimilar joins. That phenomenon was connected with undesirable structure of that zoneconsisted of great amount of coarse ferrite grains and acicular austenite precipitates. High welding inputs do notdeteriorate stress corrosion cracking resistance of welds.Research limitations/implications: High welding heat inputs should enhance the precipitation process ofintermetallic phases in the HAZ. It is necessary to continue the research to determine the relationship betweenwelding parameters, obtained structures, and corrosion resistance of dissimilar stainless steels welded joints.Practical implications: Application of more productive joining process for dissimilar welds like submerged arcwelding instead of currently employed gas metal arc welding (GMAW method will be profitable in terms ofreduction the welding costs.Originality/value: The stress corrosion cracking resistance of dissimilar stainless steel welded joints wasdetermined. The zone of the weaker resistance to stress corrosion cracking was pointed out.

  8. Influence of mechanical stress level in preliminary stress-corrosion testing on fatigue strength of a low-carbon steel

    International Nuclear Information System (INIS)

    Effect of corrosion and mechanical factors of preliminary stress corrosion of a metal in its fatigue strength, has been investigated. Smooth cylindrical samples of 20 steel have been tested. Preliminary corrosion under stress has been carried out under natural sea conditions. It is shown that mechanical stresses in the case of preliminary corrosion affect fatigue strength of low-carbon steels, decreasing the range of limited durability and fatigue limit. This effect increases with the increase of stress level and agressivity of corrosive medium

  9. Stress corrosion cracking of A515 grade 60 carbon steel

    International Nuclear Information System (INIS)

    An investigation was conducted to evaluate the effect of welding method plate thickness, and subsequent stress relief treatment on the stress corrosion cracking propensity of ASTM A515 Grade 60 carbon steel plate exposed to a 5 M NaNO3 solution at 1900F for eight weeks. It was found that all weld coupons receiving no thermal stress relief treatment cracked within eight weeks; all weld coupons given a vibratory stress relief cracked within eight weeks; two of the eight weld coupons stress relieved at 6000F for one hour cracked within eight weeks; none of the weld coupons stress relieved at 11000F for one hour cracked within eight weeks; and that cracking was generally more severe in coupons fabricated from 7/8 inch plate by shielded metal arc welding than it was in coupons fabricated by other welding methods. (U.S.)

  10. Effect of cold working and applied stress on the stress corrosion cracking resistance of nickel-chromium-iron alloys

    International Nuclear Information System (INIS)

    In order to grasp the stress corrosion cracking quantitative resistance of Alloys 600 and 690 in PWR primary water, the authors have studied the effect of cold working and applied stress on the stress corrosion cracking resistance of Alloys 600 and 690, in high temperature water. Stress corrosion cracking tests were conducted at 360 degrees C (633K) in a simulated PWR primary water for about 12,000 hours or 24,000 hours. From the test results, it is concluded that the stress corrosion cracking resistance in the cold worked Alloy 600 at the same applied stress level increases with an increase in cold working ratio, and the cold worked Alloys of thermally treated 690 have the excellent stress corrosion cracking resistance. Further, in this paper, the planning of stress corrosion cracking test for weld joints and weld metal of Alloy 600 is described

  11. Management of stress corrosion cracking in pressurized water reactors

    International Nuclear Information System (INIS)

    Stress Corrosion Cracking (SCC) has recently become a significant issue for pressurized water reactors (PWR) in the United States (US). Until recently, SCC in primary coolant piping systems in nuclear reactors was thought to be an issue only for Boiling Water Reactors (BWR) caused by the aggressive BWR environment, susceptible material (austenitic stainless steel) and high stresses, all of which occurred in the vicinity of pipe and nozzle weldments. However, with the discovery of stress corrosion cracking [(denoted as primary water stress corrosion cracking (PWSCC)] at several PWR plants over the past 5 years, the first being at V.C. Summer in South Carolina, the issue has become significant for the US PWR industry. Because of the significant amount of experience gained in managing SCC over the past few years, it clear that implementing a well planned proactive aging management program can be important in minimizing interruptions to plant operation due to unexpected component degradation. Implementation of aging management programs (Plant Life Management) can help minimize the impact of SCC on plant availability and safety. An effective plant management program considers the mitigation, monitoring, inspection, repair and replacement activities related to PWR SCC. This paper summarizes the PWR SCC issue in the United States including historical, regulatory, industry activities and general recommendations/approaches to manage potential degradation. (author)

  12. Iodine induced stress corrosion cracking of Zircaloy fuel cladding materials

    International Nuclear Information System (INIS)

    This report documents the work performed by the Co-ordinated Research Project (CRP) on Stress Corrosion Cracking of Zirconium Alloy Fuel Cladding. The project consisted of out-of-pile laboratory measurements of crack propagation rates in Zircaloy sheet specimens in an iodine containing atmosphere. The project was overseen by a supervisory group consisting of experts in the field, who also contributed a state of the art review. This report describes all of the work undertaken as part of the CRP, and includes: a review of the state of the art understanding of stress corrosion cracking behaviour of zirconium alloy cladding material; a description of the experimental equipment, test procedures, material characterizations and test matrix; discussion of the work undertaken by the host laboratory and the specific contributions by each of the four participant laboratories; a compilation of all experimental results obtained; and the supervisory group's analysis and discussion of the results, plus conclusions and recommendations

  13. Stress corrosion on austenitic stainless steels components after sodium draining

    International Nuclear Information System (INIS)

    The damage study performed on 316 pipes of a loop after two leakages allows to conclude that a stress corrosion process in sodium hydroxide environment has induced trans-crystaline cracks. The research of conditions inducing such a phenomenon is developed, including parametric tests under uniaxial load and some tests on pipe with welded joints. In aqueous sodium hydroxide, two corrosion processes have been revealed: a general oxidization increasing with environment aeration and a transcrystalline cracking appearing for stresses of the order of yield strength. Other conditions such a temperature (upper than 1000C) and time exposures (some tens of hours) are necessary. Cautions in order to limit introduction of wet air into drained loop and a choice of appropriate preheating conditions when restarting the installation must permit to avoid such a type of incident

  14. Stress corrosion cracking of candidate waste container materials

    International Nuclear Information System (INIS)

    Six alloys have been selected as candidate container materials for the storage of high-level nuclear waste at the proposed Yucca Mountain site in Nevada. These materials are Type 304L stainless steel (SS), Type 316L SS, Incology 825, P-deoxidized Cu, Cu-30%Ni, and Cu-7% Al. The present program has been initiated to determine whether any of these materials can survive for 300 years in the site environment without developing through-wall stress corrosion cracks, and to assess the relative resistance of these materials to stress corrosion cracking (SCC). A series of slow-strain-rate tests (SSRTs) in simulated Well J-13 water which is representative of the groundwater present at the Yucca Mountain site has been completed, and crack-growth-rate (CGR) tests are also being conducted under the same environmental conditions. 13 refs., 60 figs., 22 tabs

  15. Susceptibility to Stress Corrosion Cracking of 254SMO SS

    Directory of Open Access Journals (Sweden)

    De Micheli Lorenzo

    2002-01-01

    Full Text Available The susceptibility to stress corrosion cracking (SCC of solubilized and sensitized 254SMO SS was studied in sodium chloride, and sodium fluoride solutions at 80 °C and sulfuric acid solutions in presence of sodium chloride at 25 °C. The influence of salt concentration, pH values and the addition of thiosulfate was examined. The susceptibility to SCC was evaluated by Slow Strain Rate Tests (SSRT, at 1.5 x 10-6 s-1 strain rate. The behavior of 254SMO was compared to those of AISI 316L SS and Hastelloy C276. 254SMO showed an excellent resistance to SCC in all conditions, except in the more acidic solutions (pH <= 1 where, in the sensitized conditions, intergranular stress corrosion cracking occurred.

  16. Stresses of steam generator U-tubes affecting stress corrosion cracking

    International Nuclear Information System (INIS)

    Stress factors affecting U-bend cracking in the steam generators of PWR type reactors are discussed based on the results of stress corrosion cracking tests of Inconel 600 U-bend tube in polythionic acid solution subjected to the actual operating loads

  17. Electron caustic lithography

    OpenAIRE

    S. M. KENNEDY; Zheng, C. X.; J. Fu; Tang, W. X.; Paganin, D. M.; Jesson, D. E.

    2012-01-01

    A maskless method of electron beam lithography is described which uses the reflection of an electron beam from an electrostatic mirror to produce caustics in the demagnified image projected onto a resist–coated wafer. By varying the electron optics, e.g. via objective lens defocus, both the morphology and dimensions of the caustic features may be controlled, producing a range of bright and tightly focused projected features. The method is illustrated for line and fold caustics and is compleme...

  18. Ultrasonic inspection of turbine rotor discs for stress corrosion cracking

    International Nuclear Information System (INIS)

    Stress corrosion cracking in turbine discs and keyways has been recognised for a number of years as a problem. Magnox Electric has devised and implemented a strategy to manage the threat from SCC, based on a probabilistic risk assessment technique. An important input to the risk assessment is a knowledge of existing defects and Magnox Electric has undertaken a major programme of work to develop ultrasonic inspection techniques and equipment for SCC detection and sizing in the relevant disc geometries. (author)

  19. Stress corrosion cracking in 3,5 NiCrMoV steel in a 403 K potential-PH diagram

    Energy Technology Data Exchange (ETDEWEB)

    Hitomi, Itoh [Mitsubishi Heavy Industries, Ltd., Takasago Research and Development Center, (Japan); Takashi, Momoo [Mitsubishi Heavy Industries Ltd., Takasago Machinery Works, (Japan)

    2001-07-01

    3,5 NiCrMoV steel is used in low-pressure turbine rotors and discs. It has been pointed out that intergranular stress corrosion cracking may occur in this material in the wet region at temperatures of about 400 K. Accordingly, the authors focused on the environmental conditions under which stress corrosion cracking (SCC) occurs. A potential-pH diagram was used to investigate the region in which SCC occurs in the high strength materials that are particularly susceptible to SCC. The investigation found that SCC is initiated in this material not only in the high caustic region but in the neutral region as well. The investigation also found that initiation and propagation were accelerated in dissolved oxygen environments with increased chemical potential in the neutral region. Since careful observation of the starting point of cracks has shown that corrosion pits trigger SCC, subsequent immersion tests under constant potential were conducted. The results showed that corrosion pits are generated at the high potential range. These results led to the development of an acceleration test environment for laboratory to determine the susceptibility of SCC in field turbine disc and rotor materials. (author)

  20. Stress corrosion cracking in 3,5 NiCrMoV steel in a 403 K potential-PH diagram

    International Nuclear Information System (INIS)

    3,5 NiCrMoV steel is used in low-pressure turbine rotors and discs. It has been pointed out that intergranular stress corrosion cracking may occur in this material in the wet region at temperatures of about 400 K. Accordingly, the authors focused on the environmental conditions under which stress corrosion cracking (SCC) occurs. A potential-pH diagram was used to investigate the region in which SCC occurs in the high strength materials that are particularly susceptible to SCC. The investigation found that SCC is initiated in this material not only in the high caustic region but in the neutral region as well. The investigation also found that initiation and propagation were accelerated in dissolved oxygen environments with increased chemical potential in the neutral region. Since careful observation of the starting point of cracks has shown that corrosion pits trigger SCC, subsequent immersion tests under constant potential were conducted. The results showed that corrosion pits are generated at the high potential range. These results led to the development of an acceleration test environment for laboratory to determine the susceptibility of SCC in field turbine disc and rotor materials. (author)

  1. 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

  2. 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

  3. Stress corrosion cracking of austenitic stainless steel core internal weld

    International Nuclear Information System (INIS)

    Microstructural analyses by several advanced metallographic techniques were conducted on austenitic stainless steel mockup and core shroud welds that cracked in boiling water reactors. Contrary to previous beliefs, heat-affected zones of the cracked Type 304L as well as 304 SS core shroud welds and mockup shielded-metal-arc welds were free of grain-boundary carbides, which shows that core shroud failure cannot be explained by classical intergranular stress corrosion cracking. Neither martensite nor delta-ferrite films were present on grain boundaries. However, as a result of exposure to weld fumes, the heat-affected zones of the core shroud welds were significantly contaminated by oxygen and fluorine which migrate to grain boundaries. Significant oxygen contamination seems to promote fluorine contamination and suppress thermal sensitization. Results of slow-strain-rate tensile tests indicate also that fluorine exacerbate the susceptibility of irradiated steels to intergranular stress corrosion cracking. These observations, combined with previous reports on the strong influence of weld flux, indicate that oxygen and fluorine contamination and fluorine-catalyzed stress corrosion play a major role in cracking of core shroud welds

  4. Residual stress measurements of U-bends and correlation with accelerated stress corrosion tests

    International Nuclear Information System (INIS)

    Various experimental techniques have been used to determine the residual stresses in U-bends of steam generator tubing. These include x-ray diffraction, strain gage sectioning, and strain gage sectioning with layer removal. The relative merits of each are discussed and the results from several investigations are presented. There is a large variability, even for a given technique, but most residual stress values are compressive or low tension implying little concern for stress corrosion cracking due to fabrication

  5. Comparison of Stress Corrosion Cracking Susceptibility of Laser Machined and Milled 304 L Stainless Steel

    Science.gov (United States)

    Gupta, R. K.; Kumar, Aniruddha; Nagpure, D. C.; Rai, S. K.; Singh, M. K.; Khooha, Ajay; Singh, A. K.; Singh, Amrendra; Tiwari, M. K.; Ganesh, P.; Kaul, R.; Singh, B.

    2016-07-01

    Machining of austenitic stainless steel components is known to introduce significant enhancement in their susceptibility to stress corrosion cracking. The paper compares stress corrosion cracking susceptibility of laser machined 304 L stainless steel specimens with conventionally milled counterpart in chloride environment. With respect to conventionally milled specimens, laser machined specimens displayed more than 12 times longer crack initiation time in accelerated stress corrosion cracking test in boiling magnesium chloride as per ASTM G36. Reduced stress corrosion cracking susceptibility of laser machined surface is attributed to its predominantly ferritic duplex microstructure in which anodic ferrite phase was under compressive stress with respect to cathodic austenite.

  6. Environmental behavior and stress corrosion characteristics of nano/sub-micron E950 aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Aghion, Eli; Guinguis, Inbar [Department of Materials Engineering, Ben-Gurion University of the Negev Beer-Sheva (Israel)

    2009-11-15

    The corrosion performance and stress corrosion resistance of E950 Aluminum alloy with nano/sub-micron structure were evaluated in 3.5% NaCl solution. The results obtained indicated that the corrosion and stress corrosion resistance of E950 alloy were relatively reduced compared to that of the conventional coarse-grained alloy (Al-4.65%Mg). In particular, the inherently improved ultimate tensile strength of E950 alloy was significantly decreased under stress corrosion conditions. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  7. Addressing stress corrosion cracking on multi layer pipeline coating systems

    Energy Technology Data Exchange (ETDEWEB)

    Hardy, Scott B.; Marr, James E. [Tuboscope Pipeline Services, Houston, TX (United States); Willmot, Martyn [Jotun Group (Norway); Norman, David [David Norman Corrosion Control, Cornwall (United Kingdom); Khera, Ashish [Allied Engineering, Portland, ME (United States)

    2005-07-01

    Stress corrosion cracking (SCC) is now recognized by operators worldwide as a significant threat to the safe operation of their pipeline systems. Gas, oil, and refined products lines have all been susceptible to this form of environmentally assisted cracking. As a result, operators and regulators have been incorporating data related to the development and prevalence of SCC into their risk management systems in order that they may effectively address this time-dependant threat. The National Association of Corrosion Engineers (NACE) published the first structured methodology for stress corrosion cracking direct assessment (SCCDA) in 2004 (RP0204-2004). Operators are now beginning to apply the methods outlined in the standard to assess their systems. Research and industry experience have shown that various pipeline coating systems can be more or less effective in preventing the formation and growth of SCC. Newer pipeline coatings, such as multi layer epoxy/extruded polyolefin systems have been widely regarded as effective coating systems to address the threat posed by SCC when they are properly applied. New field studies performed on a pipeline coated with a three layer epoxy/polyethylene system have raised the possibility that operators utilizing these types of coatings may need to reassess how they manage the SCC threat. (author)

  8. Residual stresses and stress corrosion cracking in pipe fittings

    International Nuclear Information System (INIS)

    Residual stresses can play a key role in the SCC performance of susceptible materials in PWR primary water applications. Residual stresses are stresses stored within the metal that develop during deformation and persist in the absence of external forces or temperature gradients. Sources of residual stresses in pipe fittings include fabrication processes, installation and welding. There are a number of methods to characterize the magnitude and orientation of residual stresses. These include numerical analysis, chemical cracking tests, and measurement (e.g., X-ray diffraction, neutron diffraction, strain gage/hole drilling, strain gage/trepanning, strain gage/section and layer removal, and acoustics). This paper presents 400 C steam SCC test results demonstrating that residual stresses in as-fabricated Alloy 600 pipe fittings are sufficient to induce SCC. Residual stresses present in as-fabricated pipe fittings are characterized by chemical cracking tests (stainless steel fittings tested in boiling magnesium chloride solution) and by the sectioning and layer removal (SLR) technique

  9. Stress corrosion studies in solvent refined coal liquefaction pilot plants

    Energy Technology Data Exchange (ETDEWEB)

    Baylor, V.B.; Keiser, J.R.; Allen, M.D.; Lawrence, E.J.

    1980-12-01

    Coal liquefaction plants with 6000 ton/d capacity are currently being planned by DOE as a step toward commercial production of synthetic fossil fuels. These plants will demonstrate the large-scale viability of the Solvent Refined Coal (SRC) process, which has been used since 1974 in two operating pilot plants: a 50-ton/d unit at Fort Lewis, Washington, and a 6-ton/d plant in Wilsonville, Alabama. Experience in these plants has shown that austenitic stainless steels are susceptible to stress corrosion cracking associated with residual stresses from cold working or welding. The corrodents responsible for the cracking have not yet been positively identified but are suspected to include polythionic acids and chlorides. To screen candidate materials of construction for resistance to stress corrosion cracking, racks of stressed U-bend specimens in welded and as-wrought conditions have been exposed at the Wilsonville and Fort Lewis SRC pilot plants. These studies have identified alloys that are suitable for critical plant applications.

  10. Stress-corrosion cracking studies in coal-liquefaction systems

    Energy Technology Data Exchange (ETDEWEB)

    Baylor, V.B.; Keiser, J.R.

    1981-01-01

    Coal liquefaction plants with 6000 ton/d capacity are currently being planned by DOE as a step toward commercial production of synthetic fossil fuels. These plants will demonstrate the large-scale viability of the Solvent Refined Coal (SRC) process, which has been used since 1974 in two operating pilot plants: a 50-ton/d unit at Fort Lewis, Washington, and a 6-ton/d plant in Wilsonville, Alabama. Experience in these plants has shown that austenitic stainless steels are susceptible to stress corrosion cracking associated with residual stresses from cold working or welding. The corrodants responsible for the cracking have not yet been positively identified but are suspected to include polythionic acids and chlorides. To screen candidate materials of construction for resistance to stress corrosion cracking, racks of stressed U-bend specimens in welded and as-wrought conditions have been exposed at the Wilsonville and Fort Lewis SRC pilot plants. These studies have identified alloys that are suitable for critical plant applications.

  11. Investigation of corrosion and stress corrosion cracking in bolting materials on light water reactors

    International Nuclear Information System (INIS)

    Laboratory experiments performed at BNL have shown that the concentration of boric acid to a moist paste at approximately the boiling point of water can produce corrosion rates of the order of several tenths of an inch per year on bolting and piping materials, which values are consistent with service experience. Other failure evaluation experience has shown that primary coolant/lubricant interaction may lead to stress corrosion cracking (SCC) of steam generator manway studs. An investigation was also performed on eleven lubricants and their effects on A193 B7 and A540 B24 bolting materials. H2S generation by the lubricants, coefficient of friction results and transgranular SCC of the bolting materials in steam are discussed. 13 refs

  12. Laboratory stress corrosion cracking studies with sulfur acids and chlorides

    Energy Technology Data Exchange (ETDEWEB)

    Baylor, V.B.

    1985-10-01

    Stress corrosion cracking (SCC) caused by polythionic acid and/or chlorides has occurred in coal liquefaction pilot plants. This problem is also common in refineries and has been extensively researched. This study examines: (1) the relationship of the ASTM standard ferric sulfate-sulfuric acid test for determining sensitization to resistance to polythionic SCC; (2) the cracking resistance of higher-alloy. Fe-Ni-Cr materials and common austenitic stainless steels (SS); and (3) the effect of chloride concentrations up to 1% in polythionic acid solutions on cracking behavior. The ferric sulfatesulfuric acid test can be used as an acceptance test for materials resistant to polythionic acid SCC. More highly alloyed materials were more resistant to sensitization than most austenitic SS and were virtually unattacked in polythionic acid solutions containing up to 1% chloride. Chloride increased the corrosion rate and caused localized pitting but it did not significantly affect the number of failures or the failure mode.

  13. Stress corrosion cracking in quenched and underaged U-6 wt.% Nb

    International Nuclear Information System (INIS)

    Two types of stress corrosion cracking occur in U--6 wt percent Nb. Intergranular (anodic dissolution) cracking occurs in aqueous Cl- environments. Transgranular (oxide stress rupture) cracking occurs in gaseous environments containing oxygen. Aging the quenched alloy at 2000C for 2 hours increases the yield strength but only slightly lowers the stress corrosion cracking threshold. (U.S.)

  14. Stress corrosion of austenitic steels in a sodium-soda medium

    International Nuclear Information System (INIS)

    Stress corrosion was studied on the materials (alloy 800, 316 and 316 L, stainless steels, etc...) used for fast breeder reactor secondary loops containing soda-contaminated sodium at 4000C to 5500C. Under particularly severe conditions (exposure for 1000 hours at up to 10 % soda content) an intergranular stress corrosion cracking process was observed above a temperature-dependent stress threshold. (author)

  15. Sensitization, intergranular attack, stress corrosion cracking, and irradiation effects on the corrosion of iron--chromium--nickel alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wu, P.C.S.

    1978-04-01

    A literature review is presented on the sensitization, intergranular attack, and stress corrosion cracking of austenitic stainless steels with emphasis on dilute solutions at temperatures below the boiling point of water. An attempt is made to list the possible sources of contaminants during manufacture, shipping, construction and all phases of operation of the sodium containing components. The susceptibility of the different materials to stress corrosion cracking in the various contaminants is discussed and suggestions to prevent serious problems are made. (GHT)

  16. Stress corrosion cracking of several high strength ferrous and nickel alloys

    Science.gov (United States)

    Nelson, E. E.

    1971-01-01

    The stress corrosion cracking resistance of several high strength ferrous and nickel base alloys has been determined in a sodium chloride solution. Results indicate that under these test conditions Multiphase MP35N, Unitemp L605, Inconel 718, Carpenter 20Cb and 20Cb-3 are highly resistant to stress corrosion cracking. AISI 410 and 431 stainless steels, 18 Ni maraging steel (250 grade) and AISI 4130 steel are susceptible to stress corrosion cracking under some conditions.

  17. Stress corrosion cracking of carbon and low alloy steels in high temperature water

    International Nuclear Information System (INIS)

    A new set of fracture mechanics stress corrosion crack growth rate data is presented for transgranular cracking of carbon and low alloy steels exposed to high temperature water. The essential observations are as follows. Fast stress corrosion crack growth rates between 10-9 and 10-8 m/s may be observed down to 400 ppb dissolved oxygen at water conductivities of 0.5 microS/cm in refreshed autoclaves. There is no effect of specimen thickness on the stress corrosion crack growth rates. Temperature, however, clearly is a major influential parameter on stress corrosion cracking

  18. Effect of pH on the Stress Corrosion Cracking of Sensitized AISI 304 Stainless Steel

    International Nuclear Information System (INIS)

    The effect of pH on the stress corrosion cracking was studied in 0.1 M sodium thiosulfate solution using two stress corrosion cracking testing methods (constant load and slow strain rate technique). The stress corrosion cracking resistance of sensitized 304 stainless steel decreased with lowering pH of the solution. Although the results agreed well in the above two experimental methods, slow strain rate technique was more efficient than constant load method in assessing the pH effect. The acoustic emission signals during the experiments were analyzed, that supports the film rupture mechanism of stress corrosion cracking

  19. Fractomechanical study of stress corrosion from Zircaloy-4

    International Nuclear Information System (INIS)

    The susceptibility to stress corrosion (SC) from Zircaloy-4 wires in iodine solutions in different alcohols and in aqueous IM solutions of NaCl, KBr and K1 has been studied before. The study of fracture surfaces showed in all cases intragranular attack followed by transgranular propagation. The intragranular fracture, that was associated with intragranular attack accompanied by stress, progresses until it penetrates the material and then the transition to transgranular fracture mode occurs, which has been identified as the 'true' SC process. For this transition to occur a certain value for the stress intensity factor (K1) has to be attained independently of the corrosive medium that produces the SC. In the case of alcoholic solutions, the K1 value obtained is almost constant and independent of the alcohol used as a solvent (10 Mpa.m-1/2).The average value of K1 calculated for the intergranular-transgranular transition of Zry-4 in aqueous halogenous solutions is 10.3±1.8 Mpa.m-1/2. This value agrees with the results found in the literature measured with different techniques and using different test geometries (Cw)

  20. Stress corrosion cracking of low steel weldments in LWR environments

    International Nuclear Information System (INIS)

    Results obtained at VTT in the ICG-EAC Group bolt-loaded WOL specimen testing round robin for pressure vessel steel weldments in simulated PWR primary water (typical of Loviisa VVER-440 power plant) are presented. Two low alloy type A508 C1.2 steels were tested; one steel had a very low S-content (0.002% S) and the other steel had normal medium S-content (0.008/0.009% S). The low sulphur steel did not show any indication of stress corrosion crack growth, while in one specimen of normal A508 C1.2 steel minor crack extension (less than 1 mm) was locally observed at the precrack tip in the HAZ of the weldment. Crack extension was explained by a water chemistry transient in one phase of the test and the phase of cracking could be related to this occurrence by detailed fractographic examination. Because of difficulties in locating exactly the precrack tip in the HAZ of the weldment, it was observed in the end of the test that precrack tips in various specimens were located either in the weld metal or in the HAZ or in some cases also very close to the fusion line. Thus, this study was also testing the stress corrosion cracking susceptibilities of the various zones of the weldments of low alloy pressure vessel steel A508 C1.2. Stress corrosion crack extension in small amounts was observed only in one HAZ specimen of the normal medium S-content steel

  1. Micromechanical testing of stress corrosion cracking of individual grain boundaries

    International Nuclear Information System (INIS)

    Grain boundaries of different misorientation and chemistry have differing susceptibilities to stress corrosion cracking but carrying out mechanical tests on individual grain boundaries of known character has until now been very difficult. We present a method for manufacturing specimens containing a single grain boundary (in 304 stainless steel) using focused ion beam machining. A nanoindenter/atomic force microscope was used to drive controlled grain boundary crack growth under load in an active solution. Scanning electron microscopy examination confirmed the growth of the crack along the grain boundary.

  2. Stress corrosion cracking of zirconium in nitric acid

    International Nuclear Information System (INIS)

    The susceptibility of zirconium and its common alloys to stress corrosion cracking (SCC) in nitric acid was investigated by slow strain-rate and constant deflection techniques. Cracking occurred at 250C over a wide range of acid concentrations and electrochemical potentials. The crack velocity increased slightly with increasing temperature. The failure mode was transgranular and the morphology was similar to SCC failures of zirconium alloys in other environments. The fracture was very orientation-dependent suggesting that it occurs on a single crystallographic plane in the material. The results of the study are not consistent with a hydrogen mechanism for cracking

  3. Temperature effect on Zircaloy-4 stress corrosion cracking

    International Nuclear Information System (INIS)

    Stress corrosion cracking (SCC) susceptibility of Zircaloy-4 alloy in chloride, bromide and iodide solutions with variables as applied electrode potential, deformation rate and temperature have been studied. In those three halide solutions the susceptibility to SCC is only observed at potentials close to pitting potential, the crack propagation rate increases with the increase of deformation rate, and that the temperature has a notable effect only for iodide solutions. For chloride and bromide solutions and temperatures ranging between 20 to 90 C degrees it was not found measurable changes in crack propagation rates. (author)

  4. Susceptibility to Stress Corrosion Cracking of 254SMO SS

    OpenAIRE

    De Micheli Lorenzo; Agostinho Silvia Maria Leite; Trabanelli Giordano; Zucchi Fabrizio

    2002-01-01

    The susceptibility to stress corrosion cracking (SCC) of solubilized and sensitized 254SMO SS was studied in sodium chloride, and sodium fluoride solutions at 80 °C and sulfuric acid solutions in presence of sodium chloride at 25 °C. The influence of salt concentration, pH values and the addition of thiosulfate was examined. The susceptibility to SCC was evaluated by Slow Strain Rate Tests (SSRT), at 1.5 x 10-6 s-1 strain rate. The behavior of 254SMO was compared to those of AISI 316L SS and ...

  5. Stress corrosion of unalloyed steels in geological storage conditions

    International Nuclear Information System (INIS)

    The concept retained for high level and years living radioactive waste disposal is the underground storage. It is then necessary to know the behaviour in time (about 10000 years) of the different constituent elements of the containment. The storage site chosen is the Bures' ones, presenting a clay formation at 600 m of depth. Each compartment is separated of a sufficient distance in order to profit of the thermal dispersion effect in the rock for optimizing the cooling of the package. In this work, has been used an unalloyed steel sur-container. The aim is to understand the resistance of the material under corrosion and loading, and particularly the stress corrosion which is a particular case of cracking assisted by environment. The material studied is a weld of two unalloyed steels obtained by electron beam. Slow traction tests have been carried out in an autoclave in the following experimental conditions: interstitial water in equilibrium with a helium-CO2 mixture 5.4 per thousand under 50 bar and at a temperature of 90 C. The results show an influence of the hydrogen corrosion on the mechanical behaviour of the material and particularly a decrease of the size of the reduction in area, which is practically unexisting in the case of the melted zone. These results are explained into details. (O.M.)

  6. Electron caustic lithography

    Directory of Open Access Journals (Sweden)

    S. M. Kennedy

    2012-06-01

    Full Text Available A maskless method of electron beam lithography is described which uses the reflection of an electron beam from an electrostatic mirror to produce caustics in the demagnified image projected onto a resist–coated wafer. By varying the electron optics, e.g. via objective lens defocus, both the morphology and dimensions of the caustic features may be controlled, producing a range of bright and tightly focused projected features. The method is illustrated for line and fold caustics and is complementary to other methods of reflective electron beam lithography.

  7. 49 CFR 192.929 - What are the requirements for using Direct Assessment for Stress Corrosion Cracking (SCCDA)?

    Science.gov (United States)

    2010-10-01

    ... requirements for using Direct Assessment for Stress Corrosion Cracking (SCCDA)? (a) Definition. Stress... Assessment for Stress Corrosion Cracking (SCCDA)? 192.929 Section 192.929 Transportation Other Regulations... operator using direct assessment as an integrity assessment method to address stress corrosion cracking...

  8. Irradiation assisted stress corrosion cracking of core components

    International Nuclear Information System (INIS)

    A test program on a reactor core material originating from the bottom end of a VVER absorber element is being carried out in aim to characterize the changes in mechanical properties and the occurrence of irradiation assisted stress corrosion cracking in PWR environments by laboratory tests. The mechanical and microstructural properties of the absorber bottom end material have changed due to neutron exposure. However, the material's response to neutron irradiation differs from the usual response of austenitic stainless steels. Yield strength, tensile strength, and dislocation loop density are all lower than expected. An enhancing effect of Ti-carbide precipitations on the defect density is another new finding of interest. High defect density close to the Ti-carbides is presumed to result from the stress/strain field caused by the precipitations. (orig.)

  9. Stress-corrosion cracking in BWR and PWR piping

    International Nuclear Information System (INIS)

    Intergranular stress-corrosion cracking of weld-sensitized wrought stainless steel piping has been an increasingly ubiquitous and expensive problem in boiling-water reactors over the last decade. In recent months, numerous cracks have been found, even in large-diameter lines. A number of potential remedies have been developed. These are directed at providing more resistant materials, reducing weld-induced stresses, or improving the water chemistry. The potential remedies are discussed, along with the capabilities of ultrasonic testing to find and size the cracks and related safety issues. The problem has been much less severe to date in pressurized-water reactors, reflecting the use of different materials and much lower coolant oxygen levels

  10. Advances in research of stress-assisted corrosion fatigue problem

    Institute of Scientific and Technical Information of China (English)

    TANG Zhi-bo; LI Qiang

    2007-01-01

    Ceramic materials are notable for their rigidity, insulation and resistance to hostile environment. Nevertheless, if a stressed ceramic component is exposed to chemical attack, it may suffer from a form of delayed fracture known as static fatigue.From the point of view of a designer, it is clearly desirable to determine the behavior of sub-critical crack growth; the crack path and crack growth rate, as a function of material properties and loading conditions are of particular interest. This paper presents a review of advances in stress assisted corrosion problem in history and its corresponding numerical approaches in the last decades,and finally, comes up with consideration and crucial suggestions for future work.

  11. Detection of stress corrosion damages in accentuates pipework

    International Nuclear Information System (INIS)

    Lifetime extension of nuclear power plants became an important topic and resulted in the requirement of advanced safety management tools. Therefore, the improvement of existing methods of nondestructive testing techniques and the application of innovative procedures contribute to improve safety and reliability of the primary circuit boundary. Especially, advanced techniques for the nondestructive evaluation of austenitic pipes of pressurized nuclear reactors are necessary for the documentation of the integrity of the components. The Institute for Nuclear Engineering and Nondestructive Testing (IKPH) at the University of Hanover has developed an eddy current system with the emphasis on detecting stress corrosion cracks in the ground material of austenitic pipes. The development shows the application of the remote field eddy current technique for the inspection of austenitic pipes from outside. Damages in the pipework could be caused by stress corrosion cracking resulting out of the mechanical loads combined with the corrosive effects of the coolant medium. The pipings concerned are austenitic bents in the primary coolant system of a pressurized water reactor. The grade of the pipes is Nb-stabilized chromium-nickel steel X 10 CrNiNb 18 9; ident. No. 1.4550; ASI 347 having a diameter of 219.1 mm and a wall thickness of 21.3 mm. The project also comprises a computer aided remote field probe design and the experimental verification of the realized sensor systems. The application of FEM-Programs for the numerical calculation of the magnetic fields gives important information about the distribution of the eddy currents within the material. This leads to an optimized probe design in order to archive deep penetrating eddy current fields within the material. Furthermore, the realization of the testing system comprises advanced methods of signal processing for the classification of the eddy current signals. (author)

  12. PERFECT: stress corrosion cracking in reactor core internals

    International Nuclear Information System (INIS)

    The PERFECT is a European Community sponsored integrated project. The project is to develop multi-scale numerical tools capable of simulating the effects of irradiation on mechanical and corrosion properties of materials. SCK-CEN is playing a major role in the project and manages the Internals - Mechanics and corrosion sub-project in which it collaborates majorly with CEA, CIEMAT, FANP, VTT and VUB. This sub-project focuses on the description of the behaviour of reactor internals under irradiation and in contact with the reactor environment. Under these conditions, Irradiation Assisted Stress Corrosion Cracking (IASCC) can become a life-time limiting factor for the component. The objective of the work is to create and verify a predictive code for the behaviour of reactor internals, subject to IASCC. As the life-time of a component, consists of an initiation and propagation period, the IASCC module will be built around a crack initiation and a crack growth module. These modules will be supported by two modules, describing the local environmental (electrochemical) conditions in cracks and crevices and the macroscopic mechanical behaviour of cracked components. The approach to the crack initiation model will be twofold, addressing both the statistical nature of the process and the physical basis of passivity breakdown of the material. The statistical approach will be supported by systematic testing of cold worked and proton irradiated (as the initiation phenomenon is surface dominated) specimens, yielding a Weibull type of relationship between initiation and stress, environment and surface condition. The physical - deterministic - studies will be based on a point defect type of model, describing the interaction between environment and material through the passive film, formed on it. The crack propagation should be modelled by a multi-scale approach, taking into account the following aspects: microscopic crack propagation, mesoscopic crack growth, macroscopic crack

  13. Effect of cold working on the stress corrosion cracking resistance of nickel-chromium-iron alloys

    International Nuclear Information System (INIS)

    In order to grasp the stress corrosion cracking resistance of cold worked nickel base alloys in PWR primary water, the effect of cold working on the stress corrosion cracking resistance of alloys 600, X-750 and 690, in high temperature water, have been studied. Stress corrosion cracking tests were conducted at 3600C (633K) in a simulated PWR primary water for about 12,000 hours (43.2Ms). From the test results, it is concluded that the stress corrosion cracking resistance in the cold worked Alloy 600 at the same applied stress level increases with an increase in cold working ratio, and the cold worked alloys of thermally treated 690 and X-750 have excellent stress corrosion cracking resistance. (Author)

  14. Examination of stress corrosion crack tip microstructures in stainless steel

    International Nuclear Information System (INIS)

    Intergranular Stress Corrosion Cracking of austenitic stainless steel components is one of the major materials degradation processes in Boiling Water Reactors (BWRs) and its dependence on the plant water chemistry has been found to be an important factor. Of the contaminants found in BWR water, sulphate ions have been identified as the most aggressive species and their effect has been studied in previous SKI funded work. Sample preparation techniques developed recently allow the examination of stress corrosion microstructures with analysis on the nanometer scale. A sample has been prepared from material tested earlier and studied using advanced electron microscope techniques. Compositional analyses of the crack-wall oxide indicated that it is (Fe,Cr)2O3 and that this oxide incorporates up to 10 % sulphur and some nickel. However, much more sulphur is stored in a nickel sulphide phase that was found precipitated within the crack. The Fe:Cr ratio in the oxide does vary significantly from area to area. In the crack tip region, the crack was found to be following a grain boundary free of carbide precipitates. A single grain boundary precipitate some 60 nm ahead of the visible crack-tip was found and analysed. This precipitate was enriched in nickel and sulphur. Sulphur was also found within a few nanometers of the visible crack tip. The oxides in the crack-tip region were a mixture of Fe2O3 and (Fe,Cr)2O3 and incorporated nickel metal particles up to 100 nm in diameter

  15. Stress corrosion cracking of nickel-molybdenum alloys

    International Nuclear Information System (INIS)

    Intergranular stress corrosion cracking (SCC) of alloy B-2 (UNS N10665) can occur in dilute acids at low temperatures if there is short range ordering and Ni4Mo in its metallurgical structure. Certain chemistries of alloy B-2 are particularly susceptible to the rapid kinetics of the Ni4Mo transformation, which can occur within minutes of exposure to temperatures of 650--750 C such as during welding. The severity of ordering is dependent on alloy chemistry and thermomechanical processing conditions, and can result in reduced ductility at 700 C, and subsequently to SCC. SCC in the heat-affected zones of welds of fabricated equipment of alloy B-2 have been found to be associated with the presence of Ni4Mo and a short-range ordered structure. Laboratory tests confirmed that only a partially-ordered structure is needed for alloy B-2 to be highly susceptible to SCC in dilute sulfuric acid. A strong correlation was found between degree of ordering, and both susceptibility to SCC and reduced ductility at 700 C. Development of alloy B-3 (UNS N10675) overcomes this thermal instability of alloy B-2, and provides enhanced resistance to SCC in the as-welded condition. In addition to TEM evidence and ductility measurements at 700 C, a stress-corrosion cracking test in boiling 5 wt.% sulfuric acid has also been found useful in evaluating the susceptibility of Ni-Mo alloys to ordering, and to Ni4Mo formation

  16. Stress corrosion cracking behaviour of gas tungsten arc welded super austenitic stainless steel joints

    OpenAIRE

    M. Vinoth Kumar; Balasubramanian, V.; S. RAJAKUMAR; Shaju K. Albert

    2015-01-01

    Super 304H austenitic stainless steel with 3% of copper posses excellent creep strength and corrosion resistance, which is mainly used in heat exchanger tubing of the boiler. Heat exchangers are used in nuclear power plants and marine vehicles which are intended to operate in chloride rich offshore environment. Chloride stress corrosion cracking is the most likely life limiting failure with austenitic stainless steel tubing. Welding may worsen the stress corrosion cracking susceptibility of t...

  17. Stress corrosion cracking and hydrogen embrittlement of thick section high strength low alloy steel.

    OpenAIRE

    Needham, William Donald

    1986-01-01

    An experimental study was conducted to evaluate the corrosion performance of weldments of a high strength low alloy(HSLA) steel in a simulated seawater environment. This steel, designated HSLA80, was developed by the United States Navy for use in ship structural applications. Stress corrosion CRACKING(SCC) and hydrogen embrittlement(HEM) were investigated by conducting 42 Wedge-Opening load(WOL) tests as a function of stress intensity and corrosion potential and 33 Slow Strain Rate(SSR) tests...

  18. THE EFFECT OF HYDROGEN DURING STRESS CORROSION CRACKING AND CORROSION FATIGUE OF Al-Li-Cu ALLOYS IN 3.5 % NaCl SOLUTIONS

    OpenAIRE

    Magnin, T; RebiÈre, M.

    1987-01-01

    Stress corrosion cracking and corrosion fatigue tests at imposed strain rate are conducted on an industrial Al-Li-Cu alloy in a 3.5 % NaCl solution at imposed potential. In the condition of the tests and for short fatigue lifetimes, the anodic dissolution is shown to play the predominant role during corrosion-fatigue at free corrosion potential. Nevertheless a marked hydrogen embrittlement is observed at cathodic potentials during corrosion fatigue of specimens containing superficial microcra...

  19. Environmental Cracking of Corrosion Resistant Alloys in the Chemical Process Industry - A Review

    Energy Technology Data Exchange (ETDEWEB)

    Rebak, R B

    2006-12-04

    A large variety of corrosion resistant alloys are used regularly in the chemical process industry (CPI). The most common family of alloys include the iron (Fe)-based stainless steels, nickel (Ni) alloys and titanium (Ti) alloys. There also other corrosion resistant alloys but their family of alloys is not as large as for the three groups mentioned above. All ranges of corrosive environments can be found in the CPI, from caustic solutions to hot acidic environments, from highly reducing to highly oxidizing. Stainless steels are ubiquitous since numerous types of stainless steels exist, each type tailored for specific applications. In general, stainless steels suffer stress corrosion cracking (SCC) in hot chloride environments while high Ni alloys are practically immune to this type of attack. High nickel alloys are also resistant to caustic cracking. Ti alloys find application in highly oxidizing solutions. Solutions containing fluoride ions, especially acid, seem to be aggressive to almost all corrosion resistant alloys.

  20. Modelling of stress corrosion cracking in zirconium alloys

    International Nuclear Information System (INIS)

    During normal and incidental operating conditions, PWR power plants must comply with the first safety requirement, which is to ensure that the cladding wall is sound. Indeed some severe power transients potentially induce Stress Corrosion Cracking (SCC) of the zirconium alloy clad, due to strong Pellet Cladding Interaction (PCI). Since, at present, the prevention of this risk has some consequences on the French reactors manoeuvrability, a better understanding and forecast of the clad damage related to SCC/PCI is needed. With this aim, power ramp tests are performed in experimental reactors to assess the fuel rod behaviour and evaluate PCI failure risks. To study in detail SCC mechanisms, additional laboratory experiments are carried out on non-irradiated and irradiated cladding tubes. Numerical simulations of these tests have been developed aiming, on the one hand, to evaluate mechanical state variables and, on the other hand, to study consistent mechanical parameters for describing stress corrosion clad failure. The main result of this simulation is the determination of the validity ranges of the stress intensity factor, which is frequently used to model SCC. This parameter appears to be valid only at the onset of crack growth, when crack length remains short. In addition, the role of plastic strain rate and plastic strain as controlling parameters of the SCC process has been analysed in detail using the above mechanical description of the crack tip mechanical fields. Finally, the numerical determination of the first-order parameter(s) in the crack propagation rate law is completed by the development of laboratory tests focused on these parameters. These tests aim to support experimentally the results of the FE simulation. (author)

  1. EFFECTS OF CHEMISTRY AND OTHER VARIABLES ON CORROSION AND STRESS CORROSION CRACKING IN HANFORD DOUBLE SHELL TANKS

    Energy Technology Data Exchange (ETDEWEB)

    BROWN MH

    2008-11-13

    Laboratory testing was performed to develop a comprehensive understanding of the corrosivity of the tank wastes stored in Double-Shell Tanks using simulants primarily from Tanks 241-AP-105, 241-SY-103 and 241-AW-105. Additional tests were conducted using simulants of the waste stored in 241-AZ-102, 241-SY-101, 241-AN-107, and 241-AY-101. This test program placed particular emphasis on defining the range of tank waste chemistries that do not induce the onset of localized forms of corrosion, particularly pitting and stress corrosion cracking. This document summarizes the key findings of the research program.

  2. EFFECTS OF CHEMISTRY AND OTHER VARIABLES ON CORROSION AND STRESS CORROSION CRACKING IN HANFORD DOUBLE-SHELL TANKS

    International Nuclear Information System (INIS)

    Laboratory testing was performed to develop a comprehensive understanding of the corrosivity of the tank wastes stored in Double-Shell Tanks using simulants primarily from Tanks 241-AP-105, 241-SY-103 and 241-AW-105. Additional tests were conducted using simulants of the waste stored in 241-AZ-102, 241-SY-101, 241-AN-107, and 241-AY-101. This test program placed particular emphasis on defining the range of tank waste chemistries that do not induce the onset of localized forms of corrosion, particularly pitting and stress corrosion cracking. This document summarizes the key findings of the research program

  3. Stress-corrosion crack initiation behavior of carbon steel in simulated BWR environment

    International Nuclear Information System (INIS)

    Carbon steels and low-alloy steels are said to possess, even though susceptible to stress-corrosion cracking themselves, conspicuously longer life than weld-sensitized Type 304 stainless steels in actual boiling water reactor (BWR) primary coolant environments of high-temperature, high-purity water containing some dissolved oxygen. This has been examined for a carbon steel pipe material and its weld by conducting uniaxial constant-load tests as a laboratory accelerated test. By statistically analyzing the distribution of stress-corrosion cracking lifetimes and metallographical examining the features of stress-corrosion crack initiation in an SEM, following results have been obtained: (1) the stress-corrosion cracking lifetime obeys the exponential distribution model; (2) stress-corrosion cracks are initiated at the bottom of corrosion pits, and it appears possible to analyze their initiation conditions in terms of stress-intensity calculated regarding the pit as a sharp crack; (3) the microcracks as initiated at the corrosion pit are non-propagative per se, so that it is only when they have grown into a main crack by coalescence with nearby microcracks that steady propagation becomes possible; and (4) both the process of pit initiation and that of microcrack coalescence can be described as a Poisson stochastic process just as for the stainless steels in the same environment, so that the whole process of stress-corrosion crack initiation can be conceived as consisting of these two independent Poisson stochastic processes connected in serial succession

  4. Crack growth and fracture behaviour of stress corrosion cracks of turbine generator steels

    International Nuclear Information System (INIS)

    The object of this investigation was the quantifying of the behaviour of cracks which were induced during service under corrosive media. To investigate the influence of stress corrosion crack configurations on stress intensity factor, six different test materials from 2 and 3.5% NiCrMoV and 2% Cr/1% Ni steels were chosen. The stress corrosion cracks were induced at wedge loaded compact tension specimens in a corrosive media in the laboratory. Fracture mechanics tests as well as fatigue crack growth tests were performed at these specimens. All stress corrosion cracks have an intercrystalline path and a crack length longer than 1 mm; they are multiple and have branched cracks tips. The fracture mechanics tests at these stress corrosion cracks induced in the laboratory and during service of components show that their stress intensity factor is 30 to 70% smaller than the stress intensity factor calculated for single straight cracks too. Theoretical calculations arrived to the same results. Crack initiation and growth behaviour under cyclic loading starting from these stress corrosion cracks results in that the load or the stress intensity range ΔK has to be increased three times larger than the ΔK-threshold value to induce crack initiation. The crack growth velocity influenced by multiple crack tips and multiple growing cracks from these crack tips is much lower than the crack growth velocity of a normal fatigue crack (one crack tip). (orig./MM) With 32 figs

  5. Influence of burnishing on stress corrosion cracking susceptibility of duplex steel

    Directory of Open Access Journals (Sweden)

    J. Łabanowski

    2006-09-01

    Full Text Available Purpose: of the current study was to investigate the usability of burnishing-inducted surface enhancement method for improve the stress corrosion cracking resistance of duplex stainless steel.Design/methodology/approach: The surface layers upon round in cross section specimens were performed through burnishing treatment. Corrosion tests were performed with the use of Slow Strain Rate Test technique in inert (glycerin and aggressive (boiling 35% MgCl2 solution environments.Findings: It was shown that burnishing treatment increases corrosion resistance of the steel. Stress corrosion cracking resistance depends on the magnitude of cold work at surface layers. High level of cold work decreases corrosion resistance.Research limitations/implications: This study does not indicate the optimum stress level and stress distribution in surface layers for the best corrosion resistance. It is necessary to continue the research to determine burnishing parameters for demanded properties of duplex steel surface layers.Practical implications: The burnishing treatment can significantly improve stress corrosion resistance of specified parts of chemical installations working in the contact with aggressive media. Such parts as valve parts or propeller shafts can be successfully protected against corrosion attack.Originality/value: Burnishing surface enhancement for constructional parts made of duplex stainless steels exposed to corrosive environments has not been reported in literature. Application of this technology can increase life-time of chemical installation devices and improve their reliability.

  6. Stress corrosion evaluation of powder metallurgy aluminum alloy 7091 with the breaking load test method

    Science.gov (United States)

    Domack, Marcia S.

    1987-01-01

    The stress corrosion behavior of the P/M aluminum alloy 7091 is evaluated in two overaged heat treatment conditions, T7E69 and T7E70, using an accelerated test technique known as the breaking load test method. The breaking load data obtained in this study indicate that P/M 7091 alloy is highly resistant to stress corrosion in both longitudinal and transverse orientations at stress levels up to 90 percent of the material yield strength. The reduction in mean breaking stress as a result of corrosive attack is smallest for the more overaged T7E70 condition. Details of the test procedure are included.

  7. Corrosion

    Science.gov (United States)

    Slabaugh, W. H.

    1974-01-01

    Presents some materials for use in demonstration and experimentation of corrosion processes, including corrosion stimulation and inhibition. Indicates that basic concepts of electrochemistry, crystal structure, and kinetics can be extended to practical chemistry through corrosion explanation. (CC)

  8. Influence of residual compression stresses on the stress corrosion cracking behaviour of turbine rotor disc material

    International Nuclear Information System (INIS)

    In this project the influence of residual compression stresses on the stress corrosion cracking behaviour of the turbine disc steel 26 NiCrMoV 14 5 (Rp0.2 = 850 N/mm2) was investigated. The residual compression stresses were produced by shot peening and rolling. Shot peening results in residual compression stresses of -500 N/mm2 in the surface. In a depth from 600 μm there still exist stresses from -100 N/mm2. CERT experiments with shot peened and unpeened specimens under hydrogen charging conditions were performed to see, whether residual compression stresses prevent the diffusion of hydrogen into the metal. This could not be established with these experimental parameters. Stress corrosion tests were carried out with shot peened tensile specimens and modified CT 2 specimens. The shot peened cylindrical specimens dependent on the stress level, have a time to failure which is ten times and more longer in 35% NaOH + 3,5% NaCl solution in comparison to untreated specimens. The CT2 specimens had a shot peened surface and a rolled bore hole of 20 mm. The residual compression stresses in the bore hole are produced by rolling in tangential direction. Compression stresses in the surface of -400 N/mm2 can be realized, with a maximum of -600 N/mm2 in a depth of 600 μm. In a depth of 1500μm there still exist stresses of -100 N/mm2. The CT 2 specimens were charged with hydrogen and also testet in 35% NaOH + 3,3% NaCl solution. Cracking occurred within 200 test hours at the bores of the samples which were not rolled. Crack initiation was not found in the bores of the samples which were rolled. The results show, that residual compression stresses in the critical surface regions can prevent stress corrosion cracking on turbine disks. (orig./MM) With 24 annexes

  9. Mechanistic differences between transgranular and intergranular stress corrosion cracking

    International Nuclear Information System (INIS)

    Constant extension rate tests (CERT or CSRT) with the strain rate (SR) covering a 7 orders of magnitude range were applied to the study of many systems. In particular, the kinetics of SCC were measured via the stress corrosion (SCC) crack propagation rate (CPR). The main experimental findings are: a) increasing SR produces a monotonic (logarithmic) increase in CPR; b) the slopes α in log CPR vs. log SR plots take distinct values depending on the morphology: intergranular (IG) cracks are more steeply accelerated by SR than transgranular (TG), with αlG=0.4 to 0.7 and αTG=0.2 to 0.3; c) an increase in SR only shifts the log CPR vs. potential curves to higher CPR values, without changing its shape. Quantitative evaluation shows that dislocations piled-up at grain boundaries may combine with the surface mobility mechanism to give the experimental results. (author)

  10. Metallurgical evaluation of stress corrosion cracking in large diameter piping

    International Nuclear Information System (INIS)

    Ultrasonic testing (UT) of stainless-steel piping in the primary coolant water system of Savannah River Site (SRS) reactors indicates the presence of short, partly through-wall stress corrosion cracks in the heat-affected zone of approximately 7% of the circumferential pipe welds. These cracks are thought to develop by intergranular nucleation and mixed mode propagation. Metallographic evaluations have confirmed the UT indications of crack size and provided evidence that crack growth involved the accumulation of chloride ions inside the growing crack. It is postulated that the development of an oxygen depletion cell inside the crack results in the migration of chloride ions to the crack tip to balance the accumulation of positively charged metallic ions. The results of this metallurgical evaluation, combined with structural assessments of system integrity, support the existence of leak-before-break conditions in the SRS reactor piping system

  11. Two-phase flow experiments through intergranular stress corrosion cracks

    International Nuclear Information System (INIS)

    Experimental studies of critical two-phase water flow, through simulated and actual intergranular stress corrosion cracks, were performed to obtain data to evaluate a leak flow rate model and investigate acoustic transducer effectiveness in detecting and sizing leaks. The experimental program included a parametric study of the effects of crack geometry, fluid stagnation pressure and temperature, and crack surface roughness on leak flow rate. In addition, leak detection, location, and leak size estimation capabilities of several different acoustic transducers were evaluated as functions of leak rate and transducer position. This paper presents flow rate data for several different cracks and fluid conditions. It also presents the minimum flows rate detected with the acoustic sensors and a relationship between acoustic signal strength and leak flow rate

  12. Stress Corrosion Cracking Behavior of Cast Stainless Steels

    International Nuclear Information System (INIS)

    Casting of austenitic stainless steels offers the possibility of directly producing large and/or relatively complex structures, such as the first wall shield modules or the diverter cassette for the ITER fusion reactor. Casting offers major cost savings when compared to fabrication via welding of quarter modules machined from large forgings. However, the strength properties of such cast components are typically considered inferior to those of conventionally forged and annealed components. To improve and validate cast stainless steel as a substitute for wrought stainless steel, a development and testing program was initiated, utilizing nitrogen and manganese additions to promote improved performance. This paper focuses on the response of the first set of developmental alloys to neutron-irradiation and susceptibility to stress corrosion cracking. These cast materials may also have applications for different components in light water reactors. Results showed that all steels exhibited irradiation-induced hardening and a corresponding drop in ductility, as expected, although there is still considerable ductility in the irradiated samples. The cast steels all exhibited reduced hardening in comparison to a wrought reference steels, which may be related to a larger grain size. Higher nitrogen contents did not negatively influence irradiation performance. Regarding stress corrosion cracking susceptibility, the large difference in grain size limits the comparison between wrought and cast materials, and inclusions in a reference and archive cast alloy tests complicate analysis of these samples. Results suggest that the irradiated archive heat was more susceptible to cracking than the modified alloys, which may be related to the more complex microstructure. Further, the results suggest that the modified cast steel is at least as SCC resistant as wrought 316LN. The beneficial effect of nitrogen on the mechanical properties of the alloys remains after irradiation and is not

  13. Stress corrosion cracking of candidate materials for nuclear waste containers

    International Nuclear Information System (INIS)

    Types 304L and 316L stainless steel (SS), Incoloy 825, Cu, Cu-30%Ni, and Cu-7%Al have been selected as candidate materials for the containment of high-level nuclear waste at the proposed Yucca Mountain Site in Nevada. The susceptibility of these materials to stress corrosion cracking has been investigated by slow-strain-rate tests (SSRTs) in water which simulates that from well J-13 (J-13 water) and is representative of the groundwater present at the Yucca Mountain site. The SSRTs were performed on specimens exposed to simulated J-13 water at 93 degree C and at a strain rate 10-7 s-1 under crevice conditions and at a strain rate of 10-8 s-1 under both crevice and noncrevice conditions. All the tests were interrupted after nominal elongation strains of 1--4%. Examination by scanning electron microscopy showed some crack initiation in virtually all specimens. Optical microscopy of metallographically prepared transverse sections of Type 304L SS suggests that the crack depths are small (<10 μm). Preliminary results suggest that a lower strain rate increases the severity of cracking of Types 304L and 316L SS, Incoloy 825, and Cu but has virtually no effect on Cu-30%Ni and Cu-7%Al. Differences in susceptibility to cracking were evaluated in terms of a stress ratio, which is defined as the ratio of the increase in stress after local yielding in the environment to the corresponding stress increase in an identical test in air, both computed at the same strain. On the basis of this stress ratio, the ranking of materials in order of increasing resistance to cracking is: Types 304L SS < 316L SS < Incoloy 825 congruent Cu-30%Ni < Cu congruent Cu-7%Al. 9 refs., 12 figs., 7 tabs

  14. Stress corrosion cracking of candidate waste container materials; Final report

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.Y.; Maiya, P.S.; Soppet, W.K.; Diercks, D.R.; Shack, W.J.; Kassner, T.F. [Argonne National Lab., IL (United States)

    1992-06-01

    Six alloys have been selected as candidate container materials for the storage of high-level nuclear waste at the proposed Yucca mountain site in Nevada. These materials are Type 304L stainless steel (SS). Type 316L SS, Incoloy 825, phosphorus-deoxidized Cu, Cu-30%Ni, and Cu-7%Al. The present program has been initiated to determine whether any of these materials can survive for 300 years in the site environment without developing through-wall stress corrosion cracks. and to assess the relative resistance of these materials to stress corrosion cracking (SCC)- A series of slow-strain-rate tests (SSRTs) and fracture-mechanics crack-growth-rate (CGR) tests was performed at 93{degree}C and 1 atm of pressure in simulated J-13 well water. This water is representative, prior to the widespread availability of unsaturated-zone water, of the groundwater present at the Yucca Mountain site. Slow-strain-rate tests were conducted on 6.35-mm-diameter cylindrical specimens at strain rates of 10-{sup {minus}7} and 10{sup {minus}8} s{sup {minus}1} under crevice and noncrevice conditions. All tests were interrupted after nominal elongation strain of 1--4%. Scanning electron microscopy revealed some crack initiation in virtually all the materials, as well as weldments made from these materials. A stress- or strain-ratio cracking index ranks these materials, in order of increasing resistance to SCC, as follows: Type 304 SS < Type 316L SS < Incoloy 825 < Cu-30%Ni < Cu and Cu-7%Al. Fracture-mechanics CGR tests were conducted on 25.4-mm-thick compact tension specimens of Types 304L and 316L stainless steel (SS) and Incoloy 825. Crack-growth rates were measured under various load conditions: load ratios M of 0.5--1.0, frequencies of 10{sup {minus}3}-1 Hz, rise nines of 1--1000s, and peak stress intensities of 25--40 MPa{center_dot}m {sup l/2}.

  15. Intergranular failures of Alloy 600 in high temperature caustic environments

    International Nuclear Information System (INIS)

    This paper describes the results of our investigation of two commonly observed modes of failure of Alloy 600 in high temperature caustic environment namely, intergranular stress corrosion cracking (IGSCC) and intergranular attack (IGA). Specimens are studied as C-rings under constant deflection, wires with and without any externally applied load, and as straining electrodes. The potential dependence of average crack propagation rate is established in a single test by using several C-rings held at different potentials, by using a modification of the static potential gradient method of Seys and Van Haute. SCC appears to be governed by a film rupture mechanism and its propagation rate is significantly influenced by the electrochemical potential and associated surface film formation. The maximum crack propagation rate for C-rings and constant load specimens is very similar but much smaller than that calculated for a straining electrode at the same potential. IGA occurs over a wide range of potential - starting from a few tens of millivolts cathodic to the corrosion potential up to the lower end of anodic potentials normally required for SCC. IGA seems to be rather independent of stress and is generally more pronounced in the crevice area under the nuts used in C-rings. Examination of several creviced coupons shows that outside the crevice, enrichment of iron and chromium occurs on the surface as the potential is raised anodically, whereas the Ni:Fe and Ni:Cr ratios remain relatively independent of potential within the crevice

  16. Development of a Stress Corrosion Cracking Test Methodology Using Tube-shaped Specimens

    OpenAIRE

    SATO Yasumoto; He, Xue; Takeda, Yoichi; Shoji, Tetsuo

    2007-01-01

    Stress corrosion cracking (SCC) is one of the greatest concerns in nuclear aging and degradation, and studies on the measurement of stress corrosion crack growth rates (CGR) and the effects of environmental, material, and mechanical parameters on the CGR have been performed using mainly fracture mechanics specimens. However, the stress states for the fracture mechanics specimens are different from that of real field components and there is concern about the applicability of the data obtained...

  17. Ultrasonic Impact Treatment to Improve Stress Corrosion Cracking Resistance of Welded Joints of Aluminum Alloy

    Science.gov (United States)

    Yu, J.; Gou, G.; Zhang, L.; Zhang, W.; Chen, H.; Yang, Y. P.

    2016-07-01

    Stress corrosion cracking is one of the major issues for welded joints of 6005A-T6 aluminum alloy in high-speed trains. High residual stress in the welded joints under corrosion results in stress corrosion cracking. Ultrasonic impact treatment was used to control the residual stress of the welded joints of 6005A-T6 aluminum alloy. Experimental tests show that ultrasonic impact treatment can induce compressive longitudinal and transverse residual stress in the welded joint, harden the surface, and increase the tensile strength of welded joints. Salt-fog corrosion tests were conducted for both an as-welded sample and an ultrasonic impact-treated sample. The surface of the treated sample had far fewer corrosion pits than that of the untreated sample. The treated sample has higher strength and lower tensile residual stress than the untreated sample during corrosion. Therefore, ultrasonic impact treatment is an effective technique to improve the stress corrosion cracking resistance of the welded joints of 6005A-T6 aluminum alloy.

  18. Interplay of microbiological corrosion and alloy microstructure in stress corrosion cracking of weldments of advanced stainless steels

    Indian Academy of Sciences (India)

    R K Singh Raman

    2003-06-01

    This paper presents an overview of the phenomenon of stress corrosion cracking (SCC) of duplex stainless steels and their weldments in marine environments and the potential role of microbial activity in inducing SCC susceptibility. As a precursor to the topic the paper also reviews the performance of the traditional corrosion-resistant alloys and their weldments and the necessity of using duplex stainless steels (DSS), in order to alleviate corrosion problems in marine environments. Given that the performance of weldments of such steels is often unsatisfactory, this review also assesses the research needs in this area. In this context the paper also discusses the recent reports on the role of microorganisms in inducing hydrogen embrittlements and corrosion fatigue.

  19. Hydrogen embrittlement and stress corrosion cracking in metals

    International Nuclear Information System (INIS)

    The objective of this report is to elucidate the mechanism for hydrogen embrittlement (HE) and stress corrosion cracking (SCC) in metals. To this end, we investigate the common features between delayed hydride cracking (DHC) in zirconium alloys and HE in metals with no precipitation of hydrides including Fe base alloys, Nickel base alloys, Cu alloys and Al alloys. Surprisingly, as with the crack growth pattern for the DHC in zirconium alloy, the metals mentioned above show a discontinuous crack growth, striation lines and a strong dependence of yield strength when exposed to hydrogen internally and externally. This study, for the first time, analyzes the driving force for the HE in metals in viewpoints of Kim's DHC model that a driving force for the DHC in zirconium alloys is a supersaturated hydrogen concentration coming from a hysteresis of the terminal solid solubility of hydrogen, not by the stress gradient, As with the crack growing only along the hydride habit plane during the DHC in zirconium alloys, the metals exposed to hydrogen seem to have the crack growing by invoking the dislocation slip along the preferential planes as a result of some interactions of the dislocations with hydrogen. Therefore, it seems that the hydrogen plays a role in inducing the slip only on the preferential planes so as to cause a strain localization at the crack tip. Sulfur in metals is detrimental in causing a intergranular cracking due to a segregation of the hydrogens at the grain boundaries. In contrast, boron in excess of 500 ppm added to the Ni3Al intermetallic compound is found to be beneficial in suppressing the HE even though further details of the mechanism for the roles of boron and sulfur are required. Carbon, carbides precipitating semi-continuously along the grain boundaries and the CSL (coherent site lattice) boundaries is found to suppress the intergranular stress corrosion cracking (IGSCC) in Alloy 600. The higher the volume fraction of twin boundaries, the more

  20. Assessment of stress corrosion cracking in prestressing strands using AE technique

    OpenAIRE

    PERRIN, Marianne; Gaillet, Laurent; TESSIER, Christian; IDRISSI, Hassane

    2008-01-01

    Detecting corrosion of prestressing strands in concrete structures requires non-destructive techniques like acoustic emission (AE), which allows the monitoring of active defects of the structures. The aim of this work is to adapt AE to structural characteristics of bridges, to detect and localize stress corrosion cracking (hydrogen embrittlement, HE) of tendons. Accelerated corrosion tests with ammonium thiocyanate on tensioned cables have permitted to validate AE system capacity to detect s...

  1. Influence of hydrogen on corrosion and stress induced cracking of stainless steel

    OpenAIRE

    Kivisäkk, Ulf

    2010-01-01

    Hydrogen is the smallest element in the periodical table. It has been shown in several studies that hydrogen has a large influence on the corrosion and cracking behaviour of stainless steels. Hydrogen is involved in several of the most common cathode reactions during corrosion and can also cause embrittlement in many stainless steels. Some aspects of the effect of hydrogen on corrosion and hydrogen-induced stress cracking, HISC, of stainless steels were studied in this work. These aspects rel...

  2. Radiation-induced grain boundary segregation effect on stress corrosion cracking in steel

    International Nuclear Information System (INIS)

    Stress corrosion cracking of stainless steels 304L, 316 and 316L irradiated at 673 K up to the dose of 0.8 dpa is studied. It is shown that radiation-induced reduction of chromium content in the grain boundary results in corrosion cracking of the steels in water containing dissolved oxygen. Corrosion cracking in water with dissolved hydrogen occurs in the context of radiation-induced strengthening of the steel and change in its microstructure

  3. Stress corrosion characterization of turbine rotor materials: phase I

    International Nuclear Information System (INIS)

    This report describes a research program conducted to determine susceptibility of steels used in low-pressure (LP) turbine rotors of power plants to stress corrosion cracking (SCC) in LP turbine environments. The program included slow-strain-rate and sustained-load SCC tests on samples from two 3.5 NiCrMoV rotor forgings. Environments included pure NaOH solutions, 3.5% NaCl, pure water, and mixtures of NaOH and NaCl, Na2S, Na2SO4, or CuO. Tests were conducted over a temperature range of 38 to 2040C (100 to 4000F). Supplementary electrochemical data also were generated. Slow-strain-rate test results indicate that the minimum NaOH concentration required to produce detectable SCC decreases with increasing temperature. Addition of small amounts of NaCl reduced the concentration of NaOH necessary to produce SCC at 1570C (3150F). Pure 3.5% NaCl induced SCC at 1210C (2500F). SCC was not detected in either steel in tests in pure water at 1570C (3150F). Sustained-load test results indicate that long exposure times and high stress levels are necessary to initiate detectable cracking in NaOH solutions

  4. Allowing for surface preparation in stress corrosion cracking modelling

    International Nuclear Information System (INIS)

    When a 600 alloy component is significantly deformed during installation, by welding, rolling, bending, its stress corrosion cracking in Pressurized Water Nuclear Reactor's primary coolant, is significantly changed by the initial surface treatment. Therefore, the crack initiated time may be reduced by several orders of magnitude for certain surfaces preparations. Allowing for cold working of the surface, for which modelling is proposed, depends less on the degree of cold work then on the depths of the hardened layers. Honing hardens the metal over depths of about one micron for vessel head penetrations, for example, and has little influence on subsequent behaviour after the part deforms. On the other hand, coarser turning treatment produces cold worked layers which can reach several tens of microns and can very significantly reduce the initiation time compared to fine honing. So evaluation after depths of hardening is vital on test pieces for interpreting laboratory results as well as on service components for estimating their service life. Suppression by mechanical or chemical treatment of these layers, after deformation, seems to be the most appropriate solution for reducing over-stressing connected with surface treatment carried out before deformation. (author)

  5. Stress Corrosion Cracking of High-strength Drill Pipe in Sour Gas Well

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhi; LI Jing; ZENG Dezhi; HU Junying; HOU Duo; ZHANG Liehui; SHI Taihe

    2014-01-01

    In high sour gas reservoir drilling process, it happens occasionally that high-strength drill pipe suffers brittle fracture failure due to stress corrosion cracking, and poses serious hazard to drilling safety. To solve this problem, this paper studied the stress corrosion cracking mechanism and influencing factors of high-strength drill pipe in sour environment with hydrogen permeation experiments and tensile tests. We simulated practical conditions in laboratory and evaluated the stress corrosion cracking performance of the high-strength drill pipe under conditions of high stress level. For the problems occurring in use of high-strength drill pipe on site, the paper proposed a technical measure for slower stress corrosion cracking.

  6. Rapid reconstruction of natural stress corrosion cracking from Eddy current NDT data

    International Nuclear Information System (INIS)

    This paper reports the reconstruction of a stress corrosion cracking from Eddy current signals. The stress corrosion cracking was found in the steam generator tube of a nuclear power plant during ISI period, and its cross-sectional profile is reconstructed with the aid of computer simulation. A crack is modeled as a region with uniform conductivity inside, and the boundary profile and the conductivity of the crack are reconstructed. An inversion algorithm based upon the tabu search is utilized in this study. It is demonstrated in this paper that the profile of stress corrosion cracks can be well estimated from Eddy current signals within a reasonable computational time. (orig.)

  7. Stress corrosion cracks behavior and its protective technique under landfill disposal environment of the radioactive wastes

    International Nuclear Information System (INIS)

    The effects of water and addition of chemicals on the stress corrosion cracks of granite from Oshima, Ehime Prefecture, were studied. The cracking behavior was investigated by in situ observation by SEM. The stress corrosion cracks were affected by anisotropy and it grew quickly in direction of the weakest linkage. The stress corrosion cracking index and cracking velocity under the constant load were changed significantly by ζ potential. It was proved by SEM that the main mode of cracking growth was the intergranular fracture under the dry condition. (S.Y.)

  8. Demonstration through EPR tests of the sensitivity of austeno-ferritic steels to intergranular corrosion and stress corrosion cracking

    International Nuclear Information System (INIS)

    Duplex stainless steels can be sensitised to intergranular corrosion and stress corrosion cracking (SCC) under some conditions (heat treatments, welding). The aim of this work is to contribute to the validation of the EPR (Electrochemical Potentiodynamic Reactivation) test in order to determine conditions for normalisation. This method, based on the dissolution of chromium depleted areas due to precipitation of σ-phase, provides a degree of sensitisation to intergranular corrosion. The test is broaden considering the mechanical stress by the way of slow strain rate tests, performed in chloride magnesium and in a solution similar to the EPR solution. A metallurgical study puts on the precipitates and the structural modifications due to welding and heat treatments, in order to make a critical analysis of the EPR test. (author)

  9. Some considerations of radiation effects on stress corrosion cracking of fusion reactor materials

    International Nuclear Information System (INIS)

    The purpose of this evaluation was to identify potential synergisms between irradiation phenomena and stress corrosion processes. There have been few studies on the stress corrosion behavior of irradiated material and no reported studies of in-situ stress corrosion. Therefore, an assessment of potential irradiation and stress corrosion synergisms was undertaken to identify possible concerns for fusion reactor materials. Published research on radiation enhanced corrosion was reviewed and it was concluded that radiolysis is not expected to increase the corrosion rate of fusion reactor materials by more than a factor of 3; however, hydrogen uptake could increase significantly in ferritic, refractory and reactive alloys. The effect of irradiation enhanced creep on intergranular stress corrosion cracking, IGSCC, was modeled and it was concluded that irradiation creep could significantly increase the crack growth rate at stresses below the yield strength. A phosphorus segregation induced IGSCC process was also evaluated and shown that radiation induced phosphorus segregation could dominate all other IGSCC effects. Calculated K/sub IC/ and K/sub TH/ results for HT-9 were reviewed and compared with published K/sub IC/ results from the ADIP program. This comparison suggests that the model used to calculate the effects of increasing yield strength and grain boundary segregation on K/sub IC/ gives calculated values significantly less than the experimental results

  10. The role of stress in self-ordered porous anodic oxide formation and corrosion of aluminum

    Science.gov (United States)

    Capraz, Omer Ozgur

    The phenomenon of plastic flow induced by electrochemical reactions near room temperature is significant in porous anodic oxide (PAO) films, charging of lithium batteries and stress-corrosion cracking (SCC). As this phenomenon is poorly understood, fundamental insight into flow from our work may provide useful information for these problems. In-situ monitoring of the stress state allows direct correlation between stress and the current or potential, thus providing fundamental insight into technologically important deformation and failure mechanisms induced by electrochemical reactions. A phase-shifting curvature interferometry was designed to investigate the stress generation mechanisms on different systems. Resolution of our curvature interferometry was found to be ten times more powerful than that obtained by state-of-art multiple deflectometry technique and the curvature interferometry helps to resolve the conflicting reports in the literature. During this work, formation of surface patterns during both aqueous corrosion of aluminum and formation of PAO films were investigated. Interestingly, for both cases, stress induced plastic flow controls the formation of surface patterns. Pore formation mechanisms during anodizing of the porous aluminum oxide films was investigated . PAO films are formed by the electrochemical oxidation of metals such as aluminum and titanium in a solution where oxide is moderately soluble. They have been used extensively to design numerous devices for optical, catalytic, and biological and energy related applications, due to their vertically aligned-geometry, high-specific surface area and tunable geometry by adjusting process variables. These structures have developed empirically, in the absence of understanding the process mechanism. Previous experimental studies of anodizing-induced stress have extensively focused on the measurement of average stress, however the measurement of stress evolution during anodizing does not provide

  11. Evaluation of applicability on multi-axis residual stress formed by hard sphere indentation for stress corrosion cracking test

    International Nuclear Information System (INIS)

    A multi-axis stress field is indispensable for quick and quantitative evaluation of stress corrosion cracking for constructional materials and weld joints of existing industrial plants. The applicability of multi-axis residual stress field formed by pushing of a hard sphere ball made of WC into stress corrosion cracking tests was evaluated. The Brinell type hard sphere ball was stuffed into small flat-plate of type 304SS. The residual stress and displacement around the indentation were measured using an X-ray diffraction method and a displacement meter. Numerical analysis by the finite element method was conducted in order to compare with the experimental results. The numerical analysis was comparatively in agreement with the experimental results. A hard sphere ball diameter, a specimen holder hole diameter, specimen thickness, and an indentation depth were selected by numerical analysis to optimize the residual stress of specimen. The stress corrosion cracking test in chloride solution was performed using the specimen with optical residual stress condition. It is confirmed that the multi-axis residual stress field was useful in quick and quantitative stress corrosion cracking test by comparing the initiation of cracks with the distribution of residual stress obtained by numerical analysis. (author)

  12. Stress corrosion cracking behavior of Ni28Mo-alloys: Recent research data

    International Nuclear Information System (INIS)

    Nickel-molybdenum alloys of the type Ni28Mo/alloy B-2 may fail in service due to stress corrosion cracking in components, where a high heat input during manufacturing or repair such as repeated welding operations may have occurred. Therefore, various tests in solution annealed and aged condition on different alloy compositions have been done with respect to stress corrosion resistance, uniform and intergranular corrosion and time-temperature-sensitization behavior. Stress corrosion sensitivity of the Ni28Mo materials in the aged condition is dependent on the alloys degree of ordering which is delayed by increasing alloying additions of iron and chromium. Therefore, in order to improve the stress corrosion resistance these alloying additions have to be increased beyond the limits being set for the current alloy B-2 grade. Consequently, a new Ni28Mo alloy type, alloy B-4 is proposed being alloyed with 2--5 wt % Fe and 0.5--1.5 wt % Cr. This new Ni28Mo alloy exhibits a considerably improved resistance to stress corrosion cracking which is achieved without impairing the resistance to overall uniform and to intergranular corrosion. Resistance to sensitization is also improved

  13. Study and Computer Modelling of Stress corrosion cracking during DET test

    Czech Academy of Sciences Publication Activity Database

    Blahetová, M.; Lasek, S.; Blaheta, Radim

    2005-01-01

    Roč. 48, č. 1 (2005), s. 9-13. ISSN 0474-8484 Institutional research plan: CEZ:AV0Z30860518 Keywords : stress corrosion cracking * mathematical modelling Subject RIV: JL - Materials Fatigue, Friction Mechanics

  14. Stress Corrosion Cracking of Basalt/Epoxy Composites under Bending Loading

    Science.gov (United States)

    Shokrieh, Mahmood M.; Memar, Mahdi

    2010-04-01

    The purpose of this research is to study the stress corrosion behavior of basalt/epoxy composites under bending loading and submerged in 5% sulfuric acid corrosive medium. There are limited numbers of research in durability of fiber reinforced polymer composites. Moreover, studies on basalt fibers and its composites are very limited. In this research, mechanical property degradation of basalt/epoxy composites under bending loading and submerged in acidic corrosive medium is investigated. Three states of stress, equal to 30%, 50% and 70% of the ultimate strength of composites, are applied on samples. High stress states are applied to the samples to accelerate the testing procedure. Mechanical properties degradation consists of bending strength, bending modulus of elasticity and fracture energy of samples are examined. Also, a normalized strength degradation model for stress corrosion condition is presented. Finally, microscopic images of broken cross sections of samples are examined.

  15. Acoustic emission reviling and danger level evaluation of stress corrosion cracking in stainless steel pipes

    International Nuclear Information System (INIS)

    Breakdowns and catastrophic damage occurring during the operation of nuclear power stations pipelines cause substantial economic and social loss annually throughout the world. Stress corrosion, vibration, fatigue, erosion, water shock, dynamic load, construction defects/errors are the main causes of pipes failures. For these reasons and in view of the age of nuclear power station pipes, there is an increased interest in finding means to prevent potential pipe failures. Nevertheless, statistical data of pipe failures continues to show significant numbers of accidents mainly due to stress corrosion cracking (about 65-80% of total number). To this end, a complex of investigations was carried out for the reliable AE diagnosis of pipes undergone stress corrosion cracking. These include: finding AE indications (fingerprints) of flaws developing in the metal in original condition as well as in metal subjected to stress corrosion; preparing AE criteria for evaluating the danger level of defects. (author)

  16. Effect of Surface Stress Mitigation on the Corrosion Behavior of Alloy 22

    Energy Technology Data Exchange (ETDEWEB)

    Fix, D V; Yilmaz, A; Wong, L L; Estill, J C; Rebak, R B

    2004-11-10

    When metallic plates are welded, for example using the Gas Tungsten Arc Welding (GTAW) process, residual tensile stresses may develop in the vicinity of the weld seam. Processes such as Low Plasticity Burnishing (LPB) and Laser Shock Peening (LSP) could be applied locally to eliminate the residual stresses produced by welding. In this study, Alloy 22 (N06022) plates were welded and then the above-mentioned surface treatments were applied to eliminate the residual tensile stresses. The aim of the current study was to comparatively test the corrosion behavior of as-welded (ASW) plates with the corrosion behavior of plates with stress mitigated surfaces. Immersion and electrochemical tests were performed. Results from both general and localized corrosion tests show that the corrosion resistance of the mitigated plates was not affected by the surface treatments applied.

  17. Investigation for anti-stress corrosion cracking of SUS 304 stainless steel weldments

    International Nuclear Information System (INIS)

    The anti-stress corrosion cracking method by current density of cathodic protection was studied for stress corrosion cracking of SUS 304 stainless steel weldments in the environment of various MgCl2 boiling solution (wt%). Main results obtained are as follows: 1) Under the conditions below the critical current density of cathodic protection for anti-stress corrosion cracking, the latent time of crack initiation of weld heat affected zone occurs more rapidly than that of base metal because of the phenomenon of sensitizing and softening caused by weld heat cycles. 2) Under the constant current density of cathodic protection, the anti-stress corrosion cracking of weld heat affected zone can be controlled by critical concentration of MgCl2 solution. 3) The critical current density of cathodic protection of weld heat affected zone increases in proportion to concentration of MgCl2 solution. (Author)

  18. EXPERT PANEL OVERSIGHT COMMITTEE ASSESSMENT OF FISCAL YEAR 2008 CORROSION AND STRESS CORROSION CRACKING SIMULANT TESTING PROGRAM

    International Nuclear Information System (INIS)

    The Expert Panel Oversight Committee (EPOC) has been overseeing the implementation of selected parts of Recommendation III of the final report, Expert Panel workshop for Hanford Site Double-Shell Tank Waste Chemistry Optimization, RPP-RPT-22126. Recommendation III provided four specific requirements necessary for Panel approval of a proposal to revise the chemistry control limits for the Double-Shell Tanks (DSTs). One of the more significant requirements was successful performance of an accelerated stress corrosion cracking (SCC) experimental program. This testing program has evaluated the optimization of the chemistry controls to prevent corrosion in the interstitial liquid and supernatant regions of the DSTs

  19. Effect of stress corrosion cracking on stress-strain response of steel wires used in prestressed concrete beams

    International Nuclear Information System (INIS)

    This paper presents an experimental study of the stress corrosion cracking (SCC) process on 8-mm-diameter wires which are used industrially in precast concrete prestressed by pre-tension. The service life of steel wires under accelerated SCC and the reduction of their mechanical performance are studied. A dynamic analysis to detect the damage to corroded wire due to SCC before brittle failure and the influence of internal defects on the service life of stress corroded wire are also presented. The study shows that stress corrosion cracking is characterized by an evolution to SCC from pitting corrosion attacks that result in the development of both micro-cracking and micro-voids in the steel bulk. The stress level does not influence the composition of corrosion products. It is a major factor of SCC development, leading to a considerable reduction in the ultimate strain and thus to brittle failure of the corroded wires. Local defects on the steel surface increase the SCC effect due to stress corrosion concentration. A reduction in the elastic modulus and the elastic limit, which may reach 25% and 15%, respectively, can be expected due to steel micro-cracking. No damage detection through mechanical analysis seems possible before the brittle failure occurs as the corrosion is very localized and so does not globally reduce the tension in the wires.

  20. 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)

  1. Stress Corrosion Cracking of Steel and Aluminum in Sodium Hydroxide: Field Failure and Laboratory Test

    OpenAIRE

    Prawoto, Y.; Sumeru, K.; W.B. WAN NIK

    2012-01-01

    Through an investigation of the field failure analysis and laboratory experiment, a study on (stress corrosion cracking) SCC behavior of steel and aluminum was performed. All samples were extracted from known operating conditions from the field failures. Similar but accelerated laboratory test was subsequently conducted in such a way as to mimic the field failures. The crack depth and behavior of the SCC were then analyzed after the laboratory test and the mechanism of stress corrosion cracki...

  2. OBSERVATIONS OF STRESS CORROSION CRACKING BEHAVIOUR IN SUPER DUPLEX STAINLESS STEEL

    OpenAIRE

    Al-Rabie, Mohammed

    2011-01-01

    The new generation of highly alloyed super duplex stainless steels such as Zeron 100 are preferable materials for industrial applications demanding high strength, toughness and superior corrosion resistance, especially against stress corrosion cracking (SCC). SCC is an environmentally assisted failure mechanism that occurs due to exposure to an aggressive environment while under a tensile stress. The mechanism by which SCC of duplex stainless steel is expected to suffer depends on the combina...

  3. Stress corrosion cracking of an aluminum alloy used in external fixation devices.

    Science.gov (United States)

    Cartner, Jacob L; Haggard, Warren O; Ong, Joo L; Bumgardner, Joel D

    2008-08-01

    Treatment for compound and/or comminuted fractures is frequently accomplished via external fixation. To achieve stability, the compositions of external fixators generally include aluminum alloy components due to their high strength-to-weight ratios. These alloys are particularly susceptible to corrosion in chloride environments. There have been several clinical cases of fixator failure in which corrosion was cited as a potential mechanism. The aim of this study was to evaluate the effects of physiological environments on the corrosion susceptibility of aluminum 7075-T6, since it is used in orthopedic external fixation devices. Electrochemical corrosion curves and alternate immersion stress corrosion cracking tests indicated aluminum 7075-T6 is susceptible to corrosive attack when placed in physiological environments. Pit initiated stress corrosion cracking was the primary form of alloy corrosion, and subsequent fracture, in this study. Anodization of the alloy provided a protective layer, but also caused a decrease in passivity ranges. These data suggest that once the anodization layer is disrupted, accelerated corrosion processes occur. PMID:18257055

  4. Stress corrosion cracking in low-pressure steam turbines --An overview

    International Nuclear Information System (INIS)

    This paper presents an overview of stress corrosion cracking (SCC) in low-pressure (LP) turbine discs through 1993. Disc cracking experience in power plants and pertinent results of research programs are summarized. Analyses of field experiences and laboratory studies conducted in the United Kingdom, the United States, and other countries showed that stress corrosion cracking of LP turbine disc steels can occur in pure condensed steam or pure water, as well as in known cracking environments, such as hot hydroxide solutions. It has been established that stress corrosion crack initiation in LP turbine disc steels exposed to high-purity water environments typical of those found in nuclear power plants depends upon seven factors: the presence of a liquid phase; the oxygen concentration of the liquid phase (or the electrode potential corresponding to the oxygen concentration); the yield strength of the steel used in discs; the disc temperature; tensile stress level; crevices and localized corrosion within crevices; and a combination of tensile stress and a flaw of size and shape sufficient to produce a KI value greater than KISCC. While stress corrosion crack initiation depends upon the several factors listed above, the growth rate of stress corrosion cracks in LP turbine disc steels exposed to high-purity water and steam environments depends upon only three factors: the presence of a liquid phase; disc yield strength; and disc temperature. Importantly, stress corrosion crack growth rates in LP turbine disc steels are essentially independent of tensile stress level and stress intensity. Increase in both yield strength and temperature result in increased crack growth rate. 37 refs

  5. The stress corrosion cracking of copper nuclear waste containers

    International Nuclear Information System (INIS)

    The extent of stress corrosion cracking (SCC) of copper nuclear waste containers is being predicted on the basis of a limited propagation argument. In this argument, it is accepted that crack initiation may occur, but it is argued that the environmental conditions and material properties required for a through-wall crack to propagate will not be present. In this paper, the effect of one environmental parameter, the supply of oxidant (JOX), on the crack growth rate is examined. Experiments have been conducted on two grades of Cu in NaNO2 environments using two loading techniques. The supply of oxidant has been varied either electrochemically in bulk solution using different applied current densities or by embedding the loaded test specimens in compacted buffer material containing O2 as the oxidant. Measured and theoretical crack growth rates as a function of JOX are compared with the predicted oxidant flux to the containers in a disposal vault and an estimate of the maximum crack depth on a container obtained

  6. The stress corrosion cracking of copper nuclear waste containers

    International Nuclear Information System (INIS)

    The extent of stress corrosion cracking (SCC) of copper nuclear waste containers is being predicted on the basis of a 'limited propagation' argument. In this argument, it is accepted that crack initiation may occur, but it is argued that the environmental conditions and material properties required for a through-wall crack to propagate will not be present. In this paper, the effect of one environmental parameter, the supply of oxidant (Jox), on the crack growth rate is examined. Experiments have been conducted on two grades of Cu in NANO2 environments using two loading techniques. The supply of oxidant has been varied either electrochemically in bulk solution using different applied current densities or by embedding the loaded test specimens in compacted buffer material containing O2 as the oxidant. Measured and theoretical crack growth rates as a function of Jox are compared with the predicted oxidant flux to the containers in a disposal vault and an estimate of the maximum crack depth on a container obtained. (author)

  7. Stress corrosion cracking on irradiated 316 stainless steel

    Science.gov (United States)

    Furutani, Gen; Nakajima, Nobuo; Konishi, Takao; Kodama, Mitsuhiro

    2001-02-01

    Tests on irradiation-assisted stress corrosion cracking (IASCC) were carried out by using cold-worked (CW) 316 stainless steel (SS) in-core flux thimble tubes which were irradiated up to 5×10 26 n/m 2 ( E>0.1 MeV) at 310°C in a Japanese PWR. Unirradiated thimble tube was also tested for comparison with irradiated tubes. Mechanical tests such as the tensile, hardness tests and metallographic observations were performed. The susceptibility to SCC was examined by the slow strain rate test (SSRT) under PWR primary water chemistry condition and compositional analysis on the grain boundary segregation was made. Significant changes in the mechanical properties due to irradiation such as a remarkable increase of strength and hardness, and a considerable reduction of elongation were seen. SSRT results revealed that the intergranular fracture ratio (%IGSCC) increased as dissolved hydrogen (DH) increased. In addition, SSRT results in argon gas atmosphere showed a small amount of intergranular cracking. The depletion of Fe, Cr, Mo and the enrichment of Ni and Si were observed in microchemical analyses on the grain boundary.

  8. Prediction of the remaining lifetime of stainless steels under conditions of stress corrosion cracking

    International Nuclear Information System (INIS)

    The prediction of the lifetime of metal structures and equipment under conditions of stress corrosion is very complicated because of the complexity of this process of degradation. Recently a new method, based on the so-called corrosion elongation curves, has been found, which can be used to predict the time to failure under these conditions. By upgrading of these curves (and thus obtaining Upgraded Corrosion Elongation Curves - UCEC's) it has been possible to obtain a precise definition of the time needed for the initiation of the corrosion crack, and for its stable growth. It is upon this basis that diagrams for the prediction of remaining lifetime (DPRL's) have been developed. DPRL's can also be used to predict the values of various critical parameters which have to be achieved if a stress corrosion crack is to occur. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  9. Lead assisted stress corrosion cracking of nuclear steam generator tubing materials

    International Nuclear Information System (INIS)

    There have been a few field failures of nuclear steam generator tubes which were attributed to lead assisted stress corrosion. Because of the propensity of lead compounds to be found in nuclear generator sludge, considerable laboratory effort has been focused on lead assisted stress corrosion. This paper reviews the literature to organize the current knowledge about this phenomenon in terms of important parameters. It also reviews the literature in terms of current thoughts on degradation mechanisms which might explain lead assisted corrosion. Finally, this paper identifies areas where information is lacking

  10. Corrosion evaluation of alternate nuclear steam generator tubing materials

    International Nuclear Information System (INIS)

    Several materials were evaluated for use in nuclear steam generators (NSG). These materials were exposed to corrosive conditions representative of those found in nuclear steam generators. The materials evaluated were gold, titanium, tantalum, niobium, Hastelloy C-276, Hastelloy G. Nickel 200, nickel-base Alloy 625, and heat-tracked nickel-base Alloy 600. The test environments simulated acid pitting attack, caustic stress corrosion cracking and reduced sulfur attack. In the pitting environment, the monolithic materials did well, however Nickel 200, nickel-base Alloy 600 and Hastelloy G3 did poorly. The remaining alloys, nickel-base Alloy 625 and Hastelloy C-276 were relatively unaffected in the pitting environment. Tantalum, titanium, niobium, nickel-base Alloy 625 performed poorly in the environment designed to evaluate resistance to caustic cracking. Nickel-base Alloy 600 (stress-relieved), Hastelloy C-276, Hasteloy G-3 and Nickel 200 compared fair to good in the caustic sodium. The gold was unaffected in the hot caustic solution. In the environment selected to represent a reduced sulfur environment, nickel-base Alloy 625 and Hastelloy C-276 exhibited considerable resistance. The nickel-base Alloy 600 was attacked within a relatively short period of time

  11. Stainless steel waste containers: an assessment of the probability of stress corrosion cracking

    International Nuclear Information System (INIS)

    The paper summarises information obtained from the literature and discussions held with corrosion experts from universities and industry, relevant to the possibility that stainless steel radioactive waste containers containing low level and intermediate level radioactive waste (LLW and ILW) could, when buried in concrete, suffer one or more of the forms of stress corrosion cracking (SCC). Stress corrosion cracking is caused by the simultaneous and synergistic action of a corrosive environment and stress. The initiation and propagation of SCC depend on a number of factors being present, namely a certain level of stress, an environment which will cause cracking and a susceptible metal or alloy. Generally the susceptibility of a metal or alloy to SCC increases as its strength level increases. The susceptibility in a specific environment will depend on: solution concentration, pH, temperature, and electrochemical potential of the metal/alloy. It is concluded that alkaline stress corrosion cracking is unlikely to occur under even the worst case conditions, that chloride stress corrosion cracking is a distinct possibility at the higher end of the temperature range (25-80oC) and that stress corrosion related to sensitization of the steel will not be a problem for the majority of container material which is less than 5 mm in cross section. Thicker section material could become sensitized leading to a local problem in these areas. Contact with metals that are electrochemically more negative in corrosion potential is likely to reduce the incidence of SCC, at least locally. Measurement of repassivation potentials and rest potentials in solutions of relevant composition would provide a firmer prediction of the extent to which a high pH could reduce the likelihood of SCC caused by chlorides. (author)

  12. Relationships between mechanical behavior in neutral environment and stress corrosion behavior for austenitic stainless steels

    International Nuclear Information System (INIS)

    Stress corrosion of two austenitic steels: Z2CN18-10 and Z6CN18-09 is studied by means of the conventional test: MgCl2-44%-1530C. Results obtained by three methods: mechanical tests, electrochemical methods, metallographic examination are compared. Mechanical studies reveal three stress regions: elastic range, uniform plastic deformation range, strong strain hardening. Stress corrosion test results are in good agreement with those obtained by mechanical tests. However, the crack propagation mechanisms seems to depend on the anodic dissolution rather than on stress range

  13. Stress field determination in an alloy 600 stress corrosion crack specimen

    International Nuclear Information System (INIS)

    In the context of EDF studies on stress corrosion cracking rates in the Alloy 600 steam generators tubes, we studied the influence of strain hardened surface layers on the different stages of cracking for a tensile smooth specimen (TLT). The stress field was notably assessed to try and explain the slow/rapid-propagation change observed beyond the strain hardened layers. The main difficulty is to simulate in a finite element model the inner and outer surfaces of these strain hardened layers, produced by the final manufacturing stages of SG tubes which have not been heat treated. In the model, the strain hardening is introduced by simulating a multi-layer material. Residual stresses are simulated by an equivalent fictitious thermomechanical calculation, realigned with respect to X-ray measurements. The strain hardening introduction method was validated by an analytical calculation giving identical results. Stress field evolution induced by specimen tensile loading were studied using an elastoplastic 2D finite element calculations performed with the Aster Code. The stress profile obtained after load at 660 MPa shows no stress discontinuity at the boundary between the strain hardened layer and the rest of the tube. So we propose that a complementary calculation be performed, taking into account the multi-cracked state of the strain hardened zones by means of a damage variable. In fact, this state could induce stress redistribution in the un-cracked area, which would perhaps provide an explanation of the crack-ground rate change beyond the strain hardened zone. The calculations also evidence the harmful effects of plastic strains on a strain hardened layer due to the initial state of the tube (not heat-treated), to grit blasting or to shot peening. The initial compressive stress condition of this surface layer becomes, after plastic strain, a tensile stress condition. These results are confirmed by laboratory test. (author). 10 refs., 18 figs., 9 tabs., 2 appends

  14. Epidemiology and prevention of caustic ingestion in children

    DEFF Research Database (Denmark)

    Christesen, H B

    1994-01-01

    A total of 102 children less than 16 years of age admitted for caustic ingestion in the period 1976-1991 were registered. The annual incidence rate of hospitalization was 10.8:100,000 for the city of Aarhus, Denmark. Esophageal burns occurred with a frequency of 5.0:100,000 per year. Ninety...... toddlers is recommended. Information material should stress that caustics should always be inaccessible to children and stored separately, and should never be decanted....

  15. Computational modeling of the mechanism of hydrogen embrittlement (HE) and stress corrosion cracking (SCC) in metals

    Science.gov (United States)

    Cendales, E. D.; Orjuela, F. A.; Chamarraví, O.

    2016-02-01

    In this article theoretical models and some existing data sets were examined in order to model the two main causes (hydrogen embrittlement and corrosion-cracking under stress) of the called environmentally assisted cracking phenomenon (EAC). Additionally, a computer simulation of flat metal plate subject to mechanical stress and cracking due both to hydrogen embrittlement and corrosion was developed. The computational simulation was oriented to evaluate the effect on the stress-strain behavior, elongation percent and the crack growth rate of AISI SAE 1040 steel due to three corrosive enviroments (H2 @ 0.06MPa; HCl, pH=1.0; HCl, pH=2.5). From the computer simulation we conclude that cracking due to internal corrosion of the material near to the crack tip limits affects more the residual strength of the flat plate than hydrogen embrittlement and generates a failure condition almost imminent of the mechanical structural element.

  16. Determination of Stress-Corrosion Cracking in Aluminum-Lithium Alloy ML377

    Science.gov (United States)

    Valek, Bryan C.

    1995-01-01

    The use of aluminum-lithium alloys for aerospace applications is currently being studied at NASA Langley Research Center's Metallic Materials Branch. The alloys in question will operate under stress in a corrosive environment. These conditions are ideal for the phenomena of Stress-Corrosion Cracking (SCC) to occur. The test procedure for SCC calls for alternate immersion and breaking load tests. These tests were optimized for the lab equipment and materials available in the Light Alloy lab. Al-Li alloy ML377 specimens were then subjected to alternate immersion and breaking load tests to determine residual strength and resistance to SCC. Corrosion morphology and microstructure were examined under magnification. Data shows that ML377 is highly resistant to stress-corrosion cracking.

  17. Synthetic sea water - An improved stress corrosion test medium for aluminum alloys

    Science.gov (United States)

    Humphries, T. S.; Nelson, E. E.

    1973-01-01

    A major problem in evaluating the stress corrosion cracking resistance of aluminum alloys by alternate immersion in 3.5 percent salt (NaCl) water is excessive pitting corrosion. Several methods were examined to eliminate this problem and to find an improved accelerated test medium. These included the addition of chromate inhibitors, surface treatment of specimens, and immersion in synthetic sea water. The results indicate that alternate immersion in synthetic sea water is a very promising stress corrosion test medium. Neither chromate inhibitors nor surface treatment (anodize and alodine) of the aluminum specimens improved the performance of alternate immersion in 3.5 percent salt water sufficiently to be classified as an effective stress corrosion test method.

  18. Study on corrosion characteristics and stress corrosion cracking of the weldment for HT-60 steel in synthetic seawater

    International Nuclear Information System (INIS)

    The contents of this paper include the evaluation of corrosion characteristics and the behaviour of Stress Corrosion Cracking (SCC) for the weldment and Post Weld Heat Treatment(PWHT) specimen and parent of HT-60 steel using a Slow Strain Rate Test(SSRT) in synthetic seawater. Corrosion characteristics were obtained from the polarization curves by potentiostat, and SCC phenomena were evaluated through the parameters such as reduction of area and time to failure by comparing the experimental results in corrosive environment with those obtained in air. Corrosion rate of the weldment was the fastest, followed by parent and PWHT specimen. SCC phenomena between the weldment of HT-60 steel and synthetic seawater were shown. Besides, SCC was dependent upon the pulling speed greatly. Maximum severity of SCC was obtained at a speed of 10-6mm/min, whereas SCC could not be seen almost at 10-4mm/min. The resistance to SCC for PWHT specimen was improved considerably compared that of the weldment at 10-6mm/min. In case of SCC failure, it was verified from SEM examination that brittle mode and lots of pits could be seen at the fractured region near the surface of the specimen

  19. Vehicle for the detection of stress corrosion cracking in buried gas pipelines

    International Nuclear Information System (INIS)

    Stress corrosion cracking poses a serious threat to aging underground cathodically protected gas pipelines. As coatings deteriorate, local conditions conducive to corrosion and stress corrosion cracking become more common. During the last decade, there have been several ruptures in various places throughout the worked attributed to SCC. One of the most important steps in combating failure by stress corrosion cracking is to perform regular, reliable and cost effective monitoring of the pipelines. Current methods available including hydrotesting and MPI are expensive, time consuming, not conductive to regular testing and are not entirely reliable. Regular testing of pipes will improve understanding of stress corrosion of cracking, initiation, propagation and tolerance. This report describes the present state of development of the ultrasonic pipe inspection vehicle being jointly developed by C.W. Pope and Associates and the Centre for Industrial Control Sciences at the University of Newcastle, Australis. The present aim is the evaluation of unpressurized pipelines to record areas of stress corrosion cracking (SSC) at relatively low cost and with minimum sophistication. The several independent areas of the project are rapidly converging together in preparation for the field trials in November. These areas include wheel probe development, signal processing development, hardware development, radio modem communication and software development. Each of these areas are individually addressed in this report

  20. Test and research on stress corrosion crack of austenitic stainless steel in ocean environment

    International Nuclear Information System (INIS)

    The applicability of stress corrosion test performance on wedge opened self-loaded samples to study stress corrosion property of austenitic stainless steels in ocean environment including Cl-. The studied materials were 0Cr18Ni10Ti(321) austenitic stainless steel, using NaCl solution with concentration of 3.5%, 15% and 26.5% to simulate ocean and condensable ocean situation. The average stress corrosion crack propagating rate existed in 3.34 X 10-9 mm/s∼1.31 X 10-8 mm/s and incubation time were 792∼1752 h or even more when stress intensity factor K1 in scope of 35 MPa √m∼60 MPa √m. Stress corrosion crack propagating rate was immune to differing concentration of NaCl, crack incubation got shorter along with stress intensity factor K1 was higher. That was showed prefabricated fatigue crack area, stress corrosion crack propagation area and toughness fracture area connected with each other on fracture surface. (authors)

  1. Stress-corrosion crack initiation process for Alloy 182 weld metal in simulated BWR environments

    International Nuclear Information System (INIS)

    For preventing SCC from occurring in the internal structure of materials of the BWR plant, the injection of hydrogen into the core-water so as to reduce the free corrosion potential of the materials were proposed. Because of the lack of basic data of stress-corrosion cracking susceptibility in BWR environment on Ni-based alloys in comparison with stainless steels, the slow strain-rate tensile (SSRT) tests and the creviced bent-beam (CBB) test were conducted for a sensitized Alloy 182 weld metal in high-purity water environments containing dissolved oxygen (DO) and hydrogen (DH) to varied concentrations at 288 C, and the SCC initiation process were examined. The susceptibility of a material to SCC was discussed in terms of the electrode potential effect, and the effects of impurities of the testing water were examined by adding slightly Na2, SO4. In high purity waters and in the electrode potential region higher than - 0.2 V vs. SHE, the interdendritic stress-corrosion cracks were observed both in the slow strain-rate test and the creviced bent-beam test. SEM observations of sub-cracks at the specimen surfaces revealed that stress-corrosion cracks were initiated when the oxide film had cracked to under-hundred microm wide, that no such individual cracks could grow per se, but that those micro-cracks which happened to be formed in each other's vicinity would coalesce into large cracks, one of which made propagated as stress-corrosion cracking, and that the stress-corrosion cracking sensitivity became more acute on addition of impurity. In the electrode potential region lower than 0 V, on the other hand, the stress-corrosion cracks were observed to be initiated at bottoms of corrosion pits formed on the specimen surfaces in the former, whereas both type of stress-corrosion cracks were observed between 0 to -0.2V. No stress-corrosion crack was observed even though much the same corrosion pits in the CBB test at -0.4 V

  2. Standard practice for preparation and use of Bent-Beam stress-corrosion test specimens

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 This practice covers procedures for designing, preparing, and using bent-beam stress-corrosion specimens. 1.2 Different specimen configurations are given for use with different product forms, such as sheet or plate. This practice applicable to specimens of any metal that are stressed to levels less than the elastic limit of the material, and therefore, the applied stress can be accurately calculated or measured (see Note 1). Stress calculations by this practice are not applicable to plastically stressed specimens. Note 1—It is the nature of these practices that only the applied stress can be calculated. Since stress-corrosion cracking is a function of the total stress, for critical applications and proper interpretation of results, the residual stress (before applying external stress) or the total elastic stress (after applying external stress) should be determined by appropriate nondestructive methods, such as X-ray diffraction (1). 1.3 Test procedures are given for stress-corrosion testing by ex...

  3. Environmental stress-corrosion cracking of fiberglass: Lessons learned from failures in the chemical industry

    International Nuclear Information System (INIS)

    Fiberglass reinforced plastic (FRP) composite materials are often used to construct tanks, piping, scrubbers, beams, grating, and other components for use in corrosive environments. While FRP typically offers superior and cost effective corrosion resistance relative to other construction materials, the glass fibers traditionally used to provide the structural strength of the FRP can be susceptible to attack by the corrosive environment. The structural integrity of traditional FRP components in corrosive environments is usually dependent on the integrity of a corrosion-resistant barrier, such as a resin-rich layer containing corrosion resistant glass fibers. Without adequate protection, FRP components can fail under loads well below their design by an environmental stress-corrosion cracking (ESCC) mechanism when simultaneously exposed to mechanical stress and a corrosive chemical environment. Failure of these components can result in significant releases of hazardous substances into plants and the environment. In this paper, we present two case studies where fiberglass components failed due to ESCC at small chemical manufacturing facilities. As is often typical, the small chemical manufacturing facilities relied largely on FRP component suppliers to determine materials appropriate for the specific process environment and to repair damaged in-service components. We discuss the lessons learned from these incidents and precautions companies should take when interfacing with suppliers and other parties during the specification, design, construction, and repair of FRP components in order to prevent similar failures and chemical releases from occurring in the future

  4. Environmental stress-corrosion cracking of fiberglass: lessons learned from failures in the chemical industry.

    Science.gov (United States)

    Myers, T J; Kytömaa, H K; Smith, T R

    2007-04-11

    Fiberglass reinforced plastic (FRP) composite materials are often used to construct tanks, piping, scrubbers, beams, grating, and other components for use in corrosive environments. While FRP typically offers superior and cost effective corrosion resistance relative to other construction materials, the glass fibers traditionally used to provide the structural strength of the FRP can be susceptible to attack by the corrosive environment. The structural integrity of traditional FRP components in corrosive environments is usually dependent on the integrity of a corrosion-resistant barrier, such as a resin-rich layer containing corrosion resistant glass fibers. Without adequate protection, FRP components can fail under loads well below their design by an environmental stress-corrosion cracking (ESCC) mechanism when simultaneously exposed to mechanical stress and a corrosive chemical environment. Failure of these components can result in significant releases of hazardous substances into plants and the environment. In this paper, we present two case studies where fiberglass components failed due to ESCC at small chemical manufacturing facilities. As is often typical, the small chemical manufacturing facilities relied largely on FRP component suppliers to determine materials appropriate for the specific process environment and to repair damaged in-service components. We discuss the lessons learned from these incidents and precautions companies should take when interfacing with suppliers and other parties during the specification, design, construction, and repair of FRP components in order to prevent similar failures and chemical releases from occurring in the future. PMID:16950568

  5. Residual strain change resulting from stress corrosion in Carrara marble

    Science.gov (United States)

    Voigtlaender, Anne; Leith, Kerry; Krautblatter, Michael

    2016-04-01

    Residual stresses and strains have been shown to play a fundamental role in determining the elastic behavior of engineering materials, yet the effect of these strains on brittle and elastic behavior of rocks remains unclear. In order to evaluate the impact of stored elastic strains on fracture propagation in rock, we undertook a four-month-long three-point bending test on three large 1100 x 100 x 100 mm Carrara Marble samples. This test induced stable low stress conditions in which strains were concentrated at the tip of a saw cut and pre-cracked notch. A corrosive environment was created at the tip of the notch on two samples (M2 and M4) by dripping calcite saturated water (pH ~ 7.5-8). Sample M5 was loaded in the same way, but kept dry. Samples were unloaded prior to failure, and along with an additional non-loaded reference sample (M0), cored into cylindrical subsamples (ø = 50 mm, h = 100 mm) before being tested for changes in residual elastic strains at the SALSA neutron diffractometer at the Institute Laue-Langevin (ILL), Grenoble, France. Three diffraction peaks corresponding to crystallographic planes hkl (110), (104) and (006) were measured in all three spatial directions relative to the notch. Shifts in the diffraction peak position (d) with respect to a strain free state are indicative of intergranular strain, while changes in the width of the peak (FWHM) reflect changes in intragranular strain. We observe distinctly different patterns in residual and volumetric strains in hkℓ (104) and (006) for the dry M5 and wet tested samples (M2 and M4) indicating the presence of water changes the deformation mechanism, while (110) is strained in compression around 200 μstrain in all samples. A broadening of the diffraction peaks (006) and (110) in front of the crack tip is observed in M2 and M4, while M5 shows no changes in the peak width throughout the depth of the sample. We suggest water present at the crack tip increased the rate of corrosion, allowing a

  6. Ultrasonic inspection reliability for intergranular stress corrosion cracks

    Energy Technology Data Exchange (ETDEWEB)

    Heasler, P G; Taylor, T T; Spanner, J C; Doctor, S R; Deffenbaugh, J D [Pacific Northwest Lab., Richland, WA (USA)

    1990-07-01

    A pipe inspection round robin entitled Mini-Round Robin'' was conducted at Pacific Northwest Laboratory from May 1985 through October 1985. The research was sponsored by the US Nuclear Regulatory Commission, Office of Nuclear Regulatory Research under a program entitled Evaluation and Improvement of NDE Reliability for Inservice Inspection of Light Water Reactors.'' The Mini-Round Robin (MRR) measured the intergranular stress corrosion (GSC) crack detection and sizing capabilities of inservice inspection (ISI) inspectors that had passed the requirements of IEB 83-02 and the Electric Power Research Institute (EPRI) sizing training course. The MRR data base was compared with an earlier Pipe Inspection Round Robin (PIRR) that had measured the performance of inservice inspection prior to 1982. Comparison of the MRR and PIRR data bases indicates no significant change in the inspection capability for detecting IGSCC. Also, when comparing detection of long and short cracks, no difference in detection capability was measured. An improvement in the ability to differentiate between shallow and deeper IGSCC was found when the MRR sizing capability was compared with an earlier sizing round robin conducted by the EPRI. In addition to the pipe inspection round robin, a human factors study was conducted in conjunction with the Mini-Round Robin. The most important result of the human factors study is that the Relative Operating Characteristics (ROC) curves provide a better methodology for describing inspector performance than only probability of detection (POD) or single-point crack/no crack data. 6 refs., 55 figs., 18 tabs.

  7. Propagation of stress corrosion cracks in alpha-brasses

    Energy Technology Data Exchange (ETDEWEB)

    Beggs, Dennis Vinton

    1981-01-01

    Transgranular and intergranular stress corrosion cracks were investigated in alpha-brasses in a tarnishing ammoniacal solution. Surface observation indicated that the transgranular cracks propagated discontinuously by the sudden appearance of a fine crack extending several microns ahead of the previous crack tip, often associated with the detection of a discrete acoustic emission (AE). By periodically increasing the deflection, crack front markings were produced on the resulting fracture surfaces, showing that the discontinuous propagation of the crack trace was representative of the subsurface cracking. The intergranular crack trace appeared to propagate continuously at a relatively blunt crack tip and was not associated with discrete AE. Under load pulsing tests with a time between pulses, ..delta..t greater than or equal to 3 s, the transgranular fracture surfaces always exhibited crack front markings which corresponded with the applied pulses. The spacing between crack front markings, ..delta..x, decreased linearly with ..delta..t. With ..delta..t less than or equal to 1.5 s, the crack front markings were in a one-to-one correspondence with applied pulses only at relatively long crack lengths. In this case, ..delta..x = ..delta..x* which approached a limiting value of 1 ..mu..m. No crack front markings were observed on intergranular fracture surfaces produced during these tests. It is concluded that transgranular cracking occurs by discontinuous mechanical fracture of an embrittled region around the crack tip, while intergranular cracking results from a different mechanism with cracking occurring via the film-rupture mechanism.

  8. A study on the mechanism of stress corrosion cracking of duplex stainless steels in hot alkaline-sulfide solution

    Science.gov (United States)

    Chasse, Kevin Robert

    Duplex stainless steels (DSS) generally have superior strength and corrosion resistance as compared to most standard austenitic and ferritic stainless grades owing to a balanced microstructure of austenite and ferrite. As a result of having favorable properties, DSS have been selected for the construction of equipment in pulp and paper, chemical processing, nuclear, oil and gas as well as other industries. The use of DSS has been restricted in some cases because of stress corrosion cracking (SCC), which can initiate and grow in either the ferrite or austenite phase depending on the environment. Thorough understanding of SCC mechanisms of DSS in chloride- and hydrogen sulfide-containing solutions has been useful for material selection in many environments. However, understanding of SCC mechanisms of DSS in sulfide-containing caustic solutions is limited, which has restricted the capacity to optimize process and equipment design in pulp and paper environments. Process environments may contain different concentrations of hydroxide, sulfide, and chloride, altering corrosion and SCC susceptibility of each phase. Crack initiation and growth behavior will also change depending on the relative phase distribution and properties of austenite and ferrite. The role of microstructure and environment on the SCC of standard grade UNS S32205 and lean grade UNS S32101 in hot alkaline-sulfide solution were evaluated in this work using electrochemical, film characterization, mechanical testing, X-ray diffraction, and microscopy techniques. Microstructural aspects, which included residual stress state, phase distribution, phase ratio, and microhardness, were related to the propensity for SCC crack initiation in different simulated alkaline pulping liquors at 170 °C. Other grades of DSS and reference austenitic and superferritic grades of stainless steel were studied using exposure coupons for comparison to understand compositional effects and individual phase susceptibility

  9. Caustic cracking of 9Cr 1Mo steel at 3000C

    International Nuclear Information System (INIS)

    The stress corrosion cracking of correctly heat-treated 9Cr-1Mo in caustic solutions at 3000C has been examined using a bursting tube version of the slow strain rate technique. Some susceptibility was detected at all concentrations examined, the more concentrated solutions which favoured less protective oxide formation, producing the more severe cracking. The cracking in these strong solutions proceeded at velocities up to 0.1 mm h-1 and produced wide oxide filled cracks. This cracking is not strongly dependent on potential, although more anodic potentials promote thicker oxide formation while cathodic potentials favour general dissolution. Normalized and tempered, annealed, and a simulated heat-affected zone microstructure were all equally susceptible to cracking. Some constant pressure tests were performed which suggested cracking could occur at stresses below the yield stress. In more dilute solutions susceptibility was much less, and the crack velocity was about 0.01 mm h-1, i.e. ten times slower than in 8 M NaOH. The relationship between slow strain rate tests, conventional tests and practical experience are discussed. The behaviour of 9Cr 1Mo in caustic below 2 1/2 M places it in the low susceptibility category and failures under realistic conditions are unlikely. (author)

  10. Stress corrosion cracking of Zircaloy-4 in non-aqueous iodine solutions

    International Nuclear Information System (INIS)

    In the present work the susceptibility to intergranular attack and stress corrosion cracking of Zircaloy-4 in different iodine alcoholic solutions was studied. The influence of different variables such as the molecular weight of the alcohols, the water content of the solutions, the alcohol type (primary, secondary or tertiary) and the temperature was evaluated. To determine the susceptibility to stress corrosion cracking the slow strain rate technique was used. Specimens of Zircaloy-4 were also exposed between 0.5 and 300 hours to the solutions without applied stress to evaluate the susceptibility to intergranular attack. The electrochemical behavior of the material in the corrosive media was studied by potentiodynamic polarization tests. It was determined that the active species responsible for the stress corrosion cracking of Zircaloy-4 in iodine alcoholic solutions is a molecular complex between the alcohol and iodine. The intergranular attack precedes the 'true' stress corrosion cracking phenomenon (which is associated to the transgranular propagation of the crack) and it is controlled by the diffusion of the active specie to the tip of the crack. Water acts as inhibitor to intergranular attack. Except for methanolic solutions, the minimum water content necessary to inhibit stress corrosion cracking was determined. This critical water content decreases when increasing the molecular weight of the alcohol. An explanation for this behavior is proposed. The susceptibility to stress corrosion cracking also depends on the type of the alcohol used as solvent. The temperature dependence of the crack propagation rate is in agreement with a thermal activated process, and the activation energy is consistent with a process controlled by the volume diffusion of the active species. (author)

  11. Influence of texture on iodine-induced stress corrosion cracking of Zircaloy-4 cladding tubes

    Science.gov (United States)

    Schuster, I.; Lemaignan, C.

    1992-07-01

    A specific study was carried out to measure the influence of texture on the behaviour of Zircaloy-4 under iodine-induced stress corrosion cracking. The aim was to determine the relative effects of various metallurgical parameters involved in fuel rod fracture by pellet-clad interaction (PCI). Cladding tubes of different geometries were manufactured from a given Zircaloy-4 ingot. In this way tubes with different textures were obtained. Rings from these tubes were then subjected to slow tensile tests in an inert atmosphere and in an iodine vapour atmosphere. The sensitivity of the tubes to stress corrosion cracking is quantified by the loss of ductility on fracture between the tests in each atmosphere. Combined with the findings of other studies, the results showed that: (a) texture has a strong effect on the stress corrosion cracking behaviour of Zircaloy-4, (b) the mechanical properties do not have any bearing on the material behaviour under stress corrosion cracking, and that the better behaviour of a recrystallized material — compared to the same material in a stress-relieved state — can be explained solely by the texture effect, (c) texture is a more important parameter than chemical composition of Zircaloy-4, on condition that this composition remains within the ASTM specification. The conflict between the various mechanisms involved in stress corrosion crack propagation may explain these observations. Preliminary extrapolation of these conclusions to the irradiated material shows that a more specific study is needed using appropriate parameters.

  12. Effect of stress and strain on corrosion resistance of duplex stainless steel

    International Nuclear Information System (INIS)

    The interplay of the mechanical and electrochemical phenomena has been a subject of active research. In this paper, corrosion resistance studies about SAF2205 and SAF2507 duplex stainless steel were carried out under elastic stress applied (100 MPa, 300 MPa, 500 MPa) and pre-strain (5%, 10%, 15%) in 3.5% NaCl and 2 mol/L HCl solution. Potentiodynamic anodic polarization study revealed that corrosion resistance of SAF2205 duplex stainless steel decreases slightly with increasing of elastic stress level and noticeably with increasing of pre-strained level. Scanning electron microscopy investigation on surface of the electrochemical tested SAF2205 duplex stainless steel samples indicated that pitting is always located in austenite grains when pre-strain level is below 5% (including different elastic stress level) and located on intersection of ferrite and austenite grain when pre-strain level is above 5%. For SAF2507 duplex stainless steel, elastic stress and pre-strain have no effect on general corrosion and pitting corrosion. Based on deformation mechanism of duplex structure and the relationship of mechanical load and corrosion potential, Pitting corrosion behavior of duplex stainless steel is explained and discussed

  13. Review of provisions on corrosion fatigue and stress corrosion in WWER and Western LWR Codes and Standards

    International Nuclear Information System (INIS)

    Results are presented from a collaborative project performed on behalf of the European Commission, Working Group Codes and Standards. The work covered the contents of current codes and standards, plant experience and R and D results. Current fatigue design rules use S-N curves based on tests in air. Although WWER and LWR design curves are often similar they are derived, presented and used in different ways and it is neither convenient nor appropriate to harmonise them. Similarly the fatigue crack growth laws used in the various design and in-service inspection rules differ significantly with respect to both growth rates in air and the effects of water reactor environments. Harmonised approaches to the effects of WWER and LWR environments are possible based on results from R and D programmes carried out over the last decade. For carbon and low alloy steels a consistent approach to both crack initiation and growth can be formulated based on the superposition of environmentally assisted cracking effects on the fatigue crack development. The approach indicates that effects of the water environment are minimal given appropriate control of the oxygen content of the water and/or the sulphur content of the steel. For austenitic stainless steels a different mechanisms may apply and a harmonised approach is possible at present only for S-N curves. Although substantial progress has been made with respect to corrosion fatigue, more data and a clearer understanding are required in order to write code provisions particularly in the area of high cycle fatigue. Reactor operation experience shows stress corrosion cracking of austenitic steels is the most common cause of failure. These failures are associated with high residual stresses combined with high levels of dissolved oxygen or the presence of contaminants. For primary circuit internals there is a potential threat to integrity from irradiated assisted stress corrosion cracking. Design and in-service inspection rules do not at

  14. Contribution to the study of stress corrosion crack initiation in zirconium and in Zircaloy-4

    International Nuclear Information System (INIS)

    In pressurized water reactors, fuel rods are made of a sheath of Zircaloy-4 containing uranium pellets. This sheath may fail by stress corrosion which comprises two main stages: crack initiation, and crack propagation until failure. In this research thesis, the author recalls the knowledge on this failure mechanism, proposes a synthesis of mechanisms generally proposed in the literature, presents experimental means used in this study, addresses the phenomenological aspect of stress corrosion crack initiation, analyses the role of grain crystallographic orientation and its possible impact on location of crack initiation, and shows how chemical environment and mechanical stress intervene in the initiation process

  15. Design and fabrication of an apparatus to study stress corrosion cracking

    International Nuclear Information System (INIS)

    In this research thesis, the author first gives a large overview of tests methods of stress corrosion cracking: definition and generalities, stress corrosion cracking in the laboratory (test methods with imposed deformation, load or strain rate, theories of hydrogen embrittlement, of adsorption, of film breaking, and electrochemical theories), stress corrosion cracking in alkaline environment (in light water reactors, of austenitic stainless steels), and conventional tests on polycrystals and monocrystals of stainless steels in sodium hydroxide. The next parts address the core of this research, i.e. the design of an autoclave containing a tensile apparatus, the fabrication of this apparatus, the stress application device, the sample environment, pressurization, control and command, preliminary tests in a melt salt, and the first cracking tests

  16. Stress corrosion cracking of Ti- and Nb-stabilized austenitic stainless steels in 288 C water

    International Nuclear Information System (INIS)

    Intergranular stress corrosion cracking of stabilized austenitic stainless steels in 288 C water has been studied experimentally. Fracture mechanics crack growth rates were obtained with double cantilever beam specimens. Three Ti-stabilized and two Nb-stabilized stainless steels all exhibited intergranular stress corrosion cracking in simulated, faulted BWR water. The crack growth rates were similar to those of 316 NG, i.e. about one nun per year at stress intensities beyond 20 MPa√m. Extreme sensitization and coarse grains result in crack growth rates up to one hundred times faster. It is shown that weld sensitization in a very narrow zone (several hundred micrometers from the fusion line) can cause chromium carbide precipitation and corresponding chromium depletion and corresponding susceptibility to stress corrosion cracking in BWR water

  17. Stress concentrator effect on corrosion resistance of welded joints of zirconium - 2.5% niobium alloys

    International Nuclear Information System (INIS)

    Considered is the effect of notches and poor penetrations of 10 and 20% pipeline wall thickness made of Zr - 2.5% Nb alloy on corrosion resistance. Stress concentrator effects have been estimated on the basis of results of cyclic tests in 3% NaCl and pressure tests in water-vapor medium at 300 deg C and 85 atm during 1200 h. Estimated are critical strains and corresponding stresses for basic and a weldmetals. Stress concentrators are shown to low the level of critical stresses of corrosion-mechanical fracture initiation. In water-vapor mixture there found is a corrosion in some zones of welded joint heated in a process of welding over 600 deg C. For such zones registered is the effect of structural-chemical changes, caused by welding

  18. Elastic and plastic strains and the stress corrosion cracking of austenitic stainless steels. Final report

    International Nuclear Information System (INIS)

    The influence of elastic (stress) and plastic (cold work) strains on the stress corrosion cracking of a transformable austenitic stainless steel was studied in several aqueous chloride environments. Initial polarization behavior was active for all deformation conditions as well as for the annealed state. Visual observation, potential-time, and current-time curves indicated the development of a pseudo-passive (flawed) film leading to localized corrosion, occluded cells and SCC. SCC did not initiate during active corrosion regardless of the state of strain unless severe low temperature deformation produced a high percentage of martensite. Both elastic and plastic deformation increased the sensitivity to SCC when examined on the basis of percent yield strength. The corrosion potential, the critical cracking potential, and the potential at which the current changes from anodic to cathodic were essentially unaffected by deformation. It is apparent that the basic electrochemical parameters are independent of the bulk properties of the alloy and totally controlled by surface phenomena

  19. The influence of molybdenum on stress corrosion in Ultra Low Carbon Steels with copper addition

    Directory of Open Access Journals (Sweden)

    M. Mazur

    2010-07-01

    Full Text Available The influence of molybdenum content on the process of stress corrosion of ultra-low carbon structural steels with the addition of copper HSLA (High Strength Low Alloy was analyzed. The study was conducted for steels after heat treatment consisting of quenching andfollowing tempering at 600°C and it was obtained microstructure of the tempered martensite laths with copper precipitates and the phaseLaves Fe2Mo type. It was found strong influence of Laves phase precipitate on the grain boundaries of retained austenite on rate anddevelopment of stress corrosion processes. The lowest corrosion resistance was obtained for W3 steel characterized by high contents ofmolybdenum (2.94% Mo which should be connected with the intensity precipitate processes of Fe2Mo phase. For steels W1 and W2which contents molybdenum equals 1.02% and 1.88%, respectively were obtained similar courses of corrosive cracking.

  20. Stress-corrosion cracks behavior under underground disposal environment of radioactive wastes

    International Nuclear Information System (INIS)

    This study is composed by two sub-theme of study on stress-corrosion cracking under an environment of disposal on radioactive wastes and control technique on microscopic crack around the disposal cavity, and aims at experimental elucidation on forming mechanism of stress-corrosion cracking phenomenon on rocks and establishment of its control technique. In 1998 fiscal year, together with an investigation on effect of temperature on fracture toughness and on stress-corrosion cracks performance of sedimentary rocks (sandy rocks), an investigation on limit of the stress-corrosion cracking by addition of chemicals and on crack growth in a rock by in-situ observation using SEM were carried out. As a result, it was formed that fracture toughness of rocks reduced at more than 100 centigrade of temperature, that a region showing an equilibrium between water supply to crack end and crack speed appeared definitely, that a limit of stress-corrosion cracking appeared by addition of chemicals, and that as a result of observing crack advancement of saturated rock by in-situ observation of crack growth using SEM, a process zone was formed at the front of main crack due to grain boundary fracture. (G.K.)

  1. An accurately controllable imitative stress corrosion cracking for electromagnetic nondestructive testing and evaluations

    International Nuclear Information System (INIS)

    Highlights: ► We propose a method to simulate stress corrosion cracking. ► The method offers nondestructive signals similar to those of actual cracking. ► Visual and eddy current examinations validate the method. - Abstract: This study proposes a simple and cost-effective approach to fabricate an artificial flaw that is identical to stress corrosion cracking especially from the viewpoint of electromagnetic nondestructive evaluations. The key idea of the approach is to embed a partially-bonded region inside a material by bonding together surfaces that have grooves. The region is regarded as an area of uniform non-zero conductivity from an electromagnetic nondestructive point of view, and thus simulates the characteristics of stress corrosion cracking. Since the grooves are introduced using electro-discharge machining, one can control the profile of the imitative stress corrosion cracking accurately. After numerical simulation to evaluate the spatial resolution of conventional eddy current testing, six specimens made of type 316L austenitic stainless steel were fabricated on the basis of the results of the simulations. Visual and eddy current examinations were carried out to demonstrate that the artificial flaws well simulated the characteristics of actual stress corrosion cracking. Subsequent destructive test confirmed that the bonding did not change the depth profiles of the artificial flaw.

  2. Stress corrosion cracking behaviour of gas tungsten arc welded super austenitic stainless steel joints

    Directory of Open Access Journals (Sweden)

    M. Vinoth Kumar

    2015-09-01

    Full Text Available Super 304H austenitic stainless steel with 3% of copper posses excellent creep strength and corrosion resistance, which is mainly used in heat exchanger tubing of the boiler. Heat exchangers are used in nuclear power plants and marine vehicles which are intended to operate in chloride rich offshore environment. Chloride stress corrosion cracking is the most likely life limiting failure with austenitic stainless steel tubing. Welding may worsen the stress corrosion cracking susceptibility of the material. Stress corrosion cracking susceptibility of Super 304H parent metal and gas tungsten arc (GTA welded joints were studied by constant load tests in 45% boiling MgCl2 solution. Stress corrosion cracking resistance of Super 304H stainless steel was deteriorated by GTA welding due to the formation of susceptible microstructure in the HAZ of the weld joint and the residual stresses. The mechanism of cracking was found to be anodic path cracking, with transgranular nature of crack propagation. Linear relationships were derived to predict the time to failure by extrapolating the rate of steady state elongation.

  3. Stress corrosion cracking of turbine disc steels: a study of mechanism

    International Nuclear Information System (INIS)

    Stress corrosion cracking was found to affect shrunk-on discs of 900 MW-EDF turbines. Investigations revealed that intergranular cracking occurred in high-stress confined locations, where concentrations of pollutants resulting from some assembling operations could take place (MoS2 sometimes used as a lubricant, carbonated compounds with chloride as in paint marks). Laboratory tests allowed to assess the chemical conditions (pH, electrochemical potential, pollutants) responsible for the stress corrosion cracking of NiCrMo V-steels. Three main E-pH fields were found to favour stress corrosion cracking, whose boundaries may be dependant on the anionic species. The crack growth rates in these conditions were measured at 95 and 130 deg C, and compared to the observed average measurements from service. The most likely mechanism seems to involve molybdic acid, as a result of thermal decomposition of MoS2 or generated by general corrosion of Mo-containing steel. Cracks might also have been initiated by carbonated compounds. The relevance of classical models to stress corrosion cracking of disc steel was discussed with respect to electrochemical behaviour. (authors). 15 refs., 8 figs., 1 tab

  4. Influence of burnishing on stress corrosion cracking susceptibility of duplex steel

    OpenAIRE

    J. Łabanowski; A. Ossowska

    2006-01-01

    Purpose: of the current study was to investigate the usability of burnishing-inducted surface enhancement method for improve the stress corrosion cracking resistance of duplex stainless steel.Design/methodology/approach: The surface layers upon round in cross section specimens were performed through burnishing treatment. Corrosion tests were performed with the use of Slow Strain Rate Test technique in inert (glycerin) and aggressive (boiling 35% MgCl2 solution) environments.Findings: It was s...

  5. Stress corrosion cracking of steam generator components from 08X18H10T steel

    International Nuclear Information System (INIS)

    Several analyses (metallographic and electron fractographic studies, Auger electron spectroscopy of corrosion deposits, film chemical composition on fracture surfaces by SIMS, X-ray analysis...) of a cracked steam generator collector flange made of 08X18H10T steel of a PWR-440 unit, have been carried out in order to explain the stress corrosion cracking of the metal. Among other conclusions, it is shown that the trans-crystalline corrosion cracking of the steel appears to be an alkaline one under the local non-passivating effect of chloride ions and the adsorption of hydrogen by a metal at a crack tip. 8 refs., 12 figs., 2 tabs

  6. Contribution to surface physicochemical factors to stress corrosion resistance in stainless steels

    International Nuclear Information System (INIS)

    The author of this research thesis first presents and discusses the various aspects of stress corrosion cracking of Fe-Cr-Ni alloys of high purity: experimental conditions (alloy elaboration, sample preparation), corrosion results (Schaeffer diagram, crack morphology, intergranular corrosion), influence of addition elements in ferritic alloys. He reports an electrochemical study of stainless steels in magnesium chloride (experimental conditions, influence of metallurgic and environmental parameters on polarization resistance, current-voltage curves), and an analytical study of layers formed in the magnesium chloride

  7. On the stress corrosion cracking of lean duplex steel in chloride environment

    International Nuclear Information System (INIS)

    Duplex stainless steel having attractive combination of austenitic and ferritic properties is being used in industry such as petrochemical, pulp and paper mills. In this study, the corrosion and stress corrosion behavior of duplex stainless steel in 3.5% sodium chloride environment was investigated by weight loss measurements, electrochemical DC testing and slow strain rate test (SSRT). Weight loss data showed no significant corrosion after 1700 hours. Electrochemical polarization test in 3.5% NaCl solution exhibited a uniform corrosion rate of 0.008 mpy (calculated using Tafel analysis) showing passivity in the range of 735-950 mV. A comparison of the slow strain rate test in 3.5% NaCl solution with air shows almost a similar stress strain curve for duplex stainless steel. In comparison, the stress strain curves for 0.15% carbon steel show a loss of about 25% tensile elongation for the same comparison. The excellent corrosion and especially resistance to localized corrosion (pitting) is responsible for no loss of ductility in duplex stainless steel

  8. On the stress corrosion cracking of lean duplex steel in chloride environment

    Science.gov (United States)

    Tayyaba, Qanita; Farooq, Hina; Shahid, Muhammad; Jadoon, Ammer Khan; Shahzad, M.; Qureshi, A. H.

    2014-06-01

    Duplex stainless steel having attractive combination of austenitic and ferritic properties is being used in industry such as petrochemical, pulp and paper mills. In this study, the corrosion and stress corrosion behavior of duplex stainless steel in 3.5% sodium chloride environment was investigated by weight loss measurements, electrochemical DC testing and slow strain rate test (SSRT). Weight loss data showed no significant corrosion after 1700 hours. Electrochemical polarization test in 3.5% NaCl solution exhibited a uniform corrosion rate of 0.008 mpy (calculated using Tafel analysis) showing passivity in the range of 735-950 mV. A comparison of the slow strain rate test in 3.5% NaCl solution with air shows almost a similar stress strain curve for duplex stainless steel. In comparison, the stress strain curves for 0.15% carbon steel show a loss of about 25% tensile elongation for the same comparison. The excellent corrosion and especially resistance to localized corrosion (pitting) is responsible for no loss of ductility in duplex stainless steel.

  9. On the stress corrosion cracking of lean duplex steel in chloride environment

    International Nuclear Information System (INIS)

    Duplex stainless steel having attractive combination of austenitic and ferritic properties is being used in industry such as petrochemical, pulp and paper mills. In this study, the corrosion and stress corrosion behavior of duplex stainless steel in 3.5 percentage sodium chloride environment was investigated by weight loss measurements, electrochemical DC testing and slow strain rate test (SSRT). Weight loss data showed no significant corrosion after 1700 hours. Electrochemical polarization test in 3.5 percentage NaCl solution exhibited a uniform corrosion rate of 0.008 mpy (calculated using Tafel analysis) showing passivity in the range of 735-950 mV. A comparison of the slow strain rate test in 3.5 percentage NaCl solution with air shows almost a similar stress strain curve for duplex stainless steel. In comparison, the stress strain curves for 0.15percentage carbon steel show a loss of about 25 percentage tensile elongation for the same comparison. The excellent corrosion and especially resistance to localized corrosion (pitting) is responsible for no loss of ductility in duplex stainless steel. (author)

  10. Localized corrosion and stress-corrosion cracking behavior of stainless steel weldments. Annual progress report, June 1, 1980-February 28, 1981

    International Nuclear Information System (INIS)

    Pitting corrosion experiments were conducted on 308L stainless steel as a function of alloy microstructure (% delta ferrite) in acidified water-methanol solutions. Slow strain rate stress corrosion cracking studies were performed on single-phase and duplex 304 stainless steels as functions of solution chemistry, temperature, and sensitization

  11. Localized corrosion and stress-corrosion cracking behavior of stainless steel weldments. Annual progress report, June 1, 1980-February 28, 1981

    Energy Technology Data Exchange (ETDEWEB)

    Savage, W. F.; Duquette, D. J.

    1980-02-01

    Pitting corrosion experiments were conducted on 308L stainless steel as a function of alloy microstructure (% delta ferrite) in acidified water-methanol solutions. Slow strain rate stress corrosion cracking studies were performed on single-phase and duplex 304 stainless steels as functions of solution chemistry, temperature, and sensitization. (DLC)

  12. Effect of residual stress induced by pulsed-laser irradiation on initiation of chloride stress corrosion cracking in stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Eto, Shuzo, E-mail: eto@criepi.denken.or.jp; Miura, Yasufumi; Tani, Junichi; Fujii, Takashi

    2014-01-10

    The atmospheric corrosion test and residual stress measurement were performed to evaluate the effect of laser irradiation on stress corrosion cracking (SCC) initiation. Second-harmonic Nd:YAG laser pulses (pulse width: 10 ns) were irradiated on a type-304L stainless-steel plate. The specimens were placed in a chamber at 353 K with RH=35% for the corrosion test. When laser energies were 30 and 300 mJ, cracks caused by SCC or pitting were observed on the surface of the specimens. The cracks were classified into two types on the basis of cumulative probability distribution; one of the types is related to the laser irradiation condition. The mean maximum crack depths were about 27 and 52 μm when laser energies were 30 and 300 mJ, respectively. These values were the same as the depth at which the tensile residual stress was induced from the surface of the specimen by laser irradiation. These results suggest that the maximum stress corrosion crack depth was caused by the tensile residual stress induced by laser irradiation, and that the crack stopped propagating when the crack depth was larger than several dozen μm in this test set. When laser pulses of 300 mJ energy were irradiated on the surface of the specimen by shot peening, the tensile stress was induced up to 20 μm from the surface, and the compressive stress was observed at a larger depth. These results show that the laser irradiation is less effective in obtaining tensile residual stress of the specimen compared to when laser pulses are irradiated on the specimen treated by shot peening. The depth of tensile stress obtained by laser irradiation is much shorter than that of compressive stress obtained by shot peening.

  13. Stress corrosion cracking of stainless steel AISI 316L HAZ in PWR nuclear reactor environment

    International Nuclear Information System (INIS)

    In pressurized water reactors (PWRs), low alloy carbon steels and stainless steel are widely used in the primary water circuits. In most cases, Ni alloys are used to joint these materials and form dissimilar welds. These alloys are known to accommodate the differences in composition and thermal expansion of the two materials. Stress corrosion cracking of metals and alloys is caused by synergistic effects of environment, material condition and stress. Over the last thirty years, CST has been observed in dissimilar metal welds. This study presents a comparative work between the CST in the HAZ (Heat Affected Zone) of the AISI 316L in two different temperatures (303 deg C and 325 deg C). The susceptibility to stress corrosion cracking was assessed using the slow strain rate tensile (SSRT) test. The results of the SSRT tests indicated that CST is a thermally-activated mechanism and that brittle fracture caused by the corrosion process was observed at 325 deg C). (author)

  14. Galvanic and stress corrosion of copper canisters in repository environment. A short review

    International Nuclear Information System (INIS)

    The Swedish Nuclear Power Inspectorate, SKI, has studied different aspects of canister and copper corrosion as part of the general improvement of the knowledge base within the area. General and local corrosion has earlier been treated by experiments as well as by thermodynamic calculations. For completeness also galvanic and stress corrosion should be treated. The present work is a short review, intended to indicate areas needing further focus. The work consists of two parts, the first of which contains a judgement of statements concerning risk of galvanic corrosion of copper in the repository. The second part concerns threshold values for the stress intensity factor of stress corrosion in copper. A suggestion is given on how such values possibly could be measured for copper at repository conditions. In early investigations by SKB, galvanic corrosion is not mentioned or at least not treated. In later works it is treated but often in a theoretical way without indications of any further treatment or investigation. Several pieces of work indicate that further investigations are required to ensure that different types of corrosion, like galvanic, cannot occur in the repository environment. There are for example effects of grain size, grain boundary conditions, impurities and other factors that could influence the appearance of galvanic corrosion that are not treated. Those factors have to be considered to be completely sure that galvanic corrosion and related effects does not occur for the actual canister in the specific environment of the repository. The circumstances are so specific, that a rather general discussion indicating that galvanic corrosion is not probable just is not enough. Experiments should also be performed for verification. It is concluded that the following specific areas, amongst others, could benefit from further consideration. Galvanic corrosion of unbreached copper by inhomogeneities in the environment and in the copper metal should be addressed

  15. Control of stress corrosion cracking in storage tanks containing radioactive waste

    International Nuclear Information System (INIS)

    Stress corrosion of carbon steel storage tanks containing alkaline nitrate radioactive waste, at the Savannah River Plant is controlled by specification of limits on waste composition and temperature. Cases of cracking have been observed in the primary steel shell of tanks designed and built before 1960 that were attributed to a combination of high residual stresses from fabrication welding and aggressiveness of fresh wastes from the reactor fuel reprocessing plants. The fresh wastes have the highest concentration of nitrate, which has been shown to be the cracking agent. Also as the waste solutions age and are reduced in volume by evaporation of water, nitrite and hydroxide ions become more concentrated and inhibit stress corrosion. Thus, by providing a heel of aged evaporated waste in tanks that receive fresh waste, concentrations of the inhibitor ions are maintained within specified ranges to protect against nitrate cracking. Tanks designed and built since 1960 have been made of steels with greater resistance to stress corrosion; these tanks have also been heat treated after fabrication to relieve residual stresses from construction operations. Temperature limits are also specified to protect against stress corrosion at elevated temperatures

  16. AE characteristics during stress corrosion cracking of sensitized type 304 stainless steel pipes

    International Nuclear Information System (INIS)

    The objective of this study was to get a better understanding on acoustic emission (AE) characteristics during stress corrosion cracking (SCC) processes of Type 304 stainless steel, to apply AE techniques to detection and monitoring of SCC of the type experienced with stainless steel boiling water reactor piping. SCC tests were performed on pipe specimens with 20 mm inner diameter. Before testing, all pipe specimens were solution-treated and then sensitized. The SCC tests were conducted in the circulating corrosion test equipment containing the pipe specimen under three kinds of bi-axial stresses, of which Mises equivalent stresses were kept at 172 MNm (17.5 kg/mm2). The test conditions were: the test temperature: 2250C; the concentration of chloride ion: approximately 50 ppm; the concentration of dissolved oxygen: approximately 10 ppm; the flow rate of water: 10 l/hr. Main results were: (1) the failure was caused mainly by intergranular stress corrosion cracking; (2) AE characteristics during the SCC test may be divided into three stages; (3) the most probable AE sources in the 3rd stage may be the phenomena due to the propagation of intergranular stress corrosion cracks; (4) the propagation velocity of intergranular stress corrosion cracks seems to become higher, as the hoop stress applied to the pipe specimens increases, even in the cases of the same value of Mises' equivalent stress; and (5) at the leakage due to SCC, cumulative counts, signal waveforms and peak-amplitude distributions shows a great change and the leakage is readily detectable by standard AE techniques. (author)

  17. Burst Test of Stress Corrosion Cracked Stream Generator Tubes under Internal Pressure

    International Nuclear Information System (INIS)

    Outside diameter stress corrosion cracking (ODSCC) has been observed on steam generator (SG) Alloy 600HTMA tubing during in-service inspection. There is tendency for the cracking to be parallel to the axis of the tube. To prevent ODSCC tube burst due to internal pressure and maintain structural integrity, robust model to estimate burst pressure is required. These models should be validated on the basis of burst test data. This paper presents experimental burst test results with stress corrosion cracked SG tubing. The results were compared with the existing burst pressure models.

  18. 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...

  19. Stress Corrosion Evaluation of Various Metallic Materials for the International Space Station Water Recycling System

    Science.gov (United States)

    Torres, P. D.

    2015-01-01

    A stress corrosion evaluation was performed on Inconel 625, Hastelloy C276, titanium commercially pure (TiCP), Ti-6Al-4V, Ti-6Al-4V extra low interstitial, and Cronidur 30 steel as a consequence of a change in formulation of the pretreatment for processing the urine in the International Space Station Environmental Control and Life Support System Urine Processing Assembly from a sulfuric acid-based to a phosphoric acid-based solution. The first five listed were found resistant to stress corrosion in the pretreatment and brine. However, some of the Cronidur 30 specimens experienced reduction in load-carrying ability.

  20. Synergistic effect of sulfate-reducing bacteria and elastic stress on corrosion of X80 steel in soil solution

    International Nuclear Information System (INIS)

    Highlights: • The elastic stress and activities of SRB enhance corrosion independently. • The elastic stress and activities of SRB have synergistic effects on corrosion. • Activities of SRB stimulate the initiation of pitting corrosion. • The elastic stress promotes the growth of pits in the inoculated soil solution. • The elastic stress and activities of SRB induce tiny secondary corrosion pitting. - Abstract: In this paper, the individual and simultaneous effects of stress and sulfate-reducing bacteria on corrosion of X80 steel were conducted by electrochemical impedance spectroscopy, scanning electron microscope and X-ray photoelectron spectroscopy. Both elastic stress and activity of SRB enhance corrosion of the steel and, furthermore, they have synergistic effects on corrosion behavior of the steel. The activities of SRB give rise to the initiation of pits, and the applied elastic stress keeps and promotes the growth of pits. The activities of SRB and the applied elastic stress induce tiny secondary corrosion pitting at the bottom of the primary pitting

  1. Stress corrosion cracking of stainless-steel canister for concrete cask storage of spent fuel

    Science.gov (United States)

    Tani, Jun-ichi; Mayuzumi, Masami; Hara, Nobuyoshi

    2008-09-01

    Resistance to external stress corrosion cracking (ESCC) and crevice corrosion were examined for various candidate canister materials in the spent fuel dry storage condition using concrete casks. A constant load ESCC test was conducted on the candidate materials in air after deposition of simulated sea salt particles on the specimen gage section. Highly corrosion resistant stainless steels (SS), S31260 and S31254, did not fail for more than 46 000 h at 353 K with relative humidity of 35%, although the normal stainless steel, S30403 SS failed within 500 h by ESCC. Crevice corrosion potentials of S31260 and S31254 SS became larger than 0.9 V (SCE) in synthetic sea water at temperatures below 298 K, while those of S30403 and S31603 SS were less than 0 V (SCE) at the same temperature range. No rust was found on S31260 and S31254 SS specimens at temperatures below 298 K in the atmospheric corrosion test, which is consistent with the temperature dependency of crevice corrosion potential. From the test result, the critical temperature of atmospheric corrosion was estimated to be 293 K for both S31260 and S31254 SS. Utilizing the ESCC test result and the critical temperature, together with the weather station data and the estimated canister wall temperature, the integrity of canister was assessed from the view point of ESCC.

  2. Corrosion Behavior of the Stressed Sensitized Austenitic Stainless Steels of High Nitrogen Content in Seawater

    Directory of Open Access Journals (Sweden)

    A. Almubarak

    2013-01-01

    Full Text Available The purpose of this paper is to study the effect of high nitrogen content on corrosion behavior of austenitic stainless steels in seawater under severe conditions such as tensile stresses and existence of sensitization in the structure. A constant tensile stress has been applied to sensitized specimens types 304, 316L, 304LN, 304NH, and 316NH stainless steels. Microstructure investigation revealed various degrees of stress corrosion cracking. SCC was severe in type 304, moderate in types 316L and 304LN, and very slight in types 304NH and 316NH. The electrochemical polarization curves showed an obvious second current peak for the sensitized alloys which indicated the existence of second phase in the structure and the presence of intergranular stress corrosion cracking. EPR test provided a rapid and efficient nondestructive testing method for showing passivity, degree of sensitization and determining IGSCC for stainless steels in seawater. A significant conclusion was obtained that austenitic stainless steels of high nitrogen content corrode at a much slower rate increase pitting resistance and offer an excellent resistance to stress corrosion cracking in seawater.

  3. Standard Practice for Making and Using U-Bend Stress-Corrosion Test Specimens

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 This practice covers procedures for making and using U-bend specimens for the evaluation of stress-corrosion cracking in metals. The U-bend specimen is generally a rectangular strip which is bent 180° around a predetermined radius and maintained in this constant strain condition during the stress-corrosion test. Bends slightly less than or greater than 180° are sometimes used. Typical U-bend configurations showing several different methods of maintaining the applied stress are shown in Fig. 1. 1.2 U-bend specimens usually contain both elastic and plastic strain. In some cases (for example, very thin sheet or small diameter wire) it is possible to form a U-bend and produce only elastic strain. However, bent-beam (Practice G 39 or direct tension (Practice G 49)) specimens are normally used to study stress-corrosion cracking of strip or sheet under elastic strain only. 1.3 This practice is concerned only with the test specimen and not the environmental aspects of stress-corrosion testing which are discus...

  4. Storage of spent fuels: implementation of a research program on the risk of waste container rupture due to stress corrosion induced by fission products

    International Nuclear Information System (INIS)

    The following topics were dealt with: research programm on stress corrosion of spent fuel casks materials due to fission products, such as iodine, chemical interactions with zirconium, chemical aspects of stress corrosion, rupture risk assessment

  5. Velocity peaks and caustic rings

    International Nuclear Information System (INIS)

    The late infall of cold dark matter onto an isolated galaxy produces flows with definite velocity vectors at any physical point in the galactic halo. It also produces caustic rings, which are places in space where the dark matter density is very large. The self-similar model of galactic halo formation predicts that the caustic ring radii an follow the approximate law an ≅ 1/n. Bumps in the rotation curves of NGC 3198 and of our own galaxy are interpreted as due to caustic rings of dark matter

  6. Quantitative characterization of initiation and propagation in stress corrosion cracking. An approach of a phenomenological model

    International Nuclear Information System (INIS)

    A purely phenomenological study of stress corrosion cracking was performed using the couple Z2CN 18.10 (304L) austenitic stainless steel/boiling MgCl2 aqueous solution. The exploitation of the morphological information (shape of the cracks and size distribution) available after constant elongation rate tests led to the proposal of an analytical expression of the crack initiation and growth rates. This representation allowed to quantitatively characterize the influence of the applied strain rate as well as the effect of corrosion inhibitors on the crack initiation and propagation phases. It can be used in the search for the stress corrosion cracking mechanisms as a 'riddle' for the determination of the rate controlling steps. As a matter of fact, no mechanistic hypothesis has been used for its development. (author)

  7. Corrective measures and research of stress corrosion cracking of brass cooling coil in nitrite circumstances

    International Nuclear Information System (INIS)

    corrosion is attracting more and more attention in nuclear power field.as stress corrosion of nuclear safety is most dangerous, it was researched most. six heat exchange coil pipe of 2DVH and 2RRM system which was supplied cooling water by 2RRI system made water one by one in ten days after running five years. This article researched flaws through analyzing component of material, observing crack macroscopically and microcosmically, hydrochemistry and SEM analysis, and discovered the cause of flaw. ammonia which was produced by nitrite caused stress corrosion cracking of tin brass cooling coil.This article analysed the fact circs of nuclear power station and presented the corretive measure. (authors)

  8. Solvent effects on stress corrosion cracking of zirconium and Zircaloy-4 in iodine

    International Nuclear Information System (INIS)

    Localized corrosion (pitting, intergranular attack and stress corrosion cracking) of Zircaloy-4 and its principal component, zirconium, was investigated in solutions of iodine in different alcohols (methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol and 1-octanol). Intergranular attack was found in all of the solutions tested, and the attack velocity increases when the size of the alcohol molecule decreases. In some cases it was found that intergranular attack is accompanied by pitting. Slow strain-rate experiments showed that the propagation rate of stress corrosion cracks also depends on the size of the solvent molecule. From these results it may be inferred that the cause of the variation in the velocity is the steric hindrance of the alcohol molecules. The surface mobility SCC mechanism may account for these results. (author)

  9. Corrosion test qualification for in situ stress relief of recirculating steam generators' U-bends

    International Nuclear Information System (INIS)

    Highly stressed alloy 600 is susceptible to intergranular stress corrosion cracking (IGSCC) in high-purity water at nuclear steam generator (NSG) operating temperatures. Two regions in recirculating steam generators (RSG) are particularly prone to primary-side-initiated SCC: tube expansion transitions of the tube in the tubesheet and tight radii tube bends. One remedial measure to improve IGSCC in these regions is to heat the tubes and thus relieve the residual stresses that contribute significantly to the cracking problem. This article describes a corrosion test program using the accelerated SCC environments of sodium tetrathionate and sodium hydroxide to qualify an in situ stress-relief process for the most SCC-susceptible U-bends in an RSG

  10. Stress Corrosion Cracking of Steel and Aluminum in Sodium Hydroxide: Field Failure and Laboratory Test

    Directory of Open Access Journals (Sweden)

    Y. Prawoto

    2012-01-01

    Full Text Available Through an investigation of the field failure analysis and laboratory experiment, a study on (stress corrosion cracking SCC behavior of steel and aluminum was performed. All samples were extracted from known operating conditions from the field failures. Similar but accelerated laboratory test was subsequently conducted in such a way as to mimic the field failures. The crack depth and behavior of the SCC were then analyzed after the laboratory test and the mechanism of stress corrosion cracking was studied. The results show that for the same given stress relative to ultimate tensile strength, the susceptibility to SCC is greatly influenced by heat treatment. Furthermore, it was also concluded that when expressed relative to the (ultimate tensile strength UTS, aluminum has similar level of SCC susceptibility to that of steel, although with respect to the same absolute value of applied stress, aluminum is more susceptible to SCC in sodium hydroxide environment than steel.

  11. Stress corrosion cracking in high-temperature pure water and selective corrosion of nickel-bearing 13Cr martensitic stainless steels

    International Nuclear Information System (INIS)

    Mechanical and corrosion properties of 13 mass% Cr martensitic stainless steels containing 2∼5 mass% nickel were studied in various tempered states. Effects of metallurgical variable were examined by the following tests: (a) Conventional mechanical and metallurgical tests, (b) selective corrosion test in 0.88 kmol/m3 HNO3 at 293 K, and (c) slow strain rate stress corrosion cracking test in high purity water at 561 K. The following results are obtained: (1) The 13 % Cr martensitic stainless steels containing 3.5∼5 mass% nickel shows superior mechanical properties and machinability to those with 0∼2 mass% nickel. (2) However, a higher nickel addition lowers the Ac1 point to the actual tempering temperature range. This makes it difficult to choose the tempering condition which satisfies the mechanical properties needed for hydraulic machinery. (3) The susceptibility to selective corrosion increases with increasing nickel content and selective corrosion occurs in a wide temperature range and consequently the selection of the tempering temperature range is limited. (4) Active path type stress corrosion cracking behavior is closely related to the selective corrosion behavior. In conclusion, it is desirable to lower the nickel and carbon contents in the steel and to carefully select the tempering temperature yielding good mechanical properties without giving rise to susceptibility to selective corrosion. (author)

  12. Effect of cold work on the growth rates of stress corrosion cracks in structural materials of nuclear systems

    International Nuclear Information System (INIS)

    The growth rates of stress corrosion cracks in austenitic stainless steels and nickel base alloy 600 exposed to simulated boiling water reactor coolant were measured by fracture mechanics testing techniques. Cold work may increase the crack growth rates up to one hundred times. In both, the annealed condition and the cold worked condition, the stress corrosion crack growth rates are independent of stress intensity over a wide K-range and crack growth rates correlate well with yield strength and hardness. In the annealed condition the fracture path is intergranular, but higher degrees of cold work introduce higher proportions of transgranular stress corrosion cracking

  13. Thermomechanical processing of 5083 aluminum to increase strength without increasing susceptibility to stress corrosion cracking

    Energy Technology Data Exchange (ETDEWEB)

    Edstrom, C. M.; Blakeslee, J. J.

    1980-09-30

    5083 aluminium with 25% cold work must be processed above 215/sup 0/C or below 70/sup 0/C to avoid forming continuous precipitate in the grain boundaries which makes the material susceptible to stress corrosion cracking. Time at temperature above 215/sup 0/C should be held to minimum (less than 30 min) to retain some strength from the 25% cold work.

  14. Thermomechanical processing of 5083 aluminum to increase strength without increasing susceptibility to stress corrosion cracking

    International Nuclear Information System (INIS)

    5083 aluminium with 25% cold work must be processed above 2150C or below 700C to avoid forming continuous precipitate in the grain boundaries which makes the material susceptible to stress corrosion cracking. Time at temperature above 2150C should be held to minimum (less than 30 min) to retain some strength from the 25% cold work

  15. Initiation of stress corrosion cracking of sensitized type 304 stainless steel

    International Nuclear Information System (INIS)

    The corrosion potential of stressed sensitized Type 304 stainless steels were studied in oxygen-containing solutions to determine the relation between potential fluctuations and the initiation of stress-corrosion cracking. An in situ scanning vibrating electrode technique was shown to detect currents coming from growing stress corrosion cracks in dilute thiosulfate solutions at temperatures below 900C. The onset of the cracking was clearly indicted by rapid decreases in the potential. It was observed that small cracks, which had grown for a limited period, were not susceptible to reinitiation of the cracking process. The onset of cracking was clearly observable by marked decreases in the potential which continued to decrease if cracking remained active and increased when cracking stopped. At and above 2000C there were no potential fluctuation indicative of the onset of stress-corrosion cracking. Small potential differences between platinum and stainless steel were observed demonstrating the presence of a single electrochemically reversible reaction determined the potential of all metals within the stainless steel autoclave, and thus masking the onset of cracking. The presence of only an iron-containing deposit on the platinum suggested that a sufficiently reversible redox couple was set up between deposited iron oxide and a soluble iron species in solution which dominated the potential of the stainless steel and the platinum

  16. Studies of stress corrosion cracking in steels used for reactor pressure vessels

    International Nuclear Information System (INIS)

    This paper reviews the state of technology concerning stress corrosion crack growth in LWR environments and reports the results from a series of experiments that attempted to duplicate the results obtained from the literature. These experiments include one conducted in a steam environment representative of the condition in the upper head of a boiling-water reactor (BWR)

  17. Acoustic emission from stress corrosion crack initiation and growth in Type 304 SS

    International Nuclear Information System (INIS)

    Acoustic emission (AE) studies of intergranular stress corrosion crack (IGSCC) initiation and growth and pit initiated crack initiation have been conducted. IGSCC occurs with a moderate number of AE events, on the order of 20 ev/mm2 of crack extension, for both crack initiation and growth processes. There was no obvious difference in the AE signal amplitude or risetime distributions for crack initiation or growth. Acoustic emission appear to emanate from plastic zone formation ahead of the crack tip and ligament or inclusion failure behind the crack. Pitting was found to occur with a significant number of AE events but there was no evidence that transgranular stress corrosion (TGSCC) produced measurable AE. The source of the AE from pitting was suggested as being from the rupture of salt caps over the pits. These results suggest that AE is a potential tool for monitoring stress corrosion cracking of reactor piping; however, development of methods to discriminate between AE from stress corrosion and other reactor noise will be necessary

  18. Stress corrosion of the alloy U-7.5 Nb-2.5 Zr

    International Nuclear Information System (INIS)

    Oxide formed on U-7.5 Nb-2.5 Zr at room temperature during stress corrosion cracking in oxygen is identical to the natural oxide of the alloy. It is formed by UO2 with Nb and Zr and is associated with an increased Nb content at the interface. This oxide would be responsible for cracking

  19. Stress corrosion crack growth rates in NiCrMoV turbine disc steels

    International Nuclear Information System (INIS)

    Stress corrosion crack growth rates were obtained from precracked WOL specimens in simulated turbine environments - pure NaOH solutions, dilute NaOH-NaCl solutions and pure water. Tests were performed at 157 C on steels with yield strength in the range 706-1124 MPa

  20. Stress corrosion of the pressure vessel steel A-533-B in high-temperature water

    International Nuclear Information System (INIS)

    Stress corrosion of the pressure vessel steel A-533-B can be induced by accelerated laboratory tests in oxygenous water at high temperature. Cracking has occurred in water with 8 ppm O2 but not in water with less than 10 ppb O2. High load during deformation also introduces cracks. (G.B.)

  1. Use of a constant deflection test to evaluate susceptibility to irradiation-assisted stress corrosion cracking

    International Nuclear Information System (INIS)

    A constant deflection test was developed to evaluate the susceptibility of irradiated stainless steel (SS) to irradiation-assisted stress corrosion cracking. The test was shown useful in supplementing constant extension rate tensile or slow strain rate tensile, constant load, and swelling mandrel tests that have been used in the past. Preliminary data showing the susceptibility of commercial-purity type 304 SS (UNS S30400) as a function of stress, strain, and fast neutron fluence (E > 1 MeV) were presented

  2. Influence of residual stresses and loading frequencies on corrosion fatigue crack growth behavior of weldments

    Science.gov (United States)

    Kitsunai, Y.; Tanaka, M.; Yoshihisa, E.

    1998-04-01

    The effect of residual stresses and loading frequencies on corrosion fatigue crack growth behavior under synthetic seawater with a free corrosion potential was examined using center-cracked tension (CCT) and single edge-cracked tension (SECT) specimens machined from mild steel butt-welded joints and the parent material. A series of fatigue crack growth tests were carried out with a sinusoidal loading wave form at a stress ratio of 0.05 with a loading frequency of 0.017 to 6.7 Hz. The results show that the crack growth resistance of a weld metal in the SECT specimen is higher than that in the CCT specimen regardless of testing conditions. The discrepancy is attributed to the differences in residual stress distribution at the crack tip in the two specimen geometries. The crack growth rate of the weld metal in the CCT specimen in seawater increased with decreasing loading frequency. The acceleration of the crack growth rate may be related to the occurrence of brittle striation or cleavage due to hydrogen embrittlement. It was found that the corrosion fatigue crack growth rate of a welded joint with tensile residual stress can be predicted using the effective stress intensity factor range, which takes into account both the residual stress and the loading frequency effects.

  3. Causticizing for Black Liquor Gasifiers

    Energy Technology Data Exchange (ETDEWEB)

    Scott Sinquefeld; James Cantrell; Xiaoyan Zeng; Alan Ball; Jeff Empie

    2009-01-07

    The cost-benefit outlook of black liquor gasification (BLG) could be greatly improved if the smelt causticization step could be achieved in situ during the gasification step. Or, at a minimum, the increase in causticizing load associated with BLG could be mitigated. A number of chemistries have been proven successful during black liquor combustion. In this project, three in situ causticizing processes (titanate, manganate, and borate) were evaluated under conditions suitable for high temperature entrained flow BLG, and low temperature steam reforming of black liquor. The evaluation included both thermodynamic modeling and lab experimentation. Titanate and manganate were tested for complete direct causticizing (to thus eliminate the lime cycle), and borates were evaluated for partial causticizing (to mitigate the load increase associated with BLG). Criteria included high carbonate conversion, corresponding hydroxide recovery upon hydrolysis, non process element (NPE) removal, and economics. Of the six cases (three chemistries at two BLG conditions), only two were found to be industrially viable: titanates for complete causticizing during high temperature BLG, and borates for partial causticizing during high temperature BLG. These two cases were evaluated for integration into a gasification-based recovery island. The Larsen [28] BLG cost-benefit study was used as a reference case for economic forecasting (i.e. a 1500 tpd pulp mill using BLG and upgrading the lime cycle). By comparison, using the titanate direct causticizing process yielded a net present value (NPV) of $25M over the NPV of BLG with conventional lime cycle. Using the existing lime cycle plus borate autocausticizing for extra capacity yielded a NPV of $16M.

  4. Microstructure, microchemistry and stress corrosion crack characteristics in a BWR 316LSS core shroud weld

    International Nuclear Information System (INIS)

    Material, corrosion and cracking characteristics have been examined in a 316LSS core shroud weld (total neutron fluence of ∼1.8x1024 n/m2, E>1 MeV) removed from boiling-water reactor service. The weld metal showed a duplex phase structure with austenite dendrites surrounded by narrower regions of interdendritic Cr-Mo-rich ferrite. The austenite-ferrite phase boundaries were locally depleted in Fe and enriched in Mo and P. Stress corrosion cracks propagated along phase boundaries within the duplex weld microstructure, preferentially corroding the lower Cr austenite versus the higher-Cr, ferrite. Compositional mapping revealed differences between the two-phase alloy regions, weld inclusions and oxide corrosion products that filled the cracks. The crack tips were always corrosion-product filled and suggested corrosive attack more than IGSCC. Although significant Mo and P enrichment was identified at the phase boundaries, no direct linkage to the corrosion/SCC susceptibility could be made. (author)

  5. Stress corrosion cracking behavior of friction stir welded Al 6061-T651

    International Nuclear Information System (INIS)

    In the present study, corrosion behavior of Friction Stir Welded (FSWed) Al 6061-T651 with varying welding parameters, including rotating and welding speeds, were examined. The 4 mm thick Al 6061-T651 alloy plates were friction stir welded. The resistance to corrosion was slightly improved, or at least did not decrease, for FSWed Al 6061-T651 alloy in 3.5% NaCl solution compared to the parent material. The effect of different welding conditions on the corrosion resistance was minimal. The micrographic and fractographic observations strongly suggested that the change in corrosion behavior of FSWed Al 6061-T651 was largely related to the clustering of coarse Mg2Si precipitates, due to the whirling and casting action by severe plastic flow in the weld zone. Low welding speed and/or high rotating speed tended to encourage the plastic flow per unit unit time and consequently the clustering of coarse precipitates. The resistance to SCC in 3.5% NaCl solution was considerably higher for the FSWed Al 6061-T651 compared to that of the PM counterpart. The improved SCC resistance for the FSWed specimen was due to the fast that the stress corrosion cracks were enhanced at the boundary between the DXZ and the HAZ due to the greatest galvanic corrosion potential difference between the two phases, while the tensile fracture occurred at the other area where the strength level was the lowest

  6. Stress corrosion cracking susceptibility of stainless and duplex steels

    Energy Technology Data Exchange (ETDEWEB)

    Costa, S.; Dias, C.; Pimenta, G. [Materials Laboratory, ISQ, Taguspark, Porto Salvo (Portugal); Costa, S.; Fonseca, I. [Centre for Molecular Sciences and Materials, FCUL, Lisboa (Portugal)

    2009-07-01

    Full text of publication follows: A comparative study of the influence of chloride concentration, temperature and metal crevice formation on SCC susceptibility of DIN 1.4404, 14410, 14410-CW, 1.4318 and 1.4462 steels has been performed. Single U-bend and double U-bend coupons were exposed to aqueous NaCl and MgCl{sub 2} solutions for 10 days, or until fracture, if sooner, at different temperatures. After exposure, samples were visually and dye penetrant inspected for crack or pitting determination. Results allowed producing corrosion maps accounting for the influence of [Cl{sup -}], T and crevice formation on the SCC susceptibility.

  7. Stress corrosion cracking of zirconium and its alloys in halogenide solutions

    International Nuclear Information System (INIS)

    A doctoral thesis developed at the corrosion labs in CNEA a few years ago showed that zirconium and Zircaloy-4 were susceptible to stress corrosion cracking (SCC) in chloride aqueous solutions at potentials above the pitting potential. However, the nature of the phenomenon was not elucidated. On the other hand, references about the subject were scarce and contradictory. The development of new SCC models, in particular, the surface mobility SCC mechanism suggested a review of zirconium and Zircaloy-4 SCC in halogenide aqueous solutions. This mechanism predicts that zirconium should be susceptible to SCC not only in chloride solutions but also in bromide and iodide solutions due to the low melting point of the surface compounds formed by the interaction between the metal and the environment. The present work was aimed to determine the conditions under which SCC takes place and the mechanism operating during this process. For that purpose, the effect of electrochemical potential, strain rate and temperature on the SCC susceptibility of both, zirconium and Zircaloy-4 in chloride, bromide and iodide solutions was investigated. It was observed that those materials undergo stress corrosion cracking only at potentials higher than the breakdown potential. The crack velocity increased slightly with the applied potential, and the strain rate had an accelerating effect on the crack propagation rate. In both materials two steps were found during cracking. The first one was characterized as intergranular attack assisted by stress due to an anodic dissolution process. This step is followed by a transition to a transgranular mode of propagation, which was considered as the 'true' stress corrosion cracking step. The intergranular attack is the rate-determining step due to the fact that the transgranular propagation rate is higher than the intergranular propagation rate. Several stress corrosion cracking mechanisms were analyzed to explain the transgranular cracking. The predictions

  8. Effect of induction heating stress improvement on ultrasonic response from intergranular stress corrosion cracking

    International Nuclear Information System (INIS)

    Induction heating stress improvement (IHSI) is often performed for the BWR piping weldments in order to reduce the susceptibility of intergranular stress corrosion cracking (IGSCC). Recently, in an US BWR plant, IGSCC was detected where it was not expected because the plant had implemented IGSCC countermeasures, IHSI. The objective of this work is to experimentally document the effect of IHSI on IGSCC detectability. Two IGSCC pipe samples containing a range of circumferential and axial cracks were fabricated from two 12-inch Type 304 stainless steel pipe weldments by the Creviced Pipe Test. Each sample was documented in detail by UT and PT to establish its IGSCC characteristics prior to application of IHSI and I-(Inverse)IHSI. For each sample two separate UT methods were used. One pipe sample was subjected to normal IHSI, in which the pipe OD surface was heated while the ID surface was kept cool by circulating water. The other pipe was subjected to I-IHSI, in which the pipe was heated from the ID surface followed by rapid cooling from the OD surface with water jet spray. After IHSI treatments, the two IGSCC pipe samples were ultrasonically characterized in the exact manner that was done in the initial characterization to determine if there were any noticeable changes in the UT response of the cracks as indicated by their sizes and signal amplitudes. All of the maximum echo height data from the two samples were compared in terms of the effect of the IHSI treatments. There was no statistically significant difference in the echo height due to the treatments. For both cases, the crack sizes measured after the treatments were reported to be larger than those measured before the treatments. Ultrasonic imaging of cracks was carried out by a laboratory immersion technique coupled with an automated scan probe system. The results are expressed by imaging areas of different echo height levels and of depth

  9. Effect of induction heating stress improvement on ultrasonic response from intergranular stress corrosion cracking

    Energy Technology Data Exchange (ETDEWEB)

    1991-03-01

    Induction heating stress improvement (IHSI) is often performed for the BWR piping weldments in order to reduce the susceptibility of intergranular stress corrosion cracking (IGSCC). Recently, in an US BWR plant, IGSCC was detected where it was not expected because the plant had implemented IGSCC countermeasures, IHSI. The objective of this work is to experimentally document the effect of IHSI on IGSCC detectability. Two IGSCC pipe samples containing a range of circumferential and axial cracks were fabricated from two 12-inch Type 304 stainless steel pipe weldments by the Creviced Pipe Test. Each sample was documented in detail by UT and PT to establish its IGSCC characteristics prior to application of IHSI and I-(Inverse)IHSI. For each sample two separate UT methods were used. One pipe sample was subjected to normal IHSI, in which the pipe OD surface was heated while the ID surface was kept cool by circulating water. The other pipe was subjected to I-IHSI, in which the pipe was heated from the ID surface followed by rapid cooling from the OD surface with water jet spray. After IHSI treatments, the two IGSCC pipe samples were ultrasonically characterized in the exact manner that was done in the initial characterization to determine if there were any noticeable changes in the UT response of the cracks as indicated by their sizes and signal amplitudes. All of the maximum echo height data from the two samples were compared in terms of the effect of the IHSI treatments. There was no statistically significant difference in the echo height due to the treatments. For both cases, the crack sizes measured after the treatments were reported to be larger than those measured before the treatments. Ultrasonic imaging of cracks was carried out by a laboratory immersion technique coupled with an automated scan probe system. The results are expressed by imaging areas of different echo height levels and of depth.

  10. Stress corrosion crack growth rate measurement in high temperature water using small precracked bend specimens

    International Nuclear Information System (INIS)

    The applicability of elastic-plastic fracture mechanics to stress corrosion crack growth rate measurements was studied. Several test series were performed on small elastic-plastically loaded SEN(B) specimens in high temperature water. One test was performed on a 25 mm C(T) specimen under linear-elastic loading. The tests on the SEN(B) specimens were performed using either rising displacement or a combination of rising and constant displacement loading. The test on the 25 mm C(T) specimen was performed using a combination of constant load and constant displacement. The studied materials were AISI 304 steel in sensitized, mill-annealed and irradiated conditions, AISI 316 in cold-worked condition, Inconel 82 and 182 weld metals in as-welded and thermally aged conditions and ferritic low activation steel F82H in tempered condition. The crack growth rate tests were performed in simulated pure BWR water and simulated BWR water with 10-100 ppb SO42- at 230-290 deg C. It was shown that intergranular stress corrosion cracking susceptibility can be determined using an elastic-plastic fracture mechanics approach. Fracture surface morphology in sensitized AISI 304 and welded AISI 321 steels depends on the applied loading rate in BWR water. The fracture surface morphology changes from transgranular to intergranular, when J-integral increase rate is decreased. However, extremely slow displacement rate is needed for the fracture surface morphology to be fully intergranular. Rising J results in transgranular stress corrosion cracking (or strain-induced corrosion cracking) also in the mill-annealed AISI 304 and 321 steels. Tests on irradiated AISI 304 steel showed that welding together with exposure to low neutron fluence in the BWR operating conditions results in a higher susceptibility to stress corrosion cracking than welding or irradiation alone. Ferritic low activation steel F82H (in tempered condition) is not susceptible to stress corrosion cracking under static loading

  11. Sever Gastrointestinal Caustic Injury and Surgical Treatment

    Directory of Open Access Journals (Sweden)

    A Bazrafshan

    2014-04-01

    Full Text Available Approximately 20% of caustic ingestions result in some degree of esophageal injury. Alkaline materials are the most frequent corrosive materials ingested.     The physical form and PH of ingested materials play a critical role in the site and type of gastrointestinal injury (PH > 12 or PH < 1.5, crystalline drain cleaners. Unlike Alkaline solutions, strong acids are bitter, burn on contact and usually produce vomiting but when swallowed pass rapidly through the esophagus and damage the antrum of the stomach. I will present the results of 5 cases of gastric out let obstruction after acid ingestion (subtotal gastrectomy and billroth 1 and 4 patients with extensive esophageal damage and perforation ( Total esophagectomy and gastric pull up.  

  12. Corrosion considerations for life management of Hanford high-level waste tanks

    International Nuclear Information System (INIS)

    The potential for corrosion-related aging mechanisms to be active in the Hanford Site waste tanks is frequently questioned and there are related uncertainties. This paper considers surveillance and analyses for evaluating the potential influence of corrosion processes such as stress corrosion cracking, pitting, crevice corrosion of the reinforced concrete steel on the useful life of Hanford radioactive waste tanks. There are two types of Hanford Site underground reinforced concrete, carbon steel lined waste tank structures. They primarily store caustic nitrate wastes, some at elevated temperatures, from defense reprocessing of spent nuclear fuels. Some of the Hanford waste tanks have leaked radioactive liquid waste to the soil. These leaks are possibly due to nitrate-induced stress corrosion cracking. Major efforts prescribed to avoid nitrate-induced stress corrosion cracking in newer tank designs appear successful. A potential for pitting and crevice corrosion cracking in the carbon steel liners exists. There has been no evidence of significant uniform corrosion of the carbon steel liners and there has been no evidence of waste tank degradation caused by corrosion of the concrete reinforcing steel. A waste tank life management program is being developed to qualify the Hanford waste tanks for continued safe storage of these wastes. Corrosion evaluations, structural analyses, and surveillance are required to qualify the tanks and to promptly detect evidence of possible distress

  13. Proceedings: Primary water stress corrosion cracking: 1989 EPRI remedial measures workshop

    International Nuclear Information System (INIS)

    A meeting on ''PWSCC Remedial Measures'' was organized to give those working in this area an opportunity to share their results, ideas and plans with regard to development and application of remedial measures directed against the primary water stress corrosion cracking (PWSCC) phenomenon affecting alloy 600 steam generator tubes. Topics discussed included: utility experience and strategies; nondestructive examination (NDE) methods for PWSCC; technical topics ranging from predictive methods for occurrence of PWSCC to results of corrosion tests; and services provided by vendors that can help prevent the occurrence of PWSCC or can help address problems caused by PWSCC once it occurs

  14. Effect of Superficial Atmospheric Corrosion Upon the Internal Stresses in Structural Steel Elements

    OpenAIRE

    Monel Leiba; Budescu, M.; Elena Axinte; Elena-Carmen Teleman

    2006-01-01

    A research program is presented showing the stress status determined by the corrosion phenomenon inside a specimen of a structural steel element. Several stains are studied their diameters ranging from 1~mm to 6~mm and thickness of the corroded layer under 0.5~mm. The physical modeling is the result of testing in laboratory the phenomenon of superficial atmospheric corrosion and the numerical modeling was developed under a FEM program, ALGOR. A number of 3,200 finite elements of BRICK type we...

  15. Stress Corrosion Cracking of an Austenitic Stainless Steel in Nitrite-Containing Chloride Solutions

    Directory of Open Access Journals (Sweden)

    R. K. Singh Raman

    2014-12-01

    Full Text Available This article describes the susceptibility of 316L stainless steel to stress corrosion cracking (SCC in a nitrite-containing chloride solution. Slow strain rate testing (SSRT in 30 wt. % MgCl2 solution established SCC susceptibility, as evidenced by post-SSRT fractography. Addition of nitrite to the chloride solution, which is reported to have inhibitive influence on corrosion of stainless steels, was found to increase SCC susceptibility. The susceptibility was also found to increase with nitrite concentration. This behaviour is explained on the basis of the passivation and pitting characteristics of 316L steel in chloride solution.

  16. Study of alloy 600'S stress corrosion cracking mechanisms in high temperature water

    International Nuclear Information System (INIS)

    In order to better understand the mechanisms involved in Alloy 600's stress corrosion cracking in PWR environment, laboratory tests were performed. The influence of parameters pertinent to the mechanisms was studies : hydrogen and oxygen overpressures, local chemical composition, microstructure. The results show that neither hydrogen nor dissolution/oxidation, despite their respective roles in the process, are sufficient to account for experimental facts. SEM observation of micro-cleavage facets on specimens' fracture surfaces leads to pay attention to a new mechanism of corrosion/plasticity interactions. (author). 113 refs., 73 figs., 15 tabs., 4 annexes

  17. Study of alloy 600 (NC15Fe) stress corrosion cracking mechanisms in high temperature water

    International Nuclear Information System (INIS)

    In order to better understand the mechanisms involved in Alloy 600's stress corrosion cracking in PWR environment, laboratory tests were performed. The influence of parameters pertinent to the mechanisms was studies: hydrogen and oxygen overpressures, local chemical composition, microstructure. The results show that neither hydrogen nor dissolution/oxidation, despite their respective roles in the process, are sufficient to account for experimental facts. SEM observation of micro-cleavage facets on specimens' fracture surfaces leads to pay attention to a new mechanism of corrosion/plasticity interactions. (author)

  18. Pitting Corrosion of 316L Stainless Steel under Low Stress below Yield Strength

    Institute of Scientific and Technical Information of China (English)

    L(U) Shengjie; CHENG Xuequn; LI Xiaogang

    2012-01-01

    Pitting corrosion of 316L stainless steel (316L SS) under various stress was studied by potentiodynamic polarization,electrochemical impedance spectroscopy (EIS) and Mott-Schottky (M-S) analysis in 3.5% NaCl solution.The results of polarization curves show that,with the increase of the stress,the pitting potentials and the passive current density markedly decrease firstly (180 MPa),and then increase greatly (200 MPa).The corresponding surface morphologies of the samples after the polarization test well correspond to the results.Mott-Schottky analysis proved the least Cl- adsorbed to the surface of passive film with more positive flat potential,indicating that a moderate stress could increase the pitting corrosion resistance of 316L SS in 3.5% NaCl solution.

  19. Standard practice for making and using precracked double beam stress corrosion specimens

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2000-01-01

    1.1 This practice covers procedures for fabricating, preparing, and using precracked double beam stress corrosion test specimens. This specimen configuration was formerly designated the double cantilever beam (DCB) specimen. Guidelines are given for methods of exposure and inspection. 1.2 The precracked double beam specimen, as described in this practice, is applicable for evaluation of a wide variety of metals exposed to corrosive environments. It is particularly suited to evaluation of products having a highly directional grain structure, such as rolled plate, forgings, and extrusions, when stressed in the short transverse direction. 1.3 The precracked double beam specimen may be stressed in constant displacement by bolt or wedge loading or in constant load by use of proof rings or dead weight loading. The precracked double beam specimen is amenable to exposure to aqueous or other liquid solutions by specimen immersion or by periodic dropwise addition of solution to the crack tip, or exposure to the atmos...

  20. Applied methods for mitigation of damage by stress corrosion in BWR type reactors

    International Nuclear Information System (INIS)

    The Boiling Water nuclear Reactors (BWR) have presented stress corrosion problems, mainly in components and pipes of the primary system, provoking negative impacts in the performance of energy generator plants, as well as the increasing in the radiation exposure to personnel involucred. This problem has caused development of research programs, which are guided to find solution alternatives for the phenomena control. Among results of greater relevance the control for the reactor water chemistry stands out particularly in the impurities concentration and oxidation of radiolysis products; as well as the supervision in the materials selection and the stresses levels reduction. The present work presents the methods which can be applied to diminish the problems of stress corrosion in BWR reactors. (Author)

  1. 'EMAGTRONIC', a portable tool to locate LP turbine blades endangered by stress corrosion cracking

    International Nuclear Information System (INIS)

    L.P. turbine last stage blades (material X 20 Cr 13) operating well within the moisture region require protection against water droplet erosion. To increase the resistance of the leading edge to droplet erosion, a flame hardening process at about 10000C is employed. In order to preclude stress corrosion cracking in this area, residual tensile surface stresses must be avoided. The new electromagnetic equipment gives quantifiable information regarding the residual stress state of the blades vane surface and can be used to check the blade manufacturing quality control and also for in-service inspection in power plants. (orig.)

  2. High-Performance Laser Peening for Effective Mitigation of Stress Corrosion Cracking

    Energy Technology Data Exchange (ETDEWEB)

    Hackel, L; Hao-Lin, C; Wong, F; Hill, M

    2002-10-02

    Stress corrosion cracking (SCC) in the Yucca Mountain waste package closure welds is believed to be the greatest threat to long-term containment. Use of stress mitigation to eliminate tensile stresses resulting from welding can prevent SCC. A laser technology with sufficient average power to achieve high throughput has been developed and commercially deployed with high peak power and sufficiently high average power to be an effective laser peening system. An appropriately applied version of this process could be applied to eliminate SCC in the waste package closure welds.

  3. Effect of aging treatment on the exfoliation corrosion and stress corrosion cracking behaviors of 2195 Al–Li alloy

    International Nuclear Information System (INIS)

    Highlights: • The relationship between properties and microstructures of 2195 was discussed. • The optimum heat treatment of 2195 alloy is the aged at 155 °C for 14 h temper. • The EXCO process and susceptibility of 2195 alloy can be well detected by EIS. • The SCC susceptibility of 2195 alloy in 3.5% NaCl solution is low. • Mechanical action takes the dominant part in this SCC system for 2195 alloy. - Abstract: 2195 Al–Li alloy was processed by solid solution heat treatment and then aged at different temperatures, and its microstructure, mechanical properties, inter-granular corrosion (IGC), exfoliation corrosion (EXCO) and stress corrosion cracking (SCC) behaviors were observed and determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), immersion test in IGC and EXCO solutions, electrochemical impedance spectroscopy (EIS) and slow strain rate tensile (SSRT) test. The results reveal that the size and density of T1 precipitates at grain boundary are increased with increasing aging temperature whereas the density of T1 phases in grain is increased firstly and then reduced slightly. The IGC and EXCO susceptibility of 2195 alloy is increased while its SCC susceptibility in 3.5% NaCl solution is low and hardly influenced by the aging temperature. The hardness and tensile strength are increased at first and then decreased, but the elongation and static toughness values are declined with aging temperature. The optimum heat treatment for the practical application of 2195 alloy is the aged at 155 °C for 14 h temper

  4. Stress corrosion cracking of AISI 321 stainless steel in acidic chloride solution

    Indian Academy of Sciences (India)

    Yanliang Huang

    2002-02-01

    The stress corrosion cracking (SCC) of AISI 321 stainless steel in acidic chloride solution was studied by slow strain rate (SSR) technique and fracture mechanics method. The fractured surface was characterized by cleavage fracture. In order to clarify the SCC mechanism, the effects of inhibitor KI on SCC behaviour were also included in this paper. A study showed that the inhibition effects of KI on SCC were mainly attributed to the anodic reaction of the corrosion process. The results of strain distribution in front of the crack tip of the fatigue pre-cracked plate specimens in air, in the blank solution (acidic chloride solution without inhibitor KI) and in the solution added with KI measured by speckle interferometry (SPI) support the unified mechanism of SCC and corrosion fatigue cracking (CFC).

  5. Stress corrosion cracking of A588 steel weldments in flue gas related environments

    Science.gov (United States)

    Tsay, L. W.; Chen, W. Y.; Shine, R. K.; Shine, R. H.

    2001-06-01

    This study investigated stress corrosion cracking (SCC) of A588 steel welds as determined by U-bend immersion tests and slow strain rate tensile (SSRT) tests to evaluate the steel’s cracking susceptibility in various regions of the weldments. The immersion test results indicated that the fusion zone (FZ) had better corrosion resistance than the other regions in the weld. It was also demonstrated that the columnar grain boundaries exhibited a higher resistance to corrosion than the grain interior of the FZ. However, the coarse elongated ferrite in the FZ is susceptible to hydrogen embrittlement (HE), which results in the formation of microcracks. As a result, a severe degradation of the weld’s tensile properties in the saturated H2S solution was observed. Scanning electron microscope (SEM) fractographs of tensile specimens reveal a cleavage fracture in the coarse-grained heat-affected zone (CGHAZ) and featherlike rupture in the FZ, both indicating a high sensitivity to HE.

  6. Stress corrosion cracking and corrosion fatigue on 316L stainless steel in boric acid concentrated media at 320 C

    International Nuclear Information System (INIS)

    Stress Corrosion Cracking (SCC) and Corrosion-Fatigue (CF) tests were performed in autoclave at 320 C in concentrated boric acid chlorinated media in presence of oxygen or hydrogen on type 316L austenitic stainless steel. Crack Growth Rates (CGR) are higher in non deaerated solutions for both SCC and CF than in hydrogenated solutions. CGR are relatively similar in CF and in SCC, excepted for high load ratio in CF where CGR are higher than in SCC. Detailed analysis of the fracture surface shows some distinct features between SCC and CF. Intergranular and transgranular mode of fracture are observed on SCC and CF. Fracture modes depend on the chemistry of solution in SCC and on frequency in CF. Traces of slip bands and crack front marking associated with oxide scale present on fracture surfaces exist in SCC and CF. Fatigue striations appear for low load ratio and high frequency. Secondary intergranular and transgranular cracking is observed only on SCC fracture surfaces and ligament morphology can be different in SCC relative to FC

  7. Mitigating the Risk of Stress Corrosion of Austenitic Stainless Steels in Advanced Gas Cooled Reactor Boilers

    International Nuclear Information System (INIS)

    Advanced Gas-Cooled Reactors (AGRs) operated in the UK by EDF Energy have once-through boilers, which deliver superheated steam at high temperature (∼500 deg. C) and pressure (∼150 bar) to the HP turbine. The boilers have either a serpentine or helical geometry for the tubing of the main heat transfer sections of the boiler and each individual tube is fabricated from mild steel, 9%Cr1%Mo and Type 316 austenitic stainless steel tubing. Type 316 austenitic stainless steel is used for the secondary (final) superheater and steam tailpipe sections of the boiler, which, during normal operation, should operate under dry, superheated steam conditions. This is achieved by maintaining a specified margin of superheat at the upper transition joint (UTJ) between the 9%Cr1%Mo primary superheater and the Type 316 secondary superheater sections of the boiler. Operating in this mode should eliminate the possibility of stress corrosion cracking of the Type 316 tube material on-load. In recent years, however, AGRs have suffered a variety of operational problems with their boilers that have made it difficult to maintain the specified superheat margin at the UTJ. In the case of helical boilers, the combined effects of carbon deposition on the gas side and oxide deposition on the waterside of the tubing have resulted in an increasing number of austenitic tubes operating with less than the specified superheat margin at the UTJ and hence the possibility of wetting the austenitic section of the boiler. Some units with serpentine boilers have suffered creep-fatigue damage of the high temperature sections of the boiler, which currently necessitates capping the steam outlet temperature to prevent further damage. The reduction in steam outlet temperature has meant that there is an increased risk of operation with less than the specified superheat margin at the UTJ and hence stress corrosion cracking of the austenitic sections of the boiler. In order to establish the risk of stress

  8. Detection of stress corrosion cracks and wastage in reactor pressure vessels and primary coolant system studs

    International Nuclear Information System (INIS)

    Over the last few years, nuclear plants have experienced stud bolt failures due to stress corrosion cracking and corrosion wastage. Many of these stud bolts were over 1 m long and had no heater hole. The use of conventional longitudinal wave inspection for bolts longer than 1 m has shown inconsistent results. A nondestructive testing technique was needed to inspect the stud bolts in place. The cylindrically guided wave technique was developed to inspect stud bolts of various lengths (up to 3 m) and various diameters. This technique is based on the fact that an ultrasonic wave traveling in a long cylinder becomes guided by the geometry of the cylinder. The wave begins to spread in the cylinder as interaction with the outer wall produces mode conversions. A large number of model stud bolts were tested to verify that the cylindrically guided wave technique could be used to detect crack-like defects and simulated corrosion wastage. This work shows that the cylindrically guided wave technique can be used on a wide variety of stud bolt configurations, and that the technique can be used to effectively detect the two most common modes of stud bolt failure (corrosion cracking and corrosion wastage) at early stages of development

  9. Simulated Service and Stress Corrosion Cracking Testing for Friction Stir Welded Spun Formed Domes

    Science.gov (United States)

    Stewart, Thomas J.; Torres, Pablo D.; Caratus, Andrei A.; Curreri, Peter A.

    2010-01-01

    Simulated service testing (SST) development was required to help qualify a new 2195 aluminum lithium (Al-Li) alloy spin forming dome fabrication process for the National Aeronautics and Space Administration (NASA) Exploration Development Technology Program. The application for the technology is to produce high strength low weight tank components for NASA s next generation launch vehicles. Since plate material is not currently manufactured large enough to fabricate these domes, two plates are joined by means of friction stir welding. The plates are then pre-contour machined to near final thicknesses allowing for a thicker weld land and anticipating the level of stretch induced by the spin forming process. The welded plates are then placed in a spin forming tool and hot stretched using a trace method producing incremental contours. Finally the dome receives a room temperature contour stretch to final dimensions, heat treatment, quenching, and artificial aging to emulate a T-8 condition of temper. Stress corrosion cracking (SCC) tests were also performed by alternate immersion in a sodium chloride (NaCl) solution using the typical double beam assembly and with 4-point loaded specimens and use of bent-beam stress-corrosion test specimens under alternate immersion conditions. In addition, experiments were conducted to determine the threshold stress intensity factor for SCC (K(sub ISCC)) which to our knowledge has not been determined previously for Al-Li 2195 alloy. The successful simulated service and stress corrosion testing helped to provide confidence to continue to Ares 1 scale dome fabrication

  10. Stress corrosion cracking in low-pressure steam turbine rotors: from experiment to simulation

    International Nuclear Information System (INIS)

    The Stress Corrosion Cracking ( SCC ) has appeared on the LP shrunk-on disks of the 900 MW CP0/CP1 turbines. The temperature at which this occurs is between 90 deg.C and 130 deg.C. Although conventional power stations use the same materials, the temperature of the wet steam does not rise above 70 deg.C, therefore they are not affected by stress corrosion. It becomes quickly apparent that temperature plays an important role. This has been confirmed by crack growth rate analysis using water in autoclaves. In these tests the influence of the proof stress or the material has been also monitored. The conditions that cause these cracks have also been the subject of testing. For temperatures around 95 deg.C, it has been noted that cracks appear quicker in steam than in pure water. GEC ALSTHOM has also conducted a large number of tests in pure steam at 95 deg.C. In order to progress in the study of stress corrosion, it has been decided to design and build a test loop, which allows a steam flow, at a constant temperature and wetness, to be circulated around the test samples. The test program will concern materials for LP rotors, with a coefficient charge of K = σapplied/RP0.2 between 1 and 0.2 and a maximum test duration of 50000 hours. (authors)

  11. Effect of Superficial Atmospheric Corrosion Upon the Internal Stresses in Structural Steel Elements

    Directory of Open Access Journals (Sweden)

    Monel Leiba

    2006-01-01

    Full Text Available A research program is presented showing the stress status determined by the corrosion phenomenon inside a specimen of a structural steel element. Several stains are studied their diameters ranging from 1~mm to 6~mm and thickness of the corroded layer under 0.5~mm. The physical modeling is the result of testing in laboratory the phenomenon of superficial atmospheric corrosion and the numerical modeling was developed under a FEM program, ALGOR. A number of 3,200 finite elements of BRICK type were created and the evolution of normal and tangential stresses was scrutinized under the process of loosing elementary material transformed into scrap. Stresses in the damaged sphere were graphically put into evidence and determined with accuracy due to the performances of the program, showing the local perturbations and the pattern of stress concentrators. The studies showed the importance of reproducing with both physical and mathematical methods the intricate mechanism and sometimes unpredictable effects of corrosion phenomenon upon the structural steel elements.

  12. Intergranular stress corrosion in soldered joints of stainless steel 304

    International Nuclear Information System (INIS)

    The intergranular stress cracking of welded joints of austenitic stainless steel, AISI 304, is a serious problem in BWR type reactors. It is associated with the simultaneous presence of three factors; stress, a critical media and sensibilization (DOS). EPR technique was used in order to verify the sensibilization degree in the base metal, and the zone affected by heat and welding material. The characterization of material was done. The objective of this work is the study of microstructure and the evaluation of EPR technique used for the determination of DOS in a welded plate of austenitic stainless steel AISI 304. (Author)

  13. Evaluation of the cracking by stress corrosion in nuclear reactor environments type BWR

    International Nuclear Information System (INIS)

    The stress corrosion cracking susceptibility was studied in sensitized, solution annealed 304 steel, and in 304-L welded with a heat treatment that simulated the radiation induced segregation, by the slow strain rate test technique, in a similar environment of a boiling water reactor (BWR), 288 C, 8 MPa, low conductivity and a electrochemical corrosion potential near 200 mV. vs. standard hydrogen electrode (She). The electrochemical noise technique was used for the detection of the initiation and propagation of the cracking. The steels were characterized by metallographic studies with optical and scanning electronic microscopy and by the electrochemical potentiodynamic reactivation of single loop and double loop. In all the cases, the steels present delta ferrite. The slow strain rate tests showed that the 304 steel in the solution annealed condition is susceptible to transgranular stress corrosion cracking (TGSCC), such as in a normalized condition showed granulated. In the sensitized condition the steel showed intergranular stress corrosion cracking, followed by a transition to TGSCC. The electrochemical noise time series showed that is possible associated different time sequences to different modes of cracking and that is possible detect sequentially cracking events, it is means, one after other, supported by the fractographic studies by scanning electron microscopy. The parameter that can distinguish between the different modes of cracking is the re passivation rate, obtained by the current decay rate -n- in the current transients. This is due that the re passivation rate is a function of the microstructure and the sensitization. Other statistic parameters like the localized index, Kurtosis, Skew, produce results that are related with mixed corrosion. (Author)

  14. Phenomena of the ionic transport in the stress corrosion of metals

    International Nuclear Information System (INIS)

    For the study of electrochemical conditions of propagation, a model which calculates the concentrations and potential profiles inside cracks or localized corrosion cavities, was developed. Considering transport by difussion and migration it was applied to pure metals (Zn, Fe) in solutions where pitting occurs (NaCl or Na2SO4, with borate buffer), and also extended to systems where stress corrosion cracking is present, such as Cu and yellow brass in NaNO2. Physical bases of the 'constant intermediate elongation rate technique' to predict stress corrosion cracking susceptibility was analized, studying by mathematical models: 1) dissolution current, that should be the result of superposition of repassivation transients on the fresh metal, exposed to corrosive medium by strain, with the same rate of that of a static specimen; 2) ohmic drop, that in some systems could be quite important and it must be considered in the overpotential evaluation; and 3) metallic ion concentration that, instead of what happens in a crack, never attains saturation in the analized cases. For repassivation transient according to the crak propagation models proposed by Scully and Ford it was found that, at the tip of the crack, it is unlikely that the same repassivation transients occur as in the constant intermediate elongation rate experiments. (M.E.L.)

  15. 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

  16. Laboratory results of stress corrosion cracking of steam generator tubes in a complex environment - An update

    Energy Technology Data Exchange (ETDEWEB)

    Horner, Olivier; Pavageau, Ellen-Mary; Vaillant, Francois [EDF R and D, Materials and Mechanics of Components Department, 77818 Moret-sur-Loing (France); Bouvier, Odile de [EDF Nuclear Engineering Division, Centre d' Expertise et d' Inspection dans les Domaines de la Realisation et de l' Exploitation, 93206 Saint Denis (France)

    2004-07-01

    Stress corrosion cracking occurs in the flow-restricted areas on the secondary side of steam generator tubes of Pressured Water Reactors (PWR), where water pollutants are likely to concentrate. Chemical analyses carried out during the shutdowns gave some insight into the chemical composition of these areas, which has evolved during these last years (i.e. less sodium as pollutants). It has been modeled in laboratory by tests in two different typical environments: the sodium hydroxide and the sulfate environments. These models satisfactorily describe the secondary side corrosion of steam generator tubes for old plant units. Furthermore, a third typical environment - the complex environment - which corresponds to an All Volatile Treatment (AVT) environment containing alumina, silica, phosphate and acetic acid has been recently studied. This particular environment satisfactorily reproduces the composition of the deposits observed on the surface of the steam generator tubes as well as the degradation of the tubes. A review of the recent laboratory results obtained by considering the complex environment are presented here. Several tests have been carried out in order to study initiation and propagation of secondary side corrosion cracking for some selected materials in such an environment. 600 Thermally Treated (TT) alloy reveals to be less sensitive to secondary side corrosion cracking than 600 Mill Annealed (MA) alloy. Finally, the influence of some related factors like stress, temperature and environmental factors are discussed. (authors)

  17. Localized corrosion and stress corrosion cracking of candidate materials for high-level radioactive waste disposal containers in the US: A literature review

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J.C.; McCright, R.D.

    1988-11-04

    Container materials may undergo any of several modes of degradation in this environment, including: undesirable phase transformations due to lack of phase stability; atmospheric oxidation; general aqueous corrosion; pitting; crevice corrosion; intergranular stress corrosion cracking (IGSCC); and transgranular stress corrosion cracking (TGSCC). This paper is an analysis of data from the literature relevant to the pitting, crevice corrosion, and stress corrosion cracking (SCC) of these alloys. Though all three austenitic candidates have demonstrated pitting and crevice corrosion in chloride-containing environments, Alloy 825 has the greatest resistance to these forms of localized attack. Both types 304L and 316L stainless steels are susceptible to SCC in acidic chloride media. In contrast, SCC has not been documented for Alloy 825 under comparable conditions. Gamma irradiation has been found to enhance SCC of Types 304 and 304L stainless steels, but it has no detectable effect on the resistance of Alloy 825 to SCC. Furthermore, while microbiologically induced corrosion effects have been observed for 300-series stainless steels, nickel-based alloys such as Alloy 825 seem to be immune to such problems. Of the copper-based alloys, CDA 715 has the best overall resistance to localized attack. Its resistance to pitting is comparable to that of CDA 613 and superior to that of CDA 102. Observed rates of dealloying in CDA 715 are less than those observed in CDA 613 by orders of magnitude. The resistance of CDA 715 to SCC in tarnishing ammonical environments is comparable to that of CDA 102 and superior to that of CDA 613. Its resistance to SCC in nontarnishing ammonical environments is comparable to that of CDA 613 and superior to that of CDA 102. 22 refs., 8 figs., 4 tabs.

  18. Localized corrosion and stress corrosion cracking of candidate materials for high-level radioactive waste disposal containers in the US: A literature review

    International Nuclear Information System (INIS)

    Container materials may undergo any of several modes of degradation in this environment, including: undesirable phase transformations due to lack of phase stability; atmospheric oxidation; general aqueous corrosion; pitting; crevice corrosion; intergranular stress corrosion cracking (IGSCC); and transgranular stress corrosion cracking (TGSCC). This paper is an analysis of data from the literature relevant to the pitting, crevice corrosion, and stress corrosion cracking (SCC) of these alloys. Though all three austenitic candidates have demonstrated pitting and crevice corrosion in chloride-containing environments, Alloy 825 has the greatest resistance to these forms of localized attack. Both types 304L and 316L stainless steels are susceptible to SCC in acidic chloride media. In contrast, SCC has not been documented for Alloy 825 under comparable conditions. Gamma irradiation has been found to enhance SCC of Types 304 and 304L stainless steels, but it has no detectable effect on the resistance of Alloy 825 to SCC. Furthermore, while microbiologically induced corrosion effects have been observed for 300-series stainless steels, nickel-based alloys such as Alloy 825 seem to be immune to such problems. Of the copper-based alloys, CDA 715 has the best overall resistance to localized attack. Its resistance to pitting is comparable to that of CDA 613 and superior to that of CDA 102. Observed rates of dealloying in CDA 715 are less than those observed in CDA 613 by orders of magnitude. The resistance of CDA 715 to SCC in tarnishing ammonical environments is comparable to that of CDA 102 and superior to that of CDA 613. Its resistance to SCC in nontarnishing ammonical environments is comparable to that of CDA 613 and superior to that of CDA 102. 22 refs., 8 figs., 4 tabs

  19. Hydrogen-related stress corrosion cracking in line pipe steel

    DEFF Research Database (Denmark)

    Nielsen, Lars Vendelbo

    1997-01-01

    A correlation between hydrogen concentration (C0) and the critical stress intensity factor for propagation of hydrogen-related cracks has been established by fracture mechanical testing of CT-specimens for the heat affected zone of an X-70 pipeline steel. This has been compared with field measure...

  20. Stress corrosion of stainless steels. Volume 1. 1964--1976 (citations from the NTIS data base). Report for 1964--1976

    International Nuclear Information System (INIS)

    This compilation covers research on deformation, cracking, electrochemistry, additives, kinetics, test methods, and solutions in relation to stress corrosion. A majority of the research concerns nuclear reactor materials and spacecraft components. Citations of mechanical property and compatibility data in relation to stress corrosion are included. Design criteria and corrosion resistance are also discussed

  1. Quantum caustics in the Gaussian slit experiment

    OpenAIRE

    Horie, K.; Miyazaki, H.; Tsutsui, I.; Tanimura, S.

    1998-01-01

    We study classical and quantum caustics for system with quadratic Lagrangian. Gaussian slit experiment is examined and it is pointed out that the focusing around caustics is stabilized against initial momentum fluctuations by quantum effect.

  2. Study by factorial analysis of the influence of chemical composition on the stress corrosion cracking of austenitic stainless steels

    International Nuclear Information System (INIS)

    The stress corrosion cracking of austenitic stainless steels has been treated by factorial correspondence analysis. This statistical method gives a relationship between chemical characteristics and the susceptibility of the steels to the phenomenon

  3. Embrittlement and anodic process in stress corrosion cracking: study of the influent micro-mechanical parameters

    International Nuclear Information System (INIS)

    We study the influence of local mechanical parameters on crack propagation in Stress Corrosion Cracking, at the scale of the microstructure. Two systems are compared: the CuAl9Ni3Fe2 copper-aluminium alloy in synthetic sea water under cathodic polarization, where the crack propagation mechanism is related to strain-assisted anodic dissolution, and the 316L austenitic stainless steel in MgCl2 solution, where embrittlement mechanisms related to hydrogen effects prevail. We use micro-notched tensile specimen that allow to study isolated short cracks. These experiments are modelled by means of finite elements calculations, and further characterized by Electron Back scattered Diffraction (EBSD) in the case of the 316L alloy. In terms of the local mechanical parameters that control propagation, fundamental differences are outlined between the two systems. They are discussed from the viewpoint of the available models of Stress Corrosion Cracking. (author)

  4. Stress corrosion cracks behavior and its protective technique under landfill disposal environment of the radioactive wastes

    International Nuclear Information System (INIS)

    This study is composed by two sub-theme on stress corrosion cracks wastes and on microscopic crack protection technique at circumference of disposal cavity and aims to elucidate experimentally the formation mechanism of stress corrosion cracks phenomena of rocks and to establish their protective techniques. In 1996 fiscal year, effect of water content on cracks stiffness and effect of chemicals addition on rock tensile strength were examined and AE measurement results and their mechanisms were also investigated. As a result, it was found that cracks propagation in rocks became plastic by wetting due to their water contents and wide range reduction of cracks stiffness occurs in some rocks, that formation of a process zone at a stage before stable cracks propagation was clarified by analysis of AE seismic source distribution, and that in sand rock, tensile strength at compressive cracks varied meaningfully with concentration change of chemicals and showed maximum value at a concentration of zero ζ potential. (G.K.)

  5. Aqueous chloride stress corrosion cracking of titanium - A comparison with environmental hydrogen embrittlement

    Science.gov (United States)

    Nelson, H. G.

    1974-01-01

    The physical characteristics of stress corrosion cracking of titanium in an aqueous chloride environment are compared with those of embrittlement of titanium by a gaseous hydrogen environment in an effort to help contribute to the understanding of the possible role of hydrogen in the complex stress corrosion cracking process. Based on previous studies, the two forms of embrittlement are shown to be similar at low hydrogen pressures (100 N/sq m) but dissimilar at higher hydrogen pressures. In an effort to quantify this comparison, tests were conducted in an aqueous chloride solution using the same material and test techniques as had previously been employed in a gaseous hydrogen environment. The results of these tests strongly support models based on hydrogen as the embrittling species in an aqueous chloride environment.

  6. Stress corrosion cracking resistance of aluminum alloy 7000 series after two-step aging

    Directory of Open Access Journals (Sweden)

    Jegdić Bore V.

    2015-01-01

    Full Text Available The effect of one step-and a new (short two-step aging on the resistance to stress corrosion cracking of an aluminum alloy 7000 series was investigated, using slow strain rate test and fracture mechanics method. Aging level in the tested alloy was evaluated by means of scanning electron microscopy and measurements of electrical resistivity. It was shown that the alloy after the new two-step aging is significantly more resistant to stress corrosion cracking. Values of tensile properties and fracture toughness are similar for both thermal states. Processes that take place at the crack tip have been considered. The effect of the testing solution temperature on the crack growth rate on the plateau was determined. Two values of the apparent activation energy were obtained. These values correspond to different processes that control crack growth rate on the plateau at higher and lower temperatures. [Projekat Ministarstva nauke Republike Srbije, br. TR 34028 i br. TR 34016

  7. Influence of non-destructive examination performance on reliability of pipes having stress corrosion cracks

    International Nuclear Information System (INIS)

    The fitness for service of the facilities of operational nuclear power plants is secured by proper inspections and evaluations. Defects took place in components will be detected by periodical inservice inspection, and fitness for service of cracked components during an evaluation period is evaluated. Although variation exists in the conditions used for inspection or evaluation, it is difficult to grasp about those influences on the reliability of cracked components by the deterministic evaluation like Fitness-for-Service Codes. In this study, influences of inspection parameters (defect sizing error, percentage of defect oversight, detectable defect size, successive tests) and an evaluation parameter (crack growth rate) on failure probability were evaluated for primary loop recirculation system piping of boiling water reactors in which many stress corrosion cracks took place. From these evaluations, the dominant parameters for the reliability of piping having stress corrosion cracks were clarified, and the requirements for the inspection and evaluation for revising Fitness-for-Service Codes were proposed. (author)

  8. Improved stress corrosion performance for alloy 718 via melt practice and heat treatment variation

    International Nuclear Information System (INIS)

    Alloy 718 is increasingly used in light water reactors for core internals requiring high strength, relaxation resistance, and corrosion resistance. Typical PWR primary-side applications include bolts and springs. Stress corrosion cracking (SCC) tests were conducted using alloy 718 in various melt practice and heat treatment conditions. Fatigue-precracked, 12.5-mm-thick compact fracture specimens were subjected to a constant extension rate of 1.3 x 10-9 m/s in a 360 C buffered aqueous environment. Crack growth rate was measured during testing using a reversing DC potential drop technique. Results in the form of SCC crack growth rate versus applied stress intensity demonstrate that the SCC resistance of alloy 718 can be improved by changes in melt practice and heat treatment. The SCC resistance of electroslag remelted (ESR) material is optimized by applying a high-temperature solution anneal followed by aging below the temperature region in which δ precipitates

  9. Stress corrosion cracking tests on high-level-waste container materials in simulated tuff repository environments

    International Nuclear Information System (INIS)

    Types 304L, 316L, and 321 austenitic stainless steel and Incoloy 825 are being considered as candidate container materials for emplacing high-level waste in a tuff repository. The stress corrosion cracking susceptibility of these materials under simulated tuff repository conditions was evaluated by using the notched C-ring method. The tests were conducted in boiling synthetic groundwater as well as in the steam/air phase above the boiling solutions. All specimens were in contact with crushed Topopah Spring tuff. The investigation showed that microcracks are frequently observed after testing as a result of stress corrosion cracking or intergranular attack. Results showing changes in water chemistry during test are also presented

  10. Analytical assessment for stress corrosion fatigue of CANDU fuel elements under load following conditions

    Energy Technology Data Exchange (ETDEWEB)

    Horhoianu, Grigore; Ionescu, Drags; Pauna, Eduard [Institute for Nuclear Research, Pitesti (Romania). Nuclear Fuel Engineering Lab.

    2012-03-15

    When nuclear power reactors are operated in a load following (LF) mode, the nuclear fuel may be subjected to step changes in power on weekly, daily, or even hourly basis, depending on the grid's needs. Two load following tests performed in TRIGA Research Reactor of Institute for Nuclear Research (INR) Pitesti were simulated with finite elements computer codes in order to evaluate Stress Corrosion Fatigue (SCF) of the sheath arising from expansion and contraction of the pellets in the corrosive environment. The 3D finite element analyses show that the cyclic strains give highly multiaxial stresses in the sheath at ridge region. This paper summarizes the results of the analytical assessment for SCF and their relation to CANDU fuel performance in LF tests conditions. (orig.)

  11. Probabilistic reliability assessment of a pipe with a stress-corrosion crack using the SBRA method

    Czech Academy of Sciences Publication Activity Database

    Václavek, L.; Marek, Pavel; Gajdoš, Lubomír

    Ostrava : VŠB TU, 2008 - (Strnadel, B.), s. 261-268 ISBN 978-80-248-1813-9. [Grand workshop New methods of damage and failure analysis of structural parts. Ostrava (CZ), 08.09.2008-12.09.2008] R&D Projects: GA ČR(CZ) GA103/07/0557 Institutional research plan: CEZ:AV0Z20710524 Keywords : pipe * stress -corrosion crack * probability of failure * SBRA method Subject RIV: JM - Building Engineering

  12. Heat treatment of NiCrFe alloy 600 to optimize resistance to intergranular stress corrosion

    Science.gov (United States)

    Steeves, A.F.; Bibb, A.E.

    A process of producing a NiCrFe alloy having a high resistance to stress corrosion cracking comprises heating a NiCrFe alloy to a temperature sufficient to enable the carbon present in the alloy body in the form of carbide deposits to enter into solution, rapidly cooling the alloy body, and heating the cooled body to a temperature between 1100 to 1500/sup 0/F for about 1 to 30 hours.

  13. Stress corrosion cracking studies of reactor pressure vessel steels. Final report

    International Nuclear Information System (INIS)

    The objective of this project was to perform a critical review of the information available in open literature on stress corrosion cracking of reactor pressure vessel materials in simulated light-water-reactor (LWR) conditions, develop a test procedure for conducting stress corrosion crack growth experiments in simulated LWR environments, and conduct a test program in an effort to duplicate some of the data available from the literature. The authors concluded that stress corrosion crack growth has been observed in pressure vessel steels under laboratory test conditions. The composition of the water in most cases where growth was observed is outside of the composition specified for operating conditions. Crack growth was observed in the experiments performed in this program, and it was intermittent. The cracking would start and stop for no apparent reason. In most instances, it would not restart without the change of some external variable. In a few instances, it restarted on its own. Crack growth rates as high as 3.6 x 10-9 m/sec were observed in pressure vessel steels in high-purity water with 8 ppm oxygen. These high crack growth rates were observed for extremely short bursts in crack extension. They could not be sustained for crack growth extensions greater than a few tenths of a millimeter. From the results of this project it appears highly unlikely that stress corrosion cracking will be observed in operating nuclear plants where the coolant composition is maintained within water chemistry guidelines. However, more work is needed to better define the contaminations that cause crack growth. The crack growth rates are so high and the threshold values for crack nucleation are so low that the conditions causing them need to be well defined and avoided

  14. Predictive capabilities of the surface-mobility stress corrosion cracking mechanism

    International Nuclear Information System (INIS)

    One of the most promising properties of the surf ace-mobility stress corrosion cracking mechanism is that it allows the prediction of crack velocities at any temperature, if the value at a given temperature is known. This is particularly important when crack velocities as low as 1 x 10-12 m/s or even lower are relevant, as it happens in nuclear pressure vessels, nuclear repositories, nuclear steam generators, etc. 56 refs

  15. Spectral Caustics in Attosecond Science

    Directory of Open Access Journals (Sweden)

    Dudovich N.

    2013-03-01

    Full Text Available A unique type of singularity common in wave phenomena, known as caustics, links processes observed in many different branches of physics [1]. We investigate the role of caustics in attosecond science and in particular the physical process behind high harmonic generation. By exploiting singularities of the three-step model that describes HHG, we can manipulate and enhance specific features in the emitted harmonic spectrum. This new level of control holds promises in both scientific and technological aspects of attosecond science, and provides a deeper insight into the basic mechanism underlying the high harmonic generation process.

  16. Influence of the mechanical condition of the surface of an austenitic stainless steel on its susceptibility to stress corrosion

    International Nuclear Information System (INIS)

    This research thesis reports the analysis of the relationships between cold working, stresses and susceptibility to stress corrosion (under applied or residual stresses) of a steady austenitic stainless steel (Z2 CND 17-12 or 316L) in a boiling solution of MgCl2 at 44 pc. The mechanical condition of sample surface is precisely defined by X ray diffraction. Corrosion tests are performed under uniaxial applied tensile stress. They reveal a very low cracking critical threshold which is sensitive to the level of initial residual stresses, but not much sensitive to initial cold working by tension. However, in the case of corrosion tests under residual stresses obtained by elastoplastic bending on specimens previously deformed under tension, the threshold is notably higher, and cold working rate is then an extremely important factor. Depending on the reached level, the effect can be beneficial or detrimental

  17. Effect of Aging on Fracture Toughness and Stress Corrosion Cracking Resistance of Forged 7475 Aluminum Alloy

    Institute of Scientific and Technical Information of China (English)

    LI Hongying; GENG Jinfeng; DONG Xianjuan; WANG Changjian; ZHENG Feng

    2007-01-01

    The effects of two-stage aging and retrogression and reaging heat treatment on the fracture toughness and stress corrosion cracking resistance of 7475 alloy were studied. The fracture toughness, conductivity and strength of samples of nine groups under duplex aging conditions and three retrogression and reaging heat treatments were also measured. Incorporating the microstructure and property, we found that when the condition of the first order aging kept identical, the fracture toughness and stress corrosion cracking resistance increase with aging time and the second aging temperature. The optimal treatment conditions are (115℃×7h+185℃×13h) among all tested two-stage aging treatments.Although the 7475 alloy treated by RRA method shows the highest strength and its stress corrosion cracking resistance after twenty minutes retrogression can also reach the same level as those by the optimal treatment of (115℃×7h+185℃×13h),the fracture toughness is even low.

  18. Analysis of stress corrosion cracking in alloy 718 following commercial reactor exposure

    Science.gov (United States)

    Leonard, Keith J.; Gussev, Maxim N.; Stevens, Jacqueline N.; Busby, Jeremy T.

    2015-11-01

    Alloy 718 is generally considered a highly corrosion-resistant material but can still be susceptible to stress corrosion cracking (SCC). The combination of factors leading to SCC susceptibility in the alloy is not always clear enough. In the present work, alloy 718 leaf spring (LS) materials that suffered stress corrosion damage during two 24-month cycles in pressurized water reactor service, operated to >45 MWd/mtU burn-up, was investigated. Compared to archival samples fabricated through the same processing conditions, little microstructural and property changes occurred in the material with in-service irradiation, contrary to high dose rate laboratory-based experiments reported in literature. Though the lack of delta phase formation along grain boundaries would suggest a more SCC resistant microstructure, grain boundary cracking in the material was extensive. Crack propagation routes were explored through focused ion beam milling of specimens near the crack tip for transmission electron microscopy as well as in polished plan view and cross-sectional samples for electron backscatter diffraction analysis. It has been shown in this study that cracks propagated mainly along random high-angle grain boundaries, with the material around cracks displaying a high local density of dislocations. The slip lines were produced through the local deformation of the leaf spring material above their yield strength. The cause for local SCC appears to be related to oxidation of both slip lines and grain boundaries, which under the high in-service stresses resulted in crack development in the material.

  19. Stress corrosion cracking properties of alloy 182 weld metal in PWR primary water environment

    International Nuclear Information System (INIS)

    Stress corrosion cracking tests using small U-bend specimens of an Alloy 600/182 weld were performed at 325 C. degrees in a simulated primary water environment of a pressurized water reactor. The precipitates in the matrix of Alloy 600 were identified as Cr7C3, irrespective of the intergranular and intragranular ones. The microstructure of the Alloy 182 weld metal consisted of cellular dendrites in the grains epitaxially solidified from the heat affected zone. Contrary to the Alloy 600 base metal, most of the grain boundaries of the Alloy 182 weld metal were low angle and random high angle grain boundaries, with a negligible fraction of coincidence site lattice boundaries. The stress corrosion cracks were found only in the regions of the Alloy 182 weld metal of Alloy 600/182 weldment, which suggests that the PWSCC (Primary Water Stress Corrosion Cracking) susceptibility of Alloy 182 weld metal can be higher than that of Alloy 600 base metal. The cracks were initiated at the grain boundaries on the surface, and also propagated along the random high angle grain boundaries in Alloy 182 weld metal. (authors)

  20. 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

  1. Evaluation of stress corrosion cracking in aqueous solution neutron shield of transport/storage cask for spent fuel

    International Nuclear Information System (INIS)

    Experimental evaluation proved that no chloride induced stress corrosion cracking will occur on the metal cask which utilizes propylene glycol aqueous solution as neutron shield. Crevice corrosion, precursor of cracking, occurs at about 0.4V vs. 0.1M-KCl silver silver-chloride reference electrode in aqueous solution with chloride concentration of more than 5 times higher than limit value. On the other hand, the electrochemical potential (ECP) of cask material was 0.08V in air saturated aqueous solution. Since ECP is much smaller than the crevice corrosion potential below which no crevice corrosion is expected, the possibility is very small for chloride induced stress corrosion cracking to occur on the cask. (author)

  2. Stress-Corrosion Cracking Property of Aluminum-Magnesium Alloy Processed by Equal-Channel Angular Pressing

    Directory of Open Access Journals (Sweden)

    Hiroaki Nakano

    2012-01-01

    Full Text Available Stress-corrosion cracking property of an aluminum-magnesium alloy processed by equal-channel angular pressing (ECAP was investigated by a slow strain-rate tensile technique in a 3% NaCl solution of pH 4.2 at 303 K. The maximum stress and elongation of the Al-Mg alloy were lower in the NaCl solution than in air. The stress-corrosion cracking property was evaluated by the decrease ratio of maximum stress and elongation of the Al-Mg alloy with NaCl solution, (max and (, respectively. (max and ( were lower with ECAP than without it, showing that the susceptibility of stress-corrosion cracking decreased with ECAP. The polarization curve and time dependence of the anodic current density at constant potential of the Al-Mg alloy in the NaCl solution revealed that the anodic current density was lower with ECAP than without it, or the corrosion resistance of the Al-Mg alloy was improved by ECAP. The decrease in stress-corrosion crack susceptibility of the Al-Mg alloy with ECAP is attributed to an improvement in corrosion resistance afforded by ECAP.

  3. An Investigation for Anti-Stress Corrosion Cracking of SUS 304 Stainless Steel in MgCl2 Boiling Solution

    International Nuclear Information System (INIS)

    The anti-stress corrosion cracking method by current density of cathodic protection was studied for the stress corrosion cracking of SUS304 austenitic stainless steel in the environment of 42% MgCl2 boiling solution. The correlation between the critical current density for anti-stress corrosion cracking and the initial crack intensity factor was inspected in the base metal and the welding heat affected zone. Main results obtained are as follows: 1. The critical initial crack intensity factor KIiSCC can be controlled by the current density of cathodic protection. 2. The correlation between the critical current density of cathodic protection for anti-stress corrosion cracking i (μA/cm2) and the initial crack intensity factor KIi (kg. mm-3/2) is illustrated by the following formulas. In base metal : i= 0.0689 KIi - 0.238 In heat affected zone : i=0.0724 KIi - 4.8353 3. In condition of additional below the critical current density of cathodic protection for anti-stress corrosion cracking, the stress corrosion cracking is appeared to be inter-granual fracture

  4. Fundamental aspects of stress corrosion cracking of copper relevant to the Swedish deep geologic repository concept

    Energy Technology Data Exchange (ETDEWEB)

    Bhaskaran, Ganesh; Carcea, Anatolie; Ulaganathan, Jagan; Wang, Shengchun; Huang, Yin; Newman, Roger C. [Dept. of Chemical Engineering and Applied Chemistry, Univ. of Toronto, Toronto (Canada)

    2013-03-15

    Phosphorus-doped oxygen-free copper will be used as the outer barrier in canisters that will contain spent nuclear fuel in the proposed Swedish underground repository. The possibility of stress corrosion cracking (SCC) is a concern, in view of isolated reports of cracking or intergranular corrosion of pure copper in sulfide solutions. This concern was addressed in the present work using copper tensile specimens provided by SKB. Methods included slow strain rate testing, constant strain tensile testing, electrochemical and surface analytical studies of corrosion products, and electron backscatter diffraction analysis of grain orientation effects on corrosion. The base solutions were prepared from NaCl or synthetic sea water with addition of varying amounts of sodium sulfide at room temperature and 80 degree Celsius. No SCC was found in any of the testing, for a range of sulfide concentrations from 5-50 mM at room temperature or 8 C, including tests where small anodic or cathodic potential displacements were applied from the open-circuit (corrosion) potential. Neither was SCC found in constant-strain immersion testing with very large strain. The Cu2S corrosion product is generally very coarse, fragile, and easily spalled off in severe corrosion environments, i.e. high sulfide concentration, high temperature, less perfect de aeration, etc. But it could also consist of very fine grains, relatively compact and adherent, on particular grain orientations when it was formed on an electro polished surface in a very well-deaerated solution. These orientations have not yet been identified statistically, although some preference for thin, adherent films was noted on orientations close to (100). The notion that the corrosion reaction is always controlled by inward aqueous-phase diffusion of sulfide may thus not be unconditionally correct for this range of sulfide concentrations; however it is hard to distinguish the role of diffusion within pores in the film. In the actual

  5. 1987 EPRI workshop on mechanisms of primary water intergranular stress corrosion cracking: Proceedings

    International Nuclear Information System (INIS)

    A meeting on ''Mechanisms of Primary Water IGSCC'' (PWSCC) was organized to give those working in this area an opportunity to share their results, ideas, and plans in regard to investigations of fundamental aspects of the PWSCC phenomenon affecting alloy 600 steam generator tubes. Topics discussed included: (1) General reviews of hydrogen embrittlement and film rupture - anodic dissolution mechanisms of stress corrosion cracking, (2) environmental factors involved in PWSCC, (3) the influence of microstructure on PWSCC, and (4) the influence of stress and plastic strain on PWSCC. A significant portion of the discussions of all of these topics was devoted to the subject of modelling of crack initiation and crack growth

  6. Stress corrosion of low alloy steels used in external bolting on pressurised water reactors

    International Nuclear Information System (INIS)

    The stress corrosion cracking (SCC) susceptibility of AISI 4140 and AISI 4340 steels has been evaluated in five environments, three simulating a leaking aqueous boric acid environment and two simulating ambient external conditions ie moist air and salt spray. Both steels were found to be highly susceptible to SCC in all environments at hardnesses of 400 VPN and above. The susceptibility was greatly reduced at hardnesses below 330 VPN but in one environment, viz refluxing PWR primary water, SCC was observed at hardnesses as low as 260VPN. Threshold stress intensities for SCC were frequently lower than those in the literature

  7. Stress-corrosion crasking of welded joints of zirconium alloy with 2.5% niobium

    International Nuclear Information System (INIS)

    Effect of the welding conditions and annealing temperature on resistance to stress-corrosion cracking of welded joints of zirconium alloy with 2.5% Nb and zirconium iodide in CH3OH+0.4 g/l HCl solution, the tensile stress being 0.9 σT, is studied. Time before cracking in welded joints of zirconium alloy with 2.5% Nb and zirconium iodide in initial state and after annealing at 850 K in 24 hours. Annealing at 1020 and 1270 K increases time before cracking of the basic metal and zirconium alloy with 2.5% Nb to 3500 h

  8. Stress Corrosion Cracking of ferrito-pearlitic steel in aqueous environment containing dissolved CO2

    OpenAIRE

    Vancostenoble, Alix; Duret-Thual, C.; Bosch, Cédric; Delafosse, David

    2014-01-01

    A confined aqueous environment is defined by a very low water-volume to exposed steel-area ratio. In such media containing dissolved CO2, siderite is formed and acts as a protective film. An addition of applied stress and/or environmental fluctuation can disturb the balance between the steel and this protective film, causing the fracture of the latter and leading to Stress Corrosion Cracking (SCC). The material studied is a cold drawn and rolled high strength steel composed of ferrite and sph...

  9. Primary water stress corrosion cracking of alloy 600

    International Nuclear Information System (INIS)

    As United States nuclear reactors have aged, a number of problems have arisen. Among these are primary water cracking (PWSCC) of Alloy 600 in PWRs. Since 1989, when PWSCC was identified to the Nuclear Regulatory Commission (NRC) as an emerging issue, it has been reported in several components, including control rod drive mechanism (CRDM) penetrations. To address PWSCC of CRDM penetrations at U.S. plants, the industry developed a comprehensive inspection, evaluation, repair and mitigation program. Recent pilot inspections that revealed cracking at two of the three U.S. plants inspected indicate the problem is generic. Further, results of stress analyses indicate that an area of high stress exists that could cause cracking that would follow the J-groove weld. Such cracking was identified in a foreign reactor that had a resin intrusion. PWSCC of CRDMs remains an open issue. Proactive NRC/Industry programs for inspection and repair or replacement of affected components are essential for continued operation of nuclear reactors and for license extensions. (author)

  10. SRNL SHELF LIFE STUDIES - SCC STUDIES AT ROOM TEMPERTURE [stress corrosion cracking

    Energy Technology Data Exchange (ETDEWEB)

    Mickalonis, J.; Duffey, J.

    2014-11-12

    Phase II, Series 2 corrosion testing performed by the Savannah River National Laboratory (SRNL) for the Department of Energy 3013 container has been completed. The corrosion tests are part of an integrated plan conducted jointly by Los Alamos National Laboratory and the Savannah River Site. SRNL was responsible for conducting corrosion studies in small-scale vessels to address the influence of salt composition, water loading, and type of oxide/salt contact on the relative humidity inside a 3013 container and on the resulting corrosion of Type 304L and 316L stainless steel (304L and 316L). This testing was conducted in two phases: Phase I evaluated a broad spectrum of salt compositions and initial water loadings on the salt mixtures exposed to 304L and 316L and the resulting corrosion; Phase II evaluated the corrosion of 304L at specific water loadings and a single salt composition. During Phase I testing at high initial moisture levels (0.35 to 1.24 wt%)a, the roomtemperature corrosion of 304L exposed to a series of plutonium oxide/chloride salt mixtures ranged from superficial staining to pitting and stress corrosion cracking (SCC). 304L teardrop coupons that exhibited SCC were directly exposed to a mixture composed of 98 wt % PuO2, 0.9 wt % NaCl, 0.9 wt % KCl, and 0.2 wt % CaCl2. Cracking was not observed in a 316L teardrop coupon. Pitting was also observed in this environment for both 304L and 316L with depths ranging from 20 to 100 μm. Neither pitting nor SCC was observed in mixtures with a greater chloride salt concentration (5 and 28 wt%). These results demonstrated that for a corrosive solution to form a balance existed between the water loading and the salt chloride concentration. This chloride solution results from the interaction of loaded water with the hydrating CaCl2 salt. In Phase II, Series 1 tests, the SCC results were shown to be reproducible with cracking occurring in as little as 85 days. The approximate 0.5 wt% moisture level was found to

  11. Kinetic studies of the stress corrosion cracking of D6AC steel

    Science.gov (United States)

    Noronha, P. J.

    1975-01-01

    The effect of load interactions on the crack growth velocity of D6AC steel under stress corrosion cracking conditions was determined. The environment was a 3.5 percent salt solution. The modified-wedge opening load specimens were fatigue precracked and subjected to a deadweight loading in creep machines. The effects of load shedding on incubation times and crack growth rates were measured using high-sensitivity compliance measurement techniques. Load shedding results in an incubation time, the length of which depends on the amount of load shed and the baseline stress intensity. The sequence of unloading the specimen also controls the subsequent incubation period. The incubation period is shorter when load shedding passes through zero load than when it does not if the specimen initially had the same baseline stress intensity. The crack growth rates following the incubation period are also different from the steady-state crack growth rate at the operating stress intensity. These data show that the susceptibility of this alloy system to stress corrosion cracking depends on the plane-strain fracture toughness and on the yield strength of the material.

  12. A Study on the Stress Corrosion Cracking of AISI 304 Stainless Steel

    International Nuclear Information System (INIS)

    Stress corrosion cracking phenomenon of the commercial type 304 stainless steel wire in the boiling 42% magnesium chloride solution has been investigated. Main experimental techniques were to measure the time to failure of the wire varying the applied tensile stress, to follow potential of the material versus time, to observe potentiostatic polarization behavior, and to examine the microstructure of the failed specimens. Results showed that every crack propagates in the transgranular fashion. With the more applied stress up to 53,200 psi, the more crack density appeared per unit length of specimen and the less time was taken to the final fracture. The role of applied stress seemed to be involved both in the crack initiation and in the crack propagation, but more pronounced in the latter process. Potential vs. time curve and potentiostatic polarization behavior of the wire indicated that a passive film would be present on the corroding specimen surface. Breaking of such a film induced by strain due to the applied stress would initiate crack formation when anodic dissolution of the metal was followed at the resulting bare sites. It was found that crack propagation started at the base of a pit especially when large anodic current was forced to flow into the wire. A cathodic polarization to the potential slightly more active than the steady state corrosion potential retarded remarkably the time to failure of the wire specimen. Data revealed that such a slight cathodic protection was slowing down crack propagation

  13. Stress-Corrosion Cracking Property of Aluminum-Magnesium Alloy Processed by Equal-Channel Angular Pressing

    OpenAIRE

    Hiroaki Nakano; Satoshi Oue; Seiji Taguchi; Shigeo Kobayashi; Zenji Horita

    2012-01-01

    Stress-corrosion cracking property of an aluminum-magnesium alloy processed by equal-channel angular pressing (ECAP) was investigated by a slow strain-rate tensile technique in a 3% NaCl solution of pH 4.2 at 303 K. The maximum stress and elongation of the Al-Mg alloy were lower in the NaCl solution than in air. The stress-corrosion cracking property was evaluated by the decrease ratio of maximum stress and elongation of the Al-Mg alloy with NaCl solution, ( m a x ) and ( ) , respecti...

  14. Stress Corrosion Cracking—Crevice Interaction in Austenitic Stainless Steels Characterized By Acoustic Emission

    Science.gov (United States)

    Leinonen, H.; Schildt, T.; Hänninen, H.

    2011-02-01

    Stress corrosion cracking (SCC) susceptibility of austenitic EN1.4301 (AISI 304) and EN1.4404 (AISI 316L) stainless steels was studied using the constant load method and polymer (PTFE) crevice former in order to study the effects of crevice on SCC susceptibility. The uniaxial active loading tests were performed in 50 pct CaCl2 at 373 K (100 °C) and in 0.1 M NaCl at 353 K (80 °C) under open-circuit corrosion potential (OCP) and electrochemical polarization. Pitting, crevice, and SCC corrosion were characterized and identified by acoustic emission (AE) analysis using ∆ t filtering and the linear locationing technique. The correlation of AE parameters including amplitude, duration, rise time, counts, and energy were used to identify the different types of corrosion. The stages of crevice corrosion and SCC induced by constant active load/crevice former were monitored by AE. In the early phase of the tests, some low amplitude AE activity was detected. In the steady-state phase, the AE activity was low, and toward the end of the test, it increased with the increasing amplitude of the impulses. AE allowed a good correlation between AE signals and corrosion damage. Although crevice corrosion and SCC induced AE signals overlapped slightly, a good correlation between them and microscopical characterization and stress-strain data was found. Especially, the activity of AE signals increased in the early and final stages of the SCC experiment under constant active load conditions corresponding to the changes in the measured steady-state creep strain rate of the specimen. The results of the constant active load/crevice former test indicate that a crevice can initiate SCC even in the mild chloride solution at low temperatures. Based on the mechanistic model of SCC, the rate determining step in SCC is thought to be the generation of vacancies by selective dissolution, which is supported by the low activity phase of AE during the steady-state creep strain rate region.

  15. Irradiation-Assisted Stress Corrosion Cracking of Austenitic Stainless Steels in BWR Environments

    International Nuclear Information System (INIS)

    The internal components of light water reactors are exposed to high-energy neutron irradiation and high-temperature reactor coolant. The exposure to neutron irradiation increases the susceptibility of austenitic stainless steels (SSs) to stress corrosion cracking (SCC) because of the elevated corrosion potential of the reactor coolant and the introduction of new embrittlement mechanisms through radiation damage. Various nonsensitized SSs and nickel alloys have been found to be prone to intergranular cracking after extended neutron exposure. Such cracks have been seen in a number of internal components in boiling water reactors (BWRs). The elevated susceptibility to SCC in irradiated materials, commonly referred to as irradiation-assisted stress corrosion cracking (IASCC), is a complex phenomenon that involves simultaneous actions of irradiation, stress, and corrosion. In recent years, as nuclear power plants have aged and irradiation dose increased, IASCC has become an increasingly important issue. Post-irradiation crack growth rate and fracture toughness tests have been performed to provide data and technical support for the NRC to address various issues related to aging degradation of reactor-core internal structures and components. This report summarizes the results of the last group of tests on compact tension specimens from the Halden-II irradiation. The IASCC susceptibility of austenitic SSs and heat-affected-zone (HAZ) materials sectioned from submerged arc and shielded metal arc welds was evaluated by conducting crack growth rate and fracture toughness tests in a simulated BWR environment. The fracture and cracking behavior of HAZ materials, thermally sensitized SSs and grain-boundary engineered SSs was investigated at several doses (3 dpa). These latest results were combined with previous results from Halden-I and II irradiations to analyze the effects of neutron dose, water chemistry, alloy compositions, and welding and processing conditions on IASCC. The

  16. Irradiation-Assisted Stress Corrosion Cracking of Austenitic Stainless Steels in BWR Environments

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y. [Argonne National Lab. (ANL), Argonne, IL (United States); Chopra, O. K. [Argonne National Lab. (ANL), Argonne, IL (United States); Gruber, Eugene E. [Argonne National Lab. (ANL), Argonne, IL (United States); Shack, William J. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2010-06-01

    The internal components of light water reactors are exposed to high-energy neutron irradiation and high-temperature reactor coolant. The exposure to neutron irradiation increases the susceptibility of austenitic stainless steels (SSs) to stress corrosion cracking (SCC) because of the elevated corrosion potential of the reactor coolant and the introduction of new embrittlement mechanisms through radiation damage. Various nonsensitized SSs and nickel alloys have been found to be prone to intergranular cracking after extended neutron exposure. Such cracks have been seen in a number of internal components in boiling water reactors (BWRs). The elevated susceptibility to SCC in irradiated materials, commonly referred to as irradiation-assisted stress corrosion cracking (IASCC), is a complex phenomenon that involves simultaneous actions of irradiation, stress, and corrosion. In recent years, as nuclear power plants have aged and irradiation dose increased, IASCC has become an increasingly important issue. Post-irradiation crack growth rate and fracture toughness tests have been performed to provide data and technical support for the NRC to address various issues related to aging degradation of reactor-core internal structures and components. This report summarizes the results of the last group of tests on compact tension specimens from the Halden-II irradiation. The IASCC susceptibility of austenitic SSs and heat-affected-zone (HAZ) materials sectioned from submerged arc and shielded metal arc welds was evaluated by conducting crack growth rate and fracture toughness tests in a simulated BWR environment. The fracture and cracking behavior of HAZ materials, thermally sensitized SSs and grain-boundary engineered SSs was investigated at several doses (≤3 dpa). These latest results were combined with previous results from Halden-I and II irradiations to analyze the effects of neutron dose, water chemistry, alloy compositions, and welding and processing conditions on IASCC

  17. Monte Carlo simulation of micro crack propagation behavior for stress corrosion cracking

    International Nuclear Information System (INIS)

    A calculation code of Monte Carlo simulation for micro crack propagation behavior of stress corrosion cracking has been developed. Improvements for micro crack growth rate treatments and stress distributions have been made. Calculated crack depth distributions were compared with the CBB test results for sensitized stainless steels and low carbon stainless steels with hardened layer. For sensitized stainless steels, the calculated crack depth distribution could well reproduce the CBB test results by taking into account crack growth rates obtained from experiments. For low carbon stainless steels, although considering stress distributions improved the overestimation of crack depths, the calculated crack depth distribution could not well reproduce the CBB test result. The results revealed that the effects of the crack growth rate and the stress distribution on micro crack propagation behaviors. (author)

  18. Stress corrosion of Zircaloy-4. Fracture mechanics study of the intergranular - transgranular transition

    International Nuclear Information System (INIS)

    Stress corrosion cracking susceptibility of Zircaloy-4 wires was studied in 1M NaCl, 1M KBr and 1M KI aqueous solutions, and in iodine alcoholic solutions. In all cases, intergranular attack preceded transgranular propagation. It is generally accepted that the intergranular-transgranular transition occurs when a critical value of the stress intensity factor is reached. In the present work it was confirmed that the transition from intergranular to transgranular propagation cracking in Zircaloy-4 wires also occurs when a critical value of the stress intensity factor is reached. This critical stress intensity factor in wire samples is independent of the solution tested and close to 10 MPa.m-1/2. This value is in good agreement with those reported in the literature measured by different techniques. (author)

  19. Stress corrosion cracking of austenitic stainless steel in glycerol solution and chloride solution at elevated temperature

    International Nuclear Information System (INIS)

    Stress Corrosion Cracking (SCC) is an environmentally assisted failure caused by exposure to a corrodant while under a sustained tensile stress. SCC is most often rapid, unpredictable and catastrophic. Failure can occur in as little as a few hours or take years to happen. Most alloys are susceptible to SCC in one or more environments requiring careful consideration of alloy type in component design. In aqueous chloride environments austenitic stainless steels and many nickel based alloys are known to perform poorly. One of products Oleo chemical is glycerol solution. Glycerol solution contains chloride with concentration 50 ppm - 150 ppm. Austenitic stainless steel is usually used in distillation construction tank and pipe line of glycerol. Material AISI 304 will be failure in this glycerol solution with this concentration in 5 years. In production process, concentration of chloride in glycerol becomes more than 150 ppm at temperature 150 degree Celsius. The reason is that the experiment I conducted in high chloride with concentration such as 6000 ppm, 9000 ppm, and 12000 ppm. The stress corrosion cracking of the austenitic stainless steels of types AISI 304, 316 and 316L in glycerol solution at elevated temperature 150 degree Celsius is investigated as a function variation of chloride concentration, namely 50, 6000, 9000 and 12000 ppm using a constant load method with two kinds of initial tensile stress as 50 % and 70 % yield strength. The experiment uses a spring loaded fixture type and is based on ASTM G49 for experiment method, and E292 for geometry of specimen. Pitting corrosion occurs on the surface specimen until the stress level reaches the ultimate strength. Pitting corrosion attack and depletion occur on the surface as initiation of SCC failure as the stress reaches the ultimate strength. Failure has occurred in catastrophic brittle fracture type of transgranular. AISI 304 was more susceptible for all conditions. In chloride solution with concentration of

  20. Study on H2S stress corrosion test of welded joint for X65 pipeline steel and numerical analysis

    Institute of Scientific and Technical Information of China (English)

    金晓军; 霍立兴; 张玉凤; 白秉仁; 李晓巍; 曹军

    2004-01-01

    The susceptibility of welded joint for the X65 pipeline steel to H2S stress corrosion cracking (SCC) is investigated. SCC tests on the steel are carried out in the environment based on NACE TM-01-77 solution with saturated gaseous H2S. The threshold stress intensity factor and crack propagation velocity are calculated according to wedge-opening loading (WOL) specimens. The three-dimensional elastic-plastic finite element analysis of WOL specimens is performed by using the FEM programming package ANSYS. Stress field and concentration of hydrogen distribution property ahead of the crack tip are obtained. This paper surveyed the microstructure of welded joint and studied on the mechanical properties of X65 pipeline steel. It provides experimental basis for studying stress corrosion. The results of numerical analysis are consistent with conclusions of stress corrosion test.

  1. Hierarchical Petascale Simulation Framework For Stress Corrosion Cracking

    Energy Technology Data Exchange (ETDEWEB)

    Grama, Ananth

    2013-12-18

    A number of major accomplishments resulted from the project. These include: • Data Structures, Algorithms, and Numerical Methods for Reactive Molecular Dynamics. We have developed a range of novel data structures, algorithms, and solvers (amortized ILU, Spike) for use with ReaxFF and charge equilibration. • Parallel Formulations of ReactiveMD (Purdue ReactiveMolecular Dynamics Package, PuReMD, PuReMD-GPU, and PG-PuReMD) for Messaging, GPU, and GPU Cluster Platforms. We have developed efficient serial, parallel (MPI), GPU (Cuda), and GPU Cluster (MPI/Cuda) implementations. Our implementations have been demonstrated to be significantly better than the state of the art, both in terms of performance and scalability. • Comprehensive Validation in the Context of Diverse Applications. We have demonstrated the use of our software in diverse systems, including silica-water, silicon-germanium nanorods, and as part of other projects, extended it to applications ranging from explosives (RDX) to lipid bilayers (biomembranes under oxidative stress). • Open Source Software Packages for Reactive Molecular Dynamics. All versions of our soft- ware have been released over the public domain. There are over 100 major research groups worldwide using our software. • Implementation into the Department of Energy LAMMPS Software Package. We have also integrated our software into the Department of Energy LAMMPS software package.

  2. Caustic saving potentile in textile processing mills

    International Nuclear Information System (INIS)

    The textile processing industry of pakistan has great potential of improvement in resource consumption in various production processes. One major concern is the heavy usage of caustic soda (sodium hydroxide) especially during the mercerization process which incurs a significant cost to a textile processing mill. To reduce the unit fabric production cost and stay competitive, the industry need to minimize the caustic wastage and explore the caustic saving potential. This paper describe the detailed caustic consumption practices and saving potentials in woven textile sector based on the data base of 100 industries. Region wise caustic saving potential is also investigated . Three caustic conservation option including process improvement, reuse and recycling, and caustic recovery plants are discussed. Detailed technical and and financial requirements. saving potentials and paybacks of these options are provided. (author)

  3. Formation and application of Nano Noble metal particles to mitigate stress corrosion cracking in BWR

    International Nuclear Information System (INIS)

    Boiling water nuclear reactors (BWRs) throughout the world have applied the NobleChem™ (or noble metal chemical addition: NMCA) or Online NMCA (OLNC) process just before end-of-cycle shutdown or during an operation to mitigate the stress corrosion cracking (SCC) of structural materials in BWRs. When injected into BWR environments, the noble metal particles deposit on Type 304 stainless steel surfaces and reduce the corrosion potential, which decreases the propensity for SCC. Very fine noble metal particles are formed and able to potentially deposit inside a crack and maintain catalytic surfaces in the critical regions inside the crack. This paper demonstrates the sonochemical method for producing Pt nanoparticles and describes the feasibility of using noble metal nanoparticles to mitigate the stress corrosion cracking of structural materials in BWRs , called Nano NobleChem™. Several methods were explored to create Pt nanoparticles by the high intensity sonication of micron size of Pt and PtO2. This new approach would also enable the application of noble metal technology while the reactor is in operation. (author)

  4. Stress corrosion crack initiation of alloy 182 weld metal in primary coolant - Influence of chemical composition

    Energy Technology Data Exchange (ETDEWEB)

    Calonne, O.; Foucault, M.; Steltzlen, F. [AREVA (France); Amzallag, C. [EDF SEPTEN (France)

    2011-07-01

    Nickel-base alloys 182 and 82 have been used extensively for dissimilar metal welds. Typical applications are the J-groove welds of alloy 600 vessel head penetrations, pressurizer penetrations, heater sleeves and bottom mounted instrumented nozzles as well as some safe end butt welds. While the overall performance of these weld metals has been good, during the last decade, an increasing number of cases of stress corrosion cracking of Alloy 182 weld metal have been reported in PWRs. In this context, the role of weld defects has to be examined. Their contribution in the crack initiation mechanism requires laboratory investigations with small scale characterizations. In this study, the influence of both alloy composition and weld defects on PWSCC (Stress Corrosion Cracking in Primary Water) initiation was investigated using U-bend specimens in simulated primary water at 320 C. The main results are the following: -) the chemical compositions of the weld deposits leading to a large propensity to hot cracking are not the most susceptible to PWSCC initiation, -) macroscopically, superficial defects did not evolve during successive exposures. They can be included in large corrosion cracks but their role as 'precursors' is not yet established. (authors)

  5. Corrosion Fatigue of High-Strength Titanium Alloys Under Different Stress Gradients

    Science.gov (United States)

    Baragetti, Sergio; Villa, Francesco

    2015-05-01

    Ti-6Al-4V is the most widely used high strength-to-mass ratio titanium alloy for advanced engineering components. Its adoption in the aerospace, maritime, automotive, and biomedical sectors is encouraged when highly stressed components with severe fatigue loading are designed. The extents of its applications expose the alloy to several aggressive environments, which can compromise its brilliant mechanical characteristics, leading to potentially catastrophic failures. Ti-6Al-4V stress-corrosion cracking and corrosion-fatigue sensitivity has been known since the material testing for pressurized tanks for Apollo missions, although detailed investigations on the effects of harsh environment in terms of maximum stress reduction have been not carried out until recent times. In the current work, recent experimental results from the authors' research group are presented, quantifying the effects of aggressive environments on Ti-6Al-4V under fatigue loading in terms of maximum stress reduction. R = 0.1 axial fatigue results in laboratory air, 3.5 wt.% NaCl solution, and CH3OH methanol solution at different concentrations are obtained for mild notched specimens ( K t = 1.18) at 2e5 cycles. R = 0.1 tests are also conducted in laboratory air, inert environment, 3.5 wt.% NaCl solution for smooth, mild and sharp notched specimens, with K t ranging from 1 to 18.65, highlighting the environmental effects for the different load conditions induced by the specimen geometry.

  6. Fatigue reliability of deteriorating prestressed concrete bridges due to stress corrosion cracking

    International Nuclear Information System (INIS)

    In this paper, an analysis framework is presented to develop a relationship between fatigue reliability in a prestressed concrete bridge and the progress of stress corrosion cracking (SCC) in prestressing steel. The fatigue limit state uses a cumulative damage model for prestressing steel wires, which is a function of both stress range and minimum stress. The SCC model takes into account varying degrees of material susceptibility, stress regimes, and environmental conditions and is structured around three stages: initiation of micro-cracking, propagation, and macro-crack instability using linear elastic fracture mechanics. The framework is an overall time-dependent analysis of the safety against fatigue of a prestressed concrete bridge. It involves a stochastic analysis of the evolution of prestressing wire corrosion as a function of time and a time-dependent probabilistic analysis of the fatigue reliability of the prestressed concrete bridge suffering a certain degree of deterioration. The uncertainties involved in the fatigue model, the SCC model, and traffic actions are considered. The updating of uncertainties is simplified by considering a limited number of classes representative of the severity of SCC exposure. The framework is applied to three deteriorating highway bridges. (author)

  7. Study on irradiation assisted stress corrosion cracking of austenitic stainless steels in nuclear energy environments (Thesis)

    International Nuclear Information System (INIS)

    Irradiation assisted stress corrosion cracking (IASCC) is known as a degradation phenomenon that is caused by synergistic effects of neutron /gamma irradiation, stress/strain and high temperature water on structural materials. It is important to investigate stress corrosion cracking (SCC) and IASCC mechanisms from the viewpoint of the safety and reliability improvement in the nuclear energy system. To evaluate the influence of minor additional elements, heat treatment, cold working and neutron fluence on IASCC behavior, a slow strain rate technique (SSRT) facility for irradiated specimens has been developed and post irradiation examinations have been conducted. Based on results obtained from the IASCC studies, discussion regarding IASCC susceptibility, crack initiation and growth behaviors are described comprehensively in this paper. The followings are summarized typical findings. (1) 1 or 2 cracks of IASCC are introduced at 98-99 % of maximum stress. (2) The increase and decrease in crack growth rate are repeated alternately in the process of crack growth. (3) Although suppression of radiation hardening can be introduced with Si or Mo addition, the suppression disappear with increasing in neutron fluence. (4) Fracture mode changes from intergranular (IG) SCC to transgranular (TG) SCC with increasing in hardness which is introduced with neutron radiation and /or cold working. (author)

  8. Effect of thermomechanical treatment of the stress corrosion cracking of metastable beta III titanium

    International Nuclear Information System (INIS)

    Results of studies on the relations of microstructural changes with stress corrosion of Ti--11.5 Mo--6 Zr--4.5 Sn (Beta III) alloys are presented. It was found that this alloy is virtually immune to stress corrosion cracking if no imperfections in the surface are present. Specimens that had not been cold worked showed surface deterioration, but it was not serious enough to cause any marked reduction in yield strengths. The alloy is, however, susceptible to SCC if the surface contains an imperfection such as a fatigue crack where high stresses can concentrate during testing. These high stress levels at the crack tip may cause mechanical destruction of the passivating oxide and allow a higher concentration of chloride ions near the fresh metal surfaces. However, even with precracked specimens, crack propagation is slow as evidenced by no failures within the 720 hour test period. The extreme notch sensitivity of Beta III prevented initiation of fatigue cracks in the sections of the alloy with 20 and 50 percent cold work. More research must be done to test Beta III in this condition. However, on the basis of the research conducted thus far, SCC susceptibility of Beta III titanium alloy appears to be independent of thermomechanical pretreatment. (U.S.)

  9. Literature Survey on the Stress Corrosion Cracking of Low-Alloy Steels in High Temperature Water

    International Nuclear Information System (INIS)

    The present report is a summary of a literature survey on the stress corrosion cracking (SCC) behaviour/ mechanisms in low-alloy steels (LAS) in high-temperature water with special emphasis to primary-pressure-boundary components of boiling water reactors (BWR). A brief overview on the current state of knowledge concerning SCC of low-alloy reactor pressure vessel and piping steels under BWR conditions is given. After a short introduction on general aspects of SCC, the main influence parameter and available quantitative literature data concerning SCC of LAS in high-temperature water are discussed on a phenomenological basis followed by a summary of the most popular SCC models for this corrosion system. The BWR operating experience and service cracking incidents are discussed with respect to the existing laboratory data and background knowledge. Finally, the most important open questions and topics for further experimental investigations are outlined. (author)

  10. Literature Survey on the Stress Corrosion Cracking of Low-Alloy Steels in High Temperature Water

    Energy Technology Data Exchange (ETDEWEB)

    Seifert, H.P

    2002-02-01

    The present report is a summary of a literature survey on the stress corrosion cracking (SCC) behaviour/ mechanisms in low-alloy steels (LAS) in high-temperature water with special emphasis to primary-pressure-boundary components of boiling water reactors (BWR). A brief overview on the current state of knowledge concerning SCC of low-alloy reactor pressure vessel and piping steels under BWR conditions is given. After a short introduction on general aspects of SCC, the main influence parameter and available quantitative literature data concerning SCC of LAS in high-temperature water are discussed on a phenomenological basis followed by a summary of the most popular SCC models for this corrosion system. The BWR operating experience and service cracking incidents are discussed with respect to the existing laboratory data and background knowledge. Finally, the most important open questions and topics for further experimental investigations are outlined. (author)

  11. Stress corrosion cracking tests for low carbon stainless steels with work hardened layer

    International Nuclear Information System (INIS)

    To avoid introduction of Cr depletion at grain boundaries by welding process, low carbon stainless steels (SSs) were used in corrosive environment as one of countermeasures for Stress Corrosion Cracking (SCC). Recently, it is reported that SCCs were introduced at portion with work hardened layer although low carbon SSs had been used at core shrouds and primary loop recirculation piping in Boiling Water Reactors. To simulate and examine the phenomenon, mechanical working, metallographic observation, hardness test and SCC tests in chloride solutions were conducted for low carbon SSs. From the results of metallographic observation and hardness test, it was confirmed that slip bands were observed around the surface and hardened layer was introduced by mechanical working. From the results of SCC tests, it was noticed that cracks which introduced from the surface, had grown into the matrix. It is thought that low carbon SSs with work hardened layer have susceptibility to SCC from the above. (author)

  12. Stress corrosion cracking of HP turbine using bolts of 900 MW CP1 units

    International Nuclear Information System (INIS)

    Failures or cracks of HP turbine casing bolts of the 900 MW PWR units are due to stress corrosion in humid steam and in presence of chlorinated solvents used during maintenance operations or before the mounting of bolts. This phenomenon does not concern only the steel used (35 NCD6 or 28 CDV 5-08), for the phenomenon has been reproduced in laboratory on other steel qualities, more particularly the Z 12 CNDV 12-2 steel. This steel would present a better resistance to this type of corrosion at temperatures lower than 2500C. Action have been undertaken to avoid these problems: systematic control at each casing opening; cleaning of bolts and bores for turbines having presented the phenomenon; chlorinated products are prohibited; change of the joint which ensures tightness, utilization of the Z 12 CNDV 12-2 steel quality and, study of the increase of screwing to keep the joint tight

  13. Stress corrosion cracking in low-pressure turbine discs in an NaCl solution

    Energy Technology Data Exchange (ETDEWEB)

    Hitomi, Itoh [Mitsubishi Heavy Industries, Ltd., Takasago Research and Development Center (Japan); Takashi, Momoo [Mitsubishi Heavy Industries, Ltd., Takasago Machinery Works (Japan)

    2001-07-01

    From past research, it is known that stress corrosion cracking in low-pressure turbine discs occurs in an environment near that of deaerated pure water. Nevertheless, in units with molar ratio control, there is a possibility of NaCl concentrating as an impurity in the dry/wet boundary region. Long-term immersion tests were conducted at 373 K to 473 K with the NaCl concentration predicted to become 5%. It was found that, when FeCl{sub 3} or other oxidizer was added, corrosion increased remarkably and SCC was initiated. When cracks were initiated, they were primarily transgranular; as the test temperature was decreased, initiation was accelerated but conversely crack propagation was reduced. (author)

  14. Stress corrosion cracking in low-pressure turbine discs in an NaCl solution

    International Nuclear Information System (INIS)

    From past research, it is known that stress corrosion cracking in low-pressure turbine discs occurs in an environment near that of deaerated pure water. Nevertheless, in units with molar ratio control, there is a possibility of NaCl concentrating as an impurity in the dry/wet boundary region. Long-term immersion tests were conducted at 373 K to 473 K with the NaCl concentration predicted to become 5%. It was found that, when FeCl3 or other oxidizer was added, corrosion increased remarkably and SCC was initiated. When cracks were initiated, they were primarily transgranular; as the test temperature was decreased, initiation was accelerated but conversely crack propagation was reduced. (author)

  15. Assessment of Residual Stress on Expanded Steam Generator Tubes and Establishment of Fundamentals for Their Stress Corrosion Cracking Property

    International Nuclear Information System (INIS)

    In Korean Standard Nuclear Power(KSNP) Plants, secondary circumferential outer diameter stress corrosion cracking(ODSCC) has occurred on the expansion transition region around the top of tube sheet. The circumferential ODSCC has been known to occur more often in CE type nuclear power plants(NPPs) compared to Westinghouse or Framatone type ones. It has been often reported that the compressive residual stress was developed on the transition regions expanded by the explosive and hydraulic expansion. However, circumferential ODSCC was observed to occur on the expansion transition region around the top of tube sheet(TTS) in operating NPPs, especially very often when sludge on TTS was piled up. This means that the residual stress state on the expansion transition region might be changed by the sludge piled up on TTS, such as from compressive to tensile stress, which has not been confirmed by laboratory experiment though. Thus, in this study, the residual stress state on the transition regions developed during explosive and hydraulic expansion was measured accurately using the strain gauge relaxation and X-ray diffraction methods. Any stress state changes due to the piled sludge on TTS will be checked experimentally in the laboratory. In order to due that, experimental facilities will be set up and experimental method will be developed in this study

  16. Development of fiber-delivered laser peening system to prevent stress corrosion cracking of reactor components

    International Nuclear Information System (INIS)

    The authors have developed a system to deliver water-penetrable intense laser pulses of frequency-doubled Nd:YAG laser through optical fiber. The system is capable of improving a residual stress on water immersed metal material remotely, which is effective to prevent the initiation of stress corrosion cracking (SCC) of reactor components. Experimental results showed that a compressive residual stress with enough amplitude and depth was built in the surface layer of type 304 stainless steel (SUS304) by irradiating laser pulses through optical fiber with diameter of 1 mm. A prototype peening head with miniaturized dimensions of 88 mm x 46 mm x 25 mm was assembled to con-firm the accessibility to the heat affected zone (HAZ) along weld lines of a reactor core shroud. The accessibility was significantly improved owing to the flexible optical fiber and the miniaturized peening head. The fiber delivered system opens up the possibility of new applications of laser peening. (author)

  17. Crack growth of intergranular stress corrosion cracks in austenitic stainless steel pipes of boiling water reactors

    International Nuclear Information System (INIS)

    Intergranular stress corrosion cracking (IGSCC) of boiling water reactor (BWR) piping is considered from the crack growth rate point of view. Crack growth rate of sensitized austenitic stainless steel welds is dependent on the degree of sensitization of the material and the severity of the environment as well as the stress state. In evaluation of actual crack growth rate there are three major sources of uncertainty: knowledge of actual crack size and shape, actual stress distribution in he area of the crack and the degree of sensitization. In the report the crack growth calculations used in the USA and in Sweden are presented. Finally, the crack growth rate predictions based on mechanistic modelling of IGSCC and some needs of further research in Finland are considered

  18. Mechanistic model of stress corrosion cracking (scc) of carbon steel in acidic solution with the presence of H2s

    International Nuclear Information System (INIS)

    In oil and gas industrial environments, H2S gas is one of the corrosive species which should be a main concern in designing infrastructure made of carbon steel. Combination between the corrosive environment and stress condition will cause degradation of carbon steel increase unpredictably due to their simultaneous effects. This paper will design a model that involves electrochemical and mechanical theories to study crack growth rate under presence of H2S gas. Combination crack and corrosion propagation of carbon steel, with different hydrogen concentration has been investigated. The results indicated that high concentration of hydrogen ions showed a higher crack propagation rate. The comparison between corrosion prediction models and corrosion model developed by researchers used to verify the model accuracy showed a good agreement

  19. Applied methods for mitigation of damage by stress corrosion in BWR type reactors; Metodos aplicados para la mitigacion del dano por corrosion bajo esfuerzo en reactores BWR

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez C, R.; Diaz S, A.; Gachuz M, M.; Arganis J, C. [Instituto Nacional de Investigaciones Nucleares, Gerencia de Ciencia de Materiales, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1998-07-01

    The Boiling Water nuclear Reactors (BWR) have presented stress corrosion problems, mainly in components and pipes of the primary system, provoking negative impacts in the performance of energy generator plants, as well as the increasing in the radiation exposure to personnel involucred. This problem has caused development of research programs, which are guided to find solution alternatives for the phenomena control. Among results of greater relevance the control for the reactor water chemistry stands out particularly in the impurities concentration and oxidation of radiolysis products; as well as the supervision in the materials selection and the stresses levels reduction. The present work presents the methods which can be applied to diminish the problems of stress corrosion in BWR reactors. (Author)

  20. Stress corrosion cracking of iron-nickel-chromium alloys in primary circuit environment of PWR-type reactors

    International Nuclear Information System (INIS)

    Stress corrosion cracking of Alloy 600 steam generator tubing is a great concern for pressurized water reactors. The mechanism that controls intergranular stress corrosion cracking of Alloy 600 in primary water (lithiated-borated water) has yet to be clearly identified. A study of stress corrosion cracking behaviour, which can identify the main parameters that control the cracking phenomenon, was so necessary to understand the stress corrosion cracking process. Constant extension rate tests, and constant load tests have evidenced that Alloy 600 stress corrosion cracking involves firstly an initiation period, then a slow propagation stage with crack less than 50 to 80 micrometers, and finally a rapid propagation stage leading to failure. The influence of mechanical parameters have shown the next points: - superficial strain hardening and cold work have a strong effect of stress corrosion cracking resistance (decrease of initiation time and increase of crack growth rate), - strain rate was the most suitable parameter for describing the different stage of propagation. The creep behaviour of alloy 600 has shown an increase of creep rate in primary water compared to air, which implies a local interaction plasticity/corrosion. An assessment of the durations of the initiation and the propagation stages was attempted for the whole uniaxial tensile tests, using the macroscopic strain rate: - the initiation time is less than 100 hours and seems to be an electrochemical process, - the durations of the propagation stage are strongly dependent on the strain rate. The behaviour in high primary water temperature of Alloys 690 and 800, which replace Alloy 600, was studied to appraise their margin, and validate their choice. Then the last chapter has to objective to evaluate the crack tip strain rate, in order to better describe the evolution of the different stages of cracking. (author)

  1. Relationship between localized strain and irradiation assisted stress corrosion cracking in an austenitic alloy

    International Nuclear Information System (INIS)

    Research highlights: → Austenitic steel is more susceptible to intergranular corrosion after irradiation. → Simulation and experiment used to study cracking in irradiated austentic steel. → Cracking occurs at random high angle boundaries normal to the tensile stress. → Cracking at boundaries with high normal stress and inability to accommodate strain. → Boundary type, angle, and Taylor and Schmid factors affect strain accommodation. - Abstract: Irradiation assisted stress corrosion cracking may be linked to the local slip behavior near grain boundaries that exhibit high susceptibility to cracking. Fe-13Cr-15Ni austenitic steel was irradiated with 2 MeV protons at 360 deg. C to 5 dpa and strained in 288 deg. C simulated BWR conditions. Clusters of grains from the experiment were created in an atomistic simulation and then virtually strained using molecular dynamic simulation techniques. Cracking and grain orientation data were characterized in both the experiment and the simulation. Random high angle boundaries with high surface trace angles with respect to the tensile direction were found to be the most susceptible to cracking. Grain boundary cracking susceptibility was also found to correlate strongly with slip continuity, indicating that the strain accommodation at the boundary is related to cracking resistance. Higher cracking susceptibility was also found at grain boundaries adjacent to grains with low Schmid factor or high Taylor factor. The basic trends reported here are supported by both the experiments and the simulations.

  2. PIE technologies for the study of stress corrosion cracking of reactor structural materials

    International Nuclear Information System (INIS)

    Irradiation assisted stress corrosion cracking (IASCC) is one of the critical concerns when stainless steel components have been in service in the light water reactors (LWRs) for a long period. In general, IASCC can be reproduced on the materials irradiated over a certain threshold fluence level of fast neutron by the post-irradiation examinations (PIEs) at hot laboratories. On the other hand, recently in the Japanese boiling water reactor (BWR) power plants, many incidents of stress corrosion cracking (SCC) of structural material such as the reactor core shrouds and primary loop recirculation (PLR) system piping were reported. In order to investigate the cause of SCC, PIEs at hot laboratories were carried out on the sample material extracted from BWR power plants. SCC studies require various kind of PIE techniques, because the SCC is caused by a complicated synergistic effects of stress and chemical environment on material that suffered degradations by irradiation and/or thermal aging. In this paper, we describe the PIE techniques adopted recently for our SCC studies, especially the crack growth measurement, uniaxial constant load (UCL) tensile test method, in-situ observation during slow strain rate test (SSRT) and several metallurgical test technique using the field-emission type transmission electron microscopy (FE-TEM), focused ion beam (FIB) processing technique, three Dimensional Atom Probe (3DAP) analysis and atomic force microscopy (AFM). (author)

  3. Relative susceptibility of titanium alloys to hot-salt stress-corrosion

    Science.gov (United States)

    Gray, H. R.

    1971-01-01

    Susceptibility of titanium alloys to hot-salt stress-corrosion cracking increased as follows: Ti-2Al-11Sn-5Zr-0.2Si(679), Ti-6Al-2Sn-4Zr-2Mo(6242), Ti-6Al-4V(64), Ti-6Al-4V-3Co(643), Ti-8Al-1Mo-1V(811), and Ti-13V-11Cr-3A1(13-11-3). The Ti-5Al-6Sn-2Zr-1Mo-0.25Si(5621S) alloy was both the least and most susceptible depending on heat treatment. Such rankings can be drastically altered by heat-to-heat and processing variations. Residual compressive stresses and cyclic exposures also reduce susceptibility to stress-corrosion. Simulated turbine-engine compressor environmental variables such as air velocity, pressure, dewpoint, salt concentration, and salt deposition temperature have only minor effects. Detection of substantial concentrations of hydrogen in all corroded alloys confirmed the existence of a hydrogen embrittlement mechanism.

  4. Stress corrosion cracking of CRD stub tube joint and repair at Hamaoka Unit 1

    International Nuclear Information System (INIS)

    On November 9, 2001, after the pipe rupture incident of the Residual Heat Removal system (RHR), plant personnel found the leak from the bottom of the Reactor Pressure Vessel (RPV). Afterwards, with underwater visual inspection, plant personnel found an axial cracking on one of the stub tube's weldments. In order to join the Nickel base material (Alloy 600) stub tube, a similar weld material (Alloy 182) is deposited to the low-alloy metal (LAS) vessel. From the examination of a boat sample it was found that the cracking in the Alloy 182 weld metal was due to interdendric (intergranular) stress corrosion cracking, which had progressed into the Alloy 600. Residual and applied stress during an in-service analysis explained that the location could have high tensile stress (330MPa and over). In order to repair cracking, a replacement method was applied. The stub tube and weld joint including the crack area was completely removed, and a new stub tube consisting of high corrosion resisted material was installed and welded. Remote automatic equipment was applied during the replacement process because of the high radiation environment. After inspecting the rest of the 88 stub tube's joints, there were no indications of any further problems. For higher reliability, the application of laser-peening technique is being examined. (author)

  5. Three dimensional observations and modelling of intergranular stress corrosion cracking in austenitic stainless steel

    International Nuclear Information System (INIS)

    Stress corrosion cracking is a life-limiting factor in many components of nuclear power plant in which failure of structural components presents a substantial hazard to both safety and economic performance. Uncertainties in the kinetics of short crack behaviour can have a strong influence on lifetime prediction, and arise due both to the complexity of the underlying mechanisms and to the difficulties of making experimental observations. This paper reports on an on-going research programme into the dynamics and morphology of intergranular stress corrosion cracking in austenitic stainless steels in simulated light water environments, which makes use of recent advances in high resolution X-ray microtomography. In particular in situ, three dimensional X-ray tomographic images of intergranular stress corrosion crack nucleation and growth in sensitised austenitic stainless steel provide evidence for the development of crack bridging ligaments, caused by the resistance of non-sensitised special grain boundaries. In parallel a simple grain bridging model, introduced to quantify the effect of crack bridging on crack development, has been assessed for thermo-mechanically processed microstructures via statically loaded room temperature simulant solution tests and as well as high temperature/pressure autoclave studies. Thermo-mechanical treatments have been used to modify the grain size, grain boundary character and triple junction distributions, with a consequent effect on crack behaviour. Preliminary three-dimensional finite element models of intergranular crack propagation have been developed, with the aim of investigating the development of crack bridging and its effects on crack propagation and crack coalescence

  6. Effect of layerwise structural inhomogeneity on stress- corrosion cracking of steel tubes

    Science.gov (United States)

    Perlovich, Yu A.; Krymskaya, O. A.; Isaenkova, M. G.; Morozov, N. S.; Fesenko, V. A.; Ryakhovskikh, I. V.; Esiev, T. S.

    2016-04-01

    Based on X-ray texture and structure analysis data of the material of main gas pipelines it was shown that the layerwise inhomogeneity of tubes is formed during their manufacturing. The degree of this inhomogeneity affects on the tendency of tubes to stress- corrosion cracking under exploitation. Samples of tubes were cut out from gas pipelines located under various operating conditions. Herewith the study was conducted both for sections with detected stress-corrosion defects and without them. Distributions along tube wall thickness for lattice parameters and half-width of X-ray lines were constructed. Crystallographic texture analysis of external and internal tube layers was also carried out. Obtained data testifies about considerable layerwise inhomogeneity of all samples. Despite the different nature of the texture inhomogeneity of gas pipeline tubes, the more inhomogeneous distribution of texture or structure features causes the increasing of resistance to stress- corrosion. The observed effect can be explained by saturation with interstitial impurities of the surface layer of the hot-rolled sheet and obtained therefrom tube. This results in rising of lattice parameters in the external layer of tube as compared to those in underlying metal. Thus, internal layers have a compressive effect on external layers in the rolling plane that prevents cracks opening at the tube surface. Moreover, the high mutual misorientation of grains within external and internal layers of tube results in the necessity to change the moving crack plane, so that the crack growth can be inhibited when reaching the layer with a modified texture.

  7. Effect of Secondary Phase Precipitation on the Corrosion Behavior of Duplex Stainless Steels

    Directory of Open Access Journals (Sweden)

    Kai Wang Chan

    2014-07-01

    Full Text Available Duplex stainless steels (DSSs with austenitic and ferritic phases have been increasingly used for many industrial applications due to their good mechanical properties and corrosion resistance in acidic, caustic and marine environments. However, DSSs are susceptible to intergranular, pitting and stress corrosion in corrosive environments due to the formation of secondary phases. Such phases are induced in DSSs during the fabrication, improper heat treatment, welding process and prolonged exposure to high temperatures during their service lives. These include the precipitation of sigma and chi phases at 700–900 °C and spinodal decomposition of ferritic grains into Cr-rich and Cr-poor phases at 350–550 °C, respectively. This article gives the state-of the-art review on the microstructural evolution of secondary phase formation and their effects on the corrosion behavior of DSSs.

  8. Caustic ingestion injuries-at military hospital rawalpindi

    International Nuclear Information System (INIS)

    To study the pattern and endoscopic severity of caustic ingestion injuries presenting at Military Hospital Rawalpindi. Study Design: Descriptive study. Place and Duration of Study: The study was conducted at Medical and Gastroenterology Department Military Hospital Rawalpindi from August 2012 to April 2013. Material and Methods: Patients were selected from those who presented with caustic ingestion history in Medical OPD, ER and in medical wards. After informed consent the patient underwent upper gastrointestinal (GI) Endoscopy. Endoscopic findings were recorded. Results: Out of 50 patients, 21(42%) were males and 29 (58%) were females. Ingestion was accidental in 19 (38%) and was with intent of suicide or self-harm in 31(62%) patients. Mean age was 33.2 years (SD ± 13.2). All the patients were subjected to upper GI endoscopy and findings were recorded. Endoscopic findings were grade 0 in 4 (8%), Grade 1 in 6 (12%), grade 2a in 7 (14%), grade 2b in 10 (20%), grade 3a in 6 (12%) and grade 3b in 17 (34%) patients. Conclusion: Caustic ingestion injuries were seen more in younger females with predominant cause as suicidal intent. On endoscopic examination severe corrosive injuries were more frequent. (author)

  9. A middle age addicted man with caustic stomach

    Directory of Open Access Journals (Sweden)

    Gholamreza Nouri Broujerdi

    2014-06-01

    Full Text Available Background: The term caustic generally refers to alkaline and the term corrosive generally refers to acidic agents' injury; however, in medical literature caustic is frequently a term applied to both substances. Ingested alkali typically damage the esophagus more than stomach or duodenum, whereas acids usually cause more severe gastric injury. Since esophagus has a slightly alkaline pH, its epithelium is more resistant to acids, so that only 6 to 20% of those who ingest these substances present lesions in this organ. Case : A middle-aged addicted man who drunk hydrochloric acid accidentally had extensive necrosis of the stomach with remarkable sparing of the esophagus on second look exploration. A total gastrectomy with a Roux-en-Y esophago-jejunostomy with feeding jejunostomy was performed. Conclusion : In caustic GI injury, patients who are operated on and found to have no evidence of extensive esophago-gastric necrosis, a biopsy of the posterior gastric wall should be performed to exclude occult injury. If histologically there is a question of viability, a second look operation should be performed within 36 hours.

  10. Dissolution of copper in chloride/ammonia mixtures and the implications for the stress corrosion cracking of copper containers

    International Nuclear Information System (INIS)

    Stress-corrosion cracking is a possible failure mechanism for copper nuclear fuel waste disposal containers. One species known to cause the stress corrosion of copper alloys is ammonia. It is conceivable that ammonia could be produced in a disposal vault under certain, very specific conditions. There are a number of conditions, however, that mitigate against container failure by stress corrosion, one of which is the presence of chloride ions in deep Canadian Shield groundwaters. There are a number of reports in the literature that suggest that Cl- has an inhibitive effect on the stress corrosion of Cu alloys in ammonia solutions. The electrochemical behaviour of Cu in Cl-/ammonia solutions has been studied as a function of ammonia concentration, pH, the rate of mass transport and electrochemical potential. In particular, the effects of these parameters on the formation Of Cu2O films and the steady-state dissolution behaviour have been determined. All experiments were carried out in 0.1 mol·dm-3 NaC1 as a base solution. A series of aqueous speciation and equilibrium potential/pH diagrams are also presented for the quaternary system Cu-C1-NH3/NH4+H2O. These diagrams are used to interpret the results of the electrochemical experiments reported here. In addition, it is demonstrated how these diagrams could be used to predict the time-dependence of the susceptibility to stress corrosion cracking of Cu containers in a disposal vault. (author)

  11. Behaviour of welded high-strength, fine-grained structural steels with regard to cathodic stress crack corrosion

    International Nuclear Information System (INIS)

    The heat-affected zone is the zone most susceptible to hydrogen and naphta-cracking-gas corrosion. The material StE 355 exhibited high resistance to both corrosive substances. In materials in contact with boiler feedwater, stress relief annealing of welds will prevent cracking even in the case of high-strength StE 600. Hydrogen cracking induced by electrochemical processes was found to be temperature-dependent. (DG)

  12. Potential resistance of Alloy 82 dissimilar metal welds to primary water stress corrosion cracking

    International Nuclear Information System (INIS)

    Joints between carbon steel and Alloy 600, containing Alloy 82 weld metal, were exposed to a steam-hydrogen environment considered to simulate exposure to primary water conditions in nuclear power plants. A potentially protective external iron oxide film formed on the inner surface of the component. However, the chromium content throughout the weld is below that which would form an external chromium oxide. The results indicate that low chromium content could allow for internal oxidation below the external iron oxide which could increase susceptibility to primary water stress corrosion cracking (PWSCC) compared with an otherwise similar alloy, such as Alloy 800. (author)

  13. Effect of magnesium on lead induced stress corrosion cracking of UNS N08800

    International Nuclear Information System (INIS)

    This research is devoted to the effect of different water chemistries on the passivity and stress corrosion cracking (SCC) of the steam generator tubing alloy. The stability of passive films on UNS N08800 was investigated using cyclic polarization curves, Mott-Schottky measurements, SIMS and XPS. The SCC susceptibility was evaluated with constant extension rate tensile (CERT) tests in simulated neutral crevice chemistries at 300oC. It was found that the SCC susceptibility could be well correlated to the passivity degradation caused by harmful species such as lead. An interaction between lead and magnesium could happen at elevated temperature. (author)

  14. Macroscopic Segregation and Stress Corrosion Cracking in 7xxx Series Aluminum Alloy Arc Welds

    Science.gov (United States)

    Borchers, Tyler E.; McAllister, Donald P.; Zhang, Wei

    2015-05-01

    Arc welds of Al-Zn-Mg alloy with Al-Mg filler wire have shown a preferential macroscopic segregation of Mg and Zn to the weld toes. Islands of large precipitates, which are observed in those solute-enriched weld toes, are identified as T phase (Mg32(Al,Zn)49) using diffraction pattern analysis. The location of T precipitates consistently coincides with the initiation site for stress corrosion cracking. Therefore, it is hypothesized that they induce the crack initiation due to preferential dissolution.

  15. Statistical model of stress corrosion cracking based on extended form of Dirichlet energy

    Indian Academy of Sciences (India)

    Harry Yosh

    2013-12-01

    The mechanism of stress corrosion cracking (SCC) has been discussed for decades. Here I propose a model of SCC reflecting the feature of fracture in brittle manner based on the variational principle under approximately supposed thermal equilibrium. In that model the functionals are expressed with extended forms of Dirichlet energy, and Dirichlet principle is applied to them to solve the variational problem that represents SCC and normal extension on pipe surface. Based on the model and the maximum entropy principle, the statistical nature of SCC colony is discussed and it is indicated that the crack has discrete energy and length under ideal isotropy of materials and thermal equilibrium.

  16. Stress corrosion crack growth rate measurement in high temperature water using small precracked bend specimens

    OpenAIRE

    Toivonen, Aki

    2004-01-01

    The applicability of elastic-plastic fracture mechanics to stress corrosion crack growth rate measurements was studied. Several test series were performed on small elastic-plastically loaded SEN(B) specimens in high temperature water. One test was performed on a 25 mm C(T) specimen under linear-elastic loading. The tests on the SEN(B) specimens were performed using either rising displacement or a combination of rising and constant displacement loading. The test on the 25 mm C(T) specimen was ...

  17. Investigation of intergranular stress corrosion cracking in the fuel pool at Three Mile Island Unit 1

    International Nuclear Information System (INIS)

    An intergranular stress corrosion cracking failure of 304 stainless steel pipe in 2000 ppM B as H3BO3 + H2O at 1000C has been investigated. Constant extension rate testing has produced an intergranular type failure in material in air. Chemical analysis was performed on both the base metal and weld material, in addition to fractography, EPR testing and optical microscopy in discerning the mode of failure. Various effects of Cl-, O2, and MnS are discussed. The results have indicated that the cause of failure was the severe sensitization coupled with probable contamination by S and possibly by Cl ions

  18. SCC [stress corrosion cracking] modes of rotor materials in steam environment

    International Nuclear Information System (INIS)

    Stress corrosion cracking of steam rotors is a worldwide problem in nuclear power industry. In this paper, WOL specimens of 3.5 NiCrMoV and 2Cr1Ni alloys have been investigated in the SCC study. The experimental environment was controlled at 170 oC wet steam with different content of chloride and oxygen. The results showed that the most of SCC cracks propagated in intergranular mode, except few cracks showed a small portion of transgranular surface near the crack initiation site. The SCC crack propagation rate in the experiment is always below 10-9 m/sec. (author)

  19. The influence of molybdenum on stress corrosion in Ultra Low Carbon Steels with copper addition

    OpenAIRE

    Mazur, M.; R. Bogucki; Pytel, S.

    2010-01-01

    The influence of molybdenum content on the process of stress corrosion of ultra-low carbon structural steels with the addition of copper HSLA (High Strength Low Alloy) was analyzed. The study was conducted for steels after heat treatment consisting of quenching andfollowing tempering at 600°C and it was obtained microstructure of the tempered martensite laths with copper precipitates and the phaseLaves Fe2Mo type. It was found strong influence of Laves phase precipitate on the grain boundarie...

  20. Stress corrosion cracking susceptibility of candidate structural materials in supercritical pressurized water

    Energy Technology Data Exchange (ETDEWEB)

    Je, Hwanil, E-mail: hwanil.je@gmail.com; Kimura, Akihiko

    2014-12-15

    The stress corrosion cracking (SCC) susceptibility in supercritical pressurized water (SCPW) was investigated for the candidate structural steels of advanced fusion and fission nuclear system, which are SUS316L austenitic steel, F82H ferritic–martensitic steel and SOC-16 oxide dispersion strengthened (ODS) ferritic steel. In order to evaluate the susceptibility to SCC with those materials, slow strain rate test (SSRT) was carried out at 773 K, under a pressure of 25 MPa of SCPW with deaerated condition. High temperature tensile test in vacuum at 773 K was also performed to compare the deformation and fracture behavior between corrosive environment of SCPW and non-corrosive environment. Although SUS316L showed a change in the fracture mode in the deaerated SCPW from an entire ductile fracture at higher strain rate to a mixed mode of ductile and brittle fracture at lower one, the fracture mode of ODS steel and F82H was not changed in the tested strain rate range. Both the IGSCC and TGSCC were observed in SUS316L. And F82H steel suffered from much severer oxidation than SUS316L and SOC-16.

  1. Control of alkaline stress corrosion cracking in pressurized-water reactor steam generator tubing

    International Nuclear Information System (INIS)

    Outer-diameter stress corrosion cracking (ODSCC) of alloy 600 (UNS N06600) tubings in steam generators of the Kori-1 pressurized-water reactor (PWR) caused an unscheduled outage in 1994. Failure analysis and remedy development studies were undertaken to avoid a recurrence. Destructive examination of a removed tube indicated axial intergranular cracks developed at the top of sludge caused by a boiling crevice geometry. A high ODSCC propagation rate was attributed to high local pH and increased corrosion potential resulting from oxidized copper presumably formed during the maintenance outage and plant heatup. Remedial measures included: (1) crevice neutralization by crevice flushing with boric acid (H3BO3) and molar ratio control using ammonium chloride (NH4Cl), (2) corrosion potential reduction by hydrazine (H2NNH2) soaking and suppression of oxygen below 20 ppb to avoid copper oxide formation, (3) titanium dioxide (TiO2) inhibitor soaking, and (4) temperature reduction of 5 C. Since application of the remedy program, no significant ODSCC has been observed, which clearly demonstrates the benefit of departing from an oxidizing alkaline environment. In addition, the TiO2 inhibitor appeared to have a positive effect, warranting further examination

  2. Sulfide Stress Cracking and Electrochemical Corrosion of Precipitation Hardening Steel After Plasma Oxy-Nitriding

    Science.gov (United States)

    Granda-Gutiérrez, E. E.; Díaz-Guillén, J. C.; Díaz-Guillén, J. A.; González, M. A.; García-Vázquez, F.; Muñóz, R.

    2014-11-01

    In this paper, we present the results of a duplex plasma nitriding followed by an oxidizing stage process (which is also referred as oxy-nitriding) on the corrosion behavior of a 17-4PH precipitation hardening stainless steel. The formation of both, expanded martensite (b.c.t. α'N-phase) and chromium oxide (type Cr2O3) in the subsurface of oxy-nitrided samples at specific controlled conditions, leads in a noticeable increasing in the time-to-rupture during the sulfide stress cracking test, in comparison with an untreated reference sample. Oxy-nitriding improves the corrosion performance of the alloy when it is immersed in solutions saturated by sour gas, which extends the application potential of this type of steel in the oil and gas extraction and processing industry. The presence of the oxy-nitrided layer inhibits the corrosion process that occurs in the near-surface region, where hydrogen is liberated after the formation of iron sulfides, which finally produces a fragile fracture by micro-crack propagation; the obtained results suggest that oxy-nitriding slows this process, thus delaying the rupture of the specimen. Moreover, oxy-nitriding produces a hard, sour gas-resistant surface, but do not significantly affect the original chloride ion solution resistance of the material.

  3. Stress corrosion cracking susceptibility of candidate structural materials in supercritical pressurized water

    International Nuclear Information System (INIS)

    The stress corrosion cracking (SCC) susceptibility in supercritical pressurized water (SCPW) was investigated for the candidate structural steels of advanced fusion and fission nuclear system, which are SUS316L austenitic steel, F82H ferritic–martensitic steel and SOC-16 oxide dispersion strengthened (ODS) ferritic steel. In order to evaluate the susceptibility to SCC with those materials, slow strain rate test (SSRT) was carried out at 773 K, under a pressure of 25 MPa of SCPW with deaerated condition. High temperature tensile test in vacuum at 773 K was also performed to compare the deformation and fracture behavior between corrosive environment of SCPW and non-corrosive environment. Although SUS316L showed a change in the fracture mode in the deaerated SCPW from an entire ductile fracture at higher strain rate to a mixed mode of ductile and brittle fracture at lower one, the fracture mode of ODS steel and F82H was not changed in the tested strain rate range. Both the IGSCC and TGSCC were observed in SUS316L. And F82H steel suffered from much severer oxidation than SUS316L and SOC-16

  4. Isochromatics and caustics around the tips of interface cracks observed by digital image processing

    International Nuclear Information System (INIS)

    Photoelasticity and the caustic method are two useful optical techniques for the investigation of mixed-mode crack problems and other stress concentration problems in the vicinity of holes and bores as well as for the evaluation of contact problems. The geometry of the caustics is proportional to the stress field gradient and therefore the caustic contour can be taken as a quantity for experimental measurements. In this paper, an overview about the numerical simulation and experimental modelling of cracks arising in plane disk-like models of two-phase composite structures will be given. Shadow optical and photoelastic data were collected from digitally sharpened isochromatic fringe patterns and caustics by using a digital image analysis system. By utilizing digital image processing and computergraphics techniques, a set of menu-driven software is developed for interactively implemented caustics and fringes processing. Stress intensity factors were also obtained by a special shadow optical-grid-method and the multi-point method of caustics and isochromatics, respectively. (orig.)

  5. Stress Corrosion Cracking of the Drip Shield, the Waste Package Outer Barrier, and the Stainless Steel Structural Material

    International Nuclear Information System (INIS)

    Stress corrosion cracking is one of the most common corrosion-related causes for premature breach of metal structural components. Stress corrosion cracking is the initiation and propagation of cracks in structural components due to three factors that must be present simultaneously: metallurgical susceptibility, critical environment, and static (or sustained) tensile stresses. This report was prepared according to ''Technical Work Plan for: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package'' (BSC 2004 [DIRS 171583]). The purpose of this report is to provide an evaluation of the potential for stress corrosion cracking of the engineered barrier system components (i.e., the drip shield, waste package outer barrier, and waste package stainless steel inner structural cylinder) under exposure conditions consistent with the repository during the regulatory period of 10,000 years after permanent closure. For the drip shield and waste package outer barrier, the critical environment is conservatively taken as any aqueous environment contacting the metal surfaces. Appendix B of this report describes the development of the SCC-relevant seismic crack density model (SCDM). The consequence of a stress corrosion cracking breach of the drip shield, the waste package outer barrier, or the stainless steel inner structural cylinder material is the initiation and propagation of tight, sometimes branching, cracks that might be induced by the combination of an aggressive environment and various tensile stresses that can develop in the drip shields or the waste packages. The Stainless Steel Type 316 inner structural cylinder of the waste package is excluded from the stress corrosion cracking evaluation because the Total System Performance Assessment for License Application (TSPA-LA) does not take credit for the inner cylinder. This document provides a detailed description of the process-level models that can be applied to assess the performance of Alloy 22

  6. Stress Corrosion Cracking of the Drip Shield, the Waste Package Outer Barrier, and the Stainless Steel Structural Material

    Energy Technology Data Exchange (ETDEWEB)

    G. Gordon

    2004-10-13

    Stress corrosion cracking is one of the most common corrosion-related causes for premature breach of metal structural components. Stress corrosion cracking is the initiation and propagation of cracks in structural components due to three factors that must be present simultaneously: metallurgical susceptibility, critical environment, and static (or sustained) tensile stresses. This report was prepared according to ''Technical Work Plan for: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package'' (BSC 2004 [DIRS 171583]). The purpose of this report is to provide an evaluation of the potential for stress corrosion cracking of the engineered barrier system components (i.e., the drip shield, waste package outer barrier, and waste package stainless steel inner structural cylinder) under exposure conditions consistent with the repository during the regulatory period of 10,000 years after permanent closure. For the drip shield and waste package outer barrier, the critical environment is conservatively taken as any aqueous environment contacting the metal surfaces. Appendix B of this report describes the development of the SCC-relevant seismic crack density model (SCDM). The consequence of a stress corrosion cracking breach of the drip shield, the waste package outer barrier, or the stainless steel inner structural cylinder material is the initiation and propagation of tight, sometimes branching, cracks that might be induced by the combination of an aggressive environment and various tensile stresses that can develop in the drip shields or the waste packages. The Stainless Steel Type 316 inner structural cylinder of the waste package is excluded from the stress corrosion cracking evaluation because the Total System Performance Assessment for License Application (TSPA-LA) does not take credit for the inner cylinder. This document provides a detailed description of the process-level models that can be applied to assess the

  7. Stress corrosion cracking of nickel alloys in bicarbonate and chloride solutions

    International Nuclear Information System (INIS)

    Alloy 22 is one of the candidates for the manufacture of high level radioactive waste containers. These containers provide services in natural environments characterized by multi-ionics solutions, it is estimated they could suffer three types of deterioration: general corrosion, localized corrosion (crevice corrosion) and stress corrosion cracking (SCC). It has been confirmed that the presence of bicarbonate at temperatures above 60°C and applied potentials around +400 mVSCE are necessary in order to produce cracking, . This susceptibility may be associated to the instability of the passive film formed and to the formation of an anodic current peak in the polarization curves in these media. Until now, it is unclear the role played by each alloying element (Ni, Cr or Mo) in the SCC susceptibility of Alloy 22 in these media The aim of this work is to evaluate the SCC susceptibility of nickel-based alloys in media containing bicarbonate and chloride ions, at high temperature. Slow Strain Rate Testing (SSRT) was conducted to samples of different alloys: 22 (Ni-Cr-Mo), 600 (Ni-Cr-Fe), 800H (Ni-Fe-Cr) y 201 (99.5% Ni).This tests were conducted in 1.1 mol/L NaHCO3 +1.5 mol/L NaCl a 90°C and different applied potentials (+200mVSCE,+300 mVSCE, +400 mVSCE). These results were complemented with those obtained in a previous work, where we studied the anodic electrochemical behavior of nickel base alloys under the same conditions. It was found that alloy 22 showed a current peak in a potential range between +200 mVSCE and +300 mVSCE when immersed in bicarbonate ions containing solutions. This peak was attributed to the presence of chromium in the alloys. The SSRT showed that only alloy 22 has a clear indication of stress corrosion cracking. The current results suggested that the presence of an anodic peak in the polarization curves was not a sufficient condition for cracking. (author)

  8. 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

  9. Avoidance of stress corrosion susceptibility in high strength aluminum alloys by control of grain boundary and matrix microstructure

    Science.gov (United States)

    Adler, P.; Deiasi, R.

    1974-01-01

    The relation of microstructure to the mechanical strength and stress corrosion resistance of highest strength and overaged tempers of BAR and 7050 aluminum alloys was investigated. Comparison is made with previously studied 7075 aluminum alloy. Optical microscopy, transmission electron microscopy, and differential scanning calorimetry were used to characterize the grain morphology, matrix microstructure, and grain boundary microstructure of these tempers. Grain boundary interparticle spacing was significant to stress corrosion crack propagation for all three alloys; increasing interparticle spacing led to increased resistance to crack propagation. In addition, the fire grain size in Bar and 7050 appears to enhance crack propagation. The highest strength temper of 7050 has a comparatively high resistance to crack initiation. Overall stress corrosion behavior is dependent on environment pH, and evaluation over a range of pH is recommended.

  10. Fabrication of imitative stress corrosion cracking using diffusion bonding for the development of nondestructive testing and evaluations

    International Nuclear Information System (INIS)

    This study reports a method to fabricate imitative stress corrosion cracking suitable for the development of nondestructive testing and evaluation methods. The method is to embed a partially-bonded region, which simulates the characteristics of stress corrosion cracking, inside a material by bonding together surfaces having artificial grooves. Since the sizes of the grooves are smaller than the spatial resolution of nondestructive testing method applied, the material property realized can be regarded as uniform as the actual stress corrosion cracking. The grooves are introduced using mechanical machining, which enables one to control the characteristics of the simulated flaw. Four specimens made of type 316L austenitic stainless steel are fabricated. The method is demonstrated by visual and eddy current examinations. (author)

  11. The role of microstructure and environment on the stress corrosion cracking behavior of structural materials in nuclear power plant environments

    International Nuclear Information System (INIS)

    Structural materials such as austenitic stainless steel and nickel base alloys can be susceptible to intergranular stress corrosion cracking (IGSCC) in high temperature, high purity water environments found in nuclear power plants. Both wrought and weld metal materials have been susceptible depending on the alloy composition and the microstructure present if conducive environmental conditions exist. This work focuses on the behavior of austenitic stainless steel in oxygenated high purity high temperature water environments. The susceptibility of both wrought and weld metals to the initiation of IGSCC is discussed. The recent efforts to quantify crack growth behavior of these materials is reviewed. Weld Metal toughness issues are discussed, as they pertain to continued operation with components containing stress corrosion cracks. The background behind materials and environmental solutions to stress corrosion cracking of power plant piping is presented

  12. Imaging and size analysis of stress corrosion cracks in austenitic components using the synthetic aperture focus technique

    International Nuclear Information System (INIS)

    Riss formation and growth by intercrystalline stress corrosion cracking occurs especially in nickel alloys in case of mixed steels and also in the heat-affected zone in some austenitic Cr-Ni steels. In view of the strong branching of these cracks, amplitude-based ultrasonic methods of measurement may fail. The contribution describes the detection and size analysis of stress corrosion cracks. The synthetic aperture focus technique (SAFT) was used to improve the signal-noise ratio of the ultrasonic inspection data, especially for crack tip identification. several test bodies with intercrystalline stress corrosion cracks with depths ranging from 2.5 mm to 16 mm were analyzed successfully by a combination of conventional techniques for acquisition of B-scan data, followed by SAFT processing.

  13. Stress corrosion cracking susceptibility of the earthquake resistant NOM B457 Mexican steel

    International Nuclear Information System (INIS)

    The Mexican construction code was modified after the Mexico city 1985 earthquake, substituted the medium carbon reinforced steel NOM B6 by the new micro alloyed steel NOM B457 in 42 Kg/mm2 grade. The present study reports the evaluation of the NOM B457 steel behavior in mortar with and without 2% wt. in chlorides and in Ca(OH)2 saturated solutions. The results are compared with the NOM B6 steel behavior in the same conditions. The Stress Corrosion Cracking (SCC) is not present in all the conditions used in this study and there are not susceptibility potential range to SCC when the material is evaluated by electrochemical Tests, Constant Extension Rate Tests (CERT) and Constant Load Test at 80 % of yield stress. A susceptibility potential range to Hydrogen Induced Cracking (HIC) is detected, below -900 mV. vs Standard Calomel Electrode (SCE) by CERT at constant potential

  14. Investigation of Stress Corrosion Cracking Initiation of 7A52 Aluminum Alloy

    Institute of Scientific and Technical Information of China (English)

    LI Qi; ZHAO Junjun; ZHANG Ping

    2012-01-01

    The stress corrosion cracking(SCC) behaviour of 7A52 aluminum alloy in air and in 3.5%NaCl solution was researched by slow strain rate test(SSRT) and SEM-EDS.The SCC susceptibility was estimated with the loss of the reduction in area.The experimental results indicate that the SCC susceptibility of 7A52 aluminum alloy in 3.5% chloride solution is the highest at strain rate of 1 × 10-6 s-1.The lowest one is under the condition of 1 × 10-5 s-1.Stress concentration and anode dissolving around Al-Fe-Mn intermetallics initiate micropores which will result in microcracks.The existence of intermetallics in the microstructure may play an important role in understanding the SCC initiation mechanisms of 7A52 aluminum alloy.

  15. Stress corrosion cracking of Ni-base and Ti alloys under controlled potential

    International Nuclear Information System (INIS)

    Susceptibility to stress corrosion cracking (SCC) of alloy C-22 and Ti Gr-12, two candidate alloys for the inner-container of the multi-barrier nuclear waste package, was evaluated by using the slow-strain-rate (SSR) test technique in a deaerated acidic brine (pH ∼ 2.70) at 90 C. The strain rate used was 3.3 x 10-6 sec-1. Prior to being tested in the acidic brine, specimens of each alloy were pulled inside the test chamber in the dry condition at room temperature (RT). Then specimens were exposed to the test solution while being strained under different controlled electrochemical potentials. The magnitude of the controlled potential was selected based on the corrosion potential measured in the test solution prior to straining of the specimen. Results indicate that, for Ti Gr-12, the times to failure were significantly shorter compared to those for alloy C-22. Furthermore, Ti Gr-12 showed reduced ductility in terms of percent reduction in area and true fracture stress, as the controlled potential became more cathodic. Results also indicate that the time-to-failure and percent elongation reached the minimum values when Ti Gr-12 was tested under impressed potential of -1162 mV. Finally, metallographic examination was performed to evaluate the primary fracture, and the secondary cracking, if any, along the gage section of the broken tensile specimen

  16. Aqueous chloride stress corrosion cracking of titanium: A comparison with environmental hydrogen embrittlement

    Science.gov (United States)

    Nelson, H. G.

    1973-01-01

    The physical characteristics of stress corrosion cracking of titanium in an aqueous chloride environment are compared with those of embrittlement of titanium by a gaseous hydrogen environment in an effort to help contribute to the understanding of the possible role of hydrogen in the complex stress corrosion cracking process. Based on previous studies, the two forms of embrittlement are shown to be similar at low hydrogen pressures (100 N/sqm) but dissimilar at higher hydrogen pressures. In an effort to quantify this comparison, tests were conducted in an aqueous chloride solution using the same material and test techniques as had previously been employed in a gaseous hydrogen environment. The results of these tests strongly support models based on hydrogen as the embrittling species in an aqueous chloride environment. Further, it is shown that if hydrogen is the causal species, the effective hydrogen fugacity at the surface of titanium exposed to an aqueous chloride environment is equivalent to a molecular hydrogen pressure of approximately 10 N/sqm.

  17. Relationship between turbine rotor and disk metallurgical characteristics and stress corrosion cracking behavior. Final report

    International Nuclear Information System (INIS)

    This report describes stress corrosion test results in which several heats of turbine rotor steels specially prepared to achieve different degrees of segregation to the grain boundaries were tested in concentrated laboratory and actual steam turbine environments. Grain boundary characteristics are considered important because turbine rotor failures in field service have been of an intergranular nature and because grain boundary segregation is known to affect the impact toughness of rotor steels (''temper embrittlement''). The laboratory stress corrosion testing results showed no differences between heavily and lightly segregated test pieces which differed greatly in impact toughness. All test specimens cracked, indicating the laboratory environments may have been too severe to allow differentiation between the various metallurgical conditions, if any differences exist. Test loops and autoclaves for chemical analysis and mechanical testing were designed, installed and are operating in the field testing portion of this program. No intergranular cracking has occurred to date; hence, no differentiation between heavily and lightly segregated test pieces has been possible in field testing. Instrumented crack propagation specimens, which permit measurement of cracking as it occurs, have been installed for the continuing field testing program. Correlation of such cracking with the continuously monitored chemical composition of the environment will increase understanding of the cracking process and may give the possibility of providing an early warning of the existence of conditions which might cause turbine rotor cracking

  18. Relationship between turbine rotor and disk metallurgical characteristics and stress corrosion cracking behavior. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Gayley, H.B.

    1986-09-01

    This report describes stress corrosion test results in which several heats of turbine rotor steels specially prepared to achieve different degrees of segregation to the grain boundaries were tested in concentrated laboratory and actual steam turbine environments. Grain boundary characteristics are considered important because turbine rotor failures in field service have been of an intergranular nature and because grain boundary segregation is known to affect the impact toughness of rotor steels (''temper embrittlement''). The laboratory stress corrosion testing results showed no differences between heavily and lightly segregated test pieces which differed greatly in impact toughness. All test specimens cracked, indicating the laboratory environments may have been too severe to allow differentiation between the various metallurgical conditions, if any differences exist. Test loops and autoclaves for chemical analysis and mechanical testing were designed, installed and are operating in the field testing portion of this program. No intergranular cracking has occurred to date; hence, no differentiation between heavily and lightly segregated test pieces has been possible in field testing. Instrumented crack propagation specimens, which permit measurement of cracking as it occurs, have been installed for the continuing field testing program. Correlation of such cracking with the continuously monitored chemical composition of the environment will increase understanding of the cracking process and may give the possibility of providing an early warning of the existence of conditions which might cause turbine rotor cracking.

  19. Stress corrosion cracking of B13, a new high strength aluminium lithium alloy

    International Nuclear Information System (INIS)

    The present paper focuses on the study of SCC behaviour of a new Al-Cu-Li alloy. For this purpose, two conventional media - NaCl and NaCl + H2O2 - were used for comparison with commercial alloys 7075 and 8090. This new alloy shows lower susceptibility to SCC than conventional alloys as it does not undergo environmentally-induced embrittlement in NaCl solutions and in 1 M NaCl + 0.3% H2O2 in which the 7075 and 8090 alloys, respectively, undergo environmentally-induced fracture. Solution composition was modified in order to determine the environmental conditions and strain rates under which this new alloy will crack due to a stress corrosion cracking phenomenon. The addition of 0.6 M sulphates to 1 M NaCl + 0.3% H2O2 solution allows the definition of a range of strain rate (between 10-7 and 10-6 s-1) in which this new alloy undergoes stress corrosion cracking

  20. Scale effect on fatigue and stress corrosion cracking thresholds of structural steels

    International Nuclear Information System (INIS)

    Effect of specimen thickness on stress corrosion cracking threshold Kscc and fatigue threshold ΔKth for structural steels is considered. Inversion of the scale effect on the Kscc parameter for the steels with different strength and ductility was found. The results obtained are explained by analysis of realization of different local fracture criteria (the force and the strain criteria) and the related mechanisms (hydrogen embrittlement and anodic solution) of corrosion environment effects. Tests of the nuclear reactor steel showed that realization of plane strain conditions in fatigue crack tip does not yet provide an independence of ΔKth level on specimen thickness if thickness influences on the crack closure. Only the effective fatigue threshold ΔKtheff, calculated with taking into account the crack closure phenomenon, can be considered as characteristic of material. However hydrogenating of steel breaks such peculiarity and then ΔKtheff parameter becomes sensitive to specimen thickness. It is explained by the different effective stress ratio for different specimen thickness and correspondingly different hydrogen concentration in the crack tip. (orig.)

  1. Characteristics of acoustic emission during stress corrosion cracking of nickel base alloy

    International Nuclear Information System (INIS)

    The acoustic emission(AE) method has been utilized to study the detectability of crack initiation and growth during intergranular stress corrosion cracking(IGSCC) of Inconel 600 alloy and to evaluate its applicability as a non-destructive testing method by comparing the crack behavior with AE parameters and measuring the minimum detectable crack size. Variously heat-treated specimens were tensioned by use of a constant extension rate tester at various extension rates to yield different stress corrosion cracking behaviors of Inconel specimens. Significant AE responses were observed during IGSCC, ductile fracture and plastic deformation. The magnitude of AE peak amplitudes was in the decreasing order for IGSCC, ductile fracture and plastic deformation. AE also was effective means to identify the transition from small crack initiation and growth to dominant crack growth. Close correlation was found to exist between AE behaviors and electrochemical current changes, suggesting that the formation and breakdown of passive film is involved in IGSCC of Inconel 600. The minimum crack size detectable with AE was approximately 200 to 400μm in length and below 100μm in depth, indicating the possibility of detecting small IGSC cracks prior to the growth of single dominant cracks

  2. Effect of pre-deformation on the stress corrosion cracking susceptibility of aluminum alloy 2519

    Institute of Scientific and Technical Information of China (English)

    LI Huizhong; ZHANG Xinming; CHEN Mingan; LI Yanfang; LIANG Xiaopeng

    2007-01-01

    The effects of pre-deformation and strain rate on the stress corrosion cracking (SCC) behavior of aluminum alloy 2519 in air and in 3.5% NaCl water solution were investigated by means of slow strain rate tension (SSRT), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results indicate that the alloy is susceptible to SCC in 3.5% NaCl water solution and not in air. At the same pre-deformation, the alloy is more susceptible to SCC at 1.33 × 10-5 s-1 than at 6.66 × 10-5 s-1. Moreover, it is more susceptible to SCC at free pre-deformation than at 10% pre-deformation at the same strain rate. The number of θ precipitated along the grain boundaries is reduced and distributed discontinuously, at the same time, the precipitate-free zones (PFZ) become narrow and the susceptibility to stress corrosion cracking is reduced after 10% pre-deformation.

  3. Atom probe tomography of stress corrosion crack tips in SUS316 stainless steels

    International Nuclear Information System (INIS)

    Highlights: • Quantitative study of 3D features such as grain boundary oxides and Ni enrichment. • Features can be related to their distance from the crack tip. • Local measurement of compositions in very small volumes and specific regions. • Complementary analytical TEM data was recorded to correlate to APT results. • Both matrix elements (Fe, Cr, Ni) and oxygen diffuse along the grain boundary. - Abstract: Novel atom probe tomography (APT) data of an intergranular stress corrosion crack tip has been acquired. Using APT for stress corrosion cracking research, very small, localized features and their distribution around the crack tip can be studied in 3D. This work details the development of a technique for the preparation of atom probe needles. Initial characterization via analytical transmission electron microscopy provides with a complementary analysis and accurately locates features that can be correlated with the reconstructed APT data. Ni enrichment and intergranular oxidation ahead of the crack tip have been studied with APT in 3D and with near-atomic resolution

  4. Investigation and evaluation of stress-corrosion cracking in piping of light water reactor plants

    International Nuclear Information System (INIS)

    In 1975, a Pipe Cracking Study Group, established by the United States Nuclear Regulatory Commission (USNRC), reviewed intergranular stress-corrosion cracking (IGSCC) in Bioling Water Reactors (BWRs) and issued a report. During 1978, IGSCC was reported for the first time in large-diameter piping (> 20 in.) in a BWR in Germany. This discovery, together with the reported questions concerning the interpretation of ultrasonic inspections, led to the activation of a new Pipe Crack Study Group (PCSG) by USNRC. The charter of the new PCSG was expanded: (1) to include review of potential for stress-corrosion cracking in Pressurized Water Reactors (PWRs) as well as BWRs, (2) to examine operating experience in foreign reactors relevant to IGSCC, and (3) to study five specific questions. The PCSG limited the scope of the study to BWR and PWR piping runs and safe ends attached to the reactor pressure vessel. Not considered were components such as the reactor pressure vessel, pumps, valves, steam generators, large steam turbines, etc. Throughout this report, as well as in the title, the safe ends are arbitrarily defined as piping

  5. Probabilistic study of initiation stage of stress corrosion cracking under simulated BWR environment

    International Nuclear Information System (INIS)

    Stress corrosion cracking (SCC) has been observed near the welded zones of pipes made of austenitic stainless steel type 316L in boiling water reactors. The lifetime assessment of structures in nuclear power plants is performed on the assumption that an initial crack exists. It is said that the lifetime is greatly affected by the micro crack process of initiation, growth, and coalescence. In this process, SCC has a probabilistic feature caused by its corrosion behavior and the microstructure. In this study, slow strain rate testing (SSRT) was performed in a simulated BWR environment. The histograms of the probability density distributions for crack length initiated during SSRT were obtained. The probability density distributions for crack depth were estimated based on the aspect ratio of SCC. Then, the time variations of the probability density distributions for crack depth were expressed as a function of stress. As a result, the initiation time and the probability density distribution for crack depth at the initiation time SCC were obtained. (author)

  6. Stress corrosion cracking in steam turbine disks: analysis of field and laboratory data. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Eason, E.D.

    1985-05-01

    The field data and related laboratory data from many investigators were analyzed to identify the key variables and quantify their effects on stress corrosion cracking of turbine disks. Beginning with over 35 potential variables, pattern recognition and transformation analysis techniques were used to find and characterize the most important variables. The transformation analysis technique was also used to identify laboratory environments that are comparable to the field and to check for lab-to-lab differences in measured crack growth rate. Field data were also analyzed separately, using transformation analysis and order statistics to determine the effects of variables and produce statistical distributions of crack growth rate and failure rate with time. Models were constructed for the field and laboratory data to combine data from many sources and test conditions and to quantify the key variable effects. Two, three, and four variable models were calibrated to the available data. The four variable model is capable of correlating stress corrosion data for 19 low alloy steels with negligible increase in scatter compared to NiCrMoV data. The three variable model describes the behavior of disk steels in the field and comparable laboratory environments. 42 refs., 39 figs., 10 tabs.

  7. Stress corrosion cracking tests on electron beam welded carbon steel specimens in carbonate-bicarbonate solution

    International Nuclear Information System (INIS)

    Stress corrosion cracking tests have been performed on tapered carbon steel test pieces containing electron beam welds with a view to defining susceptibility to such cracking in a carbonate-bicarbonate solution at 90 C and an appropriate electrode potential. The tests involved applying cyclic loads to the specimens and it is shown that the threshold stress for cracking reduces linearly with increase in the magnitude of the cyclic load component. Extrapolation of these trends to zero fluctuating stress indicates static load threshold stresses in the vicinity of the yield stress (i.e. about 300 N/mm2 for parent plate without a weld, 400 N/mm2 for specimens with welds on one side only and 600 N/mm2 for specimens having welds penetrating through the thickness of the specimen). The averages of the maximum crack velocities observed were least for parent plate material and greatest for weld metal, the former being essentially intergranular in morphology and the latter mostly transgranular, with heat affected zone material being intermediate between these extremes. (author)

  8. Stress corrosion of alloy 600 tubes for steam generators: influence of surface cold working and of metallurgical structure

    International Nuclear Information System (INIS)

    The alloy 600 is used in the primary circuit of the PWR type reactors especially for the steam generator tubes (heat transfer between primary and secondary circuit). In the primary atmosphere, this alloy is sensitive to the stress corrosion cracking. It is an intergranular brittle cracking the mechanism of which is not well understood. This article describes the surface cold working influence and that of the metallurgical structure of the alloy 600 tubes used in steam generators and their cracking kinetics by stress corrosion. 2 figs

  9. Effect of dissolved oxygen content on stress corrosion cracking of a cold worked 316L stainless steel in simulated pressurized water reactor primary water environment

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Litao; Wang, Jianqiu, E-mail: wangjianqiu@imr.ac.cn

    2014-03-15

    Stress corrosion crack growth tests of a cold worked nuclear grade 316L stainless steel were conducted in simulated pressurized water reactor (PWR) primary water environment containing various dissolved oxygen (DO) contents but no dissolved hydrogen. The crack growth rate (CGR) increased with increasing DO content in the simulated PWR primary water. The fracture surface exhibited typical intergranular stress corrosion cracking (IGSCC) characteristics.

  10. Effect of dissolved oxygen content on stress corrosion cracking of a cold worked 316L stainless steel in simulated pressurized water reactor primary water environment

    Science.gov (United States)

    Zhang, Litao; Wang, Jianqiu

    2014-03-01

    Stress corrosion crack growth tests of a cold worked nuclear grade 316L stainless steel were conducted in simulated pressurized water reactor (PWR) primary water environment containing various dissolved oxygen (DO) contents but no dissolved hydrogen. The crack growth rate (CGR) increased with increasing DO content in the simulated PWR primary water. The fracture surface exhibited typical intergranular stress corrosion cracking (IGSCC) characteristics.

  11. Effect of dissolved oxygen content on stress corrosion cracking of a cold worked 316L stainless steel in simulated pressurized water reactor primary water environment

    International Nuclear Information System (INIS)

    Stress corrosion crack growth tests of a cold worked nuclear grade 316L stainless steel were conducted in simulated pressurized water reactor (PWR) primary water environment containing various dissolved oxygen (DO) contents but no dissolved hydrogen. The crack growth rate (CGR) increased with increasing DO content in the simulated PWR primary water. The fracture surface exhibited typical intergranular stress corrosion cracking (IGSCC) characteristics

  12. 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.)

  13. Detection of stress corrosion cracking of high-strength steel used in prestressed concrete structures by acoustic emission technique

    Science.gov (United States)

    Ramadan, S.; Gaillet, L.; Tessier, C.; Idrissi, H.

    2008-02-01

    The stress corrosion cracking (SCC) of high-strength steel used in prestressed concrete structures was studied by acoustic emission technique (AE). A simulated concrete pore (SCP) solution at high-alkaline (pH ≈ 12) contaminated by sulphate, chloride, and thiocyanate ions was used. The evolution of the acoustic activity recorded during the tests shows the presence of several stages related respectively to cracks initiation due to the local corrosion imposed by corrosives species, cracks propagation and steel failure. Microscopic examinations pointed out that the wires exhibited a brittle fracture mode. The cracking was found to propagate in the transgranular mode. The role of corrosives species and hydrogen in the rupture mechanism of high-strength steel was also investigated. This study shows promising results for an potential use in situ of AE for real-time health monitoring of eutectoid steel cables used in prestressed concrete structures.

  14. Stress corrosion cracking of type 304 stainless steel irradiated to very high dose

    International Nuclear Information System (INIS)

    Certain safety-related core internal structural components of light water reactors, usually fabricated from Type 304 or 316 austenitic stainless steels (SSs), accumulate very high levels of irradiation damage (20--100 displacement per atom or dpa) by the end of life. The data bases and mechanistic understanding of, the degradation of such highly irradiated components, however, are not well established. A key question is the nature of irradiation-assisted intergranular cracking at very high dose, i.e., is it purely mechanical failure or is it stress-commotion cracking? In this work, hot-cell tests and microstructural characterization were performed on Type 304 SS from the hexagonal fuel can of the decommissioned EBR-11 reactor after irradiation to ∼50 dpa at ∼370 C. Slow-strain-rate tensile tests were conducted at 289 C in air and in water at several levels of electrochemical potential (ECP), and microstructural characteristics were analyzed by scanning and transmission electron microcopies. The material deformed significantly by twinning and exhibited surprisingly high ductility in air, but was susceptible to severe intergranular stress corrosion cracking (IGSCC) at high ECP. Low levels of dissolved O and ECP were effective in suppressing the susceptibility of the heavily irradiated material to IGSCC, indicating that the stress corrosion process associated with irradiation-induced grain-boundary Cr depletion, rather than purely mechanical separation of grain boundaries, plays the dominant role. However, although IGSCC was suppressed, the material was susceptible to dislocation channeling at low ECP, and this susceptibility led to poor work-hardening capability and low ductility

  15. Improved stress corrosion cracking resistance of a novel biodegradable EW62 magnesium alloy by rapid solidification, in simulated electrolytes

    International Nuclear Information System (INIS)

    The high corrosion rate of magnesium (Mg) and Mg-alloys precludes their widespread acceptance as implantable biomaterials. Here, we investigated the potential for rapid solidification (RS) to increase the stress corrosion cracking (SCC) resistance of a novel Mg alloy, Mg–6%Nd–2%Y–0.5%Zr (EW62), in comparison to its conventionally cast (CC) counterpart. RS ribbons were extrusion consolidated in order to generate bioimplant-relevant geometries for testing and practical use. Microstructural characteristics were examined by SEM. Corrosion rates were calculated based upon hydrogen evolution during immersion testing. The surface layer of the tested alloys was analyzed by X-ray photoelectron spectroscopy (XPS). Stress corrosion resistance was assessed by slow strain rate testing and fractography. The results indicate that the corrosion resistance of the RS alloy is significantly improved relative to the CC alloy due to a supersaturated Nd enrichment that increases the Nd2O3 content in the external oxide layer, as well as a more homogeneous structure and reduced grain size. These improvements contributed to the reduced formation of hydrogen gas and hydrogen embrittlement, which reduced the SCC sensitivity relative to the CC alloy. Therefore, EW62 in the form of a rapidly solidified extruded structure may serve as a biodegradable implant for biomedical applications. - Highlights: • Here we have evaluated the corrosion resistance of a novel Mg alloy (EW62). • Rapid solidification reduces the hydrogen gas evolution and hydrogen embrittlement. • Rapid solidification increases the stress corrosion cracking resistance of EW62. • Improvement is due to enrichment with supersaturated Nd in the external oxide film. • Rapidly solidified and extruded EW62 may serve as a biodegradable medical implant

  16. Stress corrosion of austenitic steels mono and polycrystals in Mg Cl2 medium: micro fractography and study of behaviour improvements

    International Nuclear Information System (INIS)

    The austenitic steels in a hot chlorinated medium present a rupture which is macroscopically fragile, discontinuous and formed with crystallographic facets. The interpretation of these facies crystallographic character is a key for the understanding of the stress corrosion damages. The first aim of this work is then to study into details the micro fractography of 316 L steels mono and polycrystals. Two types of rupture are observed: a very fragile rupture which stresses on the possibility of the interatomic bonds weakening by the corrosive medium Mg Cl2 and a discontinuous rupture (at the micron scale) on the sliding planes which is in good agreement with the corrosion enhanced plasticity model. The second aim of this work is to search for controlling the stress corrosion by the mean of a pre-strain hardening. Two types of pre-strain hardening have been tested. A pre-strain hardening with a monotonic strain is negative. Indeed, the first cracks starts very early and the cracks propagation velocity is increased. This is explained by the corrosion enhanced plasticity model through the intensifying of the local corrosion-deformation interactions. On the other hand, a cyclic pre-strain hardening is particularly favourable. The first micro strains starts later and the strain on breaking point levels are increased. The delay of the starting of the first strains is explained by a surface distortion structure which is very homogeneous. At last, the dislocations structure created in fatigue at saturation is a planar structure of low energy which reduces the corrosion-deformation interactions, source of micro strains. (O.M.)

  17. Improved stress corrosion cracking resistance of a novel biodegradable EW62 magnesium alloy by rapid solidification, in simulated electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Hakimi, O.; Aghion, E. [Department of Materials Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105 (Israel); Goldman, J., E-mail: jgoldman@mtu.edu [Biomedical Engineering Department, Michigan Technological University, Houghton, MI, 49931 (United States)

    2015-06-01

    The high corrosion rate of magnesium (Mg) and Mg-alloys precludes their widespread acceptance as implantable biomaterials. Here, we investigated the potential for rapid solidification (RS) to increase the stress corrosion cracking (SCC) resistance of a novel Mg alloy, Mg–6%Nd–2%Y–0.5%Zr (EW62), in comparison to its conventionally cast (CC) counterpart. RS ribbons were extrusion consolidated in order to generate bioimplant-relevant geometries for testing and practical use. Microstructural characteristics were examined by SEM. Corrosion rates were calculated based upon hydrogen evolution during immersion testing. The surface layer of the tested alloys was analyzed by X-ray photoelectron spectroscopy (XPS). Stress corrosion resistance was assessed by slow strain rate testing and fractography. The results indicate that the corrosion resistance of the RS alloy is significantly improved relative to the CC alloy due to a supersaturated Nd enrichment that increases the Nd{sub 2}O{sub 3} content in the external oxide layer, as well as a more homogeneous structure and reduced grain size. These improvements contributed to the reduced formation of hydrogen gas and hydrogen embrittlement, which reduced the SCC sensitivity relative to the CC alloy. Therefore, EW62 in the form of a rapidly solidified extruded structure may serve as a biodegradable implant for biomedical applications. - Highlights: • Here we have evaluated the corrosion resistance of a novel Mg alloy (EW62). • Rapid solidification reduces the hydrogen gas evolution and hydrogen embrittlement. • Rapid solidification increases the stress corrosion cracking resistance of EW62. • Improvement is due to enrichment with supersaturated Nd in the external oxide film. • Rapidly solidified and extruded EW62 may serve as a biodegradable medical implant.

  18. Investigation into the stress corrosion cracking properties of AA2099, an aluminum-lithium-copper alloy

    Science.gov (United States)

    Padgett, Barbara Nicole

    Recently developed Al-Li-Cu alloys show great potential for implementation in the aerospace industry because of the attractive mix of good mechanical properties and low density. AA2099 is an Al-Li-Cu alloy with the following composition Al-2.69wt%Cu-1.8wt%Li-0.6wt%Zn-0.3wt%Mg-0.3wt%Mn-0.08wt%Zr. The environmental assisted cracking and localized corrosion behavior of the AA2099 was investigated in this thesis. The consequences of uncontrolled grain boundary precipitation via friction stir welding on the stress corrosion cracking (SCC) behavior of AA2099 was investigated first. Using constant extension rate testing, intergranular corrosion immersion experiments, and potentiodynamic scans, the heat-affected zone on the trailing edge of the weld (HTS) was determined to be most susceptible of the weld zones. The observed SCC behavior for the HTS was linked to the dissolution of an active phase (Al2CuLi, T1) populating the grain boundary. It should be stated that the SCC properties of AA2099 in the as-received condition were determined to be good. Focus was then given to the electrochemical behavior of precipitate phases that may occupy grain and sub-grain boundaries in AA2099. The grain boundary micro-chemistry and micro-electrochemistry have been alluded to within the literature as having significant influence on the SCC behavior of Al-Li-Cu alloys. Major precipitates found in this alloy system are T1 (Al 2CuLi), T2 (Al7.5Cu4Li), T B (Al6CuLi3), and theta (Al2 Cu). These phases were produced in bulk form so that the electrochemical nature of each phase could be characterized. It was determined T1 was most active electrochemically and theta was least. When present on grain boundaries in the alloy, electrochemical behavior of the individual precipitates aligned with the observed corrosion behavior of the alloy (e.g. TB was accompanied by general pitting corrosion and T 1 was accompanied by intergranular corrosion attack). In addition to the electrochemical behavior of

  19. Influence of Oxide Film to Stress Corrosion Cracking of Zirconium in Boiling Nitric Acid Solution

    International Nuclear Information System (INIS)

    Nuclear fuel reprocessing process acts an important role of nuclear energy cycle. In Japan, a commercial reprocessing plant has been operating at the Rokkasho reprocessing plant. Purex process that is used nitric acid and dodecane with tributyl phosphate for solvent has been adopted in the plant. Boiling nitric acid is applied to dissolve oxide spent nuclear fuel. In the boiling nitric acid solution, plant material corrodes severely and intergranular corrosion is observed in stainless steels. In order to avoid corrosion in such severe environment, some equipment in the plants has been made of zirconium, which has excellent corrosion resistance in nitric acid solutions. However, it has been known that zirconium has stress corrosion cracking (SCC) susceptibility in concentrated HNO3 with nobler corrosion potential. Nobler corrosion potential causes breakdowns of passive film having excellent protective performance and raises SCC susceptibility of zirconium in nitric acid solutions. Therefore, it is important to clarify the relationship among potential, growth and the breakdown of oxide film for the SCC initiation mechanism. In this study, we investigated the oxide film growth of zirconium with various potentials in boiling nitric acid solutions. Electrochemical tests and immersion tests with various applied potentials conducted in boiling 3. 6 and 9 mol.dm-3 HNO3. The potentials in the immersion tests were set at 1.3, 1.4 and 1.5 V vs. sat. KCl-Ag/AgCl electrode (SSE). These were in the region of trans-passive state of zirconium in boiling nitric acid solution. The test durations were 10, 100 and 500 h. After the corrosion tests, cross-sectional observations of oxide films were conducted. From the results of anodic polarization curves of zirconium in boiling nitric acid, passivity region was observed through rest potential to about 1.5 V in boiling 6 mol.dm-3 HNO3. Rapid increase of current density was observed at the potential attributed to transition from passivity

  20. Misunderstanding and Understanding of Primary Water Stress Corrosion Cracking of Structural Components in the Primary System of PWRs

    International Nuclear Information System (INIS)

    All the structural components in the primary system of pressurized water reactors that are in contact with primary water are made of austenitic Ni-Cr-Fe alloys which are known to be corrosion resistant. Nevertheless, these Ni-Cr-Fe alloys such as Alloy 600, weld 182/82, austenitic stainless steels suffer from intergranular stress corrosion cracking (IGSCC) after their 10 year operation in reactors although the environment to which they have been exposed is almost pure water of pH 6.9 to 7.2, which is called primary water stress corrosion cracking (PWSCC). Given that the underlying mechanism of PWSCC remains unidentified so far, there are many misunderstandings related to PWSCC of the structural components, which may lead to unreasonable mitigation measures. The aim of this work is to highlight understanding and misunderstanding of PWSCC related to austenitic Ni-Cr-Fe alloys

  1. Stress Corrosion Cracking in Light Water Reactors: Good Practices and Lessons Learned

    International Nuclear Information System (INIS)

    One of the IAEAs statutory objectives is to 'seek to accelerate and enlarge the contribution of atomic energy to peace, health and prosperity throughout the world'. One way this objective is achieved is through the publication of a range of technical series. Two of these are the IAEA Nuclear Energy Series and the IAEA Safety Standards Series. According to Statute Article III, A.6, the IAEA Safety Standards establish 'standards of safety for protection of health and minimization of danger to life and property.' The safety standards include the Safety Fundamentals, Safety Requirements, and Safety Guides. These standards are written primarily in a regulatory style, and are binding on the IAEA for its own programmes. The principal users are the Member States, regulatory bodies and other national authorities. The IAEA Nuclear Energy Series comprises reports designed to encourage and assist R and D on and practical application of, nuclear energy for peaceful uses. This includes practical examples to be used by Member States, owners and operators of utilities, implementing organizations, academia, and government officials; among others. This information is presented in guides, reports on technology status and advances, and best practices for peaceful uses of nuclear energy based on inputs from international experts. The IAEA Nuclear Energy Series complements the IAEA Safety Standards. Stress corrosion cracking (SCC) is a significant ageing degradation mechanism for major components of both pressurized water reactors (PWRs) and boiling water reactors (BWRs). In PWRs, the main problem with SCC has been with Alloy 600 components such as steam generator tubes, pressurizer instrument penetrations and heater sleeves, control rod drive mechanism (CRDM) nozzles, and hot leg penetrations. In BWRs, piping and other components made from austenitic stainless steel or (to a much lesser extent) nickel based alloys have experienced intergranular stress corrosion cracking (IGSCC) and

  2. Mitigation of intergranular stress corrosion cracking in RBMK reactors. Final report of the programme's steering committee

    International Nuclear Information System (INIS)

    In 2000 the IAEA initiated an Extrabudgetary Programme on Mitigation of Intergranular Stress Corrosion Cracking in RBMK Reactors to assist countries operating RBMK reactors in addressing the issue in austenitic stainless steel 300 mm diameter piping. Intergranular stress corrosion cracking of austenitic stainless steel piping in BWRs has been a major safety concern since the early seventies. Similar degradation was found in RBMK reactor piping in 1997. Early in 1998 the IAEA responded to requests for assistance from RBMK operating countries on this issue through activities organized in the framework of Technical Co-operation Department regional projects and the Extrabudgetary Programme on the Safety of WWER and RBMK Nuclear Power Plants. Results of these activities were a basis for the formulation of the objective and scope of the Extrabudgetary Programme on Mitigation of Intergranular Stress Corrosion Cracking in RBMK reactors ('the Programme'). The scope of the Programme included in-service inspection, assessment, repair and mitigation, and water chemistry and decontamination. The Programme was pursued by means of exchange of experience, formulation of guidance, transfer of technology, and training, which will assist the RBMK operators to address related safety concerns. The Programme implementation relied on voluntary extrabudgetary financial contributions from Japan, Spain, the United Kingdom and the USA, and on in kind contributions from Finland, Germany and Sweden. The Programme was implemented in close co-ordination with ongoing national and bilateral activities and major inputs to the Programme were provided through the activities of the Swedish International Project Nuclear Safety and of the US DOE International Nuclear Safety Program. The RBMK nuclear power plants in Lithuania, Russian Federation and Ukraine hosted most of the Programme activities. Support of these Member States involved in the Programme was instrumental for its successful completion in

  3. The Primary Water Stress Corrosion Cracking Mechanism of Alloy 600 Steam Generator Tubes: Materials Perspective

    International Nuclear Information System (INIS)

    The problem is that intergranular (IG) cracking of austenitic Fe-Cr-Ni alloys occurs even in Ar with no corrosion or oxidation of grain boundaries being accompanied. This fact suggests that IG cracking has nothing to do with grain boundary (GB) corrosion or oxidation. This fact cast a doubt about the current notion that applied stresses are required to initiate IG cracking or PWSCC. These facts indicate that PWSCC is closely related to internal factors of materials, not to external factors such as grain boundary oxidation or corrosion or applied stresses. Given that austenitic alloys including Alloy 600 are a kind of solid solution alloys with alloying elements dissolved in the matrix as solutes, ordering of alloying elements of Fe, Cr and Ni occur in Alloy 600 during exposure to reactor operating condition. We suggest that atomic ordering is the main internal factor to govern PWSCC or IG cracking of austenitic Fe-Cr-Ni alloys because lattice contraction due to atomic ordering induces internal stresses which are large enough to cause GB cracking. The aim of this work is to provide experimental evidence for our suggestion. To this end, water quenching (WQ) or air cooling (AC) or furnace cooling (FC) was applied respectively to Alloy 600 after solution treatment at 1095 .deg. C for 0.5h to make Alloy 600 with either disorder (DO) or different degrees of short range order, respectively. Alloy 600 showed lattice contraction upon aging at 400 .deg. C whose extent increased with increasing cooling rate: the water-quenched (WQ) Alloy 600 exhibited the largest amount of lattice contraction than the furnace-cooled (FC) or air-cooled (AC) one. Yonezawa's experiments have indeed shown that the WQ-Alloy 600 with the largest amount of lattice contraction upon aging at 400 .deg. C is the most susceptible to PWSCC when compared to the AC- or FC-Alloy 600 with the lesser amount of lattice contraction. These observations demonstrate, for the first time, that PWSCC of Alloy 600 is

  4. Effect of environmental factors of stress corrosion cracking behavior of turbine steel in pure water

    International Nuclear Information System (INIS)

    Slow Strain Rate Tests (SSRT) were carried out to investigate the effect of dissolved oxygen on stress corrosion cracking (SCC) susceptibility of 3.5NiCrMoV steels used in discs of low-pressure (LP) steam turbines in electric power generating plants. The influence of dissolved oxygen on cracking in water was studied; for this purpose, specimens were strained to fracture at 150 degree C in water environments with various amounts of dissolved oxygen. Also tests were conducted in aerated water at temperature of 50 ∼ 200 degree C and at various strain rates (5x10-8 ∼ 1x10-5 s-1). The maximum elongation of the turbine steel decreased with decreasing strain rate, and with increasing temperature. Dissolved oxygen significantly affected the SCC susceptibility of turbine steel in water. The increase of the SCC susceptibility of the turbine steel in a higher dissolved oxygen environment is due to the non protectiveness of the oxide layer of the turbine steel surface and the increase of corrosion current

  5. Growth and stability of stress corrosion cracks in large-diameter BWR piping. Volume 1: summary. Final report

    International Nuclear Information System (INIS)

    This report presents the results of a research program conducted to evaluate the behavior of hypothetical stress corrosion cracks in large diameter austenitic piping. The program included major tasks, a design margin assessment, an evaluation of crack growth and crack arrest, and development of a predictive model. As part of the margin assessment, the program developed diagrams which predicted net section collapse as a function of crack size. In addition, plasticity and dynamic load effects were also considered in evaluating collapse. Analytical methods for evaluating these effects were developed and were benchmarked by dynamic tests of 4-in.-diameter piping. The task of evaluating the growth behavior of stress corrosion cracks focused on developing constant load and cyclic growth rate data that could be used with the predictive model. Secondly, laboratory tests were performed to evaluate the conditions under which growing stress corrosion cracks would arrest when they intersected stress corrosion resistant weld metal. The third task successfully developed a model to predict the behavior of cracks in austenitic piping. This model relies on crack growth data and the critical crack size predicted by the net section collapse approach

  6. Growth and stability of stress corrosion cracks in large-diameter BWR piping. Volume 2: appendixes. Final report

    International Nuclear Information System (INIS)

    This report presents the results of a research program conducted to evaluate the behavior of hypothetical stress corrosion cracks in large diameter austenitic piping. The program included major tasks, a design margin assessment, an evaluation of crack growth and crack arrest, and development of a predictive model. As part of the margin assessment, the program developed diagrams which predicted net section collapse as a function of crack size. In addition, plasticity and dynamic load effects were also considered in evaluating collapse. Analytical methods for evaluating these effects were developed and were benchmarked by dynamic tests of 4-in.-diameter piping. The task of evaluating the growth behavior of stress corrosion cracks focused on developing constant load and cyclic growth rate data that could be used with the predictive model. Secondly, laboratory tests were performed to evaluate the conditions under which growing stress corrosion cracks would arrest when they intersected stress corrosion resistant weld metal. The third task successfully developed a model to predict the behavior of cracks in austenitic piping

  7. Growth and stability of stress corrosion cracks in large-diameter BWR piping. Volume 2: appendixes. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hale, D A; Heald, J D; Horn, R M; Jewett, C W; Kass, J N; Mehta, H S; Ranganath, S; Sharma, S R

    1982-07-01

    This report presents the results of a research program conducted to evaluate the behavior of hypothetical stress corrosion cracks in large diameter austenitic piping. The program included major tasks, a design margin assessment, an evaluation of crack growth and crack arrest, and development of a predictive model. As part of the margin assessment, the program developed diagrams which predicted net section collapse as a function of crack size. In addition, plasticity and dynamic load effects were also considered in evaluating collapse. Analytical methods for evaluating these effects were developed and were benchmarked by dynamic tests of 4-in.-diameter piping. The task of evaluating the growth behavior of stress corrosion cracks focused on developing constant load and cyclic growth rate data that could be used with the predictive model. Secondly, laboratory tests were performed to evaluate the conditions under which growing stress corrosion cracks would arrest when they intersected stress corrosion resistant weld metal. The third task successfully developed a model to predict the behavior of cracks in austenitic piping.

  8. A Model for Fracture Behaviour of a Thin-Walled Pipe Damaged by the Netof Stress Corrosion Cracks

    Czech Academy of Sciences Publication Activity Database

    Gajdoš, Lubomír

    Gyor : Society of Mechanical Engineering, 2003 - (Borb s, L.), s. 154-155 ISBN 963-9058-20-3. [Danubia-Adria Symposium on Experimental Methods in Solid Mechanics/20./. Gyor (HU), 24.07.2003-27.07.2003] R&D Projects: GA AV ČR IAA2811201 Institutional research plan: CEZ:AV0Z2071913 Keywords : stress corrosion * stress intensity factor Subject RIV: JM - Building Engineering

  9. On the Stress Corrosion Cracking and Hydrogen Embrittlement Behavior of Austenitic Stainless Steels in Boiling Saturated Magnesium Chloride Solutions

    OpenAIRE

    Alyousif, Osama M.; Rokuro Nishimura

    2012-01-01

    The stress corrosion cracking (SCC) and hydrogen embrittlement (HE) behaviors for types 304, 310, and 316 austenitic stainless steels were investigated in boiling saturated magnesium chloride solutions using a constant load method under different conditions including test temperature, applied stress, and sensitization. Both of type 304 and type 316 stainless steels showed quite similar behavior characteristics, whereas type 310 stainless steel showed a different behavior. The time to failure ...

  10. The resistance of pure copper to stress corrosion cracking in repository environments

    International Nuclear Information System (INIS)

    The risk for stress corrosion cracking (SCC) of the copper canister in the final repository for high-level radioactive waste in Sweden is low. However, it is a desire to try to elucidate and if possible quantify this minor risk. Available information from others and own work is discussed together with possible methods to estimate the resistance of pure copper to SCC in repository environments. An attempt to rationalise available crack growth rate data is made. Electrochemically controlled slow strain rate testing of pure copper was performed in a sodium nitrite solution, known to give SCC, and in a synthetic groundwater of pH 9. For reasons of comparison, testing was also performed in air. Whereas the occurrence of SCC as expected was clear in the sodium nitrite solution, it cannot be claimed that SCC has occurred in the synthetic groundwater

  11. The studies of irradiation assisted stress corrosion cracking on reactor internals stainless steel under Xe irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Rong-shan [Suzhou Nuclear Power Research Institute, Suzhou, Jiangsu Province 215004 (China); Xu, Chao-liang, E-mail: xuchaoliang@cgnpc.com.cn [Suzhou Nuclear Power Research Institute, Suzhou, Jiangsu Province 215004 (China); Liu, Xiang-bing; Huang, Ping [Suzhou Nuclear Power Research Institute, Suzhou, Jiangsu Province 215004 (China); Chen, Yu [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Beijing 100049 (China)

    2015-02-15

    Specimens of Chinese domestic reactor internals stainless steel were irradiated with 6 MeV Xe ions for three peak displacement damage of 2, 7 and 15 dpa at room temperature. The slow strain rate tests (SSRT), grazing incidence X-ray diffraction (GIXRD) and nano-indentation tests were carried out to study the IASCC properties, phase transition and nano-hardness variations. The SSRT results indicate that the IASCC susceptibility increases with irradiation damage. Ion irradiation accelerates the stress corrosion cracking (SCC). A new ferrite phase diffraction peak of α(1 1 0) after irradiated to 7 dpa and another two α phase of α(2 0 0) and α(2 1 1) after irradiated to 15 dpa were observed by GIXRD, which may be due to localized deformation. A similar trend of irradiation hardening and IASCC susceptibility was observed, which suggests an essential connection between them.

  12. Standard Test Method for Stress-Corrosion of Titanium Alloys by Aircraft Engine Cleaning Materials

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2006-01-01

    1.1 This test method establishes a test procedure for determining the propensity of aircraft turbine engine cleaning and maintenance materials for causing stress corrosion cracking of titanium alloy parts. 1.2 The evaluation is conducted on representative titanium alloys by determining the effect of contact with cleaning and maintenance materials on tendency of prestressed titanium alloys to crack when subsequently heated to elevated temperatures. 1.3 Test conditions are based upon manufacturer's maximum recommended operating solution concentration. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements, see and .

  13. Fundamental understanding and life prediction of stress corrosion cracking in BWRs and energy systems

    Energy Technology Data Exchange (ETDEWEB)

    Andresen, P.L.; Ford, F.P. [General Electric, Schenectady, NY (United States). Corporate Research and Development Center

    1998-03-01

    The objective of this paper is to present an approach for design and lifetime evaluation of environmental cracking based on experimental and fundamental modeling of the underlying processes operative in crack advance. In detailed this approach and its development and quantification for energy (hot water) systems, the requirements for a life prediction methodology will be highlighted and the shortcomings of the existing design and lifetime evaluation codes reviewed. Examples are identified of its use in a variety of cracking systems, such as stainless steels, low alloy steels, nickel base alloys, and irradiation assisted stress corrosion cracking in boiling water reactor (BWR) water, as well as preliminary use for low alloy steel and Alloy 600 in pressurized water reactors (PWRs) and turbine steels in steam turbines. Identification of the common aspects with environmental cracking in other hot water systems provides a secure basis for its extension to related energy systems. 166 refs., 49 figs.

  14. Stress Corrosion Cracking and Fatigue Crack Growth Studies Pertinent to Spacecraft and Booster Pressure Vessels

    Science.gov (United States)

    Hall, L. R.; Finger, R. W.

    1972-01-01

    This experimental program was divided into two parts. The first part evaluated stress corrosion cracking in 2219-T87 aluminum and 5Al-2.5Sn (ELI) titanium alloy plate and weld metal. Both uniform height double cantilever beam and surface flawed specimens were tested in environments normally encountered during the fabrication and operation of pressure vessels in spacecraft and booster systems. The second part studied compatibility of material-environment combinations suitable for high energy upper stage propulsion systems. Surface flawed specimens having thicknesses representative of minimum gage fuel and oxidizer tanks were tested. Titanium alloys 5Al-2.5Sn (ELI), 6Al-4V annealed, and 6Al-4V STA were tested in both liquid and gaseous methane. Aluminum alloy 2219 in the T87 and T6E46 condition was tested in fluorine, a fluorine-oxygen mixture, and methane. Results were evaluated using modified linear elastic fracture mechanics parameters.

  15. Stress corrosion cracking behavior of quenched and tempered 2.25Cr 1Mo steel

    International Nuclear Information System (INIS)

    For stress corrosion cracking (SCC) study of 2.25Cr-1Mo steel, speciemens were initially austenitized at 925 degree C for 2 hours and quenched in ice brine solution. With this process of heat treatment martensite was formed and banded morphology in the microstructure developed during previous processing was also removed. Tempering at 575 Degree C for 1h was employed to introduce ductility in the quenched martensite of the specimens. The effects of temperature variations on SCC behavior showed a successive decrease in strength and ductility of the steel. These variations in tensile properties were correlated with scanning electron microscopic (SEM) examinations. The SEM results clearly revealed that mostly transgranular cracks initiated at the edges of the tensile specimens grown perpendicular to loading axes, and their intensity is increased with the testing temperatures. (author)

  16. Stress corrosion cracking susceptibility of various austenitic stainless steel pipe welds in high temperature oxygenated water

    International Nuclear Information System (INIS)

    Stress corrosion cracking (SCC) susceptibility of various austenitic stainless steel pipe welds has been studied by means of constant load tensile tests and pipe tests in 2880C water containing 26 ppm dissolved oxygen. The results obtained are summarized as follows: (1) SCC susceptibility of SUS 304 pipe welds is comparatively low under the condition of as-welded. It becomes, however, high remarkably by grinder operation and/or low temperature sensitization heat treatment. The distribution of time of failure on SUS 304 pipe welds can be expressed as a log-normal or Weibull distribution. (2) SUS 304L, 304NG, 316NG, and 347 stainless steel pipe welds have a good SCC resistance and sensitization resistance. Furthermore, the life estimation on alternate pipe welds was conducted statistically. (author)

  17. Contribution to a model for stress corrosion cracking of Alloy 600 in PWR primary water

    International Nuclear Information System (INIS)

    Nickel base alloys such as Alloy 600 are widely used for Pressurized Water Reactors (PWR) components. One of the main drawbacks of Alloy 600 is its susceptibility to intergranular stress corrosion cracking (IGSCC) in PWR primary water. This phenomenon has been extensively studied since more than 30 years and a lot of data are now available in the literature. However, the models proposed are still under debate as the mechanisms of cracking are still not well-known. The aim of this study is to improve our knowledge of SCC mechanisms of Alloy 600 in PWR primary water. The influence of intergranular carbides precipitation and cold-working on intergranular oxide penetrations after exposure in simulated PWR primary environment was more specifically studied. The morphology, the chemical nature and crystalline structure of the oxide formed at the surface of the samples and inside the grain boundaries were characterized using analytical Transmission Electron Microscopy (TEM). (authors)

  18. Effect of chloride and oxygen on stress corrosion cracking of 304N in high temperature water

    International Nuclear Information System (INIS)

    The stress corrosion cracking (SCC) behavior and mechanism of solution- treated 304N stainless steel in high temperature water were studied by slow strain rate tensile test (SSRT) and fracture surface analysis. The results show that the SCC behavior of 304N in high temperature water reveals as transgranular cracking, and with the increasing of Cl- content, the susceptibility of SCC increases. The specimen shows brittle fracture mode when it is exposed to high temperature aerated water containing 50 mg/L Cl-. The present results also indicate that the susceptibility of chloride induced-SCC decreases significantly with decreasing of dissolved oxygen (DO) content in water, which reveals that DO plays a significant role in promoting SCC of 304N in high temperature water. (authors)

  19. Effects of heat treatments on the stress corrosion cracking of alloy 600 in high temperature waters

    International Nuclear Information System (INIS)

    The effects of low temperature ageing treatments on the susceptibility of alloy 600 to stress corrosion cracking in simulated primary side reactor water have been studied by a variety of techniques. Chromium depletion at grain boundaries was assessed by Electrochemical Potentiokinetic Reactivation (EPR) and polythionic acid tests while cracking was investigated using U bend, constant strain tensile and slow strain rate tests. The susceptibility to cracking was increased by annealing at 925deg C after a small amount of cold work and further enhanced by ageing for 60 h at 450deg C. The activation energy for cracking is in the region of 190 kJ/mol, which indicates that marked cracking is only likely at relatively high temperatures in water. (orig./HP)

  20. 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

  1. Stress-corrosion cracking of sensitized stainless steel by sulfur-containing compounds

    Energy Technology Data Exchange (ETDEWEB)

    Isaacs, H.S.; Vyas, B.; Kendig, M.W.

    1981-01-01

    The stress corrosion cracking (SCC) of sensitized Type 304 stainless steel in thiosulfate solutions has been studied using constant extension rate tests. Very low concentrations of about 6.10/sup -7/M Na/sub 2/S/sub 2/O/sub 3/ (0.1ppm) gave cracking. With boric acid added, higher concentrations (1ppm) were required. The SCC was shown to be electrochemically controlled. Below -0.5v/sub SCE/ (-0.75/sub SHE/) no SCC took place; above this potential the rate of SCC increased with potential. An induction period was required before SCC continued above -0.5v if the potential was held at or below this value for extended times. This period was associated with the build up of an aggressive solution of thiosulfate decomposition products within the crack. The cracking process has been considered to be controlled by rupture of a salt layer and not a passivating oxide.

  2. 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.

  3. Chloride stress corrosion cracking of Alloy 600 in boric acid solutions

    International Nuclear Information System (INIS)

    The high nickel austenitic alloys are generally considered to have good resistance to chloride stress corrosion cracking. In the standard boiling magnesium chloride solution tests, alloys with more than 40% nickel are immune. Nevertheless, more recent data show that cracking can occur in both Alloys 600 and 690 if the solution is acidified. In other low pH media, such as boric acid solution at 100 deg C, transgranular and intergranular cracking are observed in Alloy 600 in the presence of minor concentrations of sodium chloride (2g/I). In concentrated boric acid at higher temperatures (250 and 290 deg C), intergranular cracking also occurs, either when the chloride concentration is high, or at low chloride contents and high oxygen levels. The role of pH and a possible specific action of boric acid are discussed, together with the influence of electrochemical potential. (author)

  4. Chloride stress corrosion cracking of Alloy 600 in boric acid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Berge, Ph. [Electricite de France, 92 - Paris la Defense (France); Noel, D.; Gras, J.M.; Prieux, B. [Electricite de France, 77 - Moret-sur-Loing (France). Direction des Etudes et Recherches

    1997-10-01

    The high nickel austenitic alloys are generally considered to have good resistance to chloride stress corrosion cracking. In the standard boiling magnesium chloride solution tests, alloys with more than 40% nickel are immune. Nevertheless, more recent data show that cracking can occur in both Alloys 600 and 690 if the solution is acidified. In other low pH media, such as boric acid solution at 100 deg C, transgranular and intergranular cracking are observed in Alloy 600 in the presence of minor concentrations of sodium chloride (2g/I). In concentrated boric acid at higher temperatures (250 and 290 deg C), intergranular cracking also occurs, either when the chloride concentration is high, or at low chloride contents and high oxygen levels. The role of pH and a possible specific action of boric acid are discussed, together with the influence of electrochemical potential. (author) 21 refs.

  5. Stress-corrosion cracking of sensitized stainless steel by sulfur-containing compounds

    International Nuclear Information System (INIS)

    The stress corrosion cracking (SCC) of sensitized Type 304 stainless steel in thiosulfate solutions has been studied using constant extension rate tests. Very low concentrations of about 6.10-7M Na2S2O3 (0.1ppm) gave cracking. With boric acid added, higher concentrations (1ppm) were required. The SCC was shown to be electrochemically controlled. Below -0.5v/sub SCE/ (-0.75/sub SHE/) no SCC took place; above this potential the rate of SCC increased with potential. An induction period was required before SCC continued above -0.5v if the potential was held at or below this value for extended times. This period was associated with the build up of an aggressive solution of thiosulfate decomposition products within the crack. The cracking process has been considered to be controlled by rupture of a salt layer and not a passivating oxide

  6. Fundamental understanding and life prediction of stress corrosion cracking in BWRs and energy systems

    International Nuclear Information System (INIS)

    The objective of this paper is to present an approach for design and lifetime evaluation of environmental cracking based on experimental and fundamental modeling of the underlying processes operative in crack advance. In detailed this approach and its development and quantification for energy (hot water) systems, the requirements for a life prediction methodology will be highlighted and the shortcomings of the existing design and lifetime evaluation codes reviewed. Examples are identified of its use in a variety of cracking systems, such as stainless steels, low alloy steels, nickel base alloys, and irradiation assisted stress corrosion cracking in boiling water reactor (BWR) water, as well as preliminary use for low alloy steel and Alloy 600 in pressurized water reactors (PWRs) and turbine steels in steam turbines. Identification of the common aspects with environmental cracking in other hot water systems provides a secure basis for its extension to related energy systems. 166 refs., 49 figs

  7. Irradiation-assisted stress corrosion cracking of HTH Alloy X-750 and Alloy 625

    International Nuclear Information System (INIS)

    In-reactor testing of bolt-loaded compact tension specimens was performed in 360 C water. New data confirms previous results that high irradiation levels reduce SCC resistance in Alloy X-750. Low boron heats show improved IASCC (irradiation-assisted stress corrosion cracking). Alloy 625 is resistant to IASCC. Microstructural, microchemical, and deformation studies were carried out. Irradiation of X-750 caused significant strengthening and ductility loss associated with formation of cavities and dislocation loops. High irradiation did not cause segregation in X-750. Irradiation of 625 resulted in formation of small dislocation loops and a fine body-centered-orthorhombic phase. The strengthening due to loops and precipitates was apparently offset in 625 by partial dissolution of γ precipitates. Transmutation of boron to helium at grain boundaries, coupled with matrix strengthening, is believed to be responsible for IASCC in X-750, and the absence of these two effects results in superior IASCC resistance in 625

  8. Electrochemical Fracture Model of the Stress Corrosion Cracking of Turbine Steel in High Temperature Water

    International Nuclear Information System (INIS)

    One of the problems in using ETA in turbines is the formation of organic acids, such as acetic acid, formic acid, and galactic acid, due to the thermal decomposition. In the present work, the impact of acetic acid on the susceptibility of 3.5NiCrMoV (ASTM A470/471) turbine steel to stress corrosion cracking (SCC) was studied as a function of acetic acid concentration. The SCC behavior of turbine steel in solutions of various acetic acid concentrations was analyzed in terms of the CEFM (Coupled Environment Fracture Model) and the observed, enhanced susceptibility of SCC due to acidification of the early condensate due to acetic acid is readily accounted for by the electrochemical fracture model

  9. Stress corrosion crack growth in NiCrMoV turbine disc steels

    Energy Technology Data Exchange (ETDEWEB)

    Mcminn, A.; Lyle, F.F. Jr.; Leverant, G.R.

    1985-09-01

    The effects of metallurgical and environmental variables on stress corrosion crack growth rates in NiCrMoV turbine disc steels is examined. Steels with yield strengths of 627-1124 MPa were tested at 157 C in either pure water environments or in environments containing the ionic contaminants NaCl and NaOH and gaseous contaminants, such as air, oxygen, and carbon dioxide. The chemical composition of the metals tested and the test procedures are described. Maximum crack growth rates of all the materials in each environment are presented. The results revealed that yield strength, temper embrittlement, and the composition of the environment influence crack growth rate; however, the composition of the alloy is only significant in specific environments. Two proposed damage mechanisms for environmentally assisted cracking in low alloy steels, anodic dissolution and hydrogen embrittlement, are discussed. 28 references.

  10. Elucidating the iodine stress corrosion cracking (SCC) process for zircaloy tubing

    International Nuclear Information System (INIS)

    Several experimental investigations were made to enhance understanding of the iodine stress corrosion cracking (SCC) process for Zircaloy: (1) oxide penetration process, (2) crack initiation process, and (3) crack propagation process. Concerning the effect of the oxide layer produced by conventional steam-autoclaving, no significant difference was found between results for autoclaved and as-pickled samples. Tests with 15 species of metal iodides revealed that only those metal iodides which react thermodynamically with zirconium to produce zirconium tetraiodide (ZrI4) caused SCC of Zircaloy. Detailed SEM examinations were made on the SCC fracture surface of irradiated specimens. The crack propagation rate was expressed with a da/dt=C Ksup(n) type equation by combining results of tests and calculations with a finite element method. (author)

  11. Diffraction contrast tomography for the study of polycrystalline stainless steel microstructures and stress corrosion cracking

    International Nuclear Information System (INIS)

    X-ray diffraction contrast tomography is a non-destructive technique for the 3D characterisation of polycrystalline microstructures containing up to a few 1000 grains. The sample is illuminated with a monochromatic beam of high energy synchrotron radiation. As the sample is rotated, and as grains pass through alignments for Bragg diffraction, diffraction spots are recorded on a 2D detector placed close behind the sample. The diffraction geometry is used to assign spots to the grains from which they arise, and to determine the crystallographic orientations of grains. The spots are used as projections of the grains to reconstruct the grain shapes. The technique has been applied to several materials science investigations in stainless steels, including the 3D characterisation of grain boundary networks, and in-situ studies of intergranular stress corrosion cracking. (authors)

  12. Analytical assessment for stress corrosion fatigue of CANDU fuel elements under load following conditions

    Energy Technology Data Exchange (ETDEWEB)

    Horhoianu, Grigore; Ionescu, Dragos; Pauna, Eduard [Institute for Nuclear Research (INR), Pitesti (Romania)

    2011-07-01

    Two load following (LF) tests on CANDU type fuel elements were performed in TRIGA Research Reactor of INR Pitesti. In the first LF test the 78R fuel element has successfully experienced 367 power cycles, mostly between 23 and 56 kW/m average linear power. In the second LF test, the ME01 fuel element withstood 200 power cycles from 27 to 54 kW/m average linear power as well as additional ramps due to reactor trips and restarts during the test period. Both LF tests were simulated with finite elements computer codes in order to evaluate Stress Corrosion Fatigue (SCF) of the sheath arising from expansion and contraction of the pellets. This paper presents the analytical assessment for SCF conditions and their relation to CANDU fuel performance in LF conditions. (orig.)

  13. An electrochemical kinetics approach to the crack propagation at stress corrosion cracking of filmed metals

    International Nuclear Information System (INIS)

    An electrochemical model for crack propagation in film-covered metals, based on the film- rupture concept in stress corrosion cracking (SCC) of metals and quantitative electrochemical kinetics considerations, is presented and discussed. Using a general expression relating the rate of crack propagation with the electrochemical parameters of metal-environment systems, it is shown that the crack propagation rate depends on the rate constant of the metal dissolution reaction at the film-free crack tip, the ratio between the rate constants of the cathodic and metal dissolution reactions at the outer metal surface as well as on the reversible potentials of the cathodic, metal dissolution and film-forming reactions involved. It is also shown that the model can be applied for calculating the rate of crack propagation and explaining the differences in SCC behaviour of various metal-environment systems as well as for defining electrochemical conditions favourable for SCC. (Original)

  14. Effect of water chemistry on stress corrosion cracking of structural materials in high temperature water

    International Nuclear Information System (INIS)

    The effect of environmental factors, including concentration of chloride, content of dissolved oxygen (DO) and temperature, on the susceptibility to stress corrosion cracking (SCC) of type 304, 316Ti stainless steels (s.s.) and A533B pressure vessel steel in high temperature water (HTW) has been investigated using slow strain rate tests (SSRT) and/or U-bends, complemented by electrochemical measurements and AES analyses of the surface films. Increasing chloride concentration resulted in an increase in the susceptibility to SCC. The content of DO was a predominant factor affecting the susceptibility to SCC of A533B. The critical potential and DO content for the occurrence of SCC of 316Ti s.s. in HTW at 300 deg. C was experimentally estimated. (author)

  15. Analytical assessment for stress corrosion fatigue of CANDU fuel elements under load following conditions

    International Nuclear Information System (INIS)

    Two load following (LF) tests on CANDU type fuel elements were performed in TRIGA Research Reactor of INR Pitesti. In the first LF test the 78R fuel element has successfully experienced 367 power cycles, mostly between 23 and 56 kW/m average linear power. In the second LF test, the ME01 fuel element withstood 200 power cycles from 27 to 54 kW/m average linear power as well as additional ramps due to reactor trips and restarts during the test period. Both LF tests were simulated with finite elements computer codes in order to evaluate Stress Corrosion Fatigue (SCF) of the sheath arising from expansion and contraction of the pellets. This paper presents the analytical assessment for SCF conditions and their relation to CANDU fuel performance in LF conditions. (orig.)

  16. Hydrogen Cracking and Stress Corrosion of Pressure Vessel Steel ASTM A543

    Science.gov (United States)

    AlShawaf, Ali Hamad

    with the previously used plain carbon steel and other currently used pressure vessel steels was successfully completed. The experimental and computational results of the Q&T HSLA steel agreed well with each other. The susceptibility of the Q&T A543 steel to stress corrosion cracking was investigated using the slow strain rate testing under different environments and conditions. Also, advanced corrosion study using the electrochemical impedance spectroscopy was done at different conditions. The corrosion study revealed that this A543 steel is prone to form pits in most of the conditions. The model results in the corrosion study were validated with the Gamry Echem Analyst software that A543 steel tends to form pits in the tested environment.

  17. Stress corrosion cracking in the vessel closure head penetrations of French PWR's

    International Nuclear Information System (INIS)

    During a hydrotest in September 1991, part of the statutory decennial in-service inspection, a leak was detected on the vessel head of Bugey 3, which is one of the first 900 MW 3-loop PWR's in France. This leak was due to a cracked penetration used for a control rod drive mechanism. The investigations performed identified Primary Stress Corrosion Cracking of Alloy 600 as being the origin of this degradation. So a lot of the same design PWR's are a concern due to this generic problem. In this case, PWSCC was linked to: - hot temperature of the vessel head; - high residual stresses due to the welding process between peripherical penetrations and the vessel head; - sensitivity of forged Alloy 600 used for penetration manufacturing. This following paper will present the cracked analysis based, in particular, on the main results obtained in France on each of these items. These results come from the operating experience, the destructive examinations and the programs which are running on stress analysis and metallurgical characterizations. (authors). 9 figs., 2 tabs

  18. Factors affecting stress assisted corrosion cracking of carbon steel under industrial boiler conditions

    Science.gov (United States)

    Yang, Dong

    Failure of carbon steel boiler tubes from waterside has been reported in the utility boilers and industrial boilers for a long time. In industrial boilers, most waterside tube cracks are found near heavy attachment welds on the outer surface and are typically blunt, with multiple bulbous features indicating a discontinuous growth. These types of tube failures are typically referred to as stress assisted corrosion (SAC). For recovery boilers in the pulp and paper industry, these failures are particularly important as any water leak inside the furnace can potentially lead to smelt-water explosion. Metal properties, environmental variables, and stress conditions are the major factors influencing SAC crack initation and propagation in carbon steel boiler tubes. Slow strain rate tests (SSRT) were conducted under boiler water conditions to study the effect of temperature, oxygen level, and stress conditions on crack initation and propagation on SA-210 carbon steel samples machined out of boiler tubes. Heat treatments were also performed to develop various grain size and carbon content on carbon steel samples, and SSRTs were conducted on these samples to examine the effect of microstructure features on SAC cracking. Mechanisms of SAC crack initation and propagation were proposed and validated based on interrupted slow strain tests (ISSRT). Water chemistry guidelines are provided to prevent SAC and fracture mechanics model is developed to predict SAC failure on industrial boiler tubes.

  19. Stress corrosion cracking of hydrided zircaloy-4 claddings in iodine containing environments

    International Nuclear Information System (INIS)

    To evaluate the susceptibility to SCC of hydrided Zircaloy-4 in iodine vapours, some C-rings samples with different contents of hydrogen (100-500 ppm) were prepared using electrolytic method. The mode of stressing chosen in this work was C-ring method. The equivalent stress on the inner surface was estimated using ANSYS code (480 MPa at room temperature and 300 MPa at 320 C). With the aim to study the susceptibility of hydrided Zircaloy-4 at localised corrosion, we used the potentio-cyclic method. The samples were exposed at 85 C in a KI solution (0.55 g/l) with adjusted pH at 10.5 by LiOH addition. To establish the SCC behaviour of hydrided Zircaloy-4, the stressed C-rings were exposed 320 C in iodine vapours. The experimental results showed that the susceptibility to SCC increases with the increasing of the hydrogen content. The incipient SCC cracks were detected by metallography. The SEM investigations relieved the presence of microcracks in the oxide layer, which can promote the SCC cracks. (authors)

  20. Experimental determination of stress corrosion crack rates and service lives in a buried ERW pipeline

    International Nuclear Information System (INIS)

    Threshold stresses and crack growth rates for in-service stress corrosion cracking (SCC) of two electrical resistance weld (ERW) seam welded pipes from two 45-year-old oil pipelines were experimentally assessed. Seventeen high-pH SCC tests were carried out, in both base and ERW weld metals, at two temperatures (73 and 45 deg. C). Tapered specimens were used for base metal, and constant section specimens were developed for ERW tests, in which original surface conditions were preserved. It was found that susceptibility of the ERW seam welds is much higher than for base materials, so that the welds define the length of the pipe that is susceptible to SCC. Threshold pressure estimates for SCC initiation were defined from tests at elevated temperature, service temperature, and literature correlations. Fabrication residual stresses were also measured and taken into consideration. SCC threshold pressures for these lines are controlled by the ERW welds; the pipe tracts that are considered to be susceptible to SCC are those that undergo a service pressure of at least 2.4 MPa. For the case under study, this represents about 70% of the length of the pipeline

  1. Tracking the harmonic response of magnetically-soft sensors for wireless temperature, stress, and corrosive monitoring

    Science.gov (United States)

    Ong, Keat G.; Grimes, Craig A.

    2002-01-01

    This paper describes the application of magnetically-soft ribbon-like sensors for measurement of temperature and stress, as well as corrosive monitoring, based upon changes in the amplitudes of the higher-order harmonics generated by the sensors in response to a magnetic interrogation signal. The sensors operate independently of mass loading, and so can be placed or rigidly embedded inside nonmetallic, opaque structures such as concrete or plastic. The passive harmonic-based sensor is remotely monitored through a single coplanar interrogation and detection coil. Effects due to the relative location of the sensor are eliminated by tracking harmonic amplitude ratios, thereby, enabling wide area monitoring. The wireless, passive, mass loading independent nature of the described sensor platform makes it ideally suited for long-term structural monitoring applications, such as measurement of temperature and stress inside concrete structures. A theoretical model is presented to explain the origin and behavior of the higher-order harmonics in response to temperature and stress. c2002 Elsevier Science B.V. All rights reserved.

  2. 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

  3. Stress corrosion cracking of nickel base alloys in PWR primary water

    International Nuclear Information System (INIS)

    Stress corrosion cracking (SCC) of nickel base alloys and associated weld metals in primary water is one of the major concerns for pressurized water reactors (PWR). Since the 90's, highly cold-worked stainless steels (non-sensitized) were also found to be susceptible to SCC in PWR primary water ([1], [2], [3]). In the context of the life extension of pressurized water reactors, laboratory studies are performed in order to evaluate the SCC behaviour of components made of nickel base alloys and of stainless steels. Some examples of these laboratory studies performed at CEA will be given in the talk. This presentation deals with both initiation and propagation of stress corrosion cracks. The aims of these studies is, on one hand, to obtain more data regarding initiation time or crack growth rate and, one the other hand, to improve our knowledge of the SCC mechanisms. The aim of these approaches is to model SCC and to predict components life duration. Crack growth rate (CGR) tests on Alloy 82 with and without post weld heat treatment are performed in PWR primary water (Figure 1). The heat treatment seems to be highly beneficial by decreasing the CGR. This result could be explained by the effect of thermal treatment on the grain boundary nano-scopic precipitation in Alloy 82 [4]. The susceptibility to SCC of cold worked austenitic stainless steels is also studied. It is shown that for a given cold-working procedure, SCC susceptibility increases with increasing cold-work ([2], [5]). Despite the fact that the SCC behaviour of Alloy 600 has been widely studied for many years, recent laboratory experiments and analysis ([6], [7], [8]) showed that oxygen diffusion is not a rate-limiting step in the SCC mechanism and that chromium diffusion in the bulk close the crack tip could be a key parameter. (authors)

  4. Susceptibility of 17-4PH stainless steel to stress corrosion cracking in aqueous environments by electrochemical techniques

    International Nuclear Information System (INIS)

    The susceptibility of a 17-4PH type steel to Stress Corrosion Cracking (SCC) in low pressure steam turbine environments was assessed using slow strain rate test at 90 Centigrade and at 1.35x10-6 seg-1. Environments tested included different concentrated solutions of NaCl, NaOH and Na2SO4. It was concluded that this steel is susceptible to SCC in 20 % NaCl and pH=3 and in 20 % NaCl pH=neutral but under cathodic polarisation. The electrochemical potential noise of the specimen was monitored during the test. The naturally fluctuations in potential were arise due to spontaneous brake protective film and were characteristics of the kind of corrosion like pit or stress corrosion cracking. After that using Fast Fourier Transformer (FFT) the noise data set were analyzed to obtain power spectral density plots which showed differences between general corrosion and localized corrosion. Polarization curves were carry out at two different rates and them showed the general behavior of the systems. (Author)

  5. 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

  6. Effects of temperature and pressure on stress corrosion cracking behavior of 310S stainless steel in chloride solution

    Science.gov (United States)

    Zhong, Yunpan; Zhou, Cheng; Chen, Songying; Wang, Ruiyan

    2016-06-01

    310S is an austenitic stainless steel for high temperature applications, having strong resistance of oxidation, hydrogen embrittlement and corrosion. Stress corrosion cracking(SCC) is the main corrosion failure mode for 310S stainless steel. Past researched about SCC of 310S primarily focus on the corrosion mechanism and influence of temperature and corrosive media, but few studies concern the combined influence of temperature, pressure and chloride. For a better understanding of temperature and pressure's effects on SCC of 310S stainless steel, prepared samples are investigated via slow strain rate tensile test(SSRT) in different temperature and pressure in NACE A solution. The result shows that the SCC sensibility indexes of 310S stainless steel increase with the rise of temperature and reach maximum at 10MPa and 160°C, increasing by 22.3% compared with that at 10 MPa and 80 °C. Instead, the sensibility decreases with the pressure up. Besides, the fractures begin to transform from the ductile fracture to the brittle fracture with the increase of temperature. 310S stainless steel has an obvious tendency of stress corrosion at 10MPa and 160°C and the fracture surface exists cleavage steps, river patterns and some local secondary cracks, having obvious brittle fracture characteristics. The SCC cracks initiate from inclusions and tiny pits in the matrix and propagate into the matrix along the cross section gradually until rupture. In particular, the oxygen and chloride play an important role on the SCC of 310S stainless steel in NACE A solution. The chloride damages passivating film, causing pitting corrosion, concentrating in the cracks and accelerated SSC ultimately. The research reveals the combined influence of temperature, pressure and chloride on the SCC of 310S, which can be a guide to the application of 310S stainless steel in super-heater tube.

  7. An analysis of primary water stress corrosion cracking in PWR steam generators

    International Nuclear Information System (INIS)

    This paper discusses a fracture mechanics based model for estimating the progress of populations of longitudinal through-wall stress corrosion cracks in alloy 600 PWR steam generator tubes in the region of the roll transition. The key role played by residual stresses and their relaxation by stress corrosion cracking is described so that the proportions of cracks arresting or continuing to propagate may be estimated. The same phenomenon is also shown to account for the characteristic reduction in growth rate with increasing crack length observed by non-destructive examination of operating steam generators. Contributions to uncertainty in the results of non-destructive examinations influencing comparisons with these calculations are also examined. The initial results of this relatively simple fracture mechanics model of longitudinal crack propagation in the roll transition has quite successfully reproduced in the cases examined so far both the average crack growth rates as a function of crack length and the evolution of crack size distributions in successive reactor cycles. It can thus be used to predict the near-term future. Since there is no crack growth data to indicate a strong influence of microstructure on growth rates measured in fracture mechanics type specimens of alloy 600 (as distinct from initiation), then differences in rates observed between different reactor systems are most likely due to different residual stresses in the roll transition and/or the primary water operating temperature. A related aspect to emphasise is the fact that the curves representing crack growth rate as a function of crack length derived from non-destructive examinations are themselves generally fitted to the mean growth rates observed. In fact these measurements have large associated standard deviations (which is quantified directly in the predictive model of Hemalsteen) and is due at least in part to a random sizing error of order ± 1.0 mm. A complication affecting the

  8. Corrosion behaviour of the tool steel of the fuel charge machine during cleaning process

    International Nuclear Information System (INIS)

    In the framework of the experimentation activity of the PEC Reactor components, presently in course at the Casaccia Energy Research Centre (CRE Casaccia), the sodium removal process has been usually carried out by means of Butylcellosolve. Recently, in order to eliminate flammable organic solvent from the reactor building, it was decided to evaluate the possibility of using an atomized water method for the cleaning of the Fuel Charge Machine (FCM). Two important problems have been immediately identified: - lower removal process efficiency; since the geometries of the PEC Reactor FCM are complex, there are a number of areas of retention, where liquid access is difficult, - component damage due to the corrosion process. The main risk is associated with the formation of aqueous NaOH which can give rise to caustic stress corrosion cracking. In order to know something more about the above mentioned problems, a test programme was designed whose main aims were: - cleaning tests efficiency determination of gripper prototype by atomized water method using nitrogen gas or alternatively carbon dioxide; - study of the corrosion behaviour of tool steel in caustic solutions. This paper reports the results of the corrosion tests

  9. Effects of sensitization and service fluid chemistry on polythionic acid stress corrosion cracking of 18-8 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Nagashima, E.; Matsumoto, K.; Shibata, K. [Toyo Engineering Corp., Mobara (Japan)

    1998-12-31

    The aim of this paper is to clarify environmental effects of operational temperature and service fluid chemistry on polythionic acid stress corrosion cracking (PASCC) of 18-8 stainless steels. To evaluate the susceptibility of SCC, a new test method without handling hydrogen sulfide gas was proposed. Sensitization/desensitization behavior of materials and chemistry of corrosion products formed in contact with process streams are the two major factors to cause PASCC. For both factors, theoretical approaches, metallurgical and thermodynamic, were proven to be feasible. The results of this study would be applicable to assess the possibility of PASCC to occur in the stage of plant design as well as maintenance management.

  10. Influence of some parameters on the stress corrosion of a ABNT 304 stainless steel in MgCl2

    International Nuclear Information System (INIS)

    The susceptibility to stress corrosion cracking of the austenitic stainless steel AISI 304 in MgCl, solution was studied. When changes on the surface film were produced like a prepassivation of the steel in HNO3 solution or chromate solution or even a previous cathodic reduction. A mixture of MgCl2 + NaCl was also used in such a way that the cation influence on the scc process could be analised. Results show that the surface film seems to have great importance in the see mechanism and that addition of Na+ ions inhibit cracks at the corrosion potencial. (Author)

  11. Stress corrosion cracking behavior in gaseous oxygen of a U-7.5 Nb-2.5 Zr alloy

    International Nuclear Information System (INIS)

    Stress corrosion of the alloy U90Nb7.5Zr2.5 in oxygen is studied for temperature between -200C and 1000C under pressure varying from 0.3 x 10-6 MPa to 0.15 MPa. The domain of stress corrosion and cracking kinetics are determined in function of stress intensity, temperature and pressure. Under 0.15 MPa of oxygen embrittlement is observed for the all range of temperature studied and the phenomenon is thermally activated. At room temperature cracks are produced for all tested pressures, influence of pressure on cracking kinetics is low. Auger spectrometry analysis on the surface of cracks shows a surface mechanism to explain alloy embrittlement in gaseous oxygen

  12. Stress corrosion resistance of a steel used for the vessels (frames) of water-moderated power reactors (WMPR)

    International Nuclear Information System (INIS)

    The static crack resistance of 15Kh2MFA steel in a corrosive medium directly under conditions of neutron irradiation or of operational temperatures and pressures was studied. Samples were stressed in the off-center tension mode, subsequently held either in the core of an experimental reactor or in an autoclave, and finally loaded at room temperature up to fracture. Preliminary heat treatments were conducted. The samples were irradiated after being placed in the coolant of the core of an IRT-2000 reactor. Results indicate the absence of corrosion crack growth in the steel at given neutron flux densities, temperatures, and pressures. The fracture toughness increased with increasing stress intensity when stressing the steel specimens and subsequently holding them in the coolant medium

  13. Iodine-oxygen and cadmium-induced stress corrosion cracking of Zr-4 cladding tube

    International Nuclear Information System (INIS)

    On the basis of iodine-induced stress corrosion cracking (SCC) experiments the authors did before, iodine-oxygen and cadmium-induced SCC was studied on Zr-4 cladding tube. Specimens used in experiments are cladding tubes of a reactor fuel element made by Institute of Nonferrous Metal of China. The tube which has a length of 145 mm and an outside diameter of 15.3 mm and an inside diameter of 14.9 mm was annealed at 620 K for two hours, and then it had a fine, stress-relieved microstructure. Two end-caps were welded on the cladding tube. There was a hole of 0.8 mm diameter in a protruding melting-welding platform on one end-cap of the specimen. Before welding the end-caps, a glass ampoule filled with a certain amount of oxygen and a piece of Zr-4 material which can dash the glass ampoule were put into the cladding tube. After plug-hole welding in high pressure argon, the cladding tube was shaken in order to make the piece of Zr-4 material dash the ampoule and the oxygen fill up the space inside the cladding tube. A certain amount of iodine was charged into the cladding tube from the hole before the plug-hole welding. The plug-hole welding in high pressure argon was performed on a specially prepared equipment within 0.1-0.5 second. At a certain temperature, the pressure of argon determines the mechanical load (stress). The SCC experiments were controlled within +-3 degree C by a thermocouple welded on the specimen. The cracking of the specimen or the leak of gas was sensitively supervised and timed by vacuum alarm system. Under various conditions of stress, the experiments for 28 specimens of iodine-oxygen agent and 5 specimens of cadmium agent were undertaken

  14. On the degree of caustics of reflection

    CERN Document Server

    Josse, Alfrederic

    2012-01-01

    Given a point S and an irreducible algebraic curve C in P^2, we consider the caustic of reflection defined as the envelope of the reflected lines from the point S on the curve C. We identify this caustic with the Zariski closure of the image of C by a rational map. Thanks to a general fundamental lemma, we give a formula of the degree of the caustic of reflection in terms of multiplicity numbers of pro-branches of C. Our formula holds in the most general case. We also give some precisions about Pl\\"ucker formulas.

  15. Effect of Microstructure on the Localized Corrosion and Stress Corrosion Behaviours of Plasma-Electrolytic-Oxidation-Treated AA7075 Aluminum Alloy Forging in 3.5 wt. % NaCl Solution

    Directory of Open Access Journals (Sweden)

    A. Venugopal

    2012-01-01

    Full Text Available The influence of metallurgical heterogeneities such as coring and intermetallic phases on the corrosion and stress corrosion cracking behaviours of AA7075 aluminium alloy forging was examined in 3.5 wt. % NaCl solution with and without plasma electrolytic oxidation coating. Electrochemical test results demonstrated significant improvement in the corrosion resistance of the alloy after PEO coating. Stress corrosion results show that the metallurgical heterogeneities resulted in a loss in elongation of the uncoated sample in NaCl (11.5% when compared to the one tested in air (12.9%. The loss in elongation of the uncoated sample was shown to be due to localized corrosion-assisted mechanical cracking rather than true stress corrosion based on preexposure tensile tests followed by posttest metallographic observation of the stress corrosion tested samples. This was further confirmed by the fractographic examination of the failed samples, which exhibited a typical ductile cracking morphology for all the coated and uncoated specimens.

  16. Simulated Service and Stress Corrosion Cracking Testing for Friction Stir Welded Spun Form Domes

    Science.gov (United States)

    Stewart, Thomas J.; Torres, Pablo D.; Caratus, Andrei A.; Curreri, Peter A.

    2010-01-01

    Damage tolerance testing development was required to help qualify a new spin forming dome fabrication process for the Ares 1 program at Marshall Space Flight Center (MSFC). One challenge of the testing was due to the compound curvature of the dome. The testing was developed on a sub-scale dome with a diameter of approximately 40 inches. The simulated service testing performed was based on the EQTP1102 Rev L 2195 Aluminum Lot Acceptance Simulated Service Test and Analysis Procedure generated by Lockheed Martin for the Space Shuttle External Fuel Tank. This testing is performed on a specimen with an induced flaw of elliptical shape generated by Electrical Discharge Machining (EDM) and subsequent fatigue cycling for crack propagation to a predetermined length and depth. The specimen is then loaded in tension at a constant rate of displacement at room temperature until fracture occurs while recording load and strain. An identical specimen with a similar flaw is then proof tested at room temperature to imminent failure based on the critical offset strain achieved by the previous fracture test. If the specimen survives the proof, it is then subjected to cryogenic cycling with loads that are a percentage of the proof load performed at room temperature. If all cryogenic cycles are successful, the specimen is loaded in tension to failure at the end of the test. This standard was generated for flat plate, so a method of translating this to a specimen of compound curvature was required. This was accomplished by fabricating a fixture that maintained the curvature of the specimen rigidly with the exception of approximately one-half inch in the center of the specimen containing the induced flaw. This in conjunction with placing the center of the specimen in the center of the load train allowed for successful testing with a minimal amount of bending introduced into the system. Stress corrosion cracking (SCC) tests were performed using the typical double beam assembly and with 4

  17. Maintenance method for irradiation assisted stress corrosion cracking of PWR core internals

    International Nuclear Information System (INIS)

    Irradiation-assisted stress corrosion cracking of IASCC is a well-known result of age-related degradation of baffle former bolts which are an integral component of PWR core internals. However, methods for analyzing the causes and assessing IASCC have yet to be established and are being studied. The baffle former bolts are components of the baffle structure and in order to maintain the integrity of the baffle structure, an effective approach for maintaining the bolts must be provided. This paper proposes an effective method of maintaining the functions of the baffle structure by improving the configuration and/or material of baffle former bolts. A relaxed configuration of the bolt neck reduces the stress and can approximately halve the damage caused by IASCC. An improvement in the threshold value of materials vulnerability to IASCC would not only extend the service life of all bolts but could also substantially retard IASCC of the bolts installed at upper and lower ends where flux is low. If the threshold fluence to IASCC could be made higher than approximately 5x1025 n/m2 (E>0.1 MeV, 340degC), the bolts installed at lower and upper ends, which are conventionally replaced 30 years after plant start-up, would remain intact for 60 years after start-up. Hence, this approach is a very effective maintenance measure. (author)

  18. Oxide-induced initiation of stress corrosion cracking in irradiated stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Cookson, J.M.; Was, G.S. [Univ. of Michigan, Ann Arbor, MI (United States); Andresen, P.L. [General Electric Research and Development, Schenectady, NY (United States)

    1998-04-01

    Stainless steel (SS) samples were irradiated with protons at 400 C and strained in 288 C water to examine the role of oxide particles in the irradiation-assisted stress corrosion cracking (IASCC) process. Oxides in the matrix acted as the predominant crack initiation sites, and the amount of cracking scaled with oxide density. Intergranular cracking occurred by mechanical failure of oxide particles that created electrochemical crevices and stress concentrators from which intergranular cracks could propagate. Relatively few of the cracked oxide particles actually led to intergranular cracking in the matrix, which was consistent with the requirement that the crack tip solution had to be deaerated for an aggressive crevice chemistry to form and that the cracks in the oxides had to be well aligned with susceptible grain boundaries. Intergranular cracking occurred only when both the SS was irradiated and when straining was conducted in high-temperature water. This observation supported on IASCC mechanism that required an aggressive environment and an irradiated microstructure.

  19. Numerical investigation on stress corrosion cracking behavior of dissimilar weld joints in pressurized water reactor plants

    Directory of Open Access Journals (Sweden)

    Lingyan Zhao

    2014-07-01

    Full Text Available There have been incidents recently where stress corrosion cracking (SCC observed in the dissimilar metal weld (DMW joints connecting the reactor pressure vessel (RPV nozzle with the hot leg pipe. Due to the complex microstructure and mechanical heterogeneity in the weld region, dissimilar metal weld joints are more susceptible to SCC than the bulk steels in the simulated high temperature water environment of pressurized water reactor (PWR. Tensile residual stress (RS, in addition to operating loads, has a great contribution to SCC crack growth. Limited experimental conditions, varied influence factors and diverging experimental data make it difficult to accurately predict the SCC behavior of DMW joints with complex geometry, material configuration, operating loads and crack shape. Based on the film slip/dissolution oxidation model and elastic-plastic finite element method (EPFEM, an approach is developed to quantitatively predict the SCC growth rate of a RPV outlet nozzle DMW joint. Moreover, this approach is expected to be a pre-analytical tool for SCC experiment of DMW joints in PWR primary water environment.

  20. Integrity: A semi-mechanistic model for stress corrosion cracking of fuel

    International Nuclear Information System (INIS)

    In this paper we describe the features, validation, and illustrative applications of a semi-mechanistic model, INTEGRITY, which calculates the probability of fuel defects due to stress corrosion cracking. The model expresses the defect probability in terms of fundamental parameters such as local stresses, local strains, and fission product concentration. The assessments of defect probability continue to reflect the influence of conventional parameters like ramped power, power-ramp, burnup and Canlub coating. In addition, the INTEGRITY model provides a mechanism to account for the impacts of additional factors involving detailed fuel design and reactor operation. Some examples of the latter include pellet density, pellet shape and size, sheath diameter and thickness, pellet/sheath clearance, coolant temperature and pressure, etc. The model has been fitted to a database of 554 power-ramp irradiations of CANDU fuel with and without Canlub. For this database the INTEGRITY model calculates 75 defects vs 75 actual defects. Similarly good agreements were noted in the different sub-groups of the data involving non-Canlub, thin-Canlub, and thick-Canlub fuel. Moreover, the shapes and the locations of the defect thresholds were consistent with all the above defects as well as with additional 14 ripple defects that were not in the above database. Two illustrative examples demonstrate how the defect thresholds are influenced by changes in the internal design of the fuel element and by extended burnup. (author). 19 refs, 7 figs