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Sample records for steel heat affected

  1. Heat affected zone in surfacing chromium ledeburitic steel

    Directory of Open Access Journals (Sweden)

    M. Tonkovič Prijanovič

    2010-07-01

    Full Text Available Tools get failured during work; wear is a major factor that contributes to failures. Damaged tools are replaced or filed. This paper describes typical changes that occur in the heat affected zone of tool (HAZ, which was repaired by surfacing with a TIG and with micro-plasma procedure. Microstructure of the steel on the repaired tool was analysed by an optical and scanning electron microscope. The tool was made of chromium ledeburitic steel type W.N. 1.2379 and it was repaired by surfacing steel type W.N. 1.4718. Changes in the HAZ also depend on the type of surfacing. Besides microstructural changes, dissolution of carbides, especially primary carbides. This way the concentration of the carbide-forming elements and carbon is increased in the base around the primary carbides in the HAZ so the result is so-called secondary eutectic or secondary ledeburite.

  2. Variant analysis in coarse grain heat affected zone of low carbon steel

    Science.gov (United States)

    Razab, Mohammad Khairul Azhar Abdul; Mamat, Sarizam; Ahmad, Muhammad Iqbal; Nasir, Nurul Syahida Mohd

    2017-09-01

    Coarse Grain Heat Affected Zone (CGHAZ) is a part of Heat Affected Zone (HAZ) that affected by heat during welding process. Application of different heat input dramatically varies CGHAZ microstructures without a noticeable changing in prior austenite grain size. The unique coarse microstructure and crack initiated at CGHAZ show there were possibility changes in crystallographic structure which may relate to the variant selection phenomenon. The aims of this study are to find the effects of heat input to the variant selection especially to the biggest grain at CGHAZ, hence correlate to the toughness and properties of the welded steel. The results show that heat input affected the variant selection at the biggest CGHAZ grain of low carbon steel. As heat input increase, grain area was increased and becomes coarser. Variant selection phenomenon present at low carbon steel due to the increase in grain diameter and high angle value. It was found that variant selections had occurred during the transformation.

  3. Creep properties of simulated heat-affected zone of HR3C austenitic steel

    Czech Academy of Sciences Publication Activity Database

    Sklenička, Václav; Kuchařová, Květa; Kvapilová, Marie; Svoboda, Milan; Král, Petr; Dvořák, Jiří

    2017-01-01

    Roč. 128, JUN (2017), s. 238-247 ISSN 1044-5803 R&D Projects: GA MŠk(CZ) LQ1601 Institutional support: RVO:68081723 Keywords : HR3C steel * Welding * Heat affected zone * Creep * Microstructure * Fractography Subject RIV: JG - Metallurgy Impact factor: 2.714, year: 2016

  4. Analysis of the heat affected zone in CO2 laser cutting of stainless steel

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    Madić Miloš J.

    2012-01-01

    Full Text Available This paper presents an investigation into the effect of the laser cutting parameters on the heat affected zone in CO2 laser cutting of AISI 304 stainless steel. The mathematical model for the heat affected zone was expressed as a function of the laser cutting parameters such as the laser power, cutting speed, assist gas pressure and focus position using the artificial neural network. To obtain experimental database for the artificial neural network training, laser cutting experiment was planned as per Taguchi’s L27 orthogonal array with three levels for each of the cutting parameter. Using the 27 experimental data sets, the artificial neural network was trained with gradient descent with momentum algorithm and the average absolute percentage error was 2.33%. The testing accuracy was then verified with 6 extra experimental data sets and the average predicting error was 6.46%. Statistically assessed as adequate, the artificial neural network model was then used to investigate the effect of the laser cutting parameters on the heat affected zone. To analyze the main and interaction effect of the laser cutting parameters on the heat affected zone, 2-D and 3-D plots were generated. The analysis revealed that the cutting speed had maximum influence on the heat affected zone followed by the laser power, focus position and assist gas pressure. Finally, using the Monte Carlo method the optimal laser cutting parameter values that minimize the heat affected zone were identified.

  5. Factors Affecting Impact Toughness in Stabilized Intermediate Purity 21Cr Ferritic Stainless Steels and Their Simulated Heat-Affected Zones

    Science.gov (United States)

    Anttila, Severi; Alatarvas, Tuomas; Porter, David A.

    2017-12-01

    The correlation between simulated weld heat-affected zone microstructures and toughness parameters has been investigated in four intermediate purity 21Cr ferritic stainless steels stabilized with titanium and niobium either separately or in combination. Extensive Charpy V impact toughness testing was carried out followed by metallography including particle analysis using electron microscopy. The results confirmed that the grain size and the number density of particle clusters rich in titanium nitride and carbide with an equivalent circular diameter of 2 µm or more are statistically the most critical factors influencing the ductile-to-brittle transition temperature. Other inclusions and particle clusters, as well as grain boundary precipitates, are shown to be relatively harmless. Stabilization with niobium avoids large titanium-rich inclusions and also suppresses excessive grain growth in the heat-affected zone when reasonable heat inputs are used. Thus, in order to maximize the limited heat-affected zone impact toughness of 21Cr ferritic stainless steels containing 380 to 450 mass ppm of interstitials, the stabilization should be either titanium free or the levels of titanium and nitrogen should be moderated.

  6. Microstructural investigation of the heat-affected zone of simulated welded joint of P91 steel

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    T. Vuherer

    2013-07-01

    Full Text Available In the process of testing real components exposed to elevated temperature, it is not possible to neglect cracks. The most significant cracks can be induced by welding, which is applied for joining of structural components. Pressure equipment in service is also exposed to high pressure and high stresses. Materials for their manufacturing are designed to resist high stress at elevated temperature, and to meet requirements regarding creep resistance. The objective of this study is to investigate microstructure of different regions of the heat affected zone in T/P91 steels by using thermal simulation instead of welding.

  7. Study on impact properties of creep-resistant steel thermally simulated heat affected zone

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    Mitrović Radivoje M.

    2012-01-01

    Full Text Available The steam pipe line (SPL and steam line material, along with its welded joints, subject to damage that accumulates during operation in coal power plants. As a result of thermal fatigue, dilatation of SPL at an operating temperature may lead to cracks initiation at the critical zones within heat affected zone (HAZ of steam pipe line welded joints. By registration of thermal cycle during welding and subsequent HAZ simulation is possible to obtain target microstructure. For the simulation is chosen heat resisting steel, 12H1MF (designation 13CrMo44 according to DIN standard. From the viewpoint of mechanical properties, special attention is on impact toughness mostly because very small number of available references. After simulation of single run and multi run welding test on instrumented Charpy pendulum. Metallographic and fractographic analysis is also performed, on simulated 12H1MF steel from service and new, unused steel. The results and correlation between microstructure and impact toughness is discussed, too.

  8. Fundamental Studies of Phase Transformations and Mechanical Properties in the Heat Affected Zone of 10 wt% Nickel Steel

    Science.gov (United States)

    Barrick, Erin J.

    United States naval applications require the use of steels with high strength and resistance to fracture at low temperatures to provide good ballistic properties. In recent years, 10 wt% Ni steel has been developed with strength and toughness values exceeding those of steels currently used, and is now being considered as a candidate material to replace existing high-strength, low alloy steels. This steel has excellent toughness from the mechanically induced transformation of interlath austenite films to martensite. These austenite films are formed via a carefully developed quenching, lamellarizing, and tempering heat treatment. However, before 10 wt% Ni steel can be implemented for full-scale applications, the effects of the rapid heating and cooling rates associated with welding thermal cycles on phase transformations and mechanical properties must be understood. In this research, a fundamental understanding of phase transformations and mechanical properties in the heat-affected zone of fusion welds in 10 wt% Ni steel was developed through heating and cooling rate dilatometry experiments, gas tungsten arc welding, and simulation of gas metal arc welding. First, an investigation into the effects of heating and cooling rate on the phase transformations in 10 wt% Ni steel was performed. The Ac1 and Ac3 temperatures during heating were determined as a function of heating rate, and sluggish transformation during fast heating rates manifested itself as a high Ac3 temperature of 1050°C as opposed to a temperature of 850°C at slow heating rates. A continuous cooling transformation diagram produced for 10 wt% Ni steel reveals that martensite will form over a very wide range of cooling rates, which reflects a very high hardenability of this alloy. This is significant because the range of cooling rates for which the diagram was constructed over easily covers the range associated with fusion welding, so there would not be the need for precise control over the weld

  9. Simulated heat affected zone hardness limits of C-Mn steels used in offshore structures

    Energy Technology Data Exchange (ETDEWEB)

    Mihi, A.; Benbouta, R.; Abbassi, A. [Corrosion Laboratory, Faculty of Engineering Science, University of Batna, 05000 Batna (Algeria); Cottis, R. [Corrosion and Protection Centre, University of Manchester, P.O. Box 88, Manchester, M60 1QD (United Kingdom)

    2006-10-15

    The detrimental effect which hydrogen produces in metals, generally known as hydrogen embrittlement (HE), has always been one of the central problems of practical material technology of corrosion and protection of metals. In the present research, the influence of simulated heat affected zone (HAZ) hardness on susceptibility of a structural steel to hydrogen embrittlement was investigated mainly under slow strain rate testing (SSRT), although limited tests were carried out by means of small amplitude, cyclic (ripple) loading. These tests have been supported by detailed scanning electron fractography and hydrogen permeation measurements. A good correlation is observed between the degree of embrittlement in slow strain rate tests and the steady state hydrogen permeation current density. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  10. Control of Softening Processes in the Heat-Affected Zone During Welding of High-Strength Steels

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    Efimenko, L. A.; Kapustin, O. E.; Ramus', A. A.; Ramus', R. O.

    2016-11-01

    The hardness and the structure of the heat-affected zone (HAZ) under welding of tube steels of strength category K60 - K70 are studied. The steels are treated by regimes imitating the thermal cycles of different welding processes applied to tubes starting with manual arc welding and ending with energy-intensive automatic submerged-arc welding. The welding modes causing maximum decrease in the hardness of HAZ regions are determined. The conditions preventing softening under one-pass and multipass welding of high-strength steels are presented.

  11. The modeling of heat affected zone (HAZ in submerged arc welding (SAW surfacing steel element

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    J. Winczek

    2016-04-01

    Full Text Available In the work the bimodal heat source model in the description of the temperature field is presented. The electric arc was treated physically as one heat source, whose heat was divided: part of the heat is transferred by the direct impact of the electric arc, but another part of the heat is transferred to the weld by the melted material of the electrode. Computations of the temperature field during SAW surfacing of S355 steel element are carried out. The macrographic and metallographic analysis of the weld confirmed the depth and shapes of the fusion line and HAZ defined by the numerical simulation.

  12. The softened heat-affected zone in resistance spot welded tailor hardened boron steel: a material model for crash simulation

    NARCIS (Netherlands)

    Eller, Tom; Greve, L; Andres, M.T.; Medricky, M; Geijselaers, Hubertus J.M.; Meinders, Vincent T.; van den Boogaard, Antonius H.

    2016-01-01

    A hardness-based model for tailor hardened boron steel is presented that takes into account the softened heat-affected zone of resistance spot welds. The computational model is designed for crashworthiness simulation of fully and partially hardened components obtained by tailored tooling. Five

  13. Suppression of grain refinement in heat-affected zone of 9Cr–3W–3Co–VNb steels

    Energy Technology Data Exchange (ETDEWEB)

    Matsunaga, Tetsuya, E-mail: MATSUNAGA.Tetsuya@nims.go.jp; Hongo, Hiromichi, E-mail: HONGO.Hiromichi@nims.go.jp; Tabuchi, Masaaki, E-mail: TABUCHI.Masaaki@nims.go.jp; Sahara, Ryoji, E-mail: SAHARA.Ryoji@nims.go.jp

    2016-02-08

    Prompt phase transformations make grains in the heat-affected zone (HAZ) smaller during welding of 9% chromium (9Cr) heat-resistant steels leading to premature failure under creep conditions, which is well known as a type IV fracture. Because the type IV fracture shortens the creep lifetime of the steels, suppressing the fracture is an urgent task in the energy industry. The present study shows that boron addition and nitrogen reduction inhibit grain refinement after welding because of a change in the morphology of the precipitate at prior austenite grain boundaries. In conventional 9Cr steel (ASME Gr. 92 steel), a high amount of MX was unable to pin interface migration of the phase transformation and generated fine grains in the HAZ. In the new B-added steels, B-stabilized M{sub 23}C{sub 6} became the dominant precipitate and showed a larger pinning effect of the phase transformation than MX, which resulted in coarse grains in the HAZ. This suggests that designing stabilized M{sub 23}C{sub 6} forms a superior welded microstructure and results in a longer creep lifetime of 9Cr steels.

  14. An investigation of reheat cracking in the weld heat affected zone of type 347 stainless steel

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    Phung-On, Isaratat

    2007-12-01

    Reheat cracking has been a persistent problem for welding of many alloys such as the stabilized stainless steels: Types 321 and 347 as well as Cr-Mo-V steels. Similar problem occurs in Ni-base superalloys termed "strain-age cracking". Cracking occurs during the post weld heat treatment. The HAZ is the most susceptible area due to metallurgical reactions in solid state during both heating and cooling thermal cycle. Many investigations have been conducted to understand the RHC mechanism. There is still no comprehensive mechanism to explain its underlying mechanism. In this study, there were two proposed cracking mechanisms. The first is the formation of a PFZ resulting in local weakening and strain localization. The second is the creep-like grain boundary sliding that causes microvoid formation at the grain boundaries and the triple point junctions. Cracking occurs due to the coalescence of the microvoids that form. In this study, stabilized grade stainless steel, Type 347, was selected for investigation of reheat cracking mechanism due to the simplicity of its microstructure and understanding of its metallurgical behavior. The Gleeble(TM) 3800 system was employed due to its capability for precise control of both thermal and mechanical simulation. Cylindrical samples were subjected to thermal cycles for the HAZ simulation followed by PWHT as the reheat cracking test. "Susceptibility C-curves" were plotted as a function of PWHT temperatures and time to failure at applied stress levels of 70% and 80% yield strength. These C-curves show the possible relationship of the reheat cracking susceptibility and carbide precipitation behavior. To identify the mechanism, the sample shape was modified containing two flat surfaces at the center section. These flat surfaces were electro-polished and subjected to the HAZ simulation followed by the placement of the micro-indentation arrays. Then, the reheat cracking test was performed. The cracking mechanism was identified by tracing

  15. Analysis of thermal cycles and microstructure of heat affected zone for a low alloy carbon steel pipe under multipass weld

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae Woan; Ha, Joon Wook; Kim, Dong Jin; Kim, Jeong Tae [Doosan Heavy Industries and Construction Co., Ltd., Changwon (Korea, Republic of)

    2002-03-01

    The purpose of this study is to analyze thermal cycles and to investigate microstructures of heat affected zones for a low alloy carbon steel pipe under a multipass weld. The commercial finite element code SYSWELD is used to compute thermal cycles during multipass weld. The numerical results such as thermal cycles and size of heat affected zone are compared with those of the experiment and the two results show a good agreement. In addition, the microstructure and hardness and investigated from the weldment in detail. The weakest location is founded at intercritical region near the base metal.

  16. Normalizing effect on fatigue crack propagation at the heat-affected zone of AISI 4140 steel shielded metal arc weldings

    OpenAIRE

    B. Vargas-Arista; J. Teran-Guillen; Solis, J.; García-Cerecero,G.; Martínez-Madrid,M.

    2013-01-01

    The fractography and mechanical behaviour of fatigue crack propagation in the heat-affected zone (HAZ) of AISI 4140 steel welded using the shielded metal arc process was analysed. Different austenitic grain size was obtained by normalizing performed at 1200 °C for 5 and 10 hours after welding. Three point bending fatigue tests on pre-cracked specimens along the HAZ revealed that coarse grains promoted an increase in fatigue crack growth rate, hence causing a reduction in both fracture toughne...

  17. Hydrogen-induced cold cracking in heat-affected zone of low-carbon high-strength steel

    Science.gov (United States)

    Lan, Liangyun; Kong, Xiangwei; Hu, Zhiyong; Qiu, Chunlin

    2014-12-01

    The Y-groove cracking test by submerged arc welding was employed to study the susceptibility of a low-carbon high-strength steel to hydrogen-induced cold cracking (HICC). The morphology of hydrogen cracks was observed using an electron probe microscope. The results showed that the heat-affected zone (HAZ) has a higher susceptibility to HICC than the weld metal and that increasing heat input can improve the HICC resistance of the weldment. The intergranular microcracking is the main HICC mode at the lowest heat input condition, accompanied with some transgranular microcracks attached to complex inclusions. In combination with phase transformation behaviour in sub-zones, the effect of the phase transformation sequence is proposed to try to illustrate the fact that the fine-grained HAZ has higher probability of hydrogen cracking than the coarse-grained HAZ owing to the occurrence of hydrogen enrichment in the fine-grained HAZ after the transformation.

  18. Direct observation of phase transformations in the simulated heat-affected zone of a 9Cr martensitic steel

    Energy Technology Data Exchange (ETDEWEB)

    Mayr, P. [Graz Univ. of Tech. (Austria). IWS; Palmer, T.A.; Elmer, J.W. [Lawrence Livermore National Lab., Livermore (United States); Specht, E.D. [Oak Ridge National Lab., Oak Ridge, TN (United States)

    2008-04-15

    An experimental test melt of a boron alloyed 9Cr-3W-3Co-V,Nb steel for high temperature applications in the thermal power generation industry was produced by vacuum induction melting. This grade of steel typically displays a homogeneous tempered martensitic microstructure in the as-received, i.e. normalised and tempered, condition. However, after welding, this microstructure is significantly altered, resulting in a loss of its desired properties. The phase transformations during simulated thermal cycles typical of those experienced in the weld heat-affected zone were directly observed by in-situ X-ray diffraction experiments using synchrotron radiation. Heating rates of 10 K s{sup -1} and 100 K s{sup -1} up to a peak temperature of 1300 C are investigated here. The final microstructures observed after both simulated weld thermal cycles are primarily composed of martensite with approximately 4% retained delta ferrite and 4% retained austenite, by volume. With the temporal resolution of the in-situ X-ray diffraction technique, phase transformations from tempered martensite to austenite to delta ferrite during heating and to martensite during cooling were monitored. With this technique, the evolution of the final microstructure through both heating and cooling is monitored, providing additional context to the microstructural observations. (orig.)

  19. Continuous cooling transformation behavior and impact toughness in heat-affected zone of Nb-containing fire-resistant steel

    Science.gov (United States)

    Wang, Hong Hong; Qin, Zhan Peng; Wan, Xiang Liang; Wei, Ran; Wu, Kai Ming; Misra, Devesh

    2017-09-01

    Simulated heat-affected zone continuous cooling transformation diagram was developed for advanced fireresistant steel. Over a wide range of cooling rates, corresponding to t8/5 from 6 s to 150 s, granular bainite was the dominant transformation constituent, while the morphology of less dominant martensite-austenite (M-A) constituent changed from film-like to block-type constituent; but the hardness remained similar to the average value of 190-205 HV (0.2). The start and finish transformation temperature was high at 700 °C and 500 °C, and is different from the conventional high strength low alloy steels. It is believed that the high-content (0.09 wt%) of Nb may promote bainite transformation at relatively high temperatures. Martenistic matrix was not observed at high cooling rate and the film-like M-A constituent and blocky M-A constituent with thin film of retained austenite and lath martensite were observed on slow cooling. Excellent impact toughness was obtained in the heat-affected zone with 15-75 kJ/cm welding heat input.

  20. An Investigation of TIG welding parameters on microhardness and microstructure of heat affected zone of HSLA steel

    Science.gov (United States)

    Musa, M. H. A.; Maleque, M. A.; Ali, M. Y.

    2018-01-01

    Nowadays a wide variety of metal joining methods are used in fabrication industries. In this study, the effect of various welding parameters of the TIG welding process on microhardness, depth, and microstructure of the heat-affected zone (HAZ) of L450 HSLA steel and optimizing these process parameters following Taguchi experimental design was investigated. The microhardness tended to increase significantly with the increase of welding speed from 1.0 to 2.5 mm/s whereas the width of HAZ decreased. The current and arc voltage was found to be less significant in relative comparison. Microstructures of the welded samples were also studied to analyze the changes in the microstructure of the material in terms of ferrite, pearlite, bainite, and martensite formations. Welding speed was found to be the most significant factors leading to changes in microhardness and metallurgical properties. The increase of welding heat input caused an increase in width (depth) of HAZ and the growth of prior austenite grains and then enlarged the grain size of coarse grain heat affected zone (CGHAZ). However, the amount of martensite in the HAZ decreased accompanied by an opposite change of paint. It was observed that the hardness properties and the microstructural feature of HAZ area was strongly affected by the welding parameters.

  1. Effects of Notch Location on Heat-affected Zone Impact Properties of SA-516 Steels

    Science.gov (United States)

    Hong, Jaekeun; Park, Jihong; Kang, Chungyun

    In case of welding for pressure retaining parts on nuclear components, the verifications of heat affected zone (HAZ) impact properties are required according to application codes such as ASME Sec. III, RCC-M, KEPIC (Korea Electric Power Industry Code) MN, and JEA (Japan Electric Association) Code. Especially in case of Charpy V-notch tests of HAZ, the requirements of notch location and specimen direction have greatly impact on the reliability and consistency of the test results. For the establishment of newly adequate impact test requirements, the requirements about the HAZ impact tests of ASME Section III, RCC-M, KEPIC MN and JEA code were researched in this study. And also the HAZ impact test requirements about surveillance tests in nuclear reactor vessels were compared and investigated. For the effects of the notch location and specimen direction on the impact properties, SA-516 Gr.70 materials were investigated. The specimens were fabricated with using shielded metal-arc welding, and maximum heat inputs were controlled within the range of 16˜27 kJ/cm. Especially, this research showed the lateral expansion values and absorbed energies were not compatible and the impact test results were varied depending on notch location and specimen direction. Based on this study, newly adequate impact test requirements of HAZ were proposed.

  2. Normalizing effect on fatigue crack propagation at the heat-affected zone of AISI 4140 steel shielded metal arc weldings

    Directory of Open Access Journals (Sweden)

    B. Vargas-Arista

    2013-01-01

    Full Text Available The fractography and mechanical behaviour of fatigue crack propagation in the heat-affected zone (HAZ of AISI 4140 steel welded using the shielded metal arc process was analysed. Different austenitic grain size was obtained by normalizing performed at 1200 °C for 5 and 10 hours after welding. Three point bending fatigue tests on pre-cracked specimens along the HAZ revealed that coarse grains promoted an increase in fatigue crack growth rate, hence causing a reduction in both fracture toughness and critical crack length, and a transgranular brittle final fracture with an area fraction of dimple zones connecting cleavage facets. A fractographic analysis proved that as the normalizing time increased the crack length decreased. The increase in the river patterns on the fatigue crack propagation in zone II was also evidenced and final brittle fracture because of transgranular quasicleavage was observed. Larger grains induced a deterioration of the fatigue resistance of the HAZ.

  3. 2017 Accomplishments – Tritium Aging Studies on Stainless Steel Weldments and Heat-Affected Zones

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, Michael J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hitchcock, Dale [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Krentz, Tim [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); McNamara, Joy [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Duncan, Andrew [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2018-01-31

    In this study, the combined effects tritium and decay helium in forged and welded Types 304L and 21-6-9 stainless steels were studied. To measure these effects, fracture mechanic specimens were thermally precharged with tritium and aged for approximately 17 years to build in decay helium from tritium decay prior to testing. The results are compared to earlier measurements on the same alloys and weldments (4-5, 8-9). In support of Enhanced Surveillance, “Tritium Effects on Materials”, the fracture toughness properties of long-aged tritium-charged stainless-steel base metals and weldments were measured and compared to earlier measurements. The fracture-toughness data were measured by thermally precharging as-forged and as-welded specimens with tritium gas at 34.5 MPa and 350°C and aging for approximately 17 years to build-in decay helium prior to testing. These data result from the longest aged specimens ever tested in the history of the tritium effects programs at Savannah River and the fracture toughness values measured were the lowest ever recorded for tritium-exposed stainless steel. For Type 21-6-9 stainless steel, fracture toughness values were reduced to less than 2-4% of the as-forged values to 41 lbs / in specimens that contained more than 1300 appm helium from tritium decay. The fracture toughness properties of long-aged weldments were also measured. The fracture toughness reductions were not as severe because the specimens did not retain as much tritium from the charging and aging as did the base metals. For Type 304L weldments, the specimens in this study contained approximately 600 appm helium and their fracture toughness values averaged 750 lbs / in. The results for other steels and weldments are reported and additional tests will be conducted during FY18.

  4. Validation of Temperature Histories for Structural Steel Welds Using Estimated Heat-Affected-Zone Edges

    Science.gov (United States)

    2016-10-12

    Parametric Envelopes for Stable Keyhole Plasma Arc Welding of a Titanium Alloy,” Journal of Strain Analysis for Engineering Design, 47(5), pp. 266- 275, 2012...welding, is simulation of the coupling of the heat source, which involves melting, fluid flow in the weld meltpool and heat transfer from the...generation of the solidification boundary, the surface from which heat is transferred into the HAZ, which is the region of most probable weld

  5. Study on the Toughness of X100 Pipeline Steel Heat Affected Zone

    Science.gov (United States)

    Li, Xueda; Shang, Chengjia; Ma, Xiaoping; Subramanian, S. V.

    Microstructure-property correlation of heat affected zone (HAZ) in X100 longitudinal submerged arc welding (LSAW) real weld joint was studied in this paper. Coarse grained (CG) HAZ and intercritically reheated coarse grained (ICCG) HAZ were characterized by optical microscope (OM), electron backscattered diffraction (EBSD). The microstructure of CGHAZ is mostly composed of granular bainite with low density of high angle boundaries (HAB). Prior austenite grain size is 80μm. In ICCGHAZ, coarse prior austenite grains were decorated by coarse necklacing martensite-austenite (M-A) constituents. Different layers were observed within M-A constituent, which may be martensite and austenite layers. Charpy absorbed energy of two different HAZ regions (ICCGHAZ containing and non-containing regions) was recorded using instrumental Charpy impact test machine. The results showed that the existence of ICCGHAZ resulted in the sharp drop of Charpy absorbed energy from 180J to 50J, while the existence of only CGHAZ could still lead to good toughness. The fracture surface was 60% brittle in the absence of ICCGHAZ, and 100% brittle in the presence of ICCGHAZ in the impact tested samples. The underlying reason is the microstructure of ICCGHAZ consisted of granular bainite and upper bainite with necklace-type M-A constituent along the grain boundaries. Cleavage fracture initiated from M-A constituent, either through cracking of M-A or debonding from the matrix, was observed at the fracture surface of ICCGHAZ. The presence of necklace type M-A constituent in ICCGHAZ notably increases the susceptibility of cleavage microcrack nucleation. Furthermore, the study of secondary microcracks beneath the CGHAZ and the ICCGHAZ through EBSD suggested that the fracture mechanism changes from nucleation-controlled in the CGHAZ to propagation-controlled in the ICCGHAZ because of the presence of necklace-type M-A constituent in the ICCGHAZ region. Both fracture mechanism contribute to the poor

  6. The effect of particle size on the heat affected zone during laser cladding of Ni-Cr-Si-B alloy on C45 carbon steel

    Science.gov (United States)

    Tanigawa, Daichi; Abe, Nobuyuki; Tsukamoto, Masahiro; Hayashi, Yoshihiko; Yamazaki, Hiroyuki; Tatsumi, Yoshihiro; Yoneyama, Mikio

    2018-02-01

    Laser cladding is one of the most useful surface coating methods for improving the wear and corrosion resistance of material surfaces. Although the heat input associated with laser cladding is small, a heat affected zone (HAZ) is still generated within the substrate because this is a thermal process. In order to reduce the area of the HAZ, the heat input must therefore be reduced. In the present study, we examined the effects of the powdered raw material particle size on the heat input and the extent of the HAZ during powder bed laser cladding. Ni-Cr-Si-B alloy layers were produced on C45 carbon steel substrates in conjunction with alloy powders having average particle sizes of 30, 40 and 55 μm, while measuring the HAZ area by optical microscopy. The heat input required for layer formation was found to decrease as smaller particles were used, such that the HAZ area was also reduced.

  7. HEAT RESISTANCE OF GRAPHITIZED STEEL

    Directory of Open Access Journals (Sweden)

    V. O. Savchenko

    2014-06-01

    Full Text Available Purpose. The investigation of temperature dependences of steels' mechanical properties and heat resistance under conditions of thermal cyclic loads. It's necessary to determine the mechanical properties and heat resistance indices of graphitized steels and cast iron VCh400 within the temperature range of 20…800°С. Methodology. Graphitized steels of the following chemical composition (mass %: 0.61…1.04C; 1.19…1.59%Si; 0.32…0.37%Mn; 0.12…0.17%Al; 0.008…0.014%S and 0.016…0.025%Р have been heat-treated according to the mode: heating up to 810°С – holding for 2 hours; cooling down to 680°С – holding for 2 hours with further cooling using the furnace in order to provide the ferrite-pearlite metallic base with graphite inclusions. In order to determine heat resistance indices (heat stresses index K and the material's resistance criterion at thermal cyclic load C the indices of graphitized steels' and cast irons' mechanical properties in the temperature range of 20…800°С have been investigated. Findings. It has been established that as a result of lower carbon content and smaller quantity of graphite inclusions, graphitized steel exceeds such indices of nodular cast iron VCh400 as: tensile strength and plasticity at room and high temperatures, and also heat resistance criteria K and C. This steel can be used to manufacture articles operating under conditions of thermal cyclic loads. Originality. Tensile strength and percent elongation of graphitized steels within the temperature range of 20…800°С have been determined. Calculations of heat resistance criteria to the heat stresses index K and the material's resistance criterion at thermal cyclic loads C within the temperature range 20…800°С in comparison with nodular cast iron of VCh400 grade have been carried out. Practical value. The expediency of using graphitized steel for manufacturing of articles operating under conditions of thermal cyclic loads has been shown.

  8. Identification of plasticity model parameters of the heat-affected zone in resistance spot welded martensitic boron steel

    NARCIS (Netherlands)

    Eller, Tom; Greve, L; Andres, M.T.; Medricky, M; Meinders, Vincent T.; van den Boogaard, Antonius H.; Merklein, M.

    2014-01-01

    A material model is developed that predicts the plastic behavior of fully hardened 22MnB5 base material and the heat-affected zone (HAZ) material found around its corresponding resistance spot welds (RSWs). Main focus will be on an accurate representation of strain fields up to high strains, which

  9. Plasticity and fracture modeling of the heat-affected zone in resistance spot welded tailor hardened boron steel

    NARCIS (Netherlands)

    Eller, Tom; Greve, L; Andres, M.T.; Medricky, M; Geijselaers, Hubertus J.M.; Meinders, Vincent T.; van den Boogaard, Antonius H.

    2016-01-01

    tFive hardness grades of 22MnB5 are considered, covering the full strength-range from 600 MPa in theferritic/pearlitic range to 1500 MPa in the fully hardened, martensitic state. These five grades form thebasis for a hardness-based material model for the heat-affected zone found around resistance

  10. Identification of plasticity model parameters of the heat-affected zone in resistance spot welded martensitic boron steel

    NARCIS (Netherlands)

    Eller, Tom; Greve, L; Andres, M.T.; Medricky, M; Meinders, Vincent T.; van den Boogaard, Antonius H.; Duflou, J.; Leacock, A.; Micari, F.; Hagenah, H.

    2015-01-01

    A material model is developed that predicts the plastic behaviour of fully hardened 22MnB5 base material and the heat-affected zone (HAZ) material found around its corresponding resistance spot welds (RSWs). Main focus will be on an accurate representation of strain fields up to high strains, which

  11. Effect of thermal and thermo-mechanical cycling on the boron segregation behavior in the coarse-grained heat-affected zone of low-alloy steel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sanghoon; Kang, Yongjoon; Lee, Changhee, E-mail: chlee@hanyang.ac.kr

    2016-06-15

    The boron segregation behavior in the coarse-grained heat-affected zone (CGHAZ) of 10 ppm boron-added low-alloy steel during the welding cycle was investigated by taking the changes in the microstructure and hardness into account. Various CGHAZs were simulated with a Gleeble system as a function of the heat input and external stress, and the boron segregation behavior was analyzed by secondary ion mass spectrometry (SIMS) and particle tracking autoradiography (PTA). The segregation of boron was found to initially increase, and then decrease with an increase in the heat input. This is believed to be due to the back-diffusion of boron with an increase in the exposure time at high temperature after non-equilibrium grain boundary segregation. The grain boundary segregation of boron could be decreased by an external stress applied during the welding cycle. Such behavior may be due to an increase in the grain boundary area as a result of the grain size reduction induced by the external stress. - Highlights: • Boron segregation behavior in the CGHAZ of low-alloy steel during a welding cycle was investigated. • Various CGHAZs were simulated with a Gleeble system as a function of the heat input and external stress. • Boron segregation behavior was analyzed using SIMS and PTA techniques.

  12. Factorial Analysis of Welding Current Influence on Heat Affected Zone Hardness of Cast Iron, Aluminium, and Mild Steel Weldments Cooled in Palm Oil

    Directory of Open Access Journals (Sweden)

    C. I. Nwoye

    2013-01-01

    Full Text Available Factorial analysis of heat affected zone hardness of some metals was evaluated. Three models were derived and used as tools for evaluating the welding current influence on the predictability of HAZ hardness in aluminium, cast iron, and mild steel weldments similarly cooled in palm oil. It was discovered that on welding these materials, and similarly cooling their respective weldments in palm oil, the model predicts aluminium weldment HAZ hardness by multiplying the determined general current product rule (GCPR with the ratio: HAZ hardness product of cast iron and mild steel/HAZ hardness sum of cast iron and mild steel . Computational analysis of experimental and model-predicted results indicates that aluminium, cast iron, and mild steel weldment HAZ hardness per unit welding current as evaluated from experiment and derived model are 3.3917, 4.8333, and 2.7944 and 3.3915, 4.8335, and 2.7946 (VHN A−1, respectively. Deviational analysis shows that the maximum deviation of model-predicted HAZ hardness from the experimental results is less than 0.007%. This invariably implies over 99.99 % confidence level for the derived models.

  13. Effect of Welding Thermal Cycles on Microstructure and Mechanical Properties of Simulated Heat Affected Zone for a Weldox 1300 Ultra-High Strength Alloy Steel

    Directory of Open Access Journals (Sweden)

    Węglowski M. St.

    2016-03-01

    Full Text Available In the present study, the investigation of weldability of ultra-high strength steel has been presented. The thermal simulated samples were used to investigate the effect of welding cooling time t8/5 on microstructure and mechanical properties of heat affected zone (HAZ for a Weldox 1300 ultra-high strength steel. In the frame of these investigation the microstructure was studied by light and transmission electron microscopies. Mechanical properties of parent material were analysed by tensile, impact and hardness tests. In details the influence of cooling time in the range of 2,5 ÷ 300 sec. on hardness, impact toughness and microstructure of simulated HAZ was studied by using welding thermal simulation test. The microstructure of ultra-high strength steel is mainly composed of tempered martensite. The results show that the impact toughness and hardness decrease with increase of t8/5 under condition of a single thermal cycle in simulated HAZ. The increase of cooling time to 300 s causes that the microstructure consists of ferrite and bainite mixture. Lower hardness, for t8/5 ≥ 60 s indicated that low risk of cold cracking in HAZ for longer cooling time, exists.

  14. Effect of Zr Addition on the Microstructure and Toughness of Coarse-Grained Heat-Affected Zone with High-Heat Input Welding Thermal Cycle in Low-Carbon Steel

    Science.gov (United States)

    Shi, Ming-hao; Yuan, Xiao-guang; Huang, Hong-jun; Zhang, Si

    2017-07-01

    Microstructures and toughness of coarse-grained heat-affected zone (CGHAZ) with high-heat input welding thermal cycle in Zr-containing and Zr-free low-carbon steel were investigated by means of welding thermal cycle simulation. The specimens were subjected to a welding thermal cycle with heat inputs of 100, 400, and 800 kJ cm-1 at peak temperature of 1673 K (1400 °C) using a thermal simulator. The results indicate that excellent impact toughness at the CGHAZ was obtained in Zr-containing steel. The Zr oxide is responsible for AF transformation, providing the nucleation site for the formation AF, promoting the nucleation of AF on the multi-component inclusions. High fraction of acicular ferrite (AF) appears in Zr-containing steel, acting as an obstacle to cleavage propagation due to its high-angle grain boundary. The morphology of M-A constituents plays a key role in impact toughness of CGHAZ. Large M-A constituents with lath form can assist the micro-crack initiation and seriously decrease the crack initiation energy. The relationship of AF transformation and M-A constituents was discussed in detail.

  15. Atom-Probe Tomographic Investigation of Austenite Stability and Carbide Precipitation in a TRIP-Assisted 10 Wt Pct Ni Steel and Its Weld Heat-Affected Zones

    Science.gov (United States)

    Jain, Divya; Seidman, David N.; Barrick, Erin J.; DuPont, John N.

    2018-01-01

    Newly developed low-carbon 10 wt pct Ni-Mo-Cr-V martensitic steels rely on the Ni-enriched, thermally stable austenite [formed via multistep intercritical Quench-Lamellarization-Tempering (QLT)-treatment] for their superior mechanical properties, specifically ballistic resistance. Critical to the thermal stability of austenite is its composition, which can be severely affected in the weld heat-affected zones (HAZs) and thus needs investigations. This article represents the first study of the nanoscale redistributions of C, Ni, and Mn in single-pass HAZ microstructures of QLT-treated 10 wt pct Ni steels. Local compositions of Ni-rich regions (representative of austenite compositions) in the HAZs are determined using site-specific 3-D atom-probe tomography (APT). Martensite-start temperatures are then calculated for these compositions, employing the Ghosh-Olson thermodynamic and kinetics approach. These calculations predict that austenite (present at high temperatures) in the HAZs is susceptible to a martensitic transformation upon cooling to room temperature, unlike the austenite in the QLT-treated base-metal. While C in the QLT-treated base-metal is consumed primarily in MC and M2C-type carbide precipitates (M is Mo, Cr, V), its higher concentration in the Ni-rich regions in the HAZs indicates the dissolution of carbide precipitates, particularly M2C carbide precipitates. The role of M2C carbide precipitates and austenite stability is discussed in relation to the increase in microhardness values observed in the HAZs, relative to the QLT-treated base-metal. Insights gained from this research on austenite stability and carbide precipitation in the single-pass HAZ microstructures will assist in designing multiple weld cycles for these novel 10 wt pct Ni steels.

  16. Microstructures and Mechanical Properties of Weld Metal and Heat-Affected Zone of Electron Beam-Welded Joints of HG785D Steel

    Science.gov (United States)

    Zhang, Qiang; Han, Jianmin; Tan, Caiwang; Yang, Zhiyong; Wang, Junqiang

    2016-12-01

    Vacuum electron beam welding (EBW) process was employed to butt weld 10-mm-thick HG785D high-strength steels. The penetration into the steel was adjusted by beam current. Microstructures at weld metal and heat-affected zone (HAZ) regions were comparatively observed. Mechanical properties of the EBWed joints including Vickers hardness, tensile and Charpy impact tests were evaluated. The results indicated that microstructures at the weld metal consisted of coarse lath martensite and a small amount of acicular martensite, while that in the HAZ was tempered sorbite and martensite. The grain size in the weld metal was found to be larger than that in the HAZ, and its proportion in weld metal was higher. The hardness in the weld metal was higher than the HAZ and base metal. The tensile strength and impact toughness in the HAZ was higher than that in the weld metal. All the behaviors were related to microstructure evolution caused by higher cooling rates and state of base metal. The fracture surfaces of tensile and impact tests on the optimized joint were characterized by uniform and ductile dimples. The results differed significantly from that obtained using arc welding process.

  17. Effects of heating and cooling rate on transformation behaviors in weld heat affected zone of low carbon steel; Teitanso koban no yosetsu netsu eikyobu no hentai kyodo ni oyobosu kanetsu reikyaku sokudo no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Kanetsuki, Y.; Katsumata, M. [Kobe Steel, Ltd., Kobe (Japan)

    1998-01-25

    Discussions were given on effects of welding heat cycles on transformation behaviors in a weld heat affected zone (HAZ). Test pieces are low-carbon fine ferrite pearlite organization steel sheets, which have been treated with a thermomechanical control process (TMCP). The heat cycling was experimented at a maximum temperature of 1350 degC by using a high-frequency heating coil, heating rates from 0.15 to 200 degC/s, cooling rates from 10 to 80 degC/s at an elevated temperature region (higher than 900 degC), and transformation regions (lower than 900 degC) from 0.5 to 6 degC. A transformation curve in actual welding heat cycling was interpreted from these results. Shear-type inverse transformation (from ferrite to austenite) occurs in a rate region corresponding to the heating rate realized during welding. Austenite containing internal stress and a lower structure formed by this inverse transformation accelerates transformation into grain boundary ferrite (GBF) and acerous ferrite (AF). On the other hand, slow cooling in the elevated temperature region releases the internal stress, restores the lower structure, and suppresses the GBF and AF transformation. The GBF tends to precipitate pearlite in adjacent regions and deteriorates the HAZ tenacity. 17 refs., 8 figs., 1 tab.

  18. Heat-affected zone and phase composition of 0.09 C-2 Mn-1 Si-Fe steel depending on welding technique

    Science.gov (United States)

    Popova, Natalya; Ozhiganov, Eugeniy; Nikonenko, Elena; Ababkov, Nikolay; Smirnov, Aleksander; Koneva, Nina

    2017-11-01

    The paper presents the transmission electron microscopy (TEM) investigations of the structure and phase composition of the heat-affected zone (HAZ) in welded joint modified by four types of welding, namely: electrode welding and electropercussive welding both with and without the introduction of artificial flaws. Artificial flows are aluminum pieces. TEM investigations are carried out within HAZ between the deposited and base metal at 1 mm distance to the latter. The type 0.09C-2Mn-1Si-Fe steel is used as weld material. It is shown that the welding process has an effect on the material morphology, phase composition, faulted structure and its parameters. Long-range stresses are divided into plastic and elastic components. It is demonstrated that the type of welding does not change the structural quality of welded joint represented by perlite and ferrite as contrasted with their volume fraction. According to observations, any type of welding with the introduction of artificial flaws results in the destruction of perlite. Polarization of the dislocation structure occurs. The amplitude of mean internal stresses does not practically depend on the welding type. It is shown that the introduction of artificial flaws both during electrode and electropercussive welding reduce the quantitative parameters of the faulted structure.

  19. Heat Treatment Procedure Qualification for Steel Castings

    Energy Technology Data Exchange (ETDEWEB)

    Mariol Charles; Nicholas Deskevich; Vipin Varkey; Robert Voigt; Angela Wollenburg

    2004-04-29

    Heat treatment practices used by steel foundries have been carefully studied as part of comprehensive heat treatment procedure qualification development trials. These studies highlight the relationships between critical heat treatment process control parameters and heat treatment success. Foundry heat treatment trials to develop heat treatment procedure qualifications have shed light on the relationship between heat treatment theory and current practices. Furnace load time-temperature profiles in steel foundries exhibit significant differences depending on heat treatment equipment, furnace loading practice, and furnace maintenance. Time-temperature profiles of furnace control thermocouples can be very different from the time-temperature profiles observed at the center of casting loads in the furnace. Typical austenitization temperatures and holding times used by steel foundries far exceed what is required for transformation to austenite. Quenching and hardenability concepts were also investigated. Heat treatment procedure qualification (HTPQ) schema to demonstrate heat treatment success and to pre-qualify other alloys and section sizes requiring lesser hardenability have been developed. Tempering success is dependent on both tempering time and temperature. As such, furnace temperature uniformity and control of furnace loading during tempering is critical to obtain the desired mechanical properties. The ramp-up time in the furnace prior to the establishment of steady state heat treatment conditions contributes to the extent of heat treatment performed. This influence of ramp-up to temperature during tempering has been quantified.

  20. Heat Treatment Procedure Qualification for Steel Castings

    Energy Technology Data Exchange (ETDEWEB)

    Voigt, Robert C. [Pennsylvania State Univ., University Park, PA (United States); Charles, Mariol [Pennsylvania State Univ., University Park, PA (United States); Deskevich, Nicholas [Pennsylvania State Univ., University Park, PA (United States); Varkey, Vipin [Pennsylvania State Univ., University Park, PA (United States); Wollenburg, Angela [Pennsylvania State Univ., University Park, PA (United States)

    2004-10-15

    Heat treatment practices used by steel foundries have been carefully studied as part of comprehensive heat treatment procedure qualification development trials. These studies highlight the relationships between critical heat treatment process control parameters and heat treatment success. Foundry heat treatment trials to develop heat treatment procedure qualifications have shed light on the relationship between heat treatment theory and current practices. Furnace load time-temperature profiles in steel foundries exhibit significant differences depending on heat treatment equipment, furnace loading practice, and furnace maintenance. Time-temperature profiles of furnace control thermocouples can be very different from the time-temperature profiles observed at the center of casting loads in the furnace. Typical austenitization temperatures and holding times used by steel foundries far exceed what is required for transformation to austenite. Quenching and hardenability concepts were also investigated. Heat treatment procedure qualification (HTPQ) schema to demonstrate heat treatment success and to pre-qualify other alloys and section sizes requiring lesser hardenability have been developed. Tempering success is dependent on both tempering time and temperature. As such, furnace temperature uniformity and control of furnace loading during tempering is critical to obtain the desired mechanical properties. The ramp-up time in the furnace prior to the establishment of steady state heat treatment conditions contributes to the extent of heat treatment performed. This influence of ramp-up to temperature during tempering has been quantified.

  1. Tempering-Induced Microstructural Changes in the Weld Heat-Affected Zone of 9 to 12 Pct Cr Steels and Their Influence on Sliding Wear

    Science.gov (United States)

    Velkavrh, Igor; Kafexhiu, Fevzi; Klien, Stefan; Diem, Alexander; Podgornik, Bojan

    2017-01-01

    Increasing amount of tribological applications is working under alternating high/low temperature conditions where the material is subjected to temperature fatigue mechanisms such as creep, softening due to annealing, and at the same time must withstand mechanical wear due to sliding contact with pairing bodies. Steam turbine valves, gate valves, valve heads, stems, seats and bushings, and contacting surfaces of the carrier elements are some examples of such applications. The purpose of the present study is to evaluate the potential of X20 and P91 steels as materials for applications operating under combined effect of mechanical wear and alternating high/low temperature conditions. It was focused on how the microstructural changes occurring in the weld zone affect the wear properties of the selected materials. Generally, with longer tempering time and higher tempering temperature, the number of carbide precipitates decreased, while their relative spacing increased. Before tempering, the morphology of the steel matrix (grain size, microstructure homogeneity) governed the wear resistance of both steels, while after tempering wear response was determined by the combination of the number and the size of carbide particles. After tempering, in X20 steel larger number of stable M23C6 carbides was observed as compared with P91 steel, resulting in lower wear rates. It was observed that for both steels, a similar combination of number density and size distribution of carbide particles provided the highest wear resistance.

  2. On the specific heat of carbon steels

    OpenAIRE

    Umino, Saburo

    2010-01-01

    The results of the pre:lent investigation may be summarized as follows: (1) The heat content of carbon steels at high temperatures was determined by the mixture method, while the oxidation of the specimen was prevented by passing a purified hydrogen gas through the furnace. The specimens were twelve kinds of steels with different carbon contents from 0.09 % to 2.84 % and the range of temperature was 23~250°C. (2) According to A. Meuthen, the specific heat is constant below the A1 point, but t...

  3. Improved Heat Treatment Of Steel Alloy 4340

    Science.gov (United States)

    Cooper, Lawrence B.

    1993-01-01

    New process takes significantly less time than prior heat-treatment processes. Involves placing steel plate directly in furnace and heat-treating. Plate then quenched in slowly moving oil to reduce stresses. Any deflection then pressed out. Possible uses of 4340 steel include new and improved bulletproof vests for military and police personnel and armor for bulletproof automobiles for military, police, diplomatic, and private users. Also used in other military land vehicles as tanks and in both military and civilian aircraft. Lighter armorplate enables land vehicles and aircraft to attain greater speed and maneuverability, consume less fuel, and afford better protection from snipers or terrorists.

  4. The Effect of Chemical Composition on Microstructure and Properties of Intercritically Reheated Coarse-Grained Heat-Affected Zone in X70 Steels

    Science.gov (United States)

    Zhu, Zhixiong; Kuzmikova, Lenka; Li, Huijun; Barbaro, Frank

    2013-12-01

    The current study investigates the effect of different levels of Ti, N, and Ti/N ratios on microstructure and properties in the intercritically reheated coarse-grained heat-affected zone (ICCGHAZ) of two-pass submerged arc welds in API 5L grade X70 pipe. Gleeble simulation was employed to reproduce the ICCGHAZ of actual welds. Hardness and Charpy V-notch (CVN) tests were performed on the simulated samples. The microstructure of simulated ICCGHAZ was characterized by optical microscopy and scanning electron microscopy (SEM). LePera color etching technique was employed to identify and quantify the martensitic-austenitic (M-A) constituent. Results show that the simulated ICCGHAZ exhibited extremely low toughness, but in the studied range of Ti and N, there was no correlation with Ti/N ratio. The beneficial effect of near-stoichiometric Ti/N ratio observed in coarse-grained heat-affected zone (CGHAZ) did not translate to ICCGHAZ. This was because of the negative effect of the blocky M-A constituent formed on prior austenite grain boundaries.

  5. Corrosion protection of steel in ammonia/water heat pumps

    Science.gov (United States)

    Mansfeld, Florian B.; Sun, Zhaoli

    2003-10-14

    Corrosion of steel surfaces in a heat pump is inhibited by adding a rare earth metal salt to the heat pump's ammonia/water working fluid. In preferred embodiments, the rare earth metal salt includes cerium, and the steel surfaces are cerated to enhance the corrosion-inhibiting effects.

  6. Process map for laser heat treatment of carbon steels

    Science.gov (United States)

    Ki, Hyungson; So, Sangwoo

    2012-10-01

    We propose a process map for diode-laser heat treatment of carbon steels. After first identifying a heat treatable region in terms of laser intensity and interaction time using a heat conduction model, two most important factors in heat treatment, carbon diffusion time in austenite and cooling time, are calculated and plotted in the heat treatable region. Because overall characteristics of laser heat treatment for a given steel type can be graphically visualized on a map, this map can be used in the determination of optimal process parameters. Hardening depth is also calculated using the concept of the critical effective carbon diffusion time. For demonstration and validation purposes, we have systematically conducted laser heat treatment on AISI 1020 and 1035 steel specimens using a 3 kW diode laser and measured surface hardness and hardening depth. The experimental results are in agreement with the calculated process map.

  7. Research on the mechanical, thermal, induction heating and healing properties of steel slag/steel fibers composite asphalt mixture

    NARCIS (Netherlands)

    Liu, Quantao; Li, Bin; Schlangen, H.E.J.G.; Sun, Yihan; Wu, Shaopeng

    2017-01-01

    In this paper, steel slag/steel fiber composite asphalt mixture were prepared. The effects of the addition of steel slag and/or steel fibers on the mechanical, thermal, induction heating and healing properties of asphalt mixture were investigated. The results showed that adding steel slag and/or

  8. Heat Treatment and Properties of Iron and Steel

    National Research Council Canada - National Science Library

    Digges, Thomas

    1966-01-01

    This monograph is a revision of the previous NBS Monograph 18. Its purpose is to provide an understanding of the heat treatment of iron and steels, principally to those unacquainted with this subject...

  9. The heat treatment of steel. A mathematical control problem

    Energy Technology Data Exchange (ETDEWEB)

    Hoemberg, Dietmar; Kern, Daniela

    2009-07-21

    The goal of this paper is to show how the heat treatment of steel can be modelled in terms of a mathematical optimal control problem. The approach is applied to laser surface hardening and the cooling of a steel slab including mechanical effects. Finally, it is shown how the results can be utilized in industrial practice by a coupling with machine-based control. (orig.)

  10. EFFECTS OF HEAT TREATMENTS ON MICROSTRUCTURES AND MECHANICAL PROPERTIES OF DUAL PHASE ODS STEELS FOR HIGH TEMPERATURE STRENGTH

    Directory of Open Access Journals (Sweden)

    SANGHOON NOH

    2013-11-01

    Full Text Available In the present study, the effects of various heat treatments on the microstructure and mechanical properties of dual phase ODS steels were investigated to enhance the high strength at elevated temperature. Dual phase ODS steels have been designed by the control of ferrite and austenite formers, i.e., Cr, W and Ni, C in Fe-based alloys. The ODS steels were fabricated by mechanical alloying and a hot isostatic pressing process. Heat treatments, including hot rolling-tempering and normalizing-tempering with air- and furnace-cooling, were carefully carried out. It was revealed that the grain size and oxide distributions of the ODS steels can be changed by heat treatment, which significantly affected the strengths at elevated temperature. Therefore, the high temperature strength of dual phase ODS steel can be enhanced by a proper heat treatment process with a good combination of ferrite grains, nano-oxide particles, and grain boundary sliding.

  11. New heat treatment process for advanced high-strength steels

    Science.gov (United States)

    Bublíková, D.; Jeníček, Š.; Vorel, I.; Mašek, B.

    2017-02-01

    Today’s advanced steels are required to possess high strength and ductility. It can be achieved by choosing an appropriate steel chemistry which has a substantial effect on the properties obtained by heat treatment. Mechanical properties influenced the presence of retained austenite in the final structure. Steels of this group typically require complicated heat treatment which places great demands on the equipment used. The present paper introduces new procedures aimed at simplifying the heat treatment of high-strength steels with the use of material-technological modelling. Four experimental steels were made and cast, whose main alloying additions were manganese, silicon, chromium, molybdenum and nickel. The steels were treated using the Q-P process with subsequent interrupted quenching. The resulting structure was a mixture of martensite and retained austenite. Strength levels of more than 2000 MPa combined with 10-15 % elongation were obtained. These properties thus offer potential for the manufacture of intricate closed-die forgings with a reduced weight. Intercritical annealing was obtained structure not only on the basis of martensite, but also with certain proportion of bainitic ferrite and retained austenite.

  12. Grain Refinement of Low Carbon Martensitic Steel by Heat Treatment

    Directory of Open Access Journals (Sweden)

    N. V. Kolebina

    2015-01-01

    Full Text Available The low-carbon steels have good corrosion and technological properties. Hot deformation is the main operation in manufacturing the parts from these steels. So one of the important properties of the material is a property of plasticity. The grain size significantly influences on the ductility properties of steel. The grain size of steel depends on the chemical composition of the crystallization process, heat treatment, and steel machining. There are plenty methods to have grain refinement. However, taking into account the large size of the blanks for the hydro turbine parts, the thermal cycling is an advanced method of the grain refinement adaptable to streamlined production. This work experimentally studies the heat treatment influence on the microstructure of the low-carbon 01X13N04 alloy steel and proposes the optimal regime of the heat treatment to provide a significantly reduced grain size. L.M. Kleiner, N.P. Melnikov and I.N. Bogachyova’s works focused both on the microstructure of these steels and on the influence of its parameters on the mechanical properties. The paper focuses mainly on defining an optimal regime of the heat treatment for grain refinement. The phase composition of steel and temperature of phase transformation were defined by the theoretical analysis. The dilatometric experiment was done to determine the precise temperature of the phase transformations. The analysis and comparison of the experimental data with theoretical data and earlier studies have shown that the initial sample has residual stress and chemical heterogeneity. The influence of the heat treatment on the grain size was studied in detail. It is found that at temperatures above 950 ° C there is a high grain growth. It is determined that the optimal number of cycles is two. The postincreasing number of cycles does not cause further reducing grain size because of the accumulative recrystallization process. Based on the results obtained, the thermal cycling

  13. intercritical heat treatments effects on low carbon steels quenched

    African Journals Online (AJOL)

    DR B. A. EZEKOYE

    of a duplex structure comprising hard particles embedded in a soft ferrite matrix, but then differ in the way the strain is partitioned between the phases. The purpose of this work was to investigate the effect of diverse intercritical heat treatments on the mechanical properties of six low carbon steels, containing carbon with the ...

  14. Thermoelectric System Absorbing Waste Heat from a Steel Ladle

    Science.gov (United States)

    Lu, Baiyi; Meng, Xiangning; Zhu, Miaoyong; Suzuki, Ryosuke O.

    2018-01-01

    China's iron and steel industry has made great progress in energy savings and emission reductions with the application of many waste heat recovery technologies. However, most of the medium and low temperature waste heat and radiant waste heat has not been effectively utilized. This paper proposes a thermoelectric system that generates electricity by absorbing the radiant heat from the surface of steel ladles in a steel plant. The thermoelectric behavior of modules in this system is analyzed by a numerical simulation method. The effects of external resistance and module structure on thermoelectric performance are also discussed in the temperature range of the wall surface of a steel ladle. The results show that the wall temperature has a significant influence on the thermoelectric behavior of the module, so its uniformity and stability should be considered in practical application. The ratio of the optimum external resistance to the internal resistance of the thermoelectric module is in the range of 1.6-2.0, which indicates the importance of external load optimization for a given thermoelectric system. In addition, the output power and the conversion efficiency of the module can be significantly improved by increasing the length of the thermoelectric legs and adopting a double-layer structure. Finally, through the optimization of external resistance and structure, the power output can reach 83-304 W/m2. This system is shown to be a promising approach for energy recovery.

  15. Modelling of induction heating of carbon steel tubes: Mathematical analysis, numerical simulation and validation

    Energy Technology Data Exchange (ETDEWEB)

    Di Luozzo, N. [Laboratorio de Solidos Amorfos, INTECIN, Facultad de Ingenieria, Universidad de Buenos Aires - CONICET, Paseo Colon 850, C1063ACV Buenos Aires (Argentina); Fontana, M., E-mail: mfontan2006@gmail.com [Laboratorio de Solidos Amorfos, INTECIN, Facultad de Ingenieria, Universidad de Buenos Aires - CONICET, Paseo Colon 850, C1063ACV Buenos Aires (Argentina); Arcondo, B. [Laboratorio de Solidos Amorfos, INTECIN, Facultad de Ingenieria, Universidad de Buenos Aires - CONICET, Paseo Colon 850, C1063ACV Buenos Aires (Argentina)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Numerical simulations of the heating by induction in steel tubes were performed. Black-Right-Pointing-Pointer Finite element method was employed in this electromagnetic-heat transfer coupled problem. Black-Right-Pointing-Pointer The outside temperature evolution of the steel tubes was determined experimentally and numerically. Black-Right-Pointing-Pointer Temperatures in the inner and outer tube surface and the heat affected zone were determined. - Abstract: The transient liquid phase bonding process is been performed to join carbon steel tubes. Fe{sub 96.2}B{sub 3.8} wt% amorphous ribbons of thickness a Almost-Equal-To 20 {mu}m have been employed as filler material. The tubes are aligned with their butted surfaces in contact with the amorphous layer. The joint is heated into a high frequency induction coil under Argon atmosphere. The temperature is raised at the highest possible rate to the process temperature (at about Almost-Equal-To 1250 Degree-Sign C) and then held for a predetermined time. In this paper, the numerical simulations of the heating stage of the bonding process have been made using the finite element method. This method had shown of being able to deal with these kind of coupled problems: electromagnetic field generated by alternating currents, eddy currents generated on the steel tube, heating of the steel tube due to joule effect and heat transfer by conduction, convection and radiation. The experimental heating stage, for its further simulation, was done with carbon steel tubes. In particular, we are interested in the temperature evolution of the tube upon heating: time to reach the process temperature at the joint, temperature differences between the inner and outer surface of the tube and the extension of the heat affected zone, taking into account the ferromagnetic-paramagnetic transition. The numerical simulations are validated by comparison with infrared radiation thermometer measurements of the

  16. Development of High Heat Input Welding Offshore Steel as Normalized Condition

    Science.gov (United States)

    Deng, Wei; Qin, Xiaomei

    The heavy plate used for offshore structure is one of the important strategic products. In recent years, there is an increasing demand for heavy shipbuilding steel plate with excellent weldability in high heat input welding. During the thermal cycle, the microstructure of the heat affected zone (HAZ) of plates was damaged, and this markedly reduced toughness of HAZ. So, how to improve the toughness of HAZ has been a key subject in the fields of steel research. Oxide metallurgy is considered as an effective way to improve toughness of HAZ, because it could be used to retard grain growth by fine particles, which are stable at the high temperature.The high strength steel plate, which satisfies the low temperature specification, has been applied to offshore structure. Excellent properties of the plates and welded joints were obtained by oxide metallurgy technology, latest controlled rolling and accelerated cooling technology using Ultra-Fast Cooling (an on-line accelerated cooling system). The 355MPa-grade high strength steel plates with normalizing condition were obtained, and the steels have excellent weldability with heat input energy of 79 287kJ/cm, and the nil ductility transition (NDT) temperature was -70°C, which can satisfy the construction of offshore structure in cold regions.

  17. Studying microstructure of heat resistant steel deoxidized by barium ferrosilicon

    Directory of Open Access Journals (Sweden)

    A. Z. Issagulov

    2016-07-01

    Full Text Available The paper examined the nature and distribution of non-metallic inclusions in the heat-resistant steel 12H1MF (0,12 % С, 1 % Сr, 0,5 - 0,6 Mo, 0,5 % V, ferrosilicobarim. As a reference, used by steel, deoxidized silicon. Melting was carried out in a laboratory, research-metallic inclusions, their shape and distribution, pollution index were studied according to conventional methods. Studies have shown that ferrosilicobarim deoxidation in an amount of 0,1 - 0,2 %, reduce the overall pollution index of non-metallic inclusions and change the nature of their distribution.

  18. The Development and Microstructure Analysis of High Strength Steel Plate NVE36 for Large Heat Input Welding

    Science.gov (United States)

    Peng, Zhang; Liangfa, Xie; Ming, Wei; Jianli, Li

    In the shipbuilding industry, the welding efficiency of the ship plate not only has a great effect on the construction cost of the ship, but also affects the construction speed and determines the delivery cycle. The steel plate used for large heat input welding was developed sufficiently. In this paper, the composition of the steel with a small amount of Nb, Ti and large amount of Mn had been designed in micro-alloyed route. The content of C and the carbon equivalent were also designed to a low level. The technology of oxide metallurgy was used during the smelting process of the steel. The rolling technology of TMCP was controlled at a low rolling temperature and ultra-fast cooling technology was used, for the purpose of controlling the transformation of the microstructure. The microstructure of the steel plate was controlled to be the mixed microstructure of low carbon bainite and ferrite. Large amount of oxide particles dispersed in the microstructure of steel, which had a positive effects on the mechanical property and welding performance of the steel. The mechanical property of the steel plate was excellent and the value of longitudinal Akv at -60 °C is more than 200 J. The toughness of WM and HAZ were excellent after the steel plate was welded with a large heat input of 100-250 kJ/cm. The steel plate processed by mentioned above can meet the requirement of large heat input welding.

  19. Effects of heat input on mechanical properties of metal inert gas welded 1.6 mm thick galvanized steel sheet

    Science.gov (United States)

    Rafiqul, M. I.; Ishak, M.; Rahman, M. M.

    2012-09-01

    It is usually a lot easier and less expensive to galvanize steel before it is welded into useful products. Galvanizing afterwards is almost impossible. In this research work, Galvanized Steel was welded by using the ER 308L stainless steel filler material. This work was done to find out an alternative way of welding and investigate the effects of heat input on the mechanical properties of butt welded joints of Galvanized Steel. A 13.7 kW maximum capacity MIG welding machine was used to join 1.6 mm thick sheet of galvanized steel with V groove and no gap between mm. Heat inputs was gradually increased from 21.06 to 25.07 joules/mm in this study. The result shows almost macro defects free welding and with increasing heat input the ultimate tensile strength and welding efficiency decrease. The Vickers hardness also decreases at HAZ with increasing heat input and for each individual specimen; hardness was lowest in heat affected zone (HAZ), intermediate in base metal and maximum in welded zone. The fracture for all specimens was in the heat affected zone while testing in the universal testing machine.

  20. Tribological Response of Heat Treated AISI 52100 Steels Against Steel and Ceramic Counterparts

    Directory of Open Access Journals (Sweden)

    Türedi E.

    2017-09-01

    Full Text Available AISI 52100 bearing steels are commonly used in applications requiring high hardness and abrasion resistance. The bearing steels are working under dynamic loads in service conditions and their toughness properties become important. In order to provide the desired mechanical properties, various heat treatments (austenizing, quenching and tempering are usually applied. In this study, AISI 52100 bearing steel samples were austenized at 900°C for ½ h and water quenched to room temperature. Then tempering was carried out at 795°C, 400°C and 200°C for ½ h. In order to investigate the effect of heat treatment conditions on wear behavior, dry friction tests were performed according to ASTM G99-05 Standard with a ‘ball-on-disk’ type tribometer. The samples were tested against steel and ceramic counterparts using the parameters of 100 m distance and 30 N load and 0.063 m/s rotational speed. After wear test, the surface characterization was carried out using microscopy. Wear loss values were calculated using a novel optical method on both flat and counterpart specimens.

  1. Numerical prediction of heat affected zone (HAZ) grain refinement for multiples weld-beads deposits during SMAW welding process of Cr-Mo-V steel; Prediccion numerical del afino de los granos en la zona afectada por la temperature (ZAC) para aportes de multipasadas durante el proceso de soldeo SMAW en el acero al Cr-Mo-V

    Energy Technology Data Exchange (ETDEWEB)

    Mazur, Z.; Gonzalez, G.; Urquiza, G.; Salazar, O.; Marino, C.; Hernandez, A.

    2002-07-01

    The methodology of prediction of the heat-affected zone (HAZ) microstructure in a multiple-bead wields of the two layers of 1.25 Cr-1 Mo-0.25V steel using SMAW deposition process is presented. A computer program was developed to calculate extension zones of interest of two layer multipass weld-beads HAZ and predict a percentage of HAZ coarse grains refinement for determined welding parameters, preheating temperature and weld bead overlap. The computer model has been validated by experiment depositing a series of two-year weld-beads getting reasonable concordance of model prediction and measured during experiment structural HAZ distribution. (Author) 5 refs.

  2. Heat-to-heat variation of tensile properties of annealed 2 1/4 Cr-1 Mo steel

    Energy Technology Data Exchange (ETDEWEB)

    Klueh, R. L.

    1977-07-01

    The tensile properties of twelve heats of 2/sup 1///sub 4/ Cr-1 Mo steel were examined over the range 25 to 566/sup 0/C. The twelve heats included: five air-melted tubing heats, two pieces from vacuum-arc remelted (VAR) forgings, two pieces from electroslag remelted (ESR) plates, two air-melted plates, and one air-melted forging. Tests were made on the steel in the as-received condition (vendor anneal) and, in order that all heats could be compared from a common basis, material from each of the heats was tested after it was annealed in our laboratory. For the twelve heats of steel tested, large property variations were observed. Decided differences were noted between the air-melted tubing, the air-melted plates and forging, and the ESR and VAR steels. Explanations for these differences are offered in terms of the types of precipitation reactions that occur in these steels at elevated temperatures.

  3. Creep rupture properties of P122 and P92 steel HAZs simulated by heat treatments and by a weld simulator

    Energy Technology Data Exchange (ETDEWEB)

    Albert, S.K. [IGCAR, Kalpakkam (India); Matsui, M. [Mitsubushi Heavy Industries, Nagasaki (Japan); Watanabe, T.; Hongo, H.; Kubo, K.; Tabuchi, M. [National Inst. for Materials Science, Ibaraki (Japan)

    2002-07-01

    In the present study, creep rupture properties of the heat affected zones (HAZs) of P122 and P92 steels, simulated by a heat treatments and by a weld simulator, are studied and compared with those of the actual weld joint. Specimen blanks cut out from steel plates were heated to different peak temperatures that corresponds to intercritical HAZ (ICHAZ), fine grained HAZ (FGHAZ) and coarse grained HAZ (CGHAZ) both by heat treatment and by employing a weld simulator. These were then subjected to post weld heat treatment (PWHT) and creep specimens prepared from these blanks were tested at 923 K for various stress levels. Microstructure was uniform for the specimens with HAZ simulated by heat treatment while for those produced by weld simulator, the uniform microstructures corresponding to the peak temperature of simulation was confined to only {proportional_to}10 mm at the center of the specimens. (orig.)

  4. THE HEAT TREATMENT ANALYSIS OF E110 CASE HARDENING STEEL

    Directory of Open Access Journals (Sweden)

    MAJID TOLOUEI-RAD

    2016-03-01

    Full Text Available This paper investigates mechanical and microstructural behaviour of E110 case hardening steel when subjected to different heat treatment processes including quenching, normalizing and tempering. After heat treatment samples were subjected to mechanical and metallographic analysis and the properties obtained from applying different processes were analysed. The heat treatment process had certain effects on the resultant properties and microstructures obtained for E110 steel which are described in details. Quenching produced a martensitic microstructure characterized by significant increase in material’s hardness and a significant decreased in its impact energy. Annealed specimens produced a coarse pearlitic microstructure with minimal variation in hardness and impact energy. For normalized samples, fine pearlitic microstructure was identified with a moderate increase in hardness and significant reduction in impact energy. Tempering had a significant effect on quenched specimens, with a substantial rise in material ductility and reduction of hardness with increasing tempering temperature. Furthermore, Results provide additional substantiation of temper embrittlement theory for low-carbon alloys, and indicate potential occurrence of temper embrittlement for fine pearlitic microstructures.

  5. The Micro-hardness of Heat Treated Carbon Steel

    OpenAIRE

    Petrík, Jozef

    2014-01-01

    The aim of the submitted work is to study the influence of applied loads ranging from 0.09807 N to 0.9807 N on measured values of micro-hardness of heat treated carbon steel. The influence of applied load on measured value of micro-hardness was evaluated by Meyer’s index n, PSR method and by Analysis of Variance (ANOVA). The influence of the load on the measured value of micro-hardness is statistically significant and the relationship between applied load and micro-hardness manifests the mode...

  6. Versatile and Rapid Plasma Heating Device for Steel and Aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, G.S.

    2006-03-14

    The main objective of the research was to enhance steel and aluminum manufacturing with the development of a new plasma RPD device. During the project (1) plasma devices were manufactured (2) testing for the two metals were carried out and (3) market development strategies were explored. Bayzi Corporation has invented a Rapid Plasma Device (RPD) which produces plasma, comprising of a mixture of ionized gas and free electrons. The ions, when they hit a conducting surface, deposit heat in addition to the convective heat. Two generic models called the RPD-Al and RPD-S have been developed for the aluminum market and the steel market. Aluminum melting rates increased to as high as 12.7 g/s compared to 3 g/s of the current industrial practice. The RPD melting furnace operated at higher energy efficiency of 65% unlike most industrial processes operating in the range of 13 to 50%. The RPD aluminum melting furnace produced environment friendly cleaner melts with less than 1% dross. Dross is the residue in the furnace after the melt is poured out. Cast ingots were extremely clean and shining. Current practices produce dross in the range of 3 to 12%. The RPD furnace uses very low power ~0.2 kWh/Lb to melt aluminum. RPDs operate in one atmosphere using ambient air to produce plasma while the conventional systems use expensive gases like argon, or helium in air-tight chambers. RPDs are easy to operate and do not need intensive capital investment. Narrow beam, as well as wide area plasma have been developed for different applications. An RPD was developed for thermal treatments of steels. Two different applications have been pursued. Industrial air hardening steel knife edges were subjected to plasma beam hardening. Hardness, as measured, indicated uniform distribution without any distortion. The biggest advantage with this method is that the whole part need not be heated in a furnace which will lead to oxidation and distortion. No conventional process will offer localized

  7. Effect of Post-weld Heat Treatment on the Mechanical Properties of Supermartensitic Stainless Steel Deposit

    Science.gov (United States)

    Zappa, Sebastián; Svoboda, Hernán; Surian, Estela

    2017-02-01

    Supermartensitic stainless steels have good weldability and adequate tensile property, toughness and corrosion resistance. They have been developed as an alternative technology, mainly for oil and gas industries. The final properties of a supermartensitic stainless steel deposit depend on its chemical composition and microstructure: martensite, tempered martensite, ferrite, retained austenite and carbides and/or nitrides. In these steels, the post-weld heat treatments (PWHTs) are usually double tempering ones, to ensure both complete tempering of martensite and high austenite content, to increase toughness and decrease hardness. The aim of this work was to study the effect of post-weld heat treatments (solution treatment with single and double tempering) on the mechanical properties of a supermartensitic stainless steel deposit. An all-weld metal test coupon was welded according to standard ANSI/AWS A5.22-95 using a GMAW supermartensitic stainless steel metal cored wire, under gas shielding. PWHTs were carried out varying the temperature of the first tempering treatment with and without a second tempering one, after solution treatment. All-weld metal chemical composition analysis, metallurgical characterization, hardness and tensile property measurements and Charpy-V tests were carried out. There are several factors which can be affected by the PWHTs, among them austenite content is a significant one. Different austenite contents (0-42%) were found. Microhardness, tensile property and toughness were affected with up to 15% of austenite content, by martensite tempering and carbide precipitation. The second tempering treatment seemed not to have had an important effect on the mechanical properties measured in this work.

  8. Study on stress corrosion of the zone affected by the AISI 316L steel heat under PWR reactor environment at 325 deg Celsius; Estudo da corrosao sob tensao da zona afetada pelo calor do aco AISI 316L em ambiente de reator PWR a 325 deg C

    Energy Technology Data Exchange (ETDEWEB)

    Satler Filho, Luiz F.; Schvartzman, Monica M.A.M.; Quinan, Marco A.D.; Soares, Antonio E.G., E-mail: aegs@cdtn.b, E-mail: fernandosatler@yahoo.com.b, E-mail: quinanm@cdtn.b, E-mail: monicas@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Lima, Luciana I.L., E-mail: lill@cdtn.b [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil)

    2009-07-01

    This paper evaluates the stress corrosion susceptibility of the HAZ (heat affected zone) of the AISI 316L stainless steel of a dissimilar welding done between the ASTM A-508 steel and the AISI 316L steel, using a nickel alloy, under a chemical environment similar to the PWR (Pressurized Water Reactor) nuclear reactor primary circuit. The nickel 82 and 182 alloys were used in the GTAW (Gas Tungsten Arc Welding) and SMAW (Shielded Metal Arc Welding) processes respectively. The test at slow deformation - SSRT (Slow Strain Rate Test) was applied, using a deformation rate of 3x10{sup -7} s{sup -1}, at a temperature of 325 degree Celsius and pressure of 12.5 MPa. The susceptibility under tress corrosion evaluation was performed comparing the resistance limit, the total deformation and the fracture time obtained at the inert medium (nitrogen) and at the PWR medium. Also, the fracture surfaces were observed under a scanning electron microscope, verifying the fragile fracture regions

  9. Analysis of High-Power Diode Laser Heating Effects on HY-80 Steel for Laser Assisted Friction Stir Welding Applications

    Energy Technology Data Exchange (ETDEWEB)

    Wiechec, Maxwell; Baker, Brad; McNelley, Terry; Matthews, Manyalibo; Rubenchik, Alexander; Rotter, Mark; Beach, Ray; Wu, Sheldon

    2017-01-01

    In this research, several conditions of high power diode laser heated HY-80 steel were characterized to determine the viability of using such lasers as a preheating source before friction stir welding in order to reduce frictional forces thereby reducing tool wear and increasing welding speeds. Differences in microstructures within heat affected zones were identified at specific laser powers and traverse speeds. Vickers hardness values were recorded and analyzed to validate the formation of additional martensite in diode laser heated regions of HY-80 steel. Conditions that produced little to no additional martensite were identified and relationships among high power diode laser power, traverse speed, and martensite formation were determined. The development of heat affected zones, change in grain structure, and creation of additional martensite in HY-80 can be prevented through the optimization of laser amperage and transverse speed.

  10. STRUCTURE FORMATION OF HYPOEUTECTOID CONSTRUCTIONS STEELS AT CARBONITRIDING WITH LOCAL INDUCTION CYCLIC HEATING

    Directory of Open Access Journals (Sweden)

    G. A. Tkachenko

    2010-01-01

    Full Text Available Improvement of mechanical characteristics of details of the soil-cultivating car. Structurization at cyclic heating of steels. The reasons of an intensification of diffusion at cyclic heating. Structure crushing, impact strength and hardness increase.

  11. A Novel Heat Treatment Process for Surface Hardening of Steel: Metal Melt Surface Hardening

    Science.gov (United States)

    Fu, Yong-sheng; Zhang, Wei; Xu, Xiaowei; Li, Jiehua; Li, Jun; Xia, Mingxu; Li, Jianguo

    2017-09-01

    A novel heat treatment process for surface hardening of steel has been demonstrated and named as "metal melt surface hardening (MMSH)." A surface layer with a thickness of about 400 μm and a hardness of about 700 HV has been achieved by ejecting AISI 304 stainless steel melt at a temperature of about 1783 K (1510 °C) onto the 40Cr steel surface. This proposed MMSH provides a very promising application for surface hardening of steel.

  12. Elemental distribution inside a heat treated stainless steel weld.

    CERN Multimedia

    2017-01-01

    The video shows the elemental distribution of Molybdenum (red), Manganese (green) and Chromium (blue) within a 20 μm × 20 μm × 20 μm region of a heat treated stainless steel weld. This data has been collected using 3D Focused Ion Beam Milling and Energy Dispersive X-ray Spectroscopy, an elemental characterisation analysis technique. High resolution (75 nm voxel size) mapping is necessary to gain insight into the distribution of regions with distinct elemental composition (phases), which are shown in purple (sigma) and yellow (delta ferrite) in the video. These features have important implications for the toughness and the magnetic properties of the weld, especially at cryogenic temperatures. The video shows the individual slices which were collected in a direction perpendicular to the weld bead direction, followed by a 3D representation of the gauge volume.

  13. The Micro-hardness of Heat Treated Carbon Steel

    Directory of Open Access Journals (Sweden)

    Jozef PETRÍK

    2014-04-01

    Full Text Available The aim of the submitted work is to study the influence of applied loads ranging from 0.09807 N to 0.9807 N on measured values of micro-hardness of heat treated carbon steel. The influence of applied load on measured value of micro-hardness was evaluated by Meyer’s index n, PSR method and by Analysis of Variance (ANOVA. The influence of the load on the measured value of micro-hardness is statistically significant and the relationship between applied load and micro-hardness manifests the moderate reverse ISE. As far as the relationship between measured hardness and load independent “true hardness”, the best fit was obtained between HV0.05 and “true hardness” calculated using index a2.DOI: http://dx.doi.org/10.5755/j01.ms.20.1.4017

  14. Study on Spheroidization and Related Heat Treatments of Medium Carbon Alloy Steels

    Directory of Open Access Journals (Sweden)

    Harisha S. R.

    2018-01-01

    Full Text Available The importance of medium carbon steels as engineering materials is reflected by the fact that out of the vast majority of engineering grade ferrous alloys available and used in the market today, a large proportion of them are from the family of medium carbon steels. Typically medium carbon steels have a carbon range of 0.25 to 0.65% by weight, and a manganese content ranging from 0.060 to 1.65% by weight. Medium carbon steels are more resistive to cutting, welding and forming as compared to low carbon steels. From the last two decades a number of research scholars reported the use of verity of heat treatments to tailor the properties of medium carbon steels. Spheroidizing is the novel industrial heat treatment employed to improve formability and machinability of medium/high carbon low alloy steels. This exclusive study covers procedure, the effects and possible outcomes of various heat treatments on medium carbon steels. In the present work, other related heat treatments like annealing and special treatments for property alterations which serve as pretreatments for spheroidizing are also reviewed. Medium carbon steels with property alterations by various heat treatment processes are finding increased responsiveness in transportation, aerospace, space, underwater along with other variegated fields. Improved tribological and mechanical properties consisting of impact resistance, stiffness, abrasion and strength are the main reasons for the increased attention of these steels in various industries. In the present scenario for the consolidation of important aspects of various heat treatments and effects on mechanical properties of medium carbons steel, a review of different research papers has been attempted. This review may be used as a guide to provide practical data for heat treatment industry, especially as a tool to enhance workability and tool life.

  15. Tribological Examination of Different Steel Materials after Special Heat Treatment and Salt Bath Nitriding

    Directory of Open Access Journals (Sweden)

    Opaliński M.

    2016-12-01

    Full Text Available The main aim of the presented research was examination of new tribological pairs made of different types of steel. Materials of disc probes were submitted to unusual heat treatment processes and salt bath nitriding. The research is focused on the friction coefficients and mass losses of the material probes. Based on the results it was noticed that the best wear resistant pair was bearing steel 100Cr6 coupled with high speed steel S705. The lowest friction coefficient appeared for the pair bearing steel 100Cr6 and maraging steel C350.

  16. Heat Generation and Transfer Behaviors of Ti-Coated Carbon Steel Rod Adaptable for Ablation Therapy of Oral Cancer

    OpenAIRE

    Yuji Watanabe; Shinya Matsutomo; Hideyuki Hirazawa; Hiromichi Aono; Tsunehiro Maehara; Takashi Naohara

    2013-01-01

    For the purpose of developing a novel ablation therapy for oral cancer, the heat generation and transfer properties of a Ti-coated carbon steel rod with 20-mm length and 1.8-mm outer diameter were investigated by means of a high-frequency induction technique at 300 kHz. The heat generation measurement performed using water (15 mL) revealed that the difference of the inclination angles (θ = 0°, 45° and 90°) relative to the magnetic flux direction only slightly affects the heating behavior, exh...

  17. Heat treated 9 Cr-1 Mo steel material for high temperature application

    Energy Technology Data Exchange (ETDEWEB)

    Jablonski, Paul D.; Alman, David; Dogan, Omer; Holcomb, Gordon; Cowen, Christopher

    2012-08-21

    The invention relates to a composition and heat treatment for a high-temperature, titanium alloyed, 9 Cr-1 Mo steel exhibiting improved creep strength and oxidation resistance at service temperatures up to 650.degree. C. The novel combination of composition and heat treatment produces a heat treated material containing both large primary titanium carbides and small secondary titanium carbides. The primary titanium carbides contribute to creep strength while the secondary titanium carbides act to maintain a higher level of chromium in the finished steel for increased oxidation resistance, and strengthen the steel by impeding the movement of dislocations through the crystal structure. The heat treated material provides improved performance at comparable cost to commonly used high-temperature steels such as ASTM P91 and ASTM P92, and requires heat treatment consisting solely of austenization, rapid cooling, tempering, and final cooling, avoiding the need for any hot-working in the austenite temperature range.

  18. Effect of Heat Input on Microstructure and Hardness Distribution of Laser Welded Si-Al TRIP-Type Steel

    Directory of Open Access Journals (Sweden)

    Adam Grajcar

    2014-01-01

    Full Text Available This study is concerned with issues related to laser welding of Si-Al type TRIP steels with Nb and Ti microadditions. The tests of laser welding of thermomechanically rolled sheet sections were carried out using keyhole welding and a solid-state laser. The tests carried out for various values of heat input were followed by macro- and microscopic metallographic investigations as well as by microhardness measurements of welded areas. A detailed microstructural analysis was carried out in the penetration area and in various areas of the heat affected zone (HAZ. Special attention was paid to the influence of cooling conditions on the stabilisation of retained austenite, the most characteristic structural component of TRIP steels. The tests made it possible to determine the maximum value of heat input preventing the excessive grain growth in HAZ and to identify the areas of the greatest hardness reaching 520 HV0.1.

  19. Effects of heat input rates on T-1 and T-1A steel welds

    Science.gov (United States)

    Davis, R. A.; Olsen, M. G.; Worden, S. W.

    1967-01-01

    Technology of T-1 and T-1A steels is emphasized in investigation of their weld-fabrication. Welding heat input rate, production weldment circumstances, and standards of welding control are considered.

  20. Heat Treatment and Properties of Iron and Steel

    Science.gov (United States)

    1966-11-01

    piece of a carbon or low- alloy steel in the low temperature range used for tempering from the color of the thin oxide film that forms on the cleaned... Carbonitriding 16 d. Nitriding : IQ 5.6. Surface hardening 17 a. Induction hardening 17 b. Flame hardening 17 5.7. Special treatments 17 a...steels and in cast irons. These are manganese, silicon , phosphorus, and sulfur. Steels may be broadly classified into two types, (1) carbon and (2

  1. Phase Change Predictions for Liquid Fuel in Contact with Steel Structure using the Heat Conduction Equation

    OpenAIRE

    Brear, D. J.

    1998-01-01

    When liquid fuel makes contact with steel structure the liquid can freeze as a crust and the structure can melt at the surface. The melting and freezing processes that occur can influence the mode of fuel freezing and hence fuel relocation. Furthermore the temperature gradients established in the fuel and steel phases determine the rate at which heat is transferred from fuel to steel. In this memo the 1-D transient heat conduction equations are applied to the case of initially liquid UO2 brou...

  2. Studies of the properties of heat treated rolled medium carbon steel

    Directory of Open Access Journals (Sweden)

    Daramola O. Oluyemi

    2011-01-01

    Full Text Available Investigations were carried out to study critically the effects of heat treatment on the properties of rolled medium carbon steel. Representative samples of as-rolled medium carbon steel were subjected to heat treatment processes which are; Quenching, Lamellae Formation and Tempering in the following order (Q + Q + L + T, (Q + L + T and (L + T. The steel was heated to the austenizing temperature of 830 ºC and water quenched. The quenched steel was subjected to lamellae formation by reheating it to the ferrite-austenite dual-phase region at a temperature of 745 ºC below the effective A C3 point and then rapidly quenched in water. The lamellae formed was tempered at 480 ºC to provide an alloy containing strong, tough and lath martensite in a soft and ductile ferrite matrix. Mechanical tests were carried out on the samples and the results shows that the steel developed has excellent combination of tensile strength, hardness and impact strength which is very good for structural applications. The corrosion behaviour of the samples; heat treated rolled medium carbon steel and as-rolled medium carbon steel in sodium chloride medium were also investigated from where it was also confirmed that improved corrosion resistance is achievable by the treatment.

  3. Effect of Intercritical Heat Treatment on Mechanical Properties of Reinforcing Steel Bars

    Directory of Open Access Journals (Sweden)

    MUHAMMAD ISHAQUE ABRO

    2017-07-01

    Full Text Available Intercritical heat treatments attempts were made to enhance the mechanical properties of reinforcing steel bars milled from scrap metal. For this, two grades of steel bars were obtained from different steel mills and their mechanical properties that include hardness, ultimate tensile strength, and percent elongation before and after intercritical heat treatment were determined. Results indicated that 25.5 and 17.6%, improvements in UTS (Ultimate Tensile Strength and 18.8 and 14.3% improvement in percent elongation in two grades of reinforcing steel samples containing 0.17 and 0.24% carbon respectively was achieved while heating at 750oC for 2h. Appreciable improvement in the mechanical properties was noted due to birth of sufficient quantity of martensite along with ferrite

  4. The efficacy of radiant heat controls on workers' heat stress around the blast furnace of a steel industry.

    Science.gov (United States)

    Giahi, Omid; Darvishi, Ebrahim; Aliabadi, Mohsen; Khoubi, Jamshid

    2015-01-01

    Workers' exposure to excessive heat in molten industries is mainly due to radiant heat from hot sources. The aim of this study was to evaluate the efficacy of radiant heat controls on workers heat stress around a typical blast furnace. Two main interventions were applied for reducing radiant heat around the blast furnace of a steel industry located in western Iran. These included using a heat absorbing system in the furnace body and installing reflective aluminum barrier in the main workstation. Heat stress indexes were measured before and after each intervention using the digital WBGT-meter. The results showed MRT and WBGT indexes decreased by 20 °C and 3.9 °C, respectively after using heat absorbing system and also decreased by 18.6 °C and 2.5 °C, respectively after installing a reflective barrier. These indexes decrease by 26.5 °C and 5.2 °C, respectively due to the simultaneous application of the two interventions which were statistically significant (p heat control at source can be considered as a first solution for reducing radiant heat of blast furnaces. However, the simultaneous application of interventions could noticeably reduce worker heat stress. The results provide reliable information in order to implement the effective heat controls in typical hot steel industries.

  5. Influence of heating rate on sorbitic transformation temperature of tempering C45 steel

    Directory of Open Access Journals (Sweden)

    A. Kulawik

    2011-04-01

    Full Text Available In this paper the analysis of speed heating influence on sorbitic transormation temperature of tempering C45 steel is presented. On thebasis of dilatometric research, functions associating heating time with initial and final temperature of sorbitic transformation have beendetermined as well as the size structural (γ and thermal (α expansion coefficients of quenching and tempering structures have beenestimated.

  6. Heat exchange performance of stainless steel and carbon foams modified with carbon nano fibers

    NARCIS (Netherlands)

    Tuzovskaya, I.; Pacheco Benito, Sergio; Chinthaginjala, J.K.; Reed, C.P.; Lefferts, Leonardus; van der Meer, Theodorus H.

    2012-01-01

    Carbon nanofibers (CNF), with fishbone and parallel wall structures, were grown by catalytic chemical vapor deposition on the surface of carbon foam and stainless steel foam, in order to improve their heat exchange performance. Enhancement in heat transfer efficiency between 30% and 75% was achieved

  7. Nanosized MX Precipitates in Ultra-Low-Carbon Ferritic/Martensitic Heat-Resistant Steels

    Science.gov (United States)

    Yin, Feng-Shi; Jung, Woo-Sang

    2009-02-01

    Nanosized MX precipitates in ultra-low-carbon ferritic/martensitic heat-resistant 9Cr-W-Mo-VNbTiN steels were characterized by transmission electron microscope (TEM) using carbon film replicas. The steels were prepared by vacuum induction melting followed by hot forging and rolling into plates. The plates were normalized at 1100 °C for 1 hour, cooled in air, and tempered at 700 °C for 1 hour. The results show that bimodal nanosized MX precipitates distribute densely and homogeneously in the matrix within martensitic lath after normalizing-and-tempering heat treatment. The larger nanosized MX precipitates with the size of 30 to 50 nm are rich in Nb, while the smaller ones with the size of about 10 nm contain less Nb but more V. Small addition of Ti causes an increase in the number of the larger nanosized MX precipitates. The total number density of the nanosized MX precipitates in the ultra-low-carbon ferritic/martensitic steels is measured to be over 300/ μm2, much higher than that in conventional ferritic/martensitic steels. Short-term creep test results show that the ultra-low-carbon ferritic/martensitic steels with high dense nanosized MX precipitates have much higher creep rupture strength than conventional ASME-P92 steel. The strength degradation of the ultra-low-carbon ferritic/martensitic heat-resistant steels during creep is also discussed in this article.

  8. Effect of heat treatment on corrosion behavior of duplex stainless steel in orthodontic applications

    Science.gov (United States)

    Sabea Hammood, Ali; Faraj Noor, Ahmed; Talib Alkhafagy, Mohammed

    2017-12-01

    Heat treatment is necessary for duplex stainless steel (DSS) to remove or dissolve intermetallic phases, to remove segregation and to relieve any residual thermal stress in DSS, which may be formed during production processes. In the present study, the corrosion resistance of a DSS in artificial saliva was studied by potentiodynamic measurements. The microstructure was investigated by scanning electron microscopy (SEM),x-ray diffraction (XRD) and Vickers hardness (HV). The properties were tested in as–received and in thermally treated conditions (800–900 °C, 2–8 min). The research aims to evaluate the capability of DSS for orthodontic applications, in order to substitute the austenitic grades. The results indicate that the corrosion resistance is mainly affected by the ferrite/austenite ratio. The best result was obtained with a treatment at 900 °C for 2 min.

  9. Heat Treatment of Cr- and Cr-V ledeburitic tool steels

    Directory of Open Access Journals (Sweden)

    Peter Jurči

    2014-11-01

    Full Text Available Cr- and Cr-V ledeburitic cold work tool steels belong to the most important tool materials for large series manufacturing. To enable high production stability, the tools must be heat treated before use. This overview paper brings a comprehensive study on the heat treatment of these materials, starting from the soft annealing and finishing with the tempering. Also, it describes the impact of any step of the heat treatment on the most important structural and mechanical characteristics, like the hardness, the toughness and the wear resistance. The widely used AIS D2- steel (conventionally manufactured and Vanadis 6 (PM are used as examples in most cases.

  10. Numerical model to predict microstructure of the heat treated of steel elements

    Directory of Open Access Journals (Sweden)

    T. Domański

    2011-04-01

    Full Text Available In work the presented numerical models of tool steel hardening processes take into account thermal phenomena and phase transformations. Numerical algorithm of thermal phenomena was based on the Finite Elements Methods of the heat transfer equations. In the model of phase transformations, in simulations heating process continuous heating (CHT was applied, whereas in cooling process continuous cooling (CCT of the steel at issue. The phase fraction transformed (austenite during heating and fractions during cooling of ferrite, pearlite or bainite are determined by Johnson-Mehl-Avrami formulas. The nescent fraction of martensite is determined by Koistinen and Marburger formula or modified Koistinen and Marburger formula. In the simulations of hardening was subject the fang lathe of cone (axisymmetrical object made of tool steel.

  11. Heat Generation and Transfer Behaviors of Ti-Coated Carbon Steel Rod Adaptable for Ablation Therapy of Oral Cancer

    Directory of Open Access Journals (Sweden)

    Yuji Watanabe

    2013-02-01

    Full Text Available For the purpose of developing a novel ablation therapy for oral cancer, the heat generation and transfer properties of a Ti-coated carbon steel rod with 20-mm length and 1.8-mm outer diameter were investigated by means of a high-frequency induction technique at 300 kHz. The heat generation measurement performed using water (15 mL revealed that the difference of the inclination angles (θ = 0°, 45° and 90° relative to the magnetic flux direction only slightly affects the heating behavior, exhibiting the overlapped temperature curves during an induction time of 1200 s. These results suggest that the effect of the shape magnetic anisotropy is almost eliminated, being convenient for the precise control of the ablation temperature in clinical use. In the experiments utilizing a tissue-mimicking phantom, the heat transfer concentrically occurred in the lateral direction for both the planar surface and a 10-mm deep cross-section. However, the former exhibited a considerably lower increase in temperature (ΔT, probably due to the effect of heat dissipation to the ambient air. No significant heat transfer was found to occur to the lower side of the inserted Ti-coated carbon steel rod, which is situated in the longitudinal direction.

  12. Computer simulation of working stress of heat treated steel specimen

    OpenAIRE

    B. Smoljan; D. Iljkić; S. Smokvina Hanza

    2009-01-01

    Purpose: In this paper, the prediction of working stress of quenched and tempered steel has been done. The working stress was characterized by yield strength and fracture toughness. The method of computer simulation of working stress was applied in workpiece of complex form.Design/methodology/approach: Hardness distribution of quenched and tempered workpiece of complex form was predicted by computer simulation of steel quenching using a finite volume method. The algorithm of estimation of yie...

  13. Influence of Heat Treatments on the Corrosion Resistance of Medium -Carbon Steel using Sulfuric Spring Water

    Directory of Open Access Journals (Sweden)

    Ikhlas Basheer

    2015-02-01

    Full Text Available The corrosion is one of the important problems that may be occur to the parts of machinery and equipment after manufactured and when used as a result of exposure to corrosive media. Plain-carbon steel is considered as one of the most common minerals used in industrial applications. Some of heat treatments can have direct effect on the corrosion rate of steel by building up galvanic corrosion cells between its microscopic phases. Therefore, to adopt one of kinds of the plain-carbon steel and the most commonly used in industry to be study subject, that is medium carbon steel and took samples of this steel has been treated thermally in three methods which the normalising, annealing, and hardening .The corrosive media used in the research is Sulfuric Spring, it contains many chemical compounds to show its influence on the corrosion of steel. The weight loss method is used to determine corrosion rate and to compare between the results obtained, show that the greatest corrosion resistance of the annealed steel and the corrosion resistance of the hardened steel is the lowest while the corrosion  resistance of the normalised steel is in-between them.         Calcium carbonate was formed on the metal surface which acts as an isolating layer which decrease corrosion rate with time

  14. Performance testing of the AST-50O model of district heating network heat exchanger with 08Cr14 steel tubes

    Energy Technology Data Exchange (ETDEWEB)

    Afanas' ev, A.A.; Borisov, V.P.; Grebennikov, V.N.; Dolinin, E.L.; Krutikov, P.G.; Shishkunov, V.A.; Stogov, V.I.

    1984-02-01

    Test results of network heat exchanger model of a nuclear boiler plant AST-500 with a tube part of 08Kh14MF ferritic-martensitic steel are presented. The model presents a one-through counterflow water-water heat-exchanger. The model was connected to the district heating network where it operated for 5000 hr at pH=7.3 and at the temperature 70-90 deg C. Rolled joints ''tube-tube sheet'' did not have traces of contact corrosion, gradual corrosion of 08Kh14MF steel did not exceed 0 003 mm/year, which ensured normal working capacity of heat-exchanger equipment for the planned 30 years.

  15. Effects of initial hardness on heat crack formation of die steel for hot working; Netsukan kakoyo kanagatako no heat crack keisei ni oyobosu shoki katasa no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Otani, N.; Tanaka, Y. [Muroran Institute of Technology, Hokkaido (Japan)

    1997-09-25

    An investigation was made on the effects of initial hardness on heat crack formation in die steel during a diecasting process. Reduction in the life of a diecast die is caused by heat crack at more than 70% attributable to thermal fatigue as a result of the quick heating and cooling cycles. Conventional simplified testing methods do not make necessarily clear their relation with actual operations. Modeling on the diecasting process, a test piece with a notch is immersed directly into Al alloy melt and quenched in water as a thermal fatigue test to discuss the relationship between heat cracks in the die steel SKD61 and the initial hardness. High-temperature tensile strength of the SKD61 largely affects crack formation. The tensile strength increases linearly at 573 K or lower as the hardness increases. However, at 673 K or higher, the tensile strength shows a nearly proportional relationship up to HRC50 with increasing hardness, but decreases at higher hardness with HRC50 as a maximum value. Raising the initial hardness up to near HRC50 presents effect in suppressing generation and propagation of heat cracks. However, raising it further will result in an inverse effect. 11 refs., 12 figs., 1 tab.

  16. Microstructural Characterization for Structural Health Monitoring of Heat-Resisting Rotor Steels

    Energy Technology Data Exchange (ETDEWEB)

    Kim, C. S.; Byeon, J. W.; Park, I. K. [Seoul National University of Technology, Seoul (Korea, Republic of)

    2008-04-15

    The typical heat-resisting rotor steels such as 2.25CrMo, 9CrMo and 12CrW steel were experimentally studied in order to understand their materials degradation under high temperature and pressure during the long-term service, and then use the basic studies for the structural health monitoring. In order to monitor the materials degradation, it was conducted by the isothermal aging for 2.25CrMo steel, creep-fatigue for 9CrMo steel and creep for 12Cr steel with the incremental step test. The ultrasonic wave properties, electrical resistivity and coercivity were interpreted in relation to microstructural changes at each material and showed strong sensitivity to the specific microstructural evolution

  17. Effect of Heat Treatment on Microstructure and Hardness of Grade 91 Steel

    Directory of Open Access Journals (Sweden)

    Triratna Shrestha

    2015-01-01

    Full Text Available Grade 91 steel (modified 9Cr-1Mo steel is considered a prospective material for the Next Generation Nuclear Power Plant for application in reactor pressure vessels at temperatures of up to 650 °C. In this study, heat treatment of Grade 91 steel was performed by normalizing and tempering the steel at various temperatures for different periods of time. Optical microscopy, scanning and transmission electron microscopy in conjunction with microhardness profiles and calorimetric plots were used to understand the microstructural evolution including precipitate structures and were correlated with mechanical behavior of the steel. Thermo-Calc™ calculations were used to support the experimental work. Furthermore, carbon isopleth and temperature dependencies of the volume fraction of different precipitates were constructed.

  18. Retained austenite variation in dual-phase steel after mechanical stressing and heat treatment

    Energy Technology Data Exchange (ETDEWEB)

    Giordano, L.; Tiziani, A.; Zambon, A. (Dipt. di Innovazione Meccanica e Gestionale, Padua Univ. (Italy)); Matteazzi, P. (Ist. di Chimica, Univ. di Udine (Italy))

    1991-01-20

    Retained austenite changes in a dual-phase steel have been studied after mechanical and thermal treatments. In order to determine the quantitative variations of retained austenite, whose amount in the examined steel is of the order of 5%, Moessbauer spectroscopy has been used. Retained austenite undergoes a martensitic transformation during deformation, but does not transform under the heat treatments performed on the sheet during anticorrosion and painting processes. (orig.).

  19. Optimizing Heat Treatment Process of Fe-13Cr-3Mo-3Ni Martensitic Stainless of Steel

    Science.gov (United States)

    Anwar, M. S.; Prifiharni, S.; Mabruri, E.

    2017-05-01

    The Fe-13Cr-3Mo-3Ni stainless steels are modified into martensitic stainless steels for steam turbine blades application. The working temperature of steam turbine was around 600 - 700 °C. The improvement properties of turbine blade material is necessary to maintain steam turbine work. The previous research revealed that it has corrosion resistance of Fe-13Cr-3Mo-3Ni which is better than 13Cr stainless steels in the chloride environment. In this work, the effect of heat treatment on microstructure and hardness of Fe-13Cr-3Mo-3Ni stainless steels has been studied. The steel was prepared by induction melting followed by hot forging. The steels were austenitized at 1000, 1050, and 1100 °C for 1 hour and were tempered at 600, 650, and 700 °C for 1 hour. The steels were then subjected to metallographic observation and hardness test of Rockwell C. The optimal heat treatment of Fe-13Cr-3Mo-3Ni was carried out austenitized in 1050 °C and tempered in 600 - 700 °C.

  20. Effect of Heat Treatment Technique on the Low Temperature Impact Toughness of Steel EQ70 for Offshore Structure

    Science.gov (United States)

    Tao, Su-Fen; Xia, Yun-Jin; Wang, Fu-Ming; Li, Jie; Fan, Ding-Dong

    2017-09-01

    Circle quenching and tempering (CQ&T), intercritical quenching and tempering (IQ&T) and regular quenching and tempering (Q&T) were used to study the influence of heat treatment techniques on the low temperature impact toughness of steel EQ70 for offshore structure. The steels with 2.10 wt. % Ni (steel A) and 1.47 wt. % Ni (steel B) were chosen to analyze the effect of Ni content on the low temperature impact toughness of steel EQ70 for offshore structure. The fracture morphologies were examined by using a scanning electron microscope (SEM, JSM-6480LV), and microstructures etched by 4 vol. % nitric acid were observed on a type 9XB-PC optical microscope. The results show that the impact toughness of steel A is higher than that of steel B at the same test temperature and heat treatment technique. For steel B, the energy absorbed is, in descending order, CQ&T, Q&T and IQ&T, while for steel A, that is CQ&T, IQ&T and Q&T. The effects of heat treatment on the low temperature impact toughness are different for steels A and B, the absorbed energy changes more obviously for steel A. The results can be significant references for actual heat treatment techniques in steel plant.

  1. Dilatometric and hardness analysis of C45 steel tempering with different heating-up rates

    Directory of Open Access Journals (Sweden)

    A. Kulawik

    2012-01-01

    Full Text Available Modelling of technological processes of heat treatment or welding, involving multiple heat source transitions, requires considering the phenomenon of tempering. In work have been presented results of dilatometric research of hardened C45 steel subjected to tempering. The analysis of the influence of heating rate at the kinetic determined from dilatometric curves has been made. There have also been estimated quantities of transformation expansions and thermal expansion coefficients of hardening and tempering structures (austenite, ferrite, pearlite, martensite and sorbite. The analysis of tempering time influence on the hardness of tempered steel has been made. Functions associating hardness with tempering time (rate of heating-up in technological processes based on short-timed action of a heat source (eg. laser treatment have been suggested.

  2. Influence of the heat treatment on the microstructure and properties of austenitic cast steel

    Directory of Open Access Journals (Sweden)

    P. Bała

    2010-07-01

    Full Text Available Exploitation investigations of a centrifugally cast pipe of austenitic cast steel indicated a significant influence of its microstructure on functional properties. Determination of the possibility of forming the microstructure and properties of the investigated cast steel by heat treatments was the aim of the presented paper. According to the Standard ASTM A 297, material from which the pipe was made is determined as HF type cast steel. The solution heat treatment from a temperature of 1080 °C was performed and followed by the microstructure observations and hardness measurements. It was found, that the solution heat treatment from this temperature will notsignificantly improve the material strength properties. However, it will visibly influence its fracture toughness. An influence of agingperformed after the solution heat treatment on microstructure and hardness was also investigated. Cast steel was aged for 1 hour at 600°C (solution heat treatment from 1080 °C. On the basis of the obtained results it was found, that the solution heat treatment temperature should be the maximum permissible by the Standard i.e. 1150 °C. Heating the supersaturated material (from 1150 °C even toa temperature of 600 °C should not cause the carbide precipitation in a form of the continuous network in grain boundaries, which woulddecrease fracture toughness of the investigated cast steel. Due to fracture toughness a service exposure of this material should not exceed 600 °C. The permissible service exposure up to 900 °C, given for this material in the Standard, is correct only on account of heat and high temperature creep resistance but not fracture toughness.

  3. Effect of Microstructure on the Wear Behavior of Heat Treated SS-304 Stainless Steel

    Directory of Open Access Journals (Sweden)

    S. Kumar

    2016-12-01

    Full Text Available Sliding wear characteristics of some heat treated SS-304 stainless steel against EN-8 steel in dry condition have been studied in the present experimental work. Samples of SS-304 stainless steel have been heated in a muffle furnace in desired temperature and allowed to dwell for two hours. The heated specimen are then cooled in different media namely inside the furnace, open air, cutting grade oil (grade 44 and water at room temperature to obtain different grades of heat treatment. Microstructures and corresponding micro hardness of the samples have been measured along with Feritscopic studies. Wear characteristics have been studied in a multi tribo-tester (Ducom in dry sliding condition against EN-8 steel roller. Speed, load on job and duration of test run have been considered as the experimental parameters. The wear of the samples have been obtained directly from ‘Winducom 2006’ software. Mass loss of the samples before and after operation has also been considered as the measure of wear in the present study. All the samples have been slid against EN-8 steel roller with fixed experimental parameters. The data have been plotted, compared and analyzed. Effect of microstructures as well as micro hardness on the wear behavior has been studied and concluded accordingly.

  4. A dilatometric study of the phase transformations in 300 and 350 maraging steels during continuous heating rates

    Directory of Open Access Journals (Sweden)

    Leandro Gomes de Carvalho

    2013-01-01

    Full Text Available The influences of the chemical composition and heating rate have been studied in 300 and 350 maraging steels using dilatometry. For these tests, heating was carried out with heating rates of 1, 10 and 28 °C/s. The results have shown that the precipitation mechanism for both materials in the studied range is by lattice diffusion. Furthermore, Co and Ti contents influence strongly the precipitation. The lattice diffusion mechanism in the martensite reversion is influenced by Ni and Co contents and heating rate. For small heating rates ( ~1 °C/s this mechanism prevails in the 300 maraging steel while for the 350 maraging steel has a minor importance. The mechanism of martensite reversion for 350 maraging steel in the studied range is mainly by shear mechanism. For higher heating rates (~28 ºC/s the shear mechanism prevails in both maraging steels.

  5. Heuristic algorithms for scheduling heat-treatment furnaces of steel ...

    Indian Academy of Sciences (India)

    treatment furnaces in a steel-casting foundry, a special problem of batch processor scheduling, ... production management is to maximize throughput and reduce flow time and WIP. This motivated the choice of ..... A computational experiment is appropriate in order to provide a perspective on the relative effectiveness of any ...

  6. Intercritical Heat Treatment Effects on Low Carbon Steels Quenched ...

    African Journals Online (AJOL)

    Six low carbon steels containing carbon in the range 0.13-0.18wt%C were studied after intercritical quenching, intercritical quenching with low temperature tempering, intercritical annealing and intercritical normalizing using specimens originally quenched from intermediate austenitizing temperature (9500C). The studies ...

  7. intercritical heat treatments effects on low carbon steels quenched

    African Journals Online (AJOL)

    DR B. A. EZEKOYE

    Department of Physics and Astronomy, University of Nigeria, Nsukka. 2. E-mail: benjamin.ezekoye@unn.edu.ng; bezekoye@yahoo.com. ABSTRACT. Six low carbon steels containing carbon in the range 0.13-0.18wt%C were studied after intercritical quenching, intercritical quenching with low temperature tempering, ...

  8. Evolution of radiation defect and radiation hardening in heat treated SA508 Gr3 steel

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Hyung-Ha; Kwon, Junhyun [Nuclear Materials Division, Korea Atomic Energy Research Institute, 989-111 Daeduck-daero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Shin, Chansun, E-mail: c.shin@mju.ac.kr [Department of Materials Science and Engineering, Myongji University, 116 Myongji-ro, Cheoin-gu, Youngin-shi, Gyeonggi-do 449-728 (Korea, Republic of)

    2014-01-15

    The formation of radiation defects and corresponding radiation hardening in heat-treated SA508 Gr3 steel after Fe ion irradiation were investigated by means of transmission electron microscopy and a nano-indentation technique. As the residual dislocation density is increased in the matrix, the formation of radiation defects is considerably weakened. Comparison between the characteristics of the radiation defect and an evaluation of radiation hardening indicates that a large dislocation loop contributes little to the radiation hardening in the heat-treated SA508 Gr3 steel.

  9. Evolution of radiation defect and radiation hardening in heat treated SA508 Gr3 steel

    Science.gov (United States)

    Jin, Hyung-Ha; Kwon, Junhyun; Shin, Chansun

    2014-01-01

    The formation of radiation defects and corresponding radiation hardening in heat-treated SA508 Gr3 steel after Fe ion irradiation were investigated by means of transmission electron microscopy and a nano-indentation technique. As the residual dislocation density is increased in the matrix, the formation of radiation defects is considerably weakened. Comparison between the characteristics of the radiation defect and an evaluation of radiation hardening indicates that a large dislocation loop contributes little to the radiation hardening in the heat-treated SA508 Gr3 steel.

  10. Effect of heat treatment on the structure and properties of bearing steel 11Kh18M-ShD

    Science.gov (United States)

    Shchipunov, V. S.; Ostrovskaya, E. A.; Burkin, V. S.; Girt, N. P.

    1981-10-01

    Heat treatment of steel 11Kh18M-ShD does not ensure the necessary level of hardness if the steel as-received consists of peartlite, isolated sections of ferrite, and a small quantity of excess carbides. Therefore, we suggest that the microstructure of steel 11Kh18M-ShD in the annealed condition be given for each shipment of the steel.

  11. Simulation of Distortion and Residual Stress Development During Heat Treatment of Steel Castings

    Energy Technology Data Exchange (ETDEWEB)

    Beckermann, Christoph; Carlson, Kent

    2011-07-22

    Heat treatment and associated processing, such as quenching, are critical during high strength steel casting production. These processes must be managed closely to prevent thermal and residual stresses that may result in distortion, cracking (particularly after machining), re-work, and weld repair. The risk of casting distortion limits aggressive quenching that can be beneficial to the process and yield an improved outcome. As a result of these distortions, adjustments must be made to the casting or pattern design, or tie bars must be added. Straightening castings after heat treatments can be both time-consuming and expensive. Residual stresses may reduce a casting's overall service performance, possibly resulting in catastrophic failure. Stress relieving may help, but expends additional energy in the process. Casting software is very limited in predicting distortions during heat treatment, so corrective measures most often involve a tedious trial-and-error procedure. An extensive review of existing heat treatment residual stress and distortion modeling revealed that it is vital to predict the phase transformations and microstructure of the steel along with the thermal stress development during heat treatment. After reviewing the state-of-the-art in heat treatment residual stress and distortion modeling, an existing commercial code was selected because of its advanced capabilities in predicting phase transformations, the evolving microstructure and related properties along with thermal stress development during heat treatment. However, this software was developed for small parts created from forgings or machined stock, and not for steel castings. Therefore, its predictive capabilities for heat treatment of steel castings were investigated. Available experimental steel casting heat treatment data was determined to be of insufficient detail and breadth, and so new heat treatment experiments were designed and performed, casting and heat treating modified versions

  12. Effects of Heating and Cooling Rates on Phase Transformations in 10 Wt Pct Ni Steel and Their Application to Gas Tungsten Arc Welding

    Science.gov (United States)

    Barrick, Erin J.; Jain, Divya; DuPont, John N.; Seidman, David N.

    2017-10-01

    10 wt pct Ni steel is a high-strength steel that possesses good ballistic resistance from the deformation induced transformation of austenite to martensite, known as the transformation-induced-plasticity effect. The effects of rapid heating and cooling rates associated with welding thermal cycles on the phase transformations and microstructures, specifically in the heat-affected zone, were determined using dilatometry, microhardness, and microstructural characterization. Heating rate experiments demonstrate that the Ac3 temperature is dependent on heating rate, varying from 1094 K (821 °C) at a heating rate of 1 °C/s to 1324 K (1051 °C) at a heating rate of 1830 °C/s. A continuous cooling transformation diagram produced for 10 wt pct Ni steel reveals that martensite will form over a wide range of cooling rates, which reflects a very high hardenability of this alloy. These results were applied to a single pass, autogenous, gas tungsten arc weld. The diffusion of nickel from regions of austenite to martensite during the welding thermal cycle manifests itself in a muddled, rod-like lath martensitic microstructure. The results of these studies show that the nickel enrichment of the austenite in 10 wt pct Ni steel plays a critical role in phase transformations during welding.

  13. Effects of Heating and Cooling Rates on Phase Transformations in 10 Wt Pct Ni Steel and Their Application to Gas Tungsten Arc Welding

    Science.gov (United States)

    Barrick, Erin J.; Jain, Divya; DuPont, John N.; Seidman, David N.

    2017-12-01

    10 wt pct Ni steel is a high-strength steel that possesses good ballistic resistance from the deformation induced transformation of austenite to martensite, known as the transformation-induced-plasticity effect. The effects of rapid heating and cooling rates associated with welding thermal cycles on the phase transformations and microstructures, specifically in the heat-affected zone, were determined using dilatometry, microhardness, and microstructural characterization. Heating rate experiments demonstrate that the Ac3 temperature is dependent on heating rate, varying from 1094 K (821 °C) at a heating rate of 1 °C/s to 1324 K (1051 °C) at a heating rate of 1830 °C/s. A continuous cooling transformation diagram produced for 10 wt pct Ni steel reveals that martensite will form over a wide range of cooling rates, which reflects a very high hardenability of this alloy. These results were applied to a single pass, autogenous, gas tungsten arc weld. The diffusion of nickel from regions of austenite to martensite during the welding thermal cycle manifests itself in a muddled, rod-like lath martensitic microstructure. The results of these studies show that the nickel enrichment of the austenite in 10 wt pct Ni steel plays a critical role in phase transformations during welding.

  14. Ice melting properties of steel slag asphalt concrete with microwave heating

    Science.gov (United States)

    Li, Bin; Sun, Yihan; Liu, Quantao; Fang, Hao; Wu, Shaopeng; Tang, Jin; Ye, Qunshan

    2017-03-01

    The ice on the surface of asphalt pavement in winter significantly influences the road transportation safety. This paper aims at the improvement of the ice melting efficiency on the surface of asphalt pavement. The steel slag asphalt concrete was prepared and the high ice melting efficiency was achieved with the microwave heating. A series of experiments were conducted to evaluate the ice melting performance of steel slag asphalt concrete, including the heating test, ice melting test, thermal conductivity test and so on. The results indicated that the microwave heating of steel slag concrete can improve the efficiency of deicing, mainly because the heating rates of steel slag asphalt mixture are much better than traditional limestone asphalt mixture. According to different thickness lever of ice, the final temperatures of each sample were very close to each other at the end of melting test. It is believed the thickness of the ice has a limited impact on the ice melting efficiency. According to the heating tests results, the bonding of ice and asphalt concrete is defined failure at the moment when the surface temperature of the ice reached 3 °C.

  15. Detrimental Cr-rich Phases Precipitation on SAF 2205 Duplex Stainless Steels Welds After Heat Treatment

    Directory of Open Access Journals (Sweden)

    Argelia Fabiola Miranda Pérez

    Full Text Available Abstract The austeno-ferritic Stainless Steels are commonly employed in various applications requiring structural performances with enhanced corrosion resistance. Their characteristics can be worsened if the material is exposed to thermal cycles, since the high-temperature decomposition of ferrite causes the formation of detrimental secondary phases. The Submerged Arc Welding (SAW process is currently adopted for joining DSS owing to its relatively simple execution, cost savings, and using molten slag and granular flux from protecting the seam of atmospheric gases. However, since it produces high contents of δ-ferrite in the heat affected zone and low content of γ-austenite in the weld, high-Ni filler materials must be employed, to avoid excessive ferritization of the joint. The present work is aimed to study the effect of 3 and 6 hours isothermal heat treatments at 850°C and 900°C in a SAF 2205 DSS welded joint in terms of phases precipitation. The results showed the presence of σ-phase at any time-temperature combination, precipitating at the δ/γ interphases and often accompanied by the presence of χ-phase. However, certain differences in secondary phases amounts were revealed among the different zones constituting the joint, ascribable both to peculiar elements partitioning and to the different morphology pertaining to each microstructure.

  16. Determination of optimum heat treatment conditions for hardness criterion of multicomponent steel based on fuzzy mathematical simulation

    Directory of Open Access Journals (Sweden)

    Александр Алексеевич Радченко

    2016-06-01

    Full Text Available The mathematical simulation of high-strength cast steel grade alloyed with manganese, nickel, chromium and molybdenum, and heat treatment conditions on the steel hardness are done. The model is developed on the basis of orthogonal experimental design, in which the input variables are considered as fuzzy numbers. The optimal heat treatment conditions for steels 25ГНХМЛ, 35ГНХМЛ, 40ГНХМЛ are determined

  17. Occupational Heat Stress Impacts on Health and Productivity in a Steel Industry in Southern India.

    Science.gov (United States)

    Krishnamurthy, Manikandan; Ramalingam, Paramesh; Perumal, Kumaravel; Kamalakannan, Latha Perumal; Chinnadurai, Jeremiah; Shanmugam, Rekha; Srinivasan, Krishnan; Venugopal, Vidhya

    2017-03-01

    Workers laboring in steel industries in tropical settings with high ambient temperatures are subjected to thermally stressful environments that can create well-known risks of heat-related illnesses and limit workers' productivity. A cross-sectional study undertaken in a steel industry in a city nicknamed "Steel City" in Southern India assessed thermal stress by wet bulb globe temperature (WBGT) and level of dehydration from urine color and urine specific gravity. A structured questionnaire captured self-reported heat-related health symptoms of workers. Some 90% WBGT measurements were higher than recommended threshold limit values (27.2-41.7°C) for heavy and moderate workloads and radiational heat from processes were very high in blooming-mill/coke-oven (67.6°C globe temperature). Widespread heat-related health concerns were prevalent among workers, including excessive sweating, fatigue, and tiredness reported by 50% workers. Productivity loss was significantly reported high in workers with direct heat exposures compared to those with indirect heat exposures (χ2 = 26.1258, degrees of freedom = 1, p work capacities. Health and productivity risks in developing tropical country work settings can be further aggravated by the predicted temperature rise due to climate change, without appropriate interventions. Apart from industries enhancing welfare facilities and designing control interventions, further physiological studies with a seasonal approach and interventional studies are needed to strengthen evidence for developing comprehensive policies to protect workers employed in high heat industries.

  18. Effect of Intercritical Heat Treatment on Mechanical Properties of Plain Carbon Dual Phase Steel

    Directory of Open Access Journals (Sweden)

    Imtiaz Ali Soomro

    2017-12-01

    Full Text Available Mechanical properties of DP (Dual Phase steels are greatly influenced by the microstructural features such as grain size, morphology and martensite volume fraction (Vm%. These microstructural features can be altered by changing the soaking time and temperature within intercritical zone. Present study aims to study the effect of intercritical annealing temperature and soaking time on Vm% and its effects on mechanical properties of plain low carbon steel grade (AISI 1020 steel having ferritemartensitemicrostructure. Nine DP steel specimens with various amount of martensite were produced via intercritical heat treatment. Mechanical properties including TS (Tensile Strength, hardness and toughness were characterized and co-related with martensite volume fraction. It was found that increasing the intercritical annealing temperature and soaking time increases the Vm%. The optimum TS and hardness were found at 64Vm% and then decrease with further increase in Vm%. The toughness was found to have linear relationship with Vm%.

  19. Fatigue crack growth retardation in spot heated mild steel sheet

    Indian Academy of Sciences (India)

    A fatigue crack can be effectively retarded by heating a spot near the crack tip under nil remote stress condition. The subcritical spot heating at a proper position modifies the crack growth behaviour in a way, more or less, similar to specimen subjected to overload spike. It is observed that the extent of crack growth retardation ...

  20. Effect of post-weld heat treatment and neutron irradiation on a dissimilar-metal joint between F82H steel and 316L stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Haiying, E-mail: haigirl1983@gmail.com [SOKENDAI - The Graduated University for Advanced Studies, Toki (Japan); Nagasaka, Takuya [SOKENDAI - The Graduated University for Advanced Studies, Toki (Japan); National Institute for Fusion Science, Toki (Japan); Kometani, Nobuyuki [Nagoya University, Nagoya (Japan); Muroga, Takeo [SOKENDAI - The Graduated University for Advanced Studies, Toki (Japan); National Institute for Fusion Science, Toki (Japan); Guan, Wenhai; Nogami, Shuhei; Yabuuchi, Kiyohiro; Iwata, Takuya; Hasegawa, Akira [Tohoku University, Sendai (Japan); Yamazaki, Masanori [International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University (Japan); Kano, Sho; Satoh, Yuhki; Abe, Hiroaki [Institute for Materials Research, Tohoku University, Sendai (Japan); Tanigawa, Hiroyasu [Japan Atomic Energy Agency, Rokkasho (Japan)

    2015-10-15

    Highlights: • Significant hardening after neutron irradiation at 300 °C for 0.1 dpa was found in the fine-grain HAZ of F82H for the dissimilar-metal joint between F82H and 316L. • The possible hardening mechanism was explained from the viewpoint of carbon behavior. • However, the significant hardening did not degrade the impact property significantly. - Abstract: A dissimilar-metal joint between F82H steel and 316L stainless steel was fabricated by using electron beam welding (EBW). By microstructural analysis and hardness test, the heat-affected zone (HAZ) of F82H was classified into interlayer area, fine-grain area, and coarse-carbide area. Post-weld heat treatment (PWHT) was applied to control the hardness of HAZ. After PWHT at 680 °C for 1 h, neutron irradiation at 300 °C with a dose of 0.1 dpa was carried out for the joint in Belgian Reactor II (BR-II). Compared to the base metals (BMs) and weld metal (WM), significant irradiation hardening up to 450HV was found in the fine-grain HAZ of F82H. However, the impact property of F82H-HAZ specimens, which was machined with the root of the V-notch at HAZ of F82H, was not deteriorated obviously in spite of the significant irradiation hardening.

  1. An Experimental Investigation on Hardness and Microstructure of Heat Treated EN 9 Steel

    Science.gov (United States)

    Biswas, Palash; Kundu, Arnab; Mondal, Dhiraj

    2017-08-01

    In the modern engineering world, extensive research has led to the development of some special grades of steel, often suited for enhanced functions. EN 9 steel is one such grade, having major applications in power plants, automobile and aerospace industry. Different heat treatment processes are employed to achieve high hardness and high wear resistance, but machinability subsequently decreases. Existing literature is not sufficient to achieve a balance between hardness and machinability. The aim of this experimental work is to determine the hardness values and observe microstructural changes in EN9 steel, when it is subjected to annealing, normalizing and quenching. Finally, the effects of tempering after each of these heat treatments on hardness and microstructure have also been shown. It is seen that the tempering after normalizing the specimen achieved satisfactory results. The microstructure was also observed to be consisting of fine grains.

  2. Computational design of heat resistant steels with evolving and time-independent strengthening factors

    NARCIS (Netherlands)

    Lu, Q.

    2015-01-01

    Alloy design by the traditional trial and error approach is known to be a time consuming and a highly cost procedure, especially for the design of heat resistant steel where the feedback time is intrinsically long. The significant developments in computational simulation techniques in the last

  3. Plasma nitriding of AISI 52100 ball bearing steel and effect of heat ...

    Indian Academy of Sciences (India)

    C) is much lower than the standard processing temperature (∼460–580°C) needed for the plasma nitriding treatment. To understand the mechanism, effect of heat treatment on the nitrided layer steel is investigated. Experiments are performed ...

  4. Effect of heating rate on intercritical annealing of low-carbon cold-rolled steel

    Science.gov (United States)

    Thomas, Larrin

    A study was performed on the effect of heating rate on transformations during intercritical annealing of cold-rolled low-carbon sheet steels. Two sets of experiments were developed: 1) a series of alloys (1020, 1019M, 15B25) with two different cold reductions (nominally 40 and 60 pct) were heated at different rates and transformation temperatures were determined using analysis of dilatometry and metallography of intercritically annealed samples, allowing the study of the impact of composition and cold work on transformation behavior with different heating rates. 2) A cold-rolled C-Mn-Nb steel was tested with different heating rates selected for different degrees of recrystallization during austenite formation to test the impact of ferrite recrystallization on austenite formation. Heat treated samples were analyzed with SEM, EBSD, dilatometry, and microhardness to study the changes in transformation behavior. The results of this study were extended by adding step heating tests, heat treatments with an intercritical hold, and secondary ion mass spectrometry (SIMS) measurements of Mn distribution. Austenite transformation temperatures increased logarithmically with heating rate. Greater degrees of cold work led to reduced transformation temperatures across all heating rates because the energy of cold work increased the driving force for austenite formation. The relative effects of alloying additions on transformation temperatures remained with increasing heating rate. Rapid heating minimized ferrite recrystallization and pearlite spheroidization. Austenite formation occurred preferentially in recovered ferrite regions as opposed to recrystallized ferrite boundaries. Martensite was evenly distributed in slowly heated steels because austenite formed on recrystallized, equiaxed, ferrite boundaries. With rapid heating, austenite formed in directionally-oriented recovered ferrite which increased the degree of banding. The greatest degree of banding was found with

  5. Effects of Welding Heat Input on Microstructure and Electrochemical Behavior of Flux-Cored Arc-Welded Q690 HSLA Steel

    Directory of Open Access Journals (Sweden)

    Kai Wang

    2018-01-01

    Full Text Available In this work, the weld metal (WM for the Q690 high-strength low-alloy (HSLA steel was prepared through flux-cored arc welding (FCAW at 10 kJ/cm and 20 kJ/cm heat inputs. The effect of welding heat input on the relationship between the microstructural factors and the electrochemical behavior of the FCAW Q690 steel was studied. Due to the fine grain and acicular ferrite affected by the 10 kJ/cm low heat input, the WM presented similar electrochemical behavior to the Q690 base metal, which would minimize the risk of galvanic corrosion. Also, at 20 kJ/cm of high welding heat input, the WM with higher-sized bainite structure was prone to galvanic corrosion risk minimization.

  6. Fatigue crack growth retardation in spot heated mild steel sheet

    Indian Academy of Sciences (India)

    Unknown

    Department of Applied Mechanics and Hydraulics, Regional Engineering. College, Rourkela 769 008, India. MS received 29 November 2001; revised 24 June 2002. Abstract. A fatigue crack can be effectively retarded by heating a spot near the crack ...

  7. The Effect of Ultrafast Heating in Cold-Rolled Low Carbon Steel: Recrystallization and Texture Evolution

    Directory of Open Access Journals (Sweden)

    Felipe M. Castro Cerda

    2016-11-01

    Full Text Available The microstructure and texture evolution of cold-rolled low carbon steel after ultrafast heating and quenching is investigated. Experiments were carried out at heating rates of 150 °C/s and 1500 °C/s. The recrystallization of ferrite is studied by scanning electron microscopy and electron backscattered diffraction techniques. The texture evolution of cold rolled steel during ultrafast heating was studied, making it possible to estimate the precise effect of heating rate on the orientations of newly formed grains. The experimental results showed that the recrystallization of ferrite was not completed before the full transformation of austenite. The noticeable increase in the fraction of recrystallized grains of diameter less than 1 µm, when the heating rate is increased from 150 °C/s to 1500 °C/s suggests that the increase of the heating rate enhances the nucleation of ferrite. The crystallographic orientations in recrystallized ferrite are strongly influenced by the heating rates. The effect of heating rate in the releasing of stored energy, carbon diffusion and spheroidization of cementite might explain some differences in textures observed in recrystallized ferrite.

  8. Effect of tungsten addition on high-temperature properties and microstructure of alumina-forming austenitic heat-resistant steels

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Min-Ho [Division of Materials Science and Engineering, Hanyang University, Seongdong-ku, Seoul 133-791 (Korea, Republic of); Ferrous Alloy Department, Advanced Metallic Materials Division, Korea Institute of Materials Science, 797 Changwondaero, Seongsangu, Changwon, Gyeongnam 642-831 (Korea, Republic of); Moon, Joonoh; Kang, Jun-Yun; Ha, Heon-Young [Ferrous Alloy Department, Advanced Metallic Materials Division, Korea Institute of Materials Science, 797 Changwondaero, Seongsangu, Changwon, Gyeongnam 642-831 (Korea, Republic of); Choi, Baig Gyu [High Temperature Materials Department, Advanced Metallic Materials Division, Korea Institute of Materials Science, 797 Changwondaero, Seongsangu, Changwon, Gyeongnam 642-831 (Korea, Republic of); Lee, Tae-Ho [Ferrous Alloy Department, Advanced Metallic Materials Division, Korea Institute of Materials Science, 797 Changwondaero, Seongsangu, Changwon, Gyeongnam 642-831 (Korea, Republic of); Lee, Changhee, E-mail: chlee@hanyang.ac.kr [Division of Materials Science and Engineering, Hanyang University, Seongdong-ku, Seoul 133-791 (Korea, Republic of)

    2015-10-28

    High-temperature tensile and creep properties of W-added Alumina-Forming austenitic (AFA{sub W}) heat-resistant steel were investigated as compared with AFA steel without W. High-temperature tensile properties of two steels were similar to each other, but creep lifetime of AFA{sub W} steel was increased. Microstructural examination using SEM and TEM revealed that creep rate rapidly decreased when Laves phase initially precipitated. This indicated that the precipitation of Laves phase played an important role in hardening of AFA steel. It is also found that AFA{sub W} steel exhibited finer and denser Laves phase compared with AFA steel, which is due to partial substitution of W for Mo. The finer and denser distribution of Laves phase contributed to improved creep properties of AFA{sub W} steel by enhancement in precipitation hardening.

  9. Features of austenite formation in low-carbon steel upon heating in the intercritical temperature range

    Science.gov (United States)

    Panov, D. O.; Smirnov, A. I.

    2017-11-01

    The features of austenite formation upon continuous heating of low-carbon steel at the rates of 90-0.15 K/s in the intercritical temperature range (ICTR) have been studied. It has been found that, in the initially high-tempered, initially quenched, and initially cold-deformed steel, the α → γ transition in the ICTR consists of three stages. The thermokinetic diagrams of the austenite formation with the indication of the positions of the critical points Ac 1 and Ac 3 and also of the temperature ranges of the development of each identified stage of the α → γ transformation have been constructed. A complex of structural studies has been carried out, and a scheme of the austenite formation upon continuous heating at a rate of 90 K/s in the ICTR for the initially high-tempered steel, initially quenched steel, and initially cold-deformed low-carbon steel has been suggested, which reflects all stages of this process.

  10. Effects of postweld heat treatment on the dissimilar weldments of SA508 Gr. 4N Ni-Mo-Cr low alloy steels

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hong Eun; Lee, Chang Hee [Hanyang University, Seoul (Korea, Republic of); Kim, Min Chul; Lee, Ho Jin; Kim, Keong Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Jung, In Chul; Byeon, Jin Gwi [Doosan HEAVY Industries and Construction, Seoul (Korea, Republic of)

    2009-10-15

    Low alloy steels are generally employed in reactor pressure vessels (RPVs) of nuclear power plants. SA508 Gr.4N Ni-Mo-Cr low alloy steel has been studied as candidate materials for RPVs because it has excellent mechanical properties such as strength and toughness due to higher Ni and Cr contents compared with SA508 Gr.3 commercial RPV steel. In order to improve corrosion resistance of inner-wall of RPV, it is necessary to be coated by clad-welding with austenitic stainless steels such as 308L and 309L. PWHT of such dissimilar weldments results in the formation of a soft region near the weld interface on the low Cr side, and hard zone on the high Cr side of the weldment. The hardness change of weldments by formation of these characteristic zones affected overall safety margin and integrity property of RPV. In this study, effects of post-weld heat treatment (PWHT) on the microstructural and mechanical properties of dissimilar weldment between SA508 Gr.4N steel and austenitic stainless steel have been studied. The changes in microstructure, hardness and composition profiles across the weld interface were studied in detail. And, those results were compared with weldment in SA508 Gr.3 steel.

  11. Heuristic algorithms for scheduling heat-treatment furnaces of steel ...

    Indian Academy of Sciences (India)

    The scheduling of furnaces for heat-treatment of castings is of considerable interest as a large proportion of the total production time is the processing times of these ... Department of Management Studies, Indian Institute of Science, Bangalore 560 012; Singapore-MIT Alliance, School of Mechanical and Aerospace ...

  12. Numerical analysis of thermal deformation in laser beam heating of a steel plate

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chao; Kim, Yong-Rae; Kim, Jae-Woong [Yeungnam University, Kyongsan (Korea, Republic of)

    2017-05-15

    Line heating is a widely used process for plate forming or thermal straightening. Flame heating and induction heating are the traditional heating processes used by industry for line heating. However, these two heating processes are ineffective when used on small steel plates. Thus, the laser beam heating with various power profiles were carried out in this study. A comparison of numerical simulation results and experimental results found a significant difference in the thermal deformation when apply a different power profile of laser beam heating. The one-sinusoid power profile produced largest thermal deformation in this study. The laser beam heating process was simulated by established a combined heat source model, and simulated results were compared with experimental results to confirm the model’s accuracy. The mechanism of thermal deformation was investigated and the effects of model parameters were studied intensively with the finite element method. Thermal deformation was found to have a significant relationship with the amount of central zone plastic deformation. Scientists and engineers could use this study’s verified model to select appropriate parameters in laser beam heating process. Moreover, by using the developed laser beam model, the analysis of welding residual stress or hardness could also be investigated from a power profile point of view.

  13. Effects of Heat Input on Microstructure, Corrosion and Mechanical Characteristics of Welded Austenitic and Duplex Stainless Steels: A Review

    Directory of Open Access Journals (Sweden)

    Ghusoon Ridha Mohammed

    2017-01-01

    Full Text Available The effects of input heat of different welding processes on the microstructure, corrosion, and mechanical characteristics of welded duplex stainless steel (DSS are reviewed. Austenitic stainless steel (ASS is welded using low-heat inputs. However, owing to differences in the physical metallurgy between ASS and DSS, low-heat inputs should be avoided for DSS. This review highlights the differences in solidification mode and transformation characteristics between ASS and DSS with regard to the heat input in welding processes. Specifically, many studies about the effects of heat energy input in welding process on the pitting corrosion, intergranular stress, stresscorrosion cracking, and mechanical properties of weldments of DSS are reviewed.

  14. Influence of Heat Treatment on Mercury Cavitation Resistance of Surface Hardened 316LN Stainless Steel

    Energy Technology Data Exchange (ETDEWEB)

    Pawel, Steven J [ORNL; Hsu, Julia [Massachusetts Institute of Technology (MIT)

    2010-11-01

    The cavitation-erosion resistance of carburized 316LN stainless steel was significantly degraded but not destroyed by heat treatment in the temperature range 500-800 C. The heat treatments caused rejection of some carbon from the carburized layer into an amorphous film that formed on each specimen surface. Further, the heat treatments encouraged carbide precipitation and reduced hardness within the carburized layer, but the overall change did not reduce surface hardness fully to the level of untreated material. Heat treatments as short as 10 min at 650 C substantially reduced cavitation-erosion resistance in mercury, while heat treatments at 500 and 800 C were found to be somewhat less detrimental. Overall, the results suggest that modest thermal excursions perhaps the result of a weld made at some distance to the carburized material or a brief stress relief treatment will not render the hardened layer completely ineffective but should be avoided to the greatest extent possible.

  15. The Effect of Heat Treatments and Coatings on the Outgassing Rate of Stainless Steel Chambers

    Energy Technology Data Exchange (ETDEWEB)

    Mamum, Md Abdullah A. [Old Dominion Univ., Norfolk, VA (United States); Elmustafa, Abdelmageed A, [Old Dominion Univ., Norfolk, VA (United States); Stutzman, Marcy L. [JLAB, Newport News, VA (United States); Adderley, Philip A. [JLAB, Newport News, VA (United States); Poelker, Matthew [JLAB, Newport News, VA (United States)

    2014-03-01

    The outgassing rates of four nominally identical 304L stainless steel vacuum chambers were measured to determine the effect of chamber coatings and heat treatments. One chamber was coated with titanium nitride (TiN) and one with amorphous silicon (a-Si) immediately following fabrication. One chamber remained uncoated throughout, and the last chamber was first tested without any coating, and then coated with a-Si following a series of heat treatments. The outgassing rate of each chamber was measured at room temperatures between 15 and 30 deg C following bakes at temperatures between 90 and 400 deg C. Measurements for bare steel showed a significant reduction in the outgassing rate by more than a factor of 20 after a 400 deg C heat treatment (3.5 x 10{sup 12} TorrL s{sup -1}cm{sup -2} prior to heat treatment, reduced to 1.7 x 10{ sup -13} TorrL s{sup -1}cm{sup -2} following heat treatment). The chambers that were coated with a-Si showed minimal change in outgassing rates with heat treatment, though an outgassing rate reduced by heat treatments prior to a-Si coating was successfully preserved throughout a series of bakes. The TiN coated chamber exhibited remarkably low outgassing rates, up to four orders of magnitude lower than the uncoated stainless steel. An evaluation of coating composition suggests the presence of elemental titanium which could provide pumping and lead to an artificially low outgassing rate. The outgassing results are discussed in terms of diffusion-limited versus recombination-limited processes.

  16. [Association between joint of heat and noise and metabolic syndrome in steel workers].

    Science.gov (United States)

    Li, Xue; Wang, Chaoyang; Fan, Hongmin; Wang, Xiaokai; Zhang, Meihang; Jia, Chongyan; Chai, Feng; Chen, Yinping; Hu, Bo; Yuan, Juxiang; Dong, Ya'nan; Wang, Jianbo

    2015-01-01

    To analyze the relationship between joint of heat and noise, and metabolic syndrome in a steel rolling factory workers. A total of 590 steel workers were selected as subjects by cluster sampling method from workers of a steel factory. They were investigated by face to face way with the unified questionnaire which contents included personal information, occupational history, personal history, habits and other factors. Furthermore, height, weight, waist circumference and blood pressure were measured. Referring to the 2005 International Diabetes Federation (IDF) issued by the metabolic syndrome (MS) worldwide uniform definition combines waist diagnosis MS. A database was built by Epidata 3.0 software, and data was analyzed by SPSS 17.0. 571 steel workers were from 22 to 60 years, mean age (41.2 -7.9) years old. The prevalence of metabolic syndrome in steel workers was 17.9%. The prevalence of metabolic syndrome of those who exposed to high temperature was 18.8%, higher than that of those who did not expose to high temperature (5.3%), there was a statistically significant difference (P < 0.05). The prevalence of metabolic syndrome of those who exposed to noise was 20.6%, higher than that of those who did not exposed to noise (14.0%) (P < 0.05). After adjusting for the effects of confounding factors, the prevalence of MS those who exposed to high temperatures and noise is 1.118 times as high as that of those who did not exposed to high temperatures and noise. The combined effects of heat and noise is related to the increasing prevalence of MS of steel workers.

  17. Effect of Austenitizing Heat Treatment on the Microstructure and Hardness of Martensitic Stainless Steel AISI 420

    Science.gov (United States)

    Barlow, L. D.; Du Toit, M.

    2012-07-01

    The effect of austenitizing on the microstructure and hardness of two martensitic stainless steels was examined with the aim of supplying heat-treatment guidelines to the user that will ensure a martensitic structure with minimal retained austenite, evenly dispersed carbides and a hardness of between 610 and 740 HV (Vickers hardness) after quenching and tempering. The steels examined during the course of this examination conform in composition to medium-carbon AISI 420 martensitic stainless steel, except for the addition of 0.13% vanadium and 0.62% molybdenum to one of the alloys. Steel samples were austenitized at temperatures between 1000 and 1200 °C, followed by oil quenching. The as-quenched microstructures were found to range from almost fully martensitic structures to martensite with up to 35% retained austenite after quenching, with varying amounts of carbides. Optical and scanning electron microscopy was used to characterize the microstructures, and X-ray diffraction was employed to identify the carbide present in the as-quenched structures and to quantify the retained austenite contents. Hardness tests were performed to determine the effect of heat treatment on mechanical properties. As-quenched hardness values ranged from 700 to 270 HV, depending on the amount of retained austenite. Thermodynamic predictions (using the CALPHAD™ model) were employed to explain these microstructures based on the solubility of the carbide particles at various austenitizing temperatures.

  18. Effects of erodant particle shape and various heat treatments on erosion resistance of plain carbon steel

    Science.gov (United States)

    Salik, J.; Buckley, D. H.

    1981-01-01

    Erosion tests were conducted on 1045 steel samples which had been subjected to different heat treatments. The weight of material removed upon erosion with glass beads and crushed glass was measured. The data show that there is no correlation between hardness and erosion resistance. The erosion rate was strongly dependent on the shape of erodant particles, being an order of magnitude higher for erosion with crushed glass than with glass beads. Heat treatment had a profound effect on the erosion resistance when the erodant particles were glass beads but little or no effect when the particles were crushed glass. It is thus concluded that different mechanisms of material removal are involved with these two erodants. This conclusion is supported by the surface morphology of annealed 1045 steel samples which had been eroded by these two types of erodant particles. SEM micrographs of the eroded surfaces show that for erosion with glass beads it is deformation induced fracture of surface layers.

  19. High strength and heat resistant chromium steels for sodium-cooled fast reactors.

    Energy Technology Data Exchange (ETDEWEB)

    Kamal, S.; Grandy, C.; Farmer, M.; Brunsvold, A.

    2004-12-22

    This report provides the results of a preliminary phase of a project supporting the Advanced Nuclear Fuel Cycle Technology Initiative at ANL. The project targets the Generation IV nuclear energy systems, particularly the area of reducing the cost of sodium-cooled fast-reactors by utilizing innovative materials. The main goal of the project is to provide the nuclear heat exchanger designers a simplified means to quantify the cost advantages of the recently developed high strength and heat resistant ferritic steels with 9 to 13% chromium content. The emphasis in the preliminary phase is on two steels that show distinctive advantages and have been proposed as candidate materials for heat exchangers and also for reactor vessels and near-core components of Gen IV reactors. These steels are the 12Cr-2W (HCM12A) and 9Cr-1MoVNb (modified 9Cr-1Mo). When these steels are in tube form, they are referred to in ASTM Standards as T122 and T91, respectively. A simple thermal-hydraulics analytical model of a counter-flow, shell-and-tube, once-through type superheated steam generator is developed to determine the required tube length and tube wall temperature profile. The single-tube model calculations are then extended to cover the following design criteria: (i) ratio of the tube stress due to water/steam pressure to the ASME B&PV Code allowable stress, (ii) ratio of the strain due to through-tube-wall temperature differences to the material fatigue limit, (iii) overall differential thermal expansion between the tube and shell, and (iv) total amount of tube material required for the specified heat exchanger thermal power. Calculations were done for a 292 MW steam generator design with 2200 tubes and a steam exit condition of 457 C and 16 MPa. The calculations were performed with the tubes made of the two advanced ferritic steels, 12Cr-2W and 9Cr-1MoVNb, and of the most commonly used steel, 2 1/4Cr-1Mo. Compared to the 2 1/4Cr-1Mo results, the 12Cr-2W tubes required 29% less

  20. Effect of heat treatment on an AISI 304 austenitic stainless steel evaluated by the ultrasonic attenuation coefficient

    Energy Technology Data Exchange (ETDEWEB)

    Moghanizadeh, Abbas; Farzi, Abolfazl [Islamic Azad Univ., Esfarayen (Iran, Islamic Republic of). Dept. of Civil Engineering

    2016-07-01

    The properties of metals can be substantially changed by various methods, one of them is using heat treatment processes. Moreover, ultrasonic testing is the most preferred and effective, nondestructive testing technique for characterization of mechanical material properties. Austenitic stainless steel AISI 304 serves in many applications due to high strength and corrosion resistance. In certain applications, it is important to evaluate the mechanical properties of AISI 304 stainless steel. In this study, the ultrasonic method (attenuation measurement technique) is used to evaluate the hardness of AISI 304 stainless steel samples which were heat treated at different levels. Due to the heat treatment process, each sample has its specific microstructure and hardness which attenuate ultrasonic waves appropriately. The ultrasonic and hardness test show that it is possible to evaluate the hardness of AISI 304 stainless steel by ultrasonic attenuation coefficient. In addition, the relationship between ultrasonic attenuation coefficients and time of heat treatment is investigated.

  1. Developing and Studying the Methods of Hard-Facing with Heat-Resisting High-Hardness Steels

    Science.gov (United States)

    Malushin, N. N.; Kovalev, A. P.; Valuev, D. V.; Shats, E. A.; Borovikov, I. F.

    2016-08-01

    The authors develop the methods of hard-facing of mining-metallurgic equipment parts with heat-resisting high-hardness steels on the base of plasma-jet hard-facing in the shielding-alloying nitrogen atmosphere.

  2. Geological and mining factors affecting spontaneous heating of coal

    Energy Technology Data Exchange (ETDEWEB)

    Morris, R.; Atkinson, T.

    1986-04-01

    The authors define the phenomenon of spontaneous heating in underground coal mines as a combination of seam factor, geological factor and mining factor. These latter two factors are discussed in a practical manner from the early work of Fayol in 1879 through to the findings of modern day researchers. The paper assesses the significance of all relevant aspects affecting spontaneous heating of coal, and provides the basis for a better understanding of its complex causes. 7 figs., 24 refs.

  3. Assessment of Heat Stress Index, and evaluation of theirvalidity in Mobarakeh Steel Association's Mobarakeh Steel Association's

    Directory of Open Access Journals (Sweden)

    M Sadeghi Aliabadi

    2005-10-01

    Full Text Available Background and Aims: Existence of heat in industries is considered as a serious problem. Someindexes have been invited to evaluate the rate of heat loud on worker. These indexes have beenused & comprised in different researches. This research validity of some of these indexes wasevaluated.Method: In purpose of evaluation of indexes and environmental factor ordinary and CataTermometer, WBCT Meter instrument and Humidity Meter was used. As a first step Molding unitdivided into 15 stations, and in the second step parameters measurement was begone . After thatthe obtained figures was used in special equation to calculate heat stress indexes.Mouth, skin, and core body temperature of 90 healthy and adopted male worker was recorded.Then the obtained result was analysed by Spss, and mean, standard deviation and correlationcoficient was ealeutated for each of them.Results: At first mean, minimum, maximum and standard deviation was calculated forenvironmental parameter and indexes.At the second step the relationship between personalfactors (mouth, skin and core body temperature and parameters and environmental indexes. (Airtemperature, radiation temperature, air velocity and relative humidity was assessed.The result showed no significance relationship between personal factor and heat stressor. Factor(p>5% only purse index had significance relationship (p=0/005, and the others indexes did notshowed significance relationship.Conclusion: In this research the relationship between purse and all variables was significance.Therefore this index considered as a first valid index in this research.WBGTindex shows the most relationship after the purse index in comparison with other indexes.Because of the other indexes's no significance relationship, so pours had a good validity in thisresearch.

  4. Optimization of Composition and Heat Treating of Die Steels for Extended Lifetime

    Energy Technology Data Exchange (ETDEWEB)

    David Schwam; John F. Wallace; Quanyou Zhou

    2002-01-30

    An ''average'' die casting die costs fifty thousand dollars. A die used in making die cast aluminum engine blocks can cost well over one million dollars. These costs provide a strong incentive for extension of die life. While vacuum quenched Premium Grade H13 dies have become the most widely used in the United States, tool makers and die casters are constantly searching for new steels and heat treating procedures to extend die life. This project was undertaken to investigate the effects of composition and heat treating on die life and optimize these parameters.

  5. Effect of heat input on dilution and heat affected zone in submerged ...

    Indian Academy of Sciences (India)

    Effect of heat input on dilution and heat affected zone in submerged arc welding process. HARI OM1,∗ and SUNIL PANDEY2. 1Department of Mechanical Engineering, YMCA University of Science and. Technology, Sector 06, Faridabad 121 006, India. 2Department of Mechanical Engineering, Indian Institute of Technology ...

  6. Technological practicability of the numerical modeling of induction heating process in steel pieces

    Energy Technology Data Exchange (ETDEWEB)

    Iagar, A.; Sora, I.; Radu, D.; Panoiu, C.; Abrudean, C.

    2009-07-01

    This paper presents the numerical modeling (using the Finite Difference Method-FDM, and Finite Element Method- FEM) of the electromagnetic and thermal fields in a steel piece heated up inside an induction crucible furnace, and the experimental validations. Both modeling have been validated experimentally, so they can be used in designing the equipment and in the numerical control of induction heating process. The program based on FDM can be used in the first stage of designing due to the reduced CPU time. In this stage the inductor parameters and heating time can be estimated, and a study of the influence of diverse factors upon the heating process can be achieved. The FLUX 2D program can be used in the optimization stage, because it allows a more thorough analysis of the phenomena. (Author) 29 refs.

  7. Heat input effect on the microstructural transformation and mechanical properties in GTAW welds of a 409L ferritic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Delgado, J. A.; Ambriz, R. R.; Cuenca-Alvarez, R.; Alatorre, N.; Curiel, F. F.

    2016-10-01

    Welds without filler metal and welds using a conventional austenitic stainless steel filler metal (ER308L) were performed to join a ferritic stainless steel with Gas Tungsten Arc Welding process (GTAW). Welding parameters were adjusted to obtain three different heat input values. Microstructure reveals the presence of coarse ferritic matrix and martensite laths in the Heat Affected Zone (HAZ). Dilution between filler and base metal was correlated with the presence of austenite, martensite and ferrite in the weld metal. Weld thermal cycles were measured to correlate the microstructural transformation in the HAZ. Microhardness measurements (maps and profiles) allow to identify the different zones of the welded joints (weld metal, HAZ, and base metal). Comparing the base metal with the weld metal and the HAZ, a hardness increment (∼172 HV{sub 0}.5 to ∼350 HV{sub 0}.5 and ∼310 HV{sub 0}.5, respectively) was observed, which has been attributed to the martensite formation. Tensile strength of the welded joints without filler metal increased moderately with respect to base metal. In contrast, ductility was approximately 25% higher than base metal, which provided a toughness improvement of the welded joints. (Author)

  8. Transient Response to Rapid Cooling of a Stainless Steel Sodium Heat Pipe

    Science.gov (United States)

    Mireles, Omar R.; Houts, Michael G.

    2011-01-01

    Compact fission power systems are under consideration for use in long duration space exploration missions. Power demands on the order of 500 W, to 5 kW, will be required for up to 15 years of continuous service. One such small reactor design consists of a fast spectrum reactor cooled with an array of in-core alkali metal heat pipes coupled to thermoelectric or Stirling power conversion systems. Heat pipes advantageous attributes include a simplistic design, lack of moving parts, and well understood behavior. Concerns over reactor transients induced by heat pipe instability as a function of extreme thermal transients require experimental investigations. One particular concern is rapid cooling of the heat pipe condenser that would propagate to cool the evaporator. Rapid cooling of the reactor core beyond acceptable design limits could possibly induce unintended reactor control issues. This paper discusses a series of experimental demonstrations where a heat pipe operating at near prototypic conditions experienced rapid cooling of the condenser. The condenser section of a stainless steel sodium heat pipe was enclosed within a heat exchanger. The heat pipe - heat exchanger assembly was housed within a vacuum chamber held at a pressure of 50 Torr of helium. The heat pipe was brought to steady state operating conditions using graphite resistance heaters then cooled by a high flow of gaseous nitrogen through the heat exchanger. Subsequent thermal transient behavior was characterized by performing an energy balance using temperature, pressure and flow rate data obtained throughout the tests. Results indicate the degree of temperature change that results from a rapid cooling scenario will not significantly influence thermal stability of an operating heat pipe, even under extreme condenser cooling conditions.

  9. Residual stress distributions in a P91 steel-pipe girth weld before and after post weld heat treatment

    Energy Technology Data Exchange (ETDEWEB)

    Paddea, S., E-mail: s.paddea@open.ac.uk [Materials Engineering, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Francis, J.A. [School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Manchester M13 9PL (United Kingdom); Paradowska, A.M. [ISIS Facility, Rutherford-Appleton Laboratory, Didcot OX11 0QX, Oxon (United Kingdom); Bouchard, P.J. [Materials Engineering, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Shibli, I.A. [European Technology Development Ltd., Leatherhead KT22 7RD, Surrey (United Kingdom)

    2012-02-01

    Highlights: Black-Right-Pointing-Pointer Residual stresses in a pipe girth weld in P91 steel have been measured in both the as-welded and PWHT conditions. Black-Right-Pointing-Pointer The highest tensile residual stresses coincided with the HAZ boundary and the microstructural region that is prone to type IV cracking. Black-Right-Pointing-Pointer Compressive residual stresses were measured in the weld metal, in a location corresponding to the final weld pass. Black-Right-Pointing-Pointer The location of the peak compressive stresses can be explained by the effect of solid-state phase transformation. - Abstract: In this study the residual stresses in a pipe girth weld in a ferritic-martensitic power plant steel were measured by neutron diffraction and compared with the corresponding metallurgical zones in the weld region. It was found that, in both the as-welded and post-weld heat treated condition, the highest tensile stresses resided near the outer boundary of the heat-affected zone (HAZ), and towards the weld root region. Substantial tensile direct and hydrostatic stresses existed across the HAZ, including the fine-grained and intercritically annealed regions, where premature type IV creep failures manifest in 9-12 Cr steel welds. Compressive stresses were found in the weld metal coinciding with the last weld bead to be deposited. Constrained cooling tests on test coupons illustrated that these compressive stresses can be explained in terms of the influence that solid-state phase transformations have on the accumulation of stress in welds.

  10. Effect of irrigation and stainless steel drills on dental implant bed heat generation.

    Science.gov (United States)

    Bullon, B; Bueno, E F; Herrero, M; Fernandez-Palacin, A; Rios, J V; Bullon, P; Gil, F J

    2015-02-01

    The objective of this study is assessing the influence of the use of different drill types and external irrigation on heat generation in the bone. In-vitro study to compare two different sequences for implant-bed preparation by means of two stainless steels: precipitation-hardening stainless steel (AISI 420B) (K drills), and martensitic stainless steel (AISI 440) (S drills). Besides, the drilled sequences were realized without irrigation, and with external irrigation by means of normal saline solution at room temperature. The study was realized on bovine ribs using: K without irrigation (KSI) and with irrigation (KCI) and S without irrigation (SSI) and with irrigation (SCI) with five drills for each system. Each drill was used 100 times. Bone temperature was measured with a thermocouple immediately after drilled. Average bone temperature with irrigation was for K drills 17.58±3.32 °C and for S drills 16.66±1.30 °C. Average bone temperature without irrigation was for K drills 23.58±2.94 °C and for S drills 19.41±2.27 °C. Statistically significant differences were found between K without irrigation versus S with irrigation and K with irrigation (pirrigated groups (K=5.6%, S=5.1% vs. without irrigation groups K=9.4%, S=9.3%). The first K drill generated more heat than the remaining drills. No significant differences were detected among temperature values in any of the analyzed drill groups. Unlike irrigation, drill use and type were observed to have no significant impact on heat generation. The stainless steel AISI 420B presents better mechanical properties and corrosion resistance than AISI440.

  11. Effect of Welding Heat Input on the Microstructure and Toughness in Simulated CGHAZ of 800 MPa-Grade Steel for Hydropower Penstocks

    Directory of Open Access Journals (Sweden)

    Qingfeng Ding

    2017-03-01

    Full Text Available To determine the appropriate welding heat input for simulated coarse grained heat affected zone (CGHAZ of 800 MPa-grade steel used in hydropower penstocks, the microstructural evolution, hardness, and 50% fraction appearance transition temperature (50% FATT were investigated. The results indicated that when the cooling rate (heat input is reduced (increased, the impact toughness at −20 °C and hardness of the simulated CGHAZ decreased. When the heat input increased from 18 to 81 kJ/cm, the 50% FATT increased from −80 °C to −11 °C. At 18 kJ/cm, the microstructures consisted of lath bainite and granular bainite, but lath bainite decreased with increasing heat input. The increase in the 50% FATT was attributed mainly to an increase in the austenite grain size and effective grain size, and a decrease in lath bainite and the fraction of HAGBs (misorientation: ≥15°.

  12. Fast-heating for intercritical annealing of cold-rolled quenching and partitioning steel

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Geng, E-mail: liug1988@126.com [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Zhang, Shengen, E-mail: zhangshengen@mater.ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Li, Jun; Wang, Jian; Meng, Qingge [Research Institute of Baoshan Iron and Steel Co., Ltd, Shanghai 201900 (China)

    2016-07-04

    In this study, fast-heating (300 °C/s) was applied to achieve the intercritical annealing of a cold-rolled quenching and partitioning (Q&P) steel with a wide range of soaking temperature (770–850 °C) and soaking time (0–120 s) for austenitization. The dilatometry and microstructural analysis revealed that in contrast to the conventional heating rate (5 °C/s), a fast-heating rate led to an accelerated transformation and grain refinement of the prior austenite in the Q&P samples. The microstructures of the Q&P treated samples subjected to different intercritical annealing conditions were studied in detail by various material characterization techniques including electron microscopy, electron probe micro-analysis, and X-ray diffraction. The working hardening behavior and the mechanical stability of the retained austenite were discussed on the basis of the typical stress-strain curves. The statistics of the ultimate tensile strength vs. total elongation of each sample under the orthogonal annealing conditions suggest that, for the investigated steel, the fast-heating process improved the strength with approximately 90 MPa on average within the elongation ranged from 17 to 27%.

  13. Heat treatment of long term serviced Cr – Mo cast steel

    Directory of Open Access Journals (Sweden)

    G. Golanski

    2010-01-01

    Full Text Available The paper presents results of research on the influence of heat treatment on the structure and properties of L20HM cast steel after long term operation at elevated temperature. Investigated cast steel was taken out from an outer frame of a steam turbine serviced for 167 424 hours at the temp. of 535 oC and pressure 12.75 MPa. In post-operating condition the investigated cast steel was characterized by mechanical properties below the required minimum and by high brittleness. Performed research on the influence of austenitizing parameters has revealed that the range of austenitizing temperatures for the examined cast steel: Ac3 + 30 ÷ 60 oC ensures obtaining of a fine austenite grain, homogeneous in size. It has been proved that tempering of bainititc – ferritic structure above 680 ÷ 690 oC causes an increase of impact energy along with a decrease of mechanical properties below the required minimum. Moreover, it has been noticed that applying of under-annealing instead of tempering, after full-annealing, guarantees the required impact energy of KV > 27J, with the mechanical properties similar to those after service.

  14. Failure Mechanism of a Stellite Coating on Heat-Resistant Steel

    Science.gov (United States)

    Wang, Dong; Zhao, Haixing; Wang, Huang; Li, Yuyan; Liu, Xia; He, Guo

    2017-09-01

    The Stellite 21 coating on the heat-resistant steel X12CrMoWVNbN10-1-1 (so-called COSTE) used in a steam turbine valve was found to be fatigue broken after service at around 873 K (600 °C) for about 8 years. In order to investigate the failure mechanism, a fresh Stellite 21 coating was also prepared on the same COSTE steel substrate by using the similar deposition parameters for comparison. It was found that the Stellite 21 coating was significantly diluted by the steel, resulting in a thin Fe-rich layer in the coating close to the fusion line. Such high Fe concentration together with the incessant Fe diffusion from the steel substrate to the coating during the service condition (about 873 K (600 °C) for long time) induced the eutectoid decomposition of the fcc α-Co(Fe,Cr,Mo) solid solution, forming an irregular eutectoid microstructure that was composed of the primitive cubic α'-FeCo(Cr,Mo) phase and the tetragonal σ-CrCo(Fe,Mo) phase. The brittle nature of such α'/ σ eutectoid microstructure contributed to the fatigue fracture of the Stellite 21 coating, resulting in an intergranular rupture mode.

  15. Optimisation of Mechanical Properties of 18%Ni350 Grade Maraging Steel Using Novel Heat Treatment

    Directory of Open Access Journals (Sweden)

    Marcisz J.

    2017-03-01

    Full Text Available The paper presents results of examinations of properties and microstructure of maraging steel grade MS350 (18Ni350 produced by a novel heat treatment method called „short-time ageing“. It has been found that maraging steel after application of the short-time ageing achieves unique properties, in particular good combination of strength and impact toughness. After short-time ageing for time of heating up to 600 seconds at temperature of 550°C hardness in the range from 48 to 56 HRC, tensile strength ranging from 2000 to 2250 MPa, yield strength from 1930 to 2170 MPa and total elongation in the range 7-8% as well as notch impact toughness of 20 J/cm2 at temperature minus 40°C were obtained. Results of microstructure examination in transmission electron microscope (TEM with application of high resolution technique (HRTEM have shown presence of Ni3Mo nano-precipitates of orthorhombic crystallographic structure. Precipitates were characterized by rod-like shape and were homogenously distributed in martensitic matrix of steel with high density of dislocations. The average size of cross-section of precipitates was ca. 4 nm while length reached several dozen of nm.

  16. Heat Treatment Optimization and Properties Correlation for H11-Type Hot-Work Tool Steel

    Science.gov (United States)

    Podgornik, B.; Puš, G.; Žužek, B.; Leskovšek, V.; Godec, M.

    2017-12-01

    The aim of this research was to determine the effect of vacuum-heat-treatment process parameters on the material properties and their correlations for low-Si-content AISI H11-type hot-work tool steel using a single Circumferentially Notched and fatigue Pre-cracked Tensile Bar (CNPTB) test specimen. The work was also focused on the potential of the proposed approach for designing advanced tempering diagrams and optimizing the vacuum heat treatment and design of forming tools. The results show that the CNPTB specimen allows a simultaneous determination and correlation of multiple properties for hot-work tool steels, with the compression and bending strength both increasing with hardness, and the strain-hardening exponent and bending strain increasing with the fracture toughness. On the other hand, the best machinability and surface quality of the hardened hot-work tool steel are obtained for hardness values between 46 and 50 HRC and a fracture toughness below 60 MPa√m.

  17. Effect of Process Parameters on the Total Heat Damaged Zone (HDZ) during Micro-EDM of Plastic Mold Steel 1.2738

    DEFF Research Database (Denmark)

    Puthumana, Govindan

    2016-01-01

    stresses.This paper presents the effect of process parameters on the HDZ in micro-EDM of plastic mold steel 1.2738.As the energy of the sparks increases, the thickness of the HDZ increases and the average coefficient ofcorrelation between energy and HDZ considering three different sections of the zone is 0......In micro electrical discharge machining, three subsurface layersare formed on the workpiece, they are;recast zone, heat affected zone and converted zone, primarily due to heating-quenching cycles. The HDZ inmicro-EDM is characterized by cracks and weakness in the grain boundary and thermal residual...

  18. Heat transfer and fluid flow during laser spot welding of 304 stainless steel

    CERN Document Server

    He, X; Debroy, T

    2003-01-01

    The evolution of temperature and velocity fields during laser spot welding of 304 stainless steel was studied using a transient, heat transfer and fluid flow model based on the solution of the equations of conservation of mass, momentum and energy in the weld pool. The weld pool geometry, weld thermal cycles and various solidification parameters were calculated. The fusion zone geometry, calculated from the transient heat transfer and fluid flow model, was in good agreement with the corresponding experimentally measured values for various welding conditions. Dimensional analysis was used to understand the importance of heat transfer by conduction and convection and the roles of various driving forces for convection in the weld pool. During solidification, the mushy zone grew at a rapid rate and the maximum size of the mushy zone was reached when the pure liquid region vanished. The solidification rate of the mushy zone/liquid interface was shown to increase while the temperature gradient in the liquid zone at...

  19. Influence of heat treatment on mechanical property of steel hollow sphere and its sheet construction

    Science.gov (United States)

    Yoshida, Yoshinori; Ozawa, Sho

    2017-10-01

    Heat treatments, water quenching and annealing, are performed on the metallic hollow spheres (MHS) made from steel with 4.0 mm in outer diameter. They are pierced then put on a piece of tungsten alloy wire for making a MHS thread. The thread is set in between two neighboring warps of the tungsten alloy and the thread is placed in a reticular pattern. The MHS fabric sheet which has plain weave structure is produced by the weaving process. Furthermore, a sandwich construction of the sheet with 2 sheets of aluminum plate. The influence of the heat treatments on difference of mechanical and energy absorption property are evaluated by mean of compression test for the sheet along with the thickness direction. In addition, an aluminum pipe is filled with a heat treated MHS sheet and compression test is performed for the pipe along the radial direction. Its difference of compression load and energy consumption property is investigated.

  20. Effect of heat-treatment on the hardness and mechanical properties of Boron Alloyed Steel

    Directory of Open Access Journals (Sweden)

    bin Khiyon Mohammad Raffik

    2017-01-01

    Full Text Available In an automotive industry, hot stamped, die quenched structural components have been widely used to provide extra protection against crash intrusion. Boron alloyed steel exhibit limited ductility, but it also promotes improvement in impact performance. This study analyzed the effect of cooling rate on the hardness and energy absorption. Self-quenched specimens were heated to 850°C and cooled in air of room temperature, water at room temperature and cold water. Vickers hardness test and tensile test was then carried out to analyze the effect of different quenching rate. Self-quenched specimens were compared to the properties of the die-quenched specimens obtained from commercial automobile body. Result shows that boron steel with the highest cooling rate has the highest value of hardness but low in strength.

  1. Liquid Inclusions in Heat-Resistant Steel Containing Rare Earth Elements

    Science.gov (United States)

    Li, Yandong; Liu, Chengjun; Zhang, Tongsheng; Jiang, Maofa; Peng, Cheng

    2017-04-01

    Abundant thermodynamic data of pure substances were incorporated in the coupled thermodynamic model of inclusion precipitation and solute micro-segregation during the solidification of heat-resistant steel containing rare earth elements. The liquid inclusions Ce2 x Al2 y Si1- x-y O z (0 method for generation Gibbs free energy of liquid inclusions in molten steel was given. The accuracy of accomplished model was validated through plant trials, lab-scale experiments, and the data published in the literature. The comparisons of results calculated by FactSage with the model were also discussed. Finally, the stable area of liquid inclusions was predicted and the liquid inclusions with larger size were found in the preliminary experiments.

  2. Microstructural Characterization Of Laser Heat Treated AISI 4140 Steel With Improved Fatigue Behavior

    Directory of Open Access Journals (Sweden)

    Oh M.C.

    2015-06-01

    Full Text Available The influence of surface heat treatment using laser radiation on the fatigue strength and corresponding microstructural evolution of AISI 4140 alloy steel was investigated in this research. The AISI 4140 alloy steel was radiated by a diode laser to give surface temperatures in the range between 600 and 800°C, and subsequently underwent vibration peening. The fatigue behavior of surface-treated specimens was examined using a giga-cycle ultrasonic fatigue test, and it was compared with that of non-treated and only-peened specimens. Fatigue fractured surfaces and microstructural evolution with respect to the laser treatment temperatures were investigated using an optical microscope. Hardness distribution was measured using Vickers micro-hardness. Higher laser temperature resulted in higher fatigue strength, attributed to the phase transformation.

  3. Effects Of The Combined Heat And Cryogenic Treatment On The Stability Of Austenite In A High Co-Ni Steel

    Directory of Open Access Journals (Sweden)

    Gruber M.

    2015-09-01

    Full Text Available The stability of austenite is one of the most dominant factors affecting the toughness properties of high Co-Ni steels such as Aermet 100 and AF1410. Thus, the aim of this work was to get a deeper understanding on the impact of combined heat and cryogenic treatment on the stability of retained and reverted austenite. In order to characterize the evolution of the phase fraction of austenite during tempering at different temperatures and times, X-ray diffraction analyses were carried out. The stability of austenite, which was formed during tempering, was analyzed with dilatometric investigations by studying the transformation behavior of the austenite during cooling from tempering temperature down to −100°C. Additionally, transmission electron microscopy investigations were performed to characterize the chemical composition and phase distribution of austenite and martensite before and after tempering.

  4. Effect of Heat Treatment on the Mechanical Properties and Microstructure of a API 5CT J55 Pipeline Steel

    Directory of Open Access Journals (Sweden)

    Soria-Aguilar Ma. de Jesús

    2015-09-01

    Full Text Available The effects of two different post-weld heat treatment cycles on the microstructure and mechanical properties of welded API 5CT J55 steels were investigated in the present work. Experiments were carried out based on a Taguchi experimental design. Ortogonal arrays (L9 of Taguchi and statistical analysis of variance (ANOVA were employed to determine the impact of the heat treatment parameters on the microstructure and mechanical properties of experimental steel. From the results of ANOVA, there were obtained the empirical equations for optimizing the heat treating conditions that lead to the best mechanical properties.

  5. Microstructure and Mechanical Properties of Heat-treated T92 Martensitic Heat Resistant Steel

    Science.gov (United States)

    Rajesh Kannan, P.; Muthupandi, V.; Arivazhagan, B.; Devakumaran, K.

    2017-09-01

    T92 samples were solutionized at 1,050 °C, 1,100 °C and 1,150 °C for 20 min and then tempered at 730 °C, 745 °C and 760 °C for 60 min. Optical microscopy studies were carried out to understand the microstructural evolution due to heat treatment. These heat-treated samples comprised of lath martensite microstructure in all the cases. Prior austenite grain size of the heat-treated samples increased with solutionizing temperature. Tensile properties were evaluated using micro-tensile samples. Hardness values of the heat-treated samples were estimated using Vickers hardness tester. Interestingly, for all the given tempering condition, the hardness values showed an increasing trend with solutionizing temperature while their tensile strength values tend to decrease. Fractograph analysis depicted that increasing the solutionizing temperature led to grain boundary decohesion.

  6. Effects of Induction Heat Bending Process on Microstructure and Corrosion Properties of ASME SA312 Gr.TP304 Stainless Steel Pipes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Nam In; Kim, Young Sik [Andong National University, Andong (Korea, Republic of); Kim, Kyung Soo; Chang, Hyun Young; Park, Heung Bae; Sung, Gi Ho [KEPCO Engineering and Construction Company, Seongnam (Korea, Republic of); Sung, Gi Ho [R and D Center, Busan (Korea, Republic of)

    2015-06-15

    The usage of bending products recently have increased since many industries such as automobile, aerospace, shipbuilding, and chemical plants need the application of pipings. Bending process is one of the inevitable steps to fabricate the facilities. Induction heat bending is composed of compressive bending process by local heating and cooling. This work focused on the effect of induction heat bending process on the properties of ASME SA312 Gr. TP304 stainless steel pipes. Tests were performed for base metal and bended area including extrados, intrados, crown up, and down parts. Microstructure was analyzed using an optical microscope and SEM. In order to determine intergranular corrosion resistance, Double Loop Electrochemical Potentiokinetic Reactivation (DL-EPR) test and ASTM A262 practice A and C tests were done. Every specimen revealed non-metallic inclusion free under the criteria of 1.5i of the standard and the induction heat bending process did not affect the non-metallic inclusion in the alloys. Also, all the bended specimens had finer grain size than ASTM grain size number 5 corresponding to the grain sizes of the base metal and thus the grain size of the pipe bended by induction heat bending process is acceptable. Hardness of transition start, bend, and transition end areas of ASME SA312 TP304 stainless steel was a little higher than that of base metal. Intergranular corrosion behavior was determined by ASTM A262 practice A and C and DL-EPR test, and respectively step structure, corrosion rate under 0.3 mm/y, and Degree of Sensitization (DOS) of 0.001 - 0.075 % were obtained. That is, the induction heat bending process didn't affect the intergranular corrosion behavior of ASME SA312 TP304 stainless steel.

  7. Effects of heat treatment conditions on microstructure and mechanical properties of AISI 420 steel

    Energy Technology Data Exchange (ETDEWEB)

    Scheuer, C.J.; Fraga, R.A.; Cardoso, R.P.; Brunatto, S.F. [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Departamento de Engenharia Mecanica. Grupo de Tecnologia de Fabricacao Assistida por Plasma e Metalurgia do Po

    2014-07-01

    The cycle control of heat treatments, on the quenching and tempering operation of AISI 420 stainless steel, is essential for improved material performance. The adequate choice of heat treatment parameters, can lead an optimization on its mechanical properties and corrosion resistance. Thus, this paper aims to investigate the effects of quenchants medium, and austenitizing and tempering temperatures, on the microstructure and mechanical properties of AISI 420 steel. Different heat treatments cycles were studied: 1) samples were austenitized at 1050°C and water, oil and air quenched; 2) samples were austenitized at range temperatures of 950-1050°C and oil quenched; and 3) as-quenched samples were tempering at range temperatures of 400-500°C. Treated samples were characterized by optical microscopy, X-ray diffractometry and hardness measurements. The samples hardness increases with increasing cooling rate (water > oil > air quenched). Water quenched samples presented crack after cooling to room temperature. Samples hardness also increases with austenitizing temperature increasing, and decreases with increasing tempering temperature. (author)

  8. Estimation of respiratory heat flows in prediction of heat strain among Taiwanese steel workers

    Science.gov (United States)

    Chen, Wang-Yi; Juang, Yow-Jer; Hsieh, Jung-Yu; Tsai, Perng-Jy; Chen, Chen-Peng

    2017-01-01

    International Organization for Standardization 7933 standard provides evaluation of required sweat rate (RSR) and predicted heat strain (PHS). This study examined and validated the approximations in these models estimating respiratory heat flows (RHFs) via convection ( C res) and evaporation ( E res) for application to Taiwanese foundry workers. The influence of change in RHF approximation to the validity of heat strain prediction in these models was also evaluated. The metabolic energy consumption and physiological quantities of these workers performing at different workloads under elevated wet-bulb globe temperature (30.3 ± 2.5 °C) were measured on-site and used in the calculation of RHFs and indices of heat strain. As the results show, the RSR model overestimated the C res for Taiwanese workers by approximately 3 % and underestimated the E res by 8 %. The C res approximation in the PHS model closely predicted the convective RHF, while the E res approximation over-predicted by 11 %. Linear regressions provided better fit in C res approximation ( R 2 = 0.96) than in E res approximation ( R 2 ≤ 0.85) in both models. The predicted C res deviated increasingly from the observed value when the WBGT reached 35 °C. The deviations of RHFs observed for the workers from those predicted using the RSR or PHS models did not significantly alter the heat loss via the skin, as the RHFs were in general of a level less than 5 % of the metabolic heat consumption. Validation of these approximations considering thermo-physiological responses of local workers is necessary for application in scenarios of significant heat exposure.

  9. Effects of heat treatment on properties of multi-element low alloy wear-resistant steel

    Directory of Open Access Journals (Sweden)

    SONG Xu-ding

    2007-02-01

    Full Text Available The paper has studied the mechanical properties and heat treatment effects on multi-element low alloy wear-resistant steel (MLAWS used as a material for the liner of rolling mill torii. The results show that when quenched at 900-920℃ and tempered at 350-370℃, the MLAWS has achieved hardness above 60 HRC, tensile strength greater than 1 600 MPa, impact toughness higher than 18J/cm2 and fracture toughness greater than 37 MPa

  10. Study on creep behavior of Grade 91 heat-resistant steel using theta projection method

    Science.gov (United States)

    Ren, Facai; Tang, Xiaoying

    2017-10-01

    Creep behavior of Grade 91 heat-resistant steel used for steam cooler was characterized using the theta projection method. Creep tests were conducted at the temperature of 923K under the stress ranging from 100-150MPa. Based on the creep curve results, four theta parameters were established using a nonlinear least square fitting method. Four theta parameters showed a good linearity as a function of stress. The predicted curves coincided well with the experimental data and creep curves were also modeled to the low stress level of 60MPa.

  11. Precipitation behavior in a nitride-strengthened martensitic heat resistant steel during hot deformation

    Directory of Open Access Journals (Sweden)

    Wenfeng Zhang

    2015-09-01

    Full Text Available The stress relaxation curves for three different hot deformation processes in the temperature range of 750–1000 °C were studied to develop an understanding of the precipitation behavior in a nitride-strengthened martensitic heat resistant steel (Zhang et al., Mater. Sci. Eng. A, 2015 [1]. This data article provides supporting data and detailed information on how to accurately analysis the stress relaxation data. The statistical analysis of the stress peak curves, including the number of peaks, the intensity of the peaks and the integral value of the pumps, was carried out. Meanwhile, the XRD energy spectrum data was also calculated in terms of lattice distortion.

  12. Precipitation behavior in a nitride-strengthened martensitic heat resistant steel during hot deformation.

    Science.gov (United States)

    Zhang, Wenfeng; Su, Qingyong; Xu, Mi; Yan, Wei

    2015-09-01

    The stress relaxation curves for three different hot deformation processes in the temperature range of 750-1000 °C were studied to develop an understanding of the precipitation behavior in a nitride-strengthened martensitic heat resistant steel (Zhang et al., Mater. Sci. Eng. A, 2015) [1]. This data article provides supporting data and detailed information on how to accurately analysis the stress relaxation data. The statistical analysis of the stress peak curves, including the number of peaks, the intensity of the peaks and the integral value of the pumps, was carried out. Meanwhile, the XRD energy spectrum data was also calculated in terms of lattice distortion.

  13. Influence of Heating Rate on Annealing and Reverse Transformation Behavior of TRIP Steels Having Martensite as Starting Microstructure

    Science.gov (United States)

    Kim, Jeong In; Choi, Yong Hoon; Ryu, Joo Hyun; Lee, Sea Woong; Lee, Kyooyoung; Suh, Dong-Woo

    2017-11-01

    The influence of heating rate on the annealing and transformation behavior is investigated in TRIP steel having martensite as the starting microstructure. A higher heating rate preserves the hierarchical structure of the initial microstructure before starting the reverse transformation. As the heating rate increases, the reversely transformed austenite has a propensity to develop a fine lath morphology, a consequence of the retention of pre-existing austenite and its growth along the lath boundary.

  14. A Material Perspective on Consequence of Deformation Heating During Stamping of DP Steels

    Science.gov (United States)

    Şimşir, C.; Çetin, B.; Efe, M.; Davut, K.; Bayramin, B.

    2017-09-01

    Recent studies showed that, during stamping of high strength steels at industrially relevant production rates, local temperature in the blank may rise up to 200°C - 300°C due to deformation heating. Moreover, die temperature may also rise up to 100°C - 150°C for progressive stamping dies. Based on the common assumption that the blank softens as the temperature increases, thermal softening creates a margin in Forming Limit Diagram (FLD) and therefore the FLD determined at room temperature can safely be used for those cases. In this article, the validity of this assumption on DP590 steel is questioned by high temperature tensile tests (RT - 300°C) at various strain rates (10-3 s-1 - 1 s-1). The results indicated a decrease both in uniform and total elongation in 200°C - 300°C range together with several other symptoms of Dynamic Strain Aging (DSA) at all strain rates. Concurrent with the DSA, the simulated FLD confirms the lower formability at high temperature and strain rates. Thus, it is concluded FLD determined at RT may not be valid for the investigated steels.

  15. Effect of material heat treatment on fatigue crack initiation in austenitic stainless steels in LWR environments.

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, O. K.; Alexandreanu, B.; Shack, W. J.; Energy Technology

    2005-07-31

    The ASME Boiler and Pressure Vessel Code provides rules for the design of Class 1 components of nuclear power plants. Figures I-9.1 through I-9.6 of Appendix I to Section III of the Code specify design curves for applicable structural materials. However, the effects of light water reactor (LWR) coolant environments are not explicitly addressed by the Code design curves. The existing fatigue strain-vs.-life ({var_epsilon}-N) data illustrate potentially significant effects of LWR coolant environments on the fatigue resistance of pressure vessel and piping steels. Under certain environmental and loading conditions, fatigue lives of austenitic stainless steels (SSs) can be a factor of 20 lower in water than in air. This report presents experimental data on the effect of heat treatment on fatigue crack initiation in austenitic Type 304 SS in LWR coolant environments. A detailed metallographic examination of fatigue test specimens was performed to characterize the crack morphology and fracture morphology. The key material, loading, and environmental parameters and their effect on the fatigue life of these steels are also described. Statistical models are presented for estimating the fatigue {var_epsilon}-N curves for austenitic SSs as a function of material, loading, and environmental parameters. Two methods for incorporating the effects of LWR coolant environments into the ASME Code fatigue evaluations are presented.

  16. Influence of heat treatment and KIc/HRc ratio on the dynamic wear properties of coated high speed steel

    Directory of Open Access Journals (Sweden)

    M. Sedlaček

    2017-01-01

    Full Text Available The aim of this work was to determine the impact of various heat treatments on the KIc/HRc ratio and subsequently on the wear properties of coated high-speed steel under dynamic impact loading. The results showed that hardness and improvement in the fracture toughness have significant influence on the adhesion and impact wear properties of the coated high-speed steel.

  17. Transformation of Oxide Inclusions in Type 304 Stainless Steels during Heat Treatment

    Science.gov (United States)

    Ren, Ying; Zhang, Lifeng; Pistorius, P. Chris

    2017-10-01

    Heat treatment of Type 304 stainless steel in the range of 1273 K (1000 °C) to 1473 K (1200 °C) can transform manganese silicate inclusions to manganese chromite (spinel) inclusions. During heat treatment, Cr reacts with manganese silicate to form spinel. The transformation rate of inclusions depends strongly on both temperature [in the range of 1273 K to 1473 K (1000 °C to 1200 °C)] and inclusion size. A kinetic model, developed using FactSage macros, showed that these effects agree quantitatively with diffusion-controlled transformation. A simplified analytical model, which can be used for rapid calculations, predicts similar transformation kinetics, in agreement with the experimental observations.

  18. Laws of alloyed cementite particles nucleation during heat-resistant steels carburizing

    Directory of Open Access Journals (Sweden)

    M. Yu. Semenov

    2014-01-01

    Full Text Available The article considers a problem analyzing a nucleation of cementite type carbides in carburized heat-resistant steels for the turbofan engines gear wheels.The verification of previously hypothesized mechanism of dislocation nucleation particles chromium-alloyed cementite during process of carburizing was accepted as an objective of the work.As a methodological basis of this paper were accepted the numerical experiments based on the kinetic theory of nucleation, as well as on the known results of experimental studies.According to the kinetic theory of nucleation, a new phase in the solid solutions take place in the defects of the crystal structure of the metal such as inter-grain boundaries and dislocations clusters. A principle feature of the inter-grain boundary mechanism of nucleation is formation of carbide lattice. It is of great practical interest because the cementite lattice drops mechanical properties of hardened parts.According to the experimental studies, the average chromium concentration in the alloyed cementite twice exceeds its Cr content in the heat-resistant steels. Furthermore, the areas of abnormally high (more than ten times in comparison with the average content chromium concentration in cementite have been experimentally revealed.Numerical experiments have revealed that the nucleation of cementite particles alloyed with chromium (chromium concentration of 3% or more occurs, mainly, by the dislocation mechanism on the concentration fluctuations of the alloying element. According to calculations, an obligatory prerequisite to start an active nucleation process of new phase in the solid solution is a local increase of the chromium concentration up to 40%.Despite the lack of physical prerequisites for the formation of chromium precipitates, this phenomenon is explained by a strong chemical affinity of chromium and carbon, causing diffusion of chromium atoms in the region of the carbon atoms clusters. The formation of carbon

  19. Heat sink welding of austenitic stainless steel pipes to control distortion and residual stress

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, H.; Albert, S.K.; Bhaduri, A.K. [Materials Technology Div., Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

    2007-07-01

    Construction of India's Prototype Fast Breeder Reactor (PFBR) involves extensive welding of austenitic stainless steels pipes of different dimensions. Due to high thermal expansion coefficient and poor thermal conductivity of this class of steels, welding can result in significant distortion of these pipes. Attempts to arrest this distortion can lead to high levels of residual stresses in the welded parts. Heat sink welding is one of the techniques often employed to minimize distortion and residual stress in austenitic stainless steel pipe welding. This technique has also been employed to repair welding of the piping of the Boiling Water Reactors (BWRs) subjected to radiation induced intergranular stress corrosion cracking (IGSCC). In the present study, a comparison of the distortion in two pipe welds, one made with heat sink welding and another a normal welds. Pipes of dimensions 350{phi} x 250(L) x 8(t) mm was fabricated from 316LN plates of dimensions 1100 x 250 x 8 mm by bending and long seam (L-seam) welding by SMAW process. Two fit ups with a root gap of 2 mm, land height of 1mm and a groove angle of 70 were prepared using these pipes for circumferential seam (C-seam) welding. Dimensions at predetermined points in the fit up were made before and after welding to check the variation in radius, circumference and and ovality of the pipes. Root pass for both the pipe fit up were carried out using conventional GTAW process with 1.6 mm AWS ER 16-8-2 as consumables. Welding of one of the pipe fit ups were completed using conventions GTAW process while the other was completed using heat sink welding. For second and subsequent layers of welding using this process, water was sprayed at the root side of the joint while welding was in progress. Flow rate of the water was {proportional_to}6 1/minute. Welding parameters employed were same as those used for the other pipe weld. Results of the dimensional measurements showed that there is no circumferential shrinkage in

  20. Effect of heat input on dilution and heat affected zone in submerged ...

    Indian Academy of Sciences (India)

    Submerged arc welding (SAW) is a fusion joining process, known for its high deposition capabilities. This process is useful in joining thick section components used in various industries. Besides joining, SAW can also be used for surfacing applications. Heat Affected Zone (HAZ) produced within the base metal as a result of ...

  1. Effect of Laser Heat Treatment on Microstructures of 1Cr5Mo Steel Welded Joint

    Directory of Open Access Journals (Sweden)

    GUO Wei

    2017-01-01

    Full Text Available The surface of 1Cr5Mo heat-resistant steel welded joint was treated with CO2 laser,the microstructure and grain size grades of welded joints before and after laser heat treatment (LHT were analyzed with 4XC type optical microscope (OM,and the distribution of residual stress and retained austenite content in the surface of the welded joints were measured with X-ray diffraction (XRD stress tester.The results show that the grains of 1Cr5Mo steel welded joints are refined by LHT,and the microstructure uniformity improves significantly,the grain levels of welded zone,fusion zone,overheated zone and normalized zone increase from level 9,level 9.8,level 8 and level 10.7 to level 10,level 10.2,level 8.5 and level 11 respectively,the mechanical weak areas reduce from overheated zone,welded zone and fusion zone to the overheated zone.The tensile residual stress in the welded joint surface is eliminated by LHT and a layer of compressive residual stress with thickness of about 0.28mm is formed.The residual austenite content in the welded joint surface increases after LHT,of which the distribution is more uniform and conducive to the improvement of mechanical properties.

  2. Effect of prolonged isothermal heat treatment on the mechanical behavior of advanced NANOBAIN steel

    Science.gov (United States)

    Avishan, Behzad

    2017-09-01

    The microstructural evolution and consequent changes in strength and ductility of advanced NANOBAIN steel during prolonged isothermal heat-treatment stages were investigated. The microstructure and mechanical properties of nanostructured bainite were not expected to be influenced by extending the heat-treatment time beyond the optimum value because of the autotempering phenomenon and high tempering resistance. However, experimental results indicated that the microstructure was thermodynamically unstable and that prolonged austempering resulted in carbon depletion from high-carbon retained austenite and carbide precipitations. Therefore, austenite became thermally less stable and partially transformed into martensite during cooling to room temperature. Prolonged austempering did not lead to the typical tempering sequence of bainite, and the sizes of the microstructural constituents were independent of the extended heat-treatment times. This independence, in turn, resulted in almost constant ultimate tensile strength values. However, microstructural variations enhanced the yield strength and the hardness of the material at extended isothermal heat-treatment stages. Finally, although microstructural changes decreased the total elongation and impact toughness, considerable combinations of mechanical properties could still be achieved.

  3. Measured residual stress distributions for low and high heat input single weld beads deposited on to SA508 steel

    OpenAIRE

    Francis, J. A.; Turski, M.; Withers, P.J.

    2009-01-01

    In steel Weld.s, the development of residual stress is often complicated by the solid state phase transformations that occur upon cooling. Here the authors present bulk residual stress distributions, as measured by neutron diffraction, for the configuration of a single pass gas tungsten arc Weld. bead deposited on to a 20 mm thick SA508 steel substrate. Two specimens were manufactured, one with a low heat input (1-2 kJ mm-1) and another with a high heat input (2-4 kJ mm-1). The resulting micr...

  4. Simple Heat Treatment for Production of Hot-Dip Galvanized Dual Phase Steel Using Si-Al Steels

    Science.gov (United States)

    Equihua-Guillén, F.; García-Lara, A. M.; Muñíz-Valdes, C. R.; Ortíz-Cuellar, J. C.; Camporredondo-Saucedo, J. E.

    2014-01-01

    This work presents relevant metallurgical considerations to produce galvanized dual phase steels from low cost aluminum-silicon steels which are produced by continuous strip processing. Two steels with different contents of Si and Al were austenized in the two-phase field ferrite + austenite (α + γ) in a fast manner to obtain dual phase steels, suitable for hot-dip galvanizing process, under typical parameters of continuous annealing processing line. Tensile dual phase properties were obtained from specimens cooled from temperature below Ar3, held during 3 min, intermediate cooling at temperature above Ar1 and quenching in Zn bath at 465 °C. The results have shown typical microstructure and tensile properties of galvanized dual phase steels. Finally, the synergistic effect of aluminum, silicon, and residual chromium on martensite start temperature ( M s), critical cooling rate ( C R), volume fraction of martensite, and tensile properties has been studied.

  5. Applications of thermal energy storage to process heat and waste heat recovery in the iron and steel industry

    Science.gov (United States)

    Katter, L. B.; Peterson, D. J.

    1978-01-01

    The system identified operates from the primary arc furnace evacuation system as a heat source. Energy from the fume stream is stored as sensible energy in a solid medium (packed bed). A steam-driven turbine is arranged to generate power for peak shaving. A parametric design approach is presented since the overall system design, at optimum payback is strongly dependent upon the nature of the electric pricing structure. The scope of the project was limited to consideration of available technology so that industry-wide application could be achieved by 1985. A search of the literature, coupled with interviews with representatives of major steel producers, served as the means whereby the techniques and technologies indicated for the specific site are extrapolated to the industry as a whole and to the 1985 time frame. The conclusion of the study is that by 1985, a national yearly savings of 1.9 million barrels of oil could be realized through recovery of waste heat from primary arc furnace fume gases on an industry-wide basis. Economic studies indicate that the proposed system has a plant payback time of approximately 5 years.

  6. Microstructure and mechanical properties of hard zone in friction stir welded X80 pipeline steel relative to different heat input

    Energy Technology Data Exchange (ETDEWEB)

    Aydin, Hakan, E-mail: hakanay@uludag.edu.tr [Engineering and Architecture Faculty, Mechanical Engineering Department, Uludag University, 16059 Gorukle-Bursa (Turkey); Nelson, Tracy W. [Mechanical Engineering Department, Brigham Young University, 435 CTB, Provo, UT 84602 (United States)

    2013-12-01

    The study was conducted to investigate the microstructure and mechanical properties of the hard zone in friction stir welded X80 pipeline steel at different heat inputs. Microstructural analysis of the welds was carried out using optical microscopy, transmission electron microscopy, and microhardness. Heat input during friction stir welding process had a significant influence on the microstructure and mechanical properties in the hard zone along the advancing side of the weld nugget. Based on the results, the linear relationships between heat input and post-weld microstructures and mechanical properties in the hard zone of friction stir welded X80 steels were established. It can be concluded that with decrease in heat input the bainitic structure in the hard zone becomes finer and so hard zone strength increases.

  7. Microstructural response to heat affected zone cracking of prewelding heat-treated Inconel 939 superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, M.A., E-mail: mgonzalez@comimsa.com.mx [Facultad de Ingenieria Mecanica y Electrica (FIME-UANL), Av. Universidad s/n. Ciudad Universitaria, C.P.66451 San Nicolas de los Garza, N.L. (Mexico); Martinez, D.I., E-mail: dorairma@yahoo.com [Facultad de Ingenieria Mecanica y Electrica (FIME-UANL), Av. Universidad s/n. Ciudad Universitaria, C.P.66451 San Nicolas de los Garza, N.L. (Mexico); Perez, A., E-mail: betinperez@hotmail.com [Facultad de Ingenieria Mecanica y Electrica (FIME-UANL), Av. Universidad s/n. Ciudad Universitaria, C.P.66451 San Nicolas de los Garza, N.L. (Mexico); Guajardo, H., E-mail: hguajardo@frisa.com [FRISA Aerospace, S.A. de C.V., Valentin G. Rivero No. 200, Col. Los Trevino, C.P. 66150, Santa Caterina N.L. (Mexico); Garza, A., E-mail: agarza@comimsa.com [Corporacion Mexicana de Investigacion en Materiales S.A. de C.V. (COMIMSA), Ciencia y Tecnologia No.790, Saltillo 400, C.P. 25295 Saltillo Coah. (Mexico)

    2011-12-15

    The microstructural response to cracking in the heat-affected zone (HAZ) of a nickel-based IN 939 superalloy after prewelding heat treatments (PWHT) was investigated. The PWHT specimens showed two different microstructures: 1) spherical ordered {gamma} Prime precipitates (357-442 nm), with blocky MC and discreet M{sub 23}C{sub 6} carbides dispersed within the coarse dendrites and in the interdendritic regions; and 2) ordered {gamma} Prime precipitates in 'ogdoadically' diced cube shapes and coarse MC carbides within the dendrites and in the interdendritic regions. After being tungsten inert gas welded (TIG) applying low heat input, welding speed and using a more ductile filler alloy, specimens with microstructures consisting of spherical {gamma} Prime precipitate particles and dispersed discreet MC carbides along the grain boundaries, displayed a considerably improved weldability due to a strong reduction of the intergranular HAZ cracking associated with the liquation microfissuring phenomena. - Highlights: Black-Right-Pointing-Pointer Homogeneous microstructures of {gamma} Prime spheroids and discreet MC carbides of Ni base superalloys through preweld heat treatments. Black-Right-Pointing-Pointer {gamma} Prime spheroids and discreet MC carbides reduce the intergranular HAZ liquation and microfissuring of Nickel base superalloys. Black-Right-Pointing-Pointer Microstructure {gamma} Prime spheroids and discreet blocky type MC carbides, capable to relax the stress generated during weld cooling. Black-Right-Pointing-Pointer Low welding heat input welding speeds and ductile filler alloys reduce the HAZ cracking susceptibility.

  8. Determination of bearing steel heat treatment with the use of the acoustic emission method

    Directory of Open Access Journals (Sweden)

    T. Z. Wozniak

    2010-10-01

    Full Text Available A study on the control of an extremely important stage of the martensitic-bainitic austempering and obtaining the M-B structure in the 100CrMnSi6-4 steel with the use of the acoustic emission (AE has been undertaken. In order to enrich retained austenite with carbon, steels are austempered at appropriately low temperatures. A martensitic transformation, resulting from diffusionless and displacive transformation is associated with significant AE signs. The strain energy produced during growth due to the shape change is reduced by plastic deformation. Predominant source of (AE is the movement of dislocations in order to relieve internal stresses.The heat treatment was performed in a modern, purpose-constructed device which simultaneously records acoustic emission effects. The signals were recorded with the use of an AE analyzer 20–800 kHz, and they were received by means of a broadband piezoelectric transducer with the use of a specialist card with a sampling frequency of 1200 kHz. The results regarding a correlation of austempering temperature and the maximum number of AE events and dilatometric results have been presented. This parameter can be used for precise Ms temperature estimation. Basing on microstructural investigations, it has been found that previously formed martensite with midrib morphology also accelerates the bainitic transformation.

  9. Forta FDX 27 - duplex stainless steel for high strength gasket plate heat exchangers

    Science.gov (United States)

    Groth, A.; Schedin, E.; Sun, CC; He, Hailan; Guan, Li

    2017-09-01

    Outokumpu has developed a new duplex stainless steel with improved formability compared to other duplex grades. The so-called Forta FDX grades allows the utilization of duplex grades in more forming intensive products previously not possible and at the same time benefit from other duplex stainless steel properties for increased application performance. In this paper a Gasket Plate Heat Exchanger (GPHE) plate is formed with the new duplex grade Forta FDX 27 and compared to the baseline grade Supra 316L/4404. Detailed material characterization, strain measurements and Finite Element Analysis (FEA) were performed to further investigate the case. Small differences in measured strain distribution between Forta FDX 27 and Supra 316L/4404 were found after the stamping operation for both material grades and for the same design feature. Strain measurements showed reasonable agreement between measured experimental results and the numerical simulation for Forta FDX 27. Additionally, FEA predicts an improvement of the final strength of the product up to 30 % at the final configuration by using Forta FDX 27 instead of Supra 316L/4404.

  10. Corrosion Behavior of Pipeline Carbon Steel under Different Iron Oxide Deposits in the District Heating System

    Directory of Open Access Journals (Sweden)

    Yong-Sang Kim

    2017-05-01

    Full Text Available The corrosion behavior of pipeline steel covered by iron oxides (α-FeOOH; Fe3O4 and Fe2O3 was investigated in simulated district heating water. In potentiodynamic polarization tests; the corrosion rate of pipeline steel is increased under the iron oxide but the increaseing rate is different due to the differnet chemical reactions of the covered iron oxides. Pitting corrosion was only observed on the α-FeOOH-covered specimen; which is caused by the crevice corrosion under the α-FeOOH. From Mott-Schottky and X-ray diffraction results; the surface reaction and oxide layer were dependent on the kind of iron oxides. The iron oxides deposit increases the failure risk of the pipeline and localized corrosion can be occurred under the α-FeOOH-covered region of the pipeline. Thus, prevention methods for the iron oxide deposit in the district pipeline system such as filtering or periodic chemical cleaning are needed.

  11. TEM characterization of microstructure evolution of 12%Cr heat resistant steels

    Energy Technology Data Exchange (ETDEWEB)

    Rojas, D.; Prat, O.; Sauthoff, G. [Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany); Garcia, J. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Berlin (Germany); Kaysser-Pyzalla, A.R. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Berlin (Germany); Bochum Univ. (Germany)

    2010-07-01

    A detailed characterization of the microstructure evolution of 12%Cr heat resistant steels at different creep times (100 MPa / 650 C / 8000 h) were carried out by scanning transmission electron microscopy (STEM). The results of the microstructure analysis are correlated with the mechanical properties in order to investigate the influence of different precipitates (especially M{sub 23}C{sub 6}) on the creep strength of the alloys. Precipitation of Laves phase and Z-phase was observed after several hours creep time. Very few Z-phase of the type Cr(V,Ta)N nucleating from existing (V,Ta)(C,N) was observed. Both alloys show growth and coarsening of Laves phase, meanwhile the MX carbonitrides present a very slow growth and coarsening rate. Alloys containing Laves phase, MX and M{sub 23}C{sub 6} precipitates show best creep properties. (orig.)

  12. Design and characterization of microstructure evolution during creep of 12% Cr heat resistant steels

    Energy Technology Data Exchange (ETDEWEB)

    Rojas, D. [Max Planck Institute fuer Eisenforschung GmbH, Max Planck Str. 1, 40237 Duesseldorf (Germany); Garcia, J., E-mail: jose.garcia@helmholtz-berlin.de [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Prat, O. [Max Planck Institute fuer Eisenforschung GmbH, Max Planck Str. 1, 40237 Duesseldorf (Germany); Carrasco, C. [Universidad de Concepcion, Departamento de Ingenieria de Materiales, Edmundo Larenas 270, Concepcion (Chile); Sauthoff, G. [Max Planck Institute fuer Eisenforschung GmbH, Max Planck Str. 1, 40237 Duesseldorf (Germany); Kaysser-Pyzalla, A.R. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Ruhr Universitaet Bochum, Universitaetstr. 150 IA2, 44780 Bochum (Germany)

    2010-06-25

    12% Cr heat resistant steels with a fine dispersion of nano precipitates were designed supported by thermodynamic modeling. A detailed characterization of the microstructure evolution at different creep times (100 MPa/650 deg. C/8000 h) was carried out by scanning transmission electron microscopy (STEM). The results of the microstructure analysis are correlated with the mechanical properties in order to investigate the influence of different precipitates (especially M{sub 23}C{sub 6}) on the creep strength of the alloys. Precipitation of Laves phase and Z-phase was observed after several hours creep time. Very few Z-phase of the type Cr(V,Ta)N nucleating from existing (V,Ta)(C,N) was observed. Both alloys show growth and coarsening of Laves phase, meanwhile the MX carbonitrides present a very slow growth and coarsening rate. Alloys containing Laves phase, MX and M{sub 23}C{sub 6} precipitates show best creep properties.

  13. Microstructural Evolution of a Low-Carbon Steel during Application of Quenching and Partitioning Heat Treatments after Partial Austenitization

    NARCIS (Netherlands)

    Santofimia, M.J.; Zhao, L.; Sietsma, J.

    2008-01-01

    The “quenching and partitioning” (Q&P) process has been studied in a low-carbon steel containing 1.1 wt pct aluminum by heat treatments consisting of partial austenitization at 900 °C and subsequent rapid cooling to a quenching temperature in the range between 125 °C and 175 °C, followed by an

  14. Cleanliness of Ti-bearing Al-killed ultra-low-carbon steel during different heating processes

    Science.gov (United States)

    Guo, Jian-long; Bao, Yan-ping; Wang, Min

    2017-12-01

    During the production of Ti-bearing Al-killed ultra-low-carbon (ULC) steel, two different heating processes were used when the converter tapping temperature or the molten steel temperature in the Ruhrstahl-Heraeus (RH) process was low: heating by Al addition during the RH decarburization process and final deoxidation at the end of the RH decarburization process (process-I), and increasing the oxygen content at the end of RH decarburization, heating and final deoxidation by one-time Al addition (process-II). Temperature increases of 10°C by different processes were studied; the results showed that the two heating processes could achieve the same heating effect. The T.[O] content in the slab and the refining process was better controlled by process-I than by process-II. Statistical analysis of inclusions showed that the numbers of inclusions in the slab obtained by process-I were substantially less than those in the slab obtained by process-II. For process-I, the Al2O3 inclusions produced by Al added to induce heating were substantially removed at the end of decarburization. The amounts of inclusions were substantially greater for process-II than for process-I at different refining stages because of the higher dissolved oxygen concentration in process-II. Industrial test results showed that process-I was more beneficial for improving the cleanliness of molten steel.

  15. Application of an energy efficient casting ladle heating system used in the manufacture of stainless steel; Einsatz einer energieeffizienten Pfannenaufheizstation bei der Herstellung von Edelstahl

    Energy Technology Data Exchange (ETDEWEB)

    Poeschl, Markus [Edelstahlwerke Schmees GmbH, Langenfeld (Germany); Lodde, Marcus [Effizienz-Agentur NRW, Duisburg (Germany). prisma Consult GmbH

    2011-06-15

    In the melting area, the company has been using four conventional burners to heat the ladles. The existing flame burners heat the upside down ladles from below and consume massive amount of energy. Heat radiation and all of the waste gas are released into the facility. The material around the ladles is therefore heavily affected. The company has now installed a new energy efficient casting ladle heating system with a new kind of porous burner which heats the transport ladles without exposing them to an open flame. The combustion heat is channeled to specially adapted steel pipes via infrared radiation and convection flow. By doing this, the heat is directly transferred to the ladles and can be controlled in a more balanced manner. The company now saves around 61,400 m{sup 3}/a of natural gas, approx. 60 % of the energy required for the ladle heating and, as a result, 113.8 tonnes of CO{sub 2}-equivalent. The life span of the ladles can be increased by a factor of 2 due to the reduced exposure of the fire resistant materials. The resulting waste gas is collected and the waste heat will be reused in the facility in the future (facility heating 2011). Due to reduction in cleaning and carrying time of the ladles, Fr. Schmees expects an increase in productivity of the complete process. The heat radiation from the ladles has been reduced by 75 % which has led to a reduction of breakdowns. In addition, the noise level has sunk from 78.7 dB to 67.4 db. (orig.)

  16. AN INVESTIGATION OF METALLURGICAL FACTORS WHICH AFFECT THE FRACTURE TOUGHNESS OF ULTRA HIGH STRENGTH STEELS

    Energy Technology Data Exchange (ETDEWEB)

    Wood, William E.; Parker, Earl R.; Zackay, Victor F.

    1973-05-01

    The relationship between microstructure, heat treatment and room temperature fracture toughness has been determined for the low alloy ultra-high strength steels 4130, 4330, 4340, 4140 and 300-M. Optical metallography, microprobe analysis, and scanning electron microscopy were used to characterize the structure and morphology, while both Charpy V-notch impact tests and plane strain fracture toughness tests were used to determine the fracture properties. The normal commercial heat treatment resulted in the formation of some bainite in all the alloys. MnS inclusions on prior austenite grain boundaries were found to initiate cracks during loading. By increasing the austenitizing temperature to l200 C, the fracture toughness could be increased by at least 60%. For some alloys increasing the severity of the quench in conjunction with the higher austenitizing temperatures resulted in further increases in the fracture toughness, and the elimination of any observable upper bainite. There was no correlation between the Charpy impact test results and the fracture toughness results. The alloys 4130, 4140, 4340 all showed a severe intergranular embrittlement when austenitized at high temperatures and tempered above 200 C, while the alloys 4330 and 300-M exhibited no drop in toughness for the same heat treatment conditions. The as-quenched tensile specimens had a very low 'micro' yield strength which rapidly increased to the level of the 'macro' yield strength when tempered.

  17. Thermomechanical model of hydrogen cracking at heat affected cannon bore surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Underwood, J.H.; Vigilante, G.N.; Troiano, E. [US Army Armament RD and E Center, Watervliet, NY (United States)

    1999-07-01

    Hydrogen cracking in weldments presents major challenges, and two examples were discussed concerning hydrogen cracking in the heat-affected region of a fired cannon. The authors described the metallographic evidence of damage at different depths in the vicinity of the bore surface. The verification of near-bore temperature distributions and transient and residual stress distributions calculated using classic one-dimensional heat flow analysis was effected by way of depth of steel transformation due to firing. The results indicated that the predictions as to the depths of thermal change and hydrogen cracks agreed well with the observed depths for various crack orientations and firing temperatures. A description of laboratory fracture mechanics tests using bolt-load compact specimens was included, as well as crack growth and blunt notched tests in acid hydrogen environments. The specific instances of welding for cannons as they relate to the utility of thermal and fracture mechanics analyses and the laboratory fracture mechanics tests were discussed. 9 refs., 2 tabs., 8 figs.

  18. Oxidation Resistance of Medium-Carbon Heat-Resistant Cr-Al Steels in Extreme Conditions

    Directory of Open Access Journals (Sweden)

    Mykhail M. Yamshinskij

    2017-10-01

    for development of methodology for forecasting of the special properties of Cr-Al steels depending on their chemical composition is created. Conclusions. Optimal concentration of chrome in heat-resistant Cr steels for work of items at temperatures up to 1100 °C can be considered 25–30 %. To provide high oxidation resistance of items working at temperatures up to 1250 °C in aggressive gas environments, the concentration of Cr in a metal should be within the limits of 25–30 %, and aluminium – from 2.0 to 3.5 %, the relation [% Cr]/[% Al] = 7–10 must be executed. Various gas environments differently effect on oxidation resistance of steels. At the temperatures of 1200 °C items in the water steam environment oxidize faster, and slower in the carbon dioxide environment.

  19. Development of Next Generation Heating System for Scale Free Steel Reheating

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Arvind C. Thekdi

    2011-01-27

    The work carried out under this project includes development and design of components, controls, and economic modeling tools that would enable the steel industry to reduce energy intensity through reduction of scale formation during the steel reheating process. Application of scale free reheating offers savings in energy used for production of steel that is lost as scale, and increase in product yield for the global steel industry. The technology can be applied to a new furnace application as well as retrofit design for conversion of existing steel reheating furnaces. The development work has resulted in the knowledge base that will enable the steel industry and steel forging industry us to reheat steel with 75% to 95% reduction in scale formation and associated energy savings during the reheating process. Scale reduction also results in additional energy savings associated with higher yield from reheat furnaces. Energy used for steel production ranges from 9 MM Btu/ton to 16.6 MM Btu/ton or the industry average of approximately 13 MM Btu/ton. Hence, reduction in scale at reheating stage would represent a substantial energy reduction for the steel industry. Potential energy savings for the US steel industry could be in excess of 25 Trillion Btu/year when the technology is applied to all reheating processes. The development work has resulted in new design of reheating process and the required burners and control systems that would allow use of this technology for steel reheating in steel as well as steel forging industries.

  20. Microstructure and Mechanical Properties of Inconel 625 Alloy on Low Carbon Steel by Heat Treatment after Overlay Welding

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seungpil; Jang, Jaeho; Kim, Jungsoo; Kim, Byung Jun; Sohn, Keun Yong; Nam, Dae-Geun [Korea Institute of Industrial Technology, Busan (Korea, Republic of)

    2016-08-15

    Overlay welding technique is one of methods used to improve metal mechanical properties such as strength, toughness and corrosion resistance. Generally, Inconel 625 alloy is used for overlay welding layer on low carbon steels for economic consideration. However, the method produces some problems in the microstructure of the cast structure and some defects, caused by the elevated temperatures of the overlay process. To resolve these problems, heat treatments are required. In this study, Inconel 625 alloy was welded on a low carbon steel by the overlay welding process to investigate the resulting microstructure and mechanical properties. A double heat treatment was performed to improve the mechanical properties of the welding and substrate layers. It was found that Inconel 625 alloy had an austenite microstructure after the first heat treatment, but the low carbon steel had a ferrite-pearlite microstructure after the second heat treatment. After the double heat treatment, the sample showed the optimum hardness because of grain refinement and homogenization of the microstructure.

  1. Effect of Heat Input on Mechanical and Metallurgical Properties of Gas Tungsten Arc Welded Lean Super Martensitic Stainless Steel

    OpenAIRE

    Muthusamy,Chellappan; Karuppiah, Lingadurai; Paulraj,Sathiya; Kandasami,Devakumaran; Kandhasamy,Raja

    2016-01-01

    Welding of 6mm thick AISI: 410S lean super martensitic stainless steel (LSMSS) under different heat input of 7.97, 8.75 and 10.9 kJ/cm was carried out by gas tungsten arc welding process. The influence of heat input on metallurgical and mechanical properties in weld and HAZ region was studied. The tensile tests were carried out at different temperatures, namely at room temperature, at 600ºC, 7000C and 8000C. It is observed that rise in the heat input and temperature decreased the tensile stre...

  2. Effect of Heating Rate on Accelerated Carbide Spheroidisation (ASR in 100CrMnSi6-4 Bearing Steel

    Directory of Open Access Journals (Sweden)

    Hauserova D.

    2014-10-01

    Full Text Available Typical processing routes for bearing steels include a soft annealing stage, the purpose of which is to obtain a microstructure containing globular carbides in ferritic matrix. A newly developed process called ASR cuts the carbide spheroidisation times several fold, producing considerably finer globular carbides than conventional soft annealing. The present paper explores the effect of the heating rate and temperature on the accelerated carbide spheroidisation process and on the resulting hardness. Accelerated spheroidisation was achieved by thermal cycling for several minutes around various temperatures close to the transformation temperature at various heating rates applied by induction heating.

  3. Effect of heat treatment on the crystal structure of deformed samples of chromium-manganese steel

    Science.gov (United States)

    Chezganov, D. S.; Chikova, O. A.; Borovykh, M. A.

    2017-09-01

    Results of studying microstructures and the crystal structure of samples of 35KhGF steel (0.31-0.38 wt % C, 0.17-0.37 wt % Si, 0.95-1.25 wt % Mn, 1.0-1.3 wt % Cr, 0.06-0.12 wt % V, and the remainder was Fe) have been presented. The samples have been selected from hot-rolled pipes subjected to different heat treatments. A study has been carried out in order to explain the choice of the heat-treatment regime based on determining the structure-properties relationship that provides an increase in the corrosion resistance of pipes to the effect of hydrocarbons. Methods of the energy-dispersive X-ray spectroscopy (EDS) and electron backscatter diffraction (EBSD) have been used. In the microstructure of samples, oxide inclusions and discontinuities with sizes of 1-50 μm that presumably consist of the scale were detected. The ferrite grain size and the orientations of crystals were determined; the data on the local mechanical stresses in the Taylor orientation- factor maps were obtained. The grain refinement; the increase in the fraction of the low-angle boundaries; and the decrease in the local mechanical stresses and, therefore, the highest corrosion resistance to the effect of hydrocarbons is achieved by normalizing at 910°C.

  4. Precipitation of carbides in Cr – Mo – V cast steel after service and regenerative heat treatment

    Directory of Open Access Journals (Sweden)

    G. Golański

    2009-01-01

    Full Text Available The paper presents results of research on precipitation processes in chromium – molybdenum – vanadium cast steel. Theexamined material was the following cast steel grade: L21HMF and G17CrMoV5 – 10 (L17HMF after long-term operation at elevatedtemperatures and after regenerative heat treatment. Identification of precipitates was performed by means of the transmission electronmicroscope using carbon extraction replicas and thin foils. On the basis of identifications it has been proved that in the structure ofinvestigated cast steel grades, degraded by long-term operation, there are a few sorts of carbides with diverse stability, such as: M3C; M2C, M23C6, MC, M7C3. Moreover, the occurrence of compound complexes of precipitates – the so called “H-carbides” – has been revealed. Heat treatment of the examined cast steels contributed to changes in morphology and precipitation type. Whilst in the bainitic structure, obtained through heat treatment, only the occurrence of carbide types, such as: M3C; M23C6 and MC has been noticed.

  5. The Effect of Two-Step Heat Treatment Parameters on Microstructure and Mechanical Properties of 42SiMn Steel

    Directory of Open Access Journals (Sweden)

    Ludmila Kučerová

    2017-12-01

    Full Text Available Medium-carbon steel 42SiMn (0.4C-0.6Mn-2Si-0.03Nb was used for a two-step heat treatment consisting of a soaking hold and an annealing hold at bainite transformation temperature. Various heating temperatures, cooling rates, and bainitic hold temperatures were applied to the steel to obtain microstructures typical for TRIP (Transformation Induced Plasticity steels. TRIP steels utilize the positive effects of a multiphase microstructure with retained austenite, creating a good combination of strength and total elongation and an excellent deep-drawing ability. Typical microstructures consist of ferrite, bainite, and 10–15% of retained austenite. In this work, tensile strengths in the region of 887–1063 MPa were achieved with total elongation A5mm of 26–47%, and the final microstructures contained 4–16% of retained austenite. The most suitable microstructure and the best combination of high strength and total elongation were achieved for the processing with intercritical heating temperature of 850 °C and cooling at 30 °C/s to the bainitic hold of 400 °C. Very fine pearlite persisted in the microstructures, even after applying a cooling rate of 50 °C/s, however these small areas with extremely fine laths did not prevent the retention of up to 16% of retained austenite, and high total elongation A5mm above 40% was still reached for these microstructures.

  6. Heat treatment of nitrided layer formed on X37CrMoV5-1 hot working tool steel

    Science.gov (United States)

    Ciski, A.; Wach, P.; Tacikowski, J.; Babul, T.; Šuchmann, P.

    2017-02-01

    The paper presents the technology consisting of combination of the nitriding process with subsequent austenitizing at temperature above eutectoid temperature of the Fe-C system and further rapid cooling. Such treatment will cause formation of the martensite in the area of the primarily nitrided layer and the additional precipitation hardening by tempering of heat treated steel. The article shows that the heat treatment process of nitrided layer formed on X37CrMoV5-1 steel leads to strengthening of surface layer, the substrate and the core of nitrided part. Heat treatment of nitrided steel with the tempering in inert (nitrogen) or active (ammonia) atmosphere can increase the thickness of the layer formed by short-term nitriding process. After the nitriding process of X37CrMoV5-1 steel the nitrided layer had a thickness of about 160 μm, while a subsurface layer of iron nitrides had a thickness of 7 μm. After subsequent quenching and tempering processes, the nitrided layer undergoes additional diffusion and its thickness is increased to about 220 μm (inert atmosphere) or 280 μm (active atmosphere). If the tempering process is carried out in an inert atmosphere, the primarily formed layer of iron nitrides disappears. Tempering in an active atmosphere leads to forming of white layer with a thickness of 7 μm. Basic properties of nitrided layers formed in such way, like the hardness and the wear resistance, are presented.

  7. Heat Transfer Modeling of an Annular On-Line Spray Water Cooling Process for Electric-Resistance-Welded Steel Pipe.

    Science.gov (United States)

    Chen, Zejun; Han, Huiquan; Ren, Wei; Huang, Guangjie

    2015-01-01

    On-line spray water cooling (OSWC) of electric-resistance-welded (ERW) steel pipes can replace the conventional off-line heat treatment process and become an important and critical procedure. The OSWC process improves production efficiency, decreases costs, and enhances the mechanical properties of ERW steel pipe, especially the impact properties of the weld joint. In this paper, an annular OSWC process is investigated based on an experimental simulation platform that can obtain precise real-time measurements of the temperature of the pipe, the water pressure and flux, etc. The effects of the modes of annular spray water cooling and related cooling parameters on the mechanical properties of the pipe are investigated. The temperature evolutions of the inner and outer walls of the pipe are measured during the spray water cooling process, and the uniformity of mechanical properties along the circumferential and longitudinal directions is investigated. A heat transfer coefficient model of spray water cooling is developed based on measured temperature data in conjunction with simulation using the finite element method. Industrial tests prove the validity of the heat transfer model of a steel pipe undergoing spray water cooling. The research results can provide a basis for the industrial application of the OSWC process in the production of ERW steel pipes.

  8. Integration of coal gasification and waste heat recovery from high temperature steel slags: an emerging strategy to emission reduction

    Science.gov (United States)

    Sun, Yongqi; Sridhar, Seetharaman; Liu, Lili; Wang, Xidong; Zhang, Zuotai

    2015-01-01

    With the continuous urbanization and industrialization in the world, energy saving and greenhouse gas (GHG) emission reduction have been serious issues to be addressed, for which heat recovery from traditional energy-intensive industries makes up a significant strategy. Here we report a novel approach to extract the waste heat and iron from high temperature steel slags (1450–1650 oC) produced in the steel industry, i.e., integration of coal gasification and steel slag treatment. Both the thermodynamics and kinetics of the pertinent reactions were identified. It was clarified that the kinetic mechanism for gasification varied from A2 model to A4 model (Avrami-Erofeev) in the presence of slags. Most importantly, the steel slags acted not only as good heat carriers but also as effective catalysts where the apparent activation energy for char gasification got remarkably reduced from 95.7 kJ/mol to 12.1 kJ/mol (A2 model). Furthermore, the FeO in the slags was found to be oxidized into Fe3O4, with an extra energy release, which offered a potential for magnetic separation. Moreover, based on the present research results, an emerging concept, composed of multiple industrial sectors, was proposed, which could serve as an important route to deal with the severe environmental problems in modern society. PMID:26558350

  9. Integration of coal gasification and waste heat recovery from high temperature steel slags: an emerging strategy to emission reduction

    Science.gov (United States)

    Sun, Yongqi; Sridhar, Seetharaman; Liu, Lili; Wang, Xidong; Zhang, Zuotai

    2015-11-01

    With the continuous urbanization and industrialization in the world, energy saving and greenhouse gas (GHG) emission reduction have been serious issues to be addressed, for which heat recovery from traditional energy-intensive industries makes up a significant strategy. Here we report a novel approach to extract the waste heat and iron from high temperature steel slags (1450-1650 oC) produced in the steel industry, i.e., integration of coal gasification and steel slag treatment. Both the thermodynamics and kinetics of the pertinent reactions were identified. It was clarified that the kinetic mechanism for gasification varied from A2 model to A4 model (Avrami-Erofeev) in the presence of slags. Most importantly, the steel slags acted not only as good heat carriers but also as effective catalysts where the apparent activation energy for char gasification got remarkably reduced from 95.7 kJ/mol to 12.1 kJ/mol (A2 model). Furthermore, the FeO in the slags was found to be oxidized into Fe3O4, with an extra energy release, which offered a potential for magnetic separation. Moreover, based on the present research results, an emerging concept, composed of multiple industrial sectors, was proposed, which could serve as an important route to deal with the severe environmental problems in modern society.

  10. Study of 13Cr-4Ni-(Mo (F6NM Steel Grade Heat Treatment for Maximum Hardness Control in Industrial Heats

    Directory of Open Access Journals (Sweden)

    Massimo De Sanctis

    2017-09-01

    Full Text Available The standard NACE MR0175 (ISO 15156 requires a maximum hardness value of 23 HRC for 13Cr-4Ni-(Mo steel grade for sour service, requiring a double tempering heat treatment at temperature in the range 648–691 °C for the first tempering and 593–621 °C for the second tempering. Difficulties in limiting alloy hardness after the tempering of forged mechanical components (F6NM are often faced. Variables affecting the thermal behavior of 13Cr-4Ni-(Mo during single and double tempering treatments have been studied by means of transmission electron microscopy (TEM observations, X-ray diffraction measurements, dilatometry, and thermo-mechanical simulations. It has been found that relatively low Ac1 temperatures in this alloy induce the formation of austenite phase above 600 °C during tempering, and that the formed, reverted austenite tends to be unstable upon cooling, thus contributing to the increase of final hardness via transformation to virgin martensite. Therefore, it is necessary to increase the Ac1 temperature as much as possible to allow the tempering of martensite at the temperature range required by NACE without the detrimental formation of virgin martensite upon final cooling. Attempts to do so have been carried out by reducing both carbon (<0.02% C and nitrogen (<100 ppm levels. Results obtained herein show final hardness below NACE limits without an unacceptable loss of mechanical strength.

  11. Occupational Heat Stress Impacts on Health and Productivity in a Steel Industry in Southern India

    Directory of Open Access Journals (Sweden)

    Manikandan Krishnamurthy

    2017-03-01

    Conclusion: Preliminary evidence shows that high heat exposures and heavy workload adversely affect the workers’ health and reduce their work capacities. Health and productivity risks in developing tropical country work settings can be further aggravated by the predicted temperature rise due to climate change, without appropriate interventions. Apart from industries enhancing welfare facilities and designing control interventions, further physiological studies with a seasonal approach and interventional studies are needed to strengthen evidence for developing comprehensive policies to protect workers employed in high heat industries.

  12. Precipitation and Evolution Behavior of Carbide During Heat Treatments of GCr15 Bearing Steel

    Directory of Open Access Journals (Sweden)

    MA Chao

    2017-06-01

    Full Text Available The evolution behavior of carbides in GCr15 bearing steels after spheroidization annealing, austenitization quenching and low temperature tempering was investigated by the method of quantitative metallography. Numerical simulations on the dissolution kinetics of carbide size and composition during austenitization were performed by ThermoCalc software. The results indicate that the carbide particles formed after spheroidization annealing have a multimodal distribution whilst their size distribution changes to have a single peak after austenitization and tempering, and Cr content increases slightly after austenitization; the carbide particles appear to have larger size with higher Cr content; C rich austenite is formed during austenitization through solid solution by carbides after spheroidization annealing, and then high carbon martensite is formed after quenching and results in the high hardness; Cr atoms can partition from austenite to carbide during the dissolution of carbide, lead to the increasing Cr content of rest carbide particles; the numerical simulations indicate that the carbide particles with the diameter of 200nm cannot completely be dissolved during austenitization even if its Cr content is close to the nominal Cr content of steel, and the undissolved ones may affect the precipitation of carbides during the subsequent tempering.

  13. Development of 3D modeling technology for manufacturing finned ribbons from heat-resistant steels

    Science.gov (United States)

    Lyashkov, A. A.; Vasil'ev, E. V.; Popov, A. Y.

    2017-06-01

    The process of shaping a workpiece by a tool using the rolling method is, from the geometric point of view, a process of interaction of two conjugate surfaces. The technology of rolling finned stainless steel ribbons is close to the technology of shaping details by cutting. However, the problems of its practical implementation in the well-known papers analyzing this issue are practically not considered. As a result of the analysis of conjugate surfaces profiling methods in relation to the problem, it was concluded that it seems urgent to develop a methodology for the formation of corrugated ribbon based on 3D modeling use. The implementation of this methodology includes the creation of solid models of the product and the tool, as well as computer simulation of their shaping processes using rolling method. So, at the first stage, a 3D model of finned ribbon was developed, which was then used to produce a profile of a rolling tool. The modeling of this profile was carried out on the basis of the proposed software package in the CAD environment. The created theoretical model of the tool profile was replaced from the technological point of view by a rectilinear profile. To carry out the analysis of the obtained results, the inverse shaping problem was solved - according to the corrected profile of the tool, real profile of the corrugated ribbon is obtained. Computer modeling of extruded volumes in the process of shaping was performed. The analysis of qualitative and quantitative parameters of the extruded volumes made it possible to give recommendations on setting the increment of the tool motion parameter. Based on the results of the studies, profile parameters of the roller are assigned for its practical implementation. The proposed methodology, based on 3D-modeling, allowed to develop a technology for manufacturing finned ribbons from heat-resistant steels by rolling with high productivity, accuracy and stability of the sizes obtained.

  14. Heat input effect on the microstructural transformation and mechanical properties in GTAW welds of a 409L ferritic stainless steel

    Directory of Open Access Journals (Sweden)

    Delgado, Jorge A.

    2016-06-01

    Full Text Available Welds without filler metal and welds using a conventional austenitic stainless steel filler metal (ER308L were performed to join a ferritic stainless steel with Gas Tungsten Arc Welding process (GTAW. Welding parameters were adjusted to obtain three different heat input values. Microstructure reveals the presence of coarse ferritic matrix and martensite laths in the Heat Affected Zone (HAZ. Dilution between filler and base metal was correlated with the presence of austenite, martensite and ferrite in the weld metal. Weld thermal cycles were measured to correlate the microstructural transformation in the HAZ. Microhardness measurements (maps and profiles allow to identify the different zones of the welded joints (weld metal, HAZ, and base metal. Comparing the base metal with the weld metal and the HAZ, a hardness increment (~172 HV0.5 to ~350 HV0.5 and ~310 HV0.5, respectively was observed, which has been attributed to the martensite formation. Tensile strength of the welded joints without filler metal increased moderately with respect to base metal. In contrast, ductility was approximately 25% higher than base metal, which provided a toughness improvement of the welded joints.Se llevaron a cabo soldaduras sin material de aporte y empleando un electrodo convencional (ER308L para unir un acero inoxidable ferrítico, empleando el proceso de soldadura de arco con electrodo de tungsteno (GTAW. Los parámetros de soldadura fueron ajustados para obtener tres valores diferentes de calor de aporte. La microestructura revela la presencia de una matriz ferrítica gruesa y placas de martensita en la Zona Afectada por el Calor (ZAC. La dilución entre el metal base y de aporte fue correlacionada con la presencia de austenita, martensita y ferrita en el metal de soldadura. Los ciclos térmicos de la soldadura fueron medidos para correlacionar la transformación microestrutural en la ZAC. Mediciones de microdureza (mapas y perfiles, permitieron identificar las

  15. Effects of alloying elements and heat treatments on mechanical properties of Korean reduced-activation ferritic-martensitic steel

    Science.gov (United States)

    Chun, Y. B.; Kang, S. H.; Noh, S.; Kim, T. K.; Lee, D. W.; Cho, S.; Jeong, Y. H.

    2014-12-01

    As part of an alloy development program for Korean reduced-activation ferritic-martensitic (RAFM) steel, a total of 37 program alloys were designed and their mechanical properties were evaluated with special attention being paid to the effects of alloying elements and heat treatments. A reduction of the normalizing temperature from 1050 °C to 980 °C was found to have a positive effect on the impact resistance, resulting in a decrease in ductile-brittle transition-temperature (DBTT) of the program alloys by an average of 30 °C. The yield strength and creep rupture time are affected strongly by the tempering time at 760 °C but at the expense of ductility. Regarding the effects of the alloying elements, the addition of trace amounts of Zr enhances both the creep and impact resistance: the lowest DBTT was observed for the alloys containing 0.005 wt.% Zr, whereas the addition of 0.01 wt.% Zr extends the creep rupture-time under an accelerated condition. The enhanced impact resistance owing to the normalizing at lower temperature is attributed to a more refined grain structure, which provides more barriers to the propagation of cleavage cracks. Solution softening by Zr addition is suggested as a possible mechanism for enhanced resistance to both impact and creep of the program alloys.

  16. Heat resistance of Fe-Al intermetallics in the context of selected heat-resistant and hihg-temperature creep resistant steels

    Directory of Open Access Journals (Sweden)

    P. Baranowski

    2009-04-01

    Full Text Available Results are hereby presented of heat-resistance tests of two Fe3Al and FeAl intermetallic phase-based alloys in the context of St41k-typeboiler steel and 50H21G9N4 high-temperature creep resistant steel. It has been ascertained that heat resistance of the 50H21G9N4 steeland of the Fe3Al and FeAl intermetallic phase-based alloys significantly exceeds that of the boiler steel tested in the air atmosphere and the atmosphere of a flue gas with CO, CO2, SiO2 content alike. Improvement of these properties depends of exposure conditions. The largest differences have been observed when the tests were carried out in temperature 1023 K and in the flue gas atmosphere. The differences have been more and more noticeable as the exposition duration extended. A tendency has been also recorded of smaller mass decrements of the Fe3Al and FeAl intermetallic phase-based alloys as compared to the 50H21G9N4 steel.

  17. Effect of Heat Treatment on Microstructure and Hardness of 9Cr13Mo3Co3Nb2V Steel

    Directory of Open Access Journals (Sweden)

    HUO Dengping

    2016-12-01

    Full Text Available Effect of heat treatment on the microstructure and hardness of 9Cr13Mo3Co3Nb2V steel was studied systematically by metallographic examination and hardness testing. The results show that after quenching, cryogenic treatment and multiple tempering, the retained austenite of 9Cr13Mo3Co3Nb2V steel is adequately transformed into tempered martensite, and the significant secondary hardening effect is brought. Consequently the steel gains stable microstructure and high hardness. Secondary carbide begins to precipitate and the secondary hardening effect emerges when the tempering temperature is above 350℃, and the tempering hardness reaches the maximum value when tempering temperature range is from 480℃ to 520℃.

  18. Additive Manufacturing of 17-4 PH Stainless Steel: Post-processing Heat Treatment to Achieve Uniform Reproducible Microstructure

    Science.gov (United States)

    Cheruvathur, Sudha; Lass, Eric A.; Campbell, Carelyn E.

    2016-03-01

    17-4 precipitation hardenable (PH) stainless steel is a useful material when a combination of high strength and good corrosion resistance up to about 315°C is required. In the wrought form, this steel has a fully martensitic structure that can be strengthened by precipitation of fine Cu-rich face-centered cubic phase upon aging. When fabricated via additive manufacturing (AM), specifically laser powder-bed fusion, 17-4 PH steel exhibits a dendritic structure containing a substantial fraction of nearly 50% of retained austenite along with body centered cubic/martensite and fine niobium carbides preferentially aligned along interdendritic boundaries. The effect of post-build thermal processing on the material microstructure is studied in comparison to that of conventionally produced wrought 17-4 PH with the intention of creating a more uniform, fully martensitic microstructure. The recommended stress relief heat treatment currently employed in industry for post-processing of AM 17-4 PH steel is found to have little effect on the as-built dendritic microstructure. It is found that, by implementing the recommended homogenization heat treatment regimen of Aerospace Materials Specification 5355 for CB7Cu-1, a casting alloy analog to 17-4 PH, the dendritic solidification structure is eliminated, resulting in a microstructure containing about 90% martensite with 10% retained austenite.

  19. Technological practicability of the numericalmodeling of induction heating process in steel pieces

    Directory of Open Access Journals (Sweden)

    Iagar, A.

    2009-02-01

    Full Text Available This paper presents the numerical modeling (using the Finite Difference Method-FDM, and Finite Element Method- FEM of the electromagnetic and thermal fields in a steel piece heated up inside an induction crucible furnace, and the experimental validations. Both modelings have been validated experimentally, so they can be used in designing the equipments and in the numerical control of induction heating process. The program based on FDM can be used in the first stage of designing due to the reduced CPU time. In this stage the inductor parameters and heating time can be estimated, and a study of the influence of diverse factors upon the heating process can be achieved. The FLUX 2D program can be used in the optimization stage, because it allows a more thorough analysis of the phenomena.

    El trabajo presenta el modelado numérico (con el Método de la Diferencias Finitas-FDM y el Método de los Elementos Finitos-FEM, de los campos electromagnéticos y térmicos de una pieza de acero calentada en un horno de inducción con crisol y las validaciones experimentales. Los dos modelados siendo válidos desde el punto de vista experimental, se pueden utilizar para la proyección de unos equipos y por el control numérico del proceso de calentamiento por inducción. El programa basado en FDM se puede utilizar en la primera etapa de la proyección, gracias al tiempo corto de rodadura. En esta etapa se pueden estimar los parámetros del inductor, el tiempo de calentamiento y se puede realizar un estudio de la influencia que tienen los distintos factores sobre el proceso de calentamiento. El programa FLUX 2D se puede utilizar en la etapa de optimización, porque permite un análisis más detallado de los fenómenos.

  20. The influence of heat treatment and process parameters optimization on hardness and corrosion properties of laser alloyed X12CrNiMo steel

    CSIR Research Space (South Africa)

    Popoola, API

    2016-10-01

    Full Text Available Martensitic stainless steels are used in the production of steam turbine blades but their application is limited due to low hardness and poor corrosion resistance. Laser surface alloying and heat treatment of X12CrNiMo Martensitic stainless steel...

  1. Investigations of Temperatures of Phase Transformations of Low-Alloyed Reinforcing Steel within the Heat Treatment Temperature Range

    Directory of Open Access Journals (Sweden)

    Kargul T.

    2017-06-01

    Full Text Available The paper presents the results of DSC analysis of steel B500SP produced in the process of continuous casting, which is intended for the production reinforcement rods with high ductility. Studies were carried out in the temperature range below 1000°C in a protective atmosphere of helium during samples heating program. The main objective of the study was to determine the temperature range of austenite structure formation during heating. As a result of performed experiments: Ac1s, Ac1f – temperatures of the beginning and finish of the eutectoid transformation, Ac2 – Curie temperature of the ferrite magnetic transformation and the temperature Ac3 of transformation of proeutectoid ferrite into austenite were elaborated. Experimental determination of phase transformations temperatures of steel B500SP has great importance for production technology of reinforcement rods, because good mechanical properties of rods are formed by the special thermal treatment in Tempcore process.

  2. Effect of Cooling Rate on Microstructure and Mechanical Properties of Eutectoid Steel Under Cyclic Heat Treatment

    Science.gov (United States)

    Maji, Soma; Subhani, Amir Raza; Show, Bijay Kumar; Maity, Joydeep

    2017-07-01

    A systematic study has been carried out to ascertain the effect of cooling rate on structure and mechanical properties of eutectoid steel subjected to a novel incomplete austenitization-based cyclic heat treatment process up to 4 cycles. Each cycle consists of a short-duration holding (6 min) at 775 °C (above A1) followed by cooling at different rates (furnace cooling, forced air cooling and ice-brine quenching). Microstructure and properties are found to be strongly dependent on cooling rate. In pearlitic transformation regime, lamellar disintegration completes in 61 h and 48 min for cyclic furnace cooling. This leads to a spheroidized structure possessing a lower hardness and strength than that obtained in as-received annealed condition. On contrary, lamellar disintegration does not occur for cyclic forced air cooling with high air flow rate (78 m3 h-1). Rather, a novel microstructure consisting of submicroscopic cementite particles in a `interweaved pearlite' matrix is developed after 4 cycles. This provides an enhancement in hardness (395 HV), yield strength (473 MPa) and UTS (830 MPa) along with retention of a reasonable ductility (%Elongation = 19) as compared to as-received annealed condition (hardness = 222 HV, YS = 358 MPa, UTS = 740 MPa, %Elongation = 21).

  3. Numerical simulation of flow and heat transfer of continous cast steel slab under traveling magnetic field

    Directory of Open Access Journals (Sweden)

    Gong Haijun

    2013-03-01

    Full Text Available A unified numerical model for simulating solidification transport phenomena (STP of steel slab in electromagnetic continuous casting (EMCC process was developed. In order to solve the multi-physics fields coupled problem conveniently, the complicated bidirectional coupled process between EM and STP was simplified as a unidirectional one, and a FEM/FVM-combined numerical simulation technique was adopted. The traveling magnetic fields (TMFs applied to the EMCC process were calculated using the ANSYS11.0 software, and then the EM-data output by ANSYS were converted to FVM-format using a data-format conversion program developed previously. Thereafter, the governing equations were solved using a pressure-based Direct-SIMPLE algorithm. The simulation results of the STP in CC-process show that, due to the influences of Lorentz force and Joule heat, the two strong circulating flows and the temperature field can be obviously damped and changed once TMF with one pair of poles (1-POPs or 2-POPs is applied, which would accordingly improve the quality of casting. It was found in the present research that the integrated actions of 2-POPs TMF are superior to 1-POPs. All the computations indicate that the present numerical model of EM-STP as well as the FEM/FVM-combined technique is successful.

  4. Influence of annealing heat treatment on pitting corrosion resistance of stainless steel type 316

    Directory of Open Access Journals (Sweden)

    Amirreza Bakhtiari

    2014-07-01

    Full Text Available The effect of annealing heat treatment on pitting resistance of stainless steel type 316L has been studied using Tafel polarization and ASTM G150 for estimating of the pitting potential and CPT, respectively. The materials were tested in 3.5% NaCl solution. The chemical composition of the material was analyzed via optical emission spectrometry. It was found that the sample treated at 940°C shows better pitting corrosion resistance than samples treated at 520°C and 820°C. The treatment at 940°C produced two types of morphologies, austenitic-ferritic matrix with δ-ferrite and only small amount of the σ phase. In the range up to 820°C the σ phase embedded in the γ phase matrix and at δ/γ interface was causing brittleness of the material and aggravated corrosion resistance. The treatment at 940°C produced the microstructure which prevented the corrosion attack to develop. It was revealed that the pitting size in samples treated at 520°C and 820°C is greater than that at 940°C. In addition, depth of pitting has been considered as a factor of pitting corrosion resistance. The depth of pitting in sample treated at 940°C is low since the pitting is almost superficial, while the pitting size in samples treated in 520°C and 820°C is higher and deeper.

  5. The influence of high heat input and inclusions control for rare earth on welding in low alloy high strength steel

    Science.gov (United States)

    Chu, Rensheng; Mu, Shukun; Liu, Jingang; Li, Zhanjun

    2017-09-01

    In the current paper, it is analyzed for the influence of high heat input and inclusions control for rare earth on welding in low alloy high strength steel. It is observed for the structure for different heat input of the coarse-grained area. It is finest for the coarse grain with the high heat input of 200 kJ / cm and the coarse grain area with 400 kJ / cm is the largest. The performance with the heat input of 200 kJ / cm for -20 °C V-shaped notch oscillatory power is better than the heat input of 400 kJ / cm. The grain structure is the ferrite and bainite for different holding time. The grain structure for 5s holding time has a grain size of 82.9 μm with heat input of 200 kJ/cm and grain size of 97.9 μm for 10s holding time. For the inclusions for HSLA steel with adding rare earth, they are Al2O3-CaS inclusions in the Al2O3-CaS-CaO ternary phase diagram. At the same time, it can not be found for low melting calcium aluminate inclusions compared to the inclusions for the HSLA steel without rare earth. Most of the size for the inclusions is between 1 ~ 10μm. The overall grain structure is smaller and the welding performance is more excellent for adding rare earth.

  6. Effect of Post-Welding Heat Treatment on Mechanical Properties of Joints of Steel P92 Formed by Submerged Arc Welding

    Science.gov (United States)

    Mohyla, P.; Foldynová, K.

    2014-07-01

    Results of mechanical tests and metallographic studies of welded joints of steel P92 obtained by submerged arc welding are presented. The effect of the post-welding heat treatment on the mechanical properties of the welds is described.

  7. Multi-probe microstructure tracking during heat treatment without an in-situ setup: Case studies on martensitic steel, dual phase steel and β-Ti alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jiali, E-mail: j.zhang@mpie.de; Morsdorf, Lutz, E-mail: l.morsdorf@mpie.de; Tasan, Cemal Cem, E-mail: c.tasan@mpie.de

    2016-01-15

    In-situ scanning electron microscopy observations of the microstructure evolution during heat treatments are increasingly demanded due to the growing number of alloys with complex microstructures. Post-mortem characterization of the as-processed microstructures rarely provides sufficient insight on the exact route of the microstructure formation. On the other hand, in-situ SEM approaches are often limited due to the arising challenges upon using an in-situ heating setup, e.g. in (i) employing different detectors, (ii) preventing specimen surface degradation, or (iii) controlling and measuring the temperature precisely. Here, we explore and expand the capabilities of the “mid-way” solution by step-wise microstructure tracking, ex-situ, at selected steps of heat treatment. This approach circumvents the limitations above, as it involves an atmosphere and temperature well-controlled dilatometer, and high resolution microstructure characterization (using electron channeling contrast imaging, electron backscatter diffraction, atom probe tomography, etc.). We demonstrate the capabilities of this approach by focusing on three cases: (i) nano-scale carbide precipitation during low-temperature tempering of martensitic steels, (ii) formation of transformation-induced geometrically necessary dislocations in a dual-phase steel during intercritical annealing, and (iii) the partial recrystallization of a metastable β-Ti alloy. - Highlights: • A multi-probe method to track microstructures during heat treatment is developed. • It enables the analysis of various complex phenomena, even those at atomistic scale. • It circumvents some of the free surface effects of classical in-situ experiments.

  8. The Effect of a Two-Stage Heat-Treatment on the Microstructural and Mechanical Properties of a Maraging Steel

    Directory of Open Access Journals (Sweden)

    Thomas Hadfield Simm

    2017-11-01

    Full Text Available Maraging steels gain many of their beneficial properties from heat treatments which induce the precipitation of intermetallic compounds. We consider here a two-stage heat-treatment, first involving austenitisation, followed by quenching to produce martensite and then an ageing treatment at a lower temperature to precipitation harden the martensite of a maraging steel. It is shown that with a suitable choice of the initial austenitisation temperature, the steel can be heat treated to produce enhanced toughness, strength and creep resistance. A combination of small angle neutron scattering, scanning electron microscopy, electron back-scattered diffraction, and atom probe tomography were used to relate the microstructural changes to mechanical properties. It is shown that such a combination of characterisation methods is necessary to quantify this complex alloy, and relate these microstructural changes to mechanical properties. It is concluded that a higher austenitisation temperature leads to a greater volume fraction of smaller Laves phase precipitates formed during ageing, which increase the strength and creep resistance but reduces toughness.

  9. The Effect of a Two-Stage Heat-Treatment on the Microstructural and Mechanical Properties of a Maraging Steel.

    Science.gov (United States)

    Simm, Thomas Hadfield; Sun, Lin; Galvin, Deri Rhys; Hill, Paul; Rawson, Martin; Birosca, Soran; Gilbert, Elliot Paul; Bhadeshia, Harshad; Perkins, Karen

    2017-11-23

    Maraging steels gain many of their beneficial properties from heat treatments which induce the precipitation of intermetallic compounds. We consider here a two-stage heat-treatment, first involving austenitisation, followed by quenching to produce martensite and then an ageing treatment at a lower temperature to precipitation harden the martensite of a maraging steel. It is shown that with a suitable choice of the initial austenitisation temperature, the steel can be heat treated to produce enhanced toughness, strength and creep resistance. A combination of small angle neutron scattering, scanning electron microscopy, electron back-scattered diffraction, and atom probe tomography were used to relate the microstructural changes to mechanical properties. It is shown that such a combination of characterisation methods is necessary to quantify this complex alloy, and relate these microstructural changes to mechanical properties. It is concluded that a higher austenitisation temperature leads to a greater volume fraction of smaller Laves phase precipitates formed during ageing, which increase the strength and creep resistance but reduces toughness.

  10. Dissolution of alpha-prime precipitates in thermally embrittled S2205-duplex steels during reversion-heat treatment

    Directory of Open Access Journals (Sweden)

    V. Shamanth

    2015-01-01

    Full Text Available Duplex stainless steels offer an attractive combination of strength, corrosion resistance and cost. In annealed condition duplex steels will be in thermodynamically metastable condition but when they are subjected to intermediate homologous temperature of ∼475 °C and below significant embrittlement occurs, which is one of the key material degradation properties that limits its upper service temperature in many applications. Hence the present study is aimed to study the effect of reversion heat treatment and its time on mechanical properties of the thermally embrittled steel. The results showed that 60 min reversion heat treated samples were able to recover the mechanical properties which were very close to annealed properties because when the embrittled samples were reversion heat treated at an elevated temperature of 550 °C which is above the (α + α′ miscibility gap, the ferritic phase was homogenized again. In other words, Fe-rich α and Cr-rich α′ prime precipitates which were formed during ageing become thermodynamically unstable and dissolve inside the ferritic phase.

  11. Heat transfer in hybrid fibre reinforced concrete-steel composite column exposed to a gas-fired radiant heater

    Science.gov (United States)

    Štefan, R.; Procházka, J.; Novák, J.; Fládr, J.; Wald, F.; Kohoutková, A.; Scheinherrová, L.; Čáchová, M.

    2017-09-01

    In the paper, a gas-fired radiant heater system for testing of structural elements and materials at elevated temperatures is described. The applicability of the system is illustrated on an example of the heat transfer experiment on a hybrid fibre reinforced concrete-steel composite column specimen. The results obtained during the test are closely analysed by common data visualization techniques. The experiment is simulated by a mathematical model of heat transfer, assuming the material data of the concrete determined by in-house measurements. The measured and calculated data are compared and discussed.

  12. 9-12% Cr heat resistant steels. Alloy design, TEM characterisation of microstructure evolution and creep response at 650 C

    Energy Technology Data Exchange (ETDEWEB)

    Rojas Jara, David

    2011-03-21

    This work was carried out aiming to design and characterise 9-12% Cr steels with tailormade microstructures for applications in fossil fuel fired power plants. The investigations concentrated in the design and characterisation of heat resistant steels for applications in high oxidising atmospheres (12% Cr) and 9% Cr alloys for components such as rotors (P91). ThermoCalc calculations showed to be a reliable tool for alloy development. The modeling also provided valuable information for the adjustment of the processing parameters (austenisation and tempering temperatures). Two 12% Cr heat resistant steels with a fine dispersion of nano precipitates were designed and produced supported by thermodynamic modeling (ThermoCalc). A detailed characterisation of the microstructure evolution at different creep times (100 MPa / 650 C / 8000 h) was carried out by scanning transmission electron microscopy (STEM). The results of the microstructure analysis were correlated with the mechanical properties in order to investigate the influence of different precipitates (especially M{sub 23}C{sub 6} carbides) on the creep strength of the alloys. Precipitation of Laves phase and Z-phase was observed after several hundred hours creep time. Very few Z-phase of the type Cr(V,Ta)N nucleating from existing (V,Ta)(C,N) was observed. Both alloys show growth and coarsening of Laves phase, meanwhile the MX carbonitrides present a very slow growth and coarsening rate. Alloys containing Laves phase, MX and M{sub 23}C{sub 6} precipitates show best creep properties. The influence of hot-deformation and tempering temperature on the microstructure evolution on one of the designed 12% Cr alloys was studied during short-term creep at 80-250 MPa and 650 C. Quantitative determination of dislocation density and sub-grain size in the initial microstructure and after creep was investigated by STEM combined with the high-angle annular dark-field detector (HAADF). A correlation between microstructure

  13. The Effect of Local Heating by Laser Irradiation for Aluminum, Deep Drawing Steel and Copper Sheets in Incremental Sheet Forming

    Science.gov (United States)

    Lehtinen, Pekka; Väisänen, Tapio; Salmi, Mika

    Incremental sheet forming is a technique where a metal sheet is formed into a product usually by a CNC-controlled (Computer Numerical Control) round tipped tool. The part is formed as the tool indents into the sheet and follows a contour of the desired product. In single point incremental forming (SPIF) there is no need for tailored tools and dies, since the process requires only a CNC machine, a clamping rig and a simple tool. The effect of applying local heating by laser irradiation from the bottom side of the metal sheet is investigated with a SPIF approach. Using a laser light source for local heating should increase the material ductility and decrease material strength, and thus, increase the formability. The research was performed using 0.50-0.75 mm thick, deep drawing steel, aluminum and copper sheets. The forming was done with a round tipped tool, whose tip diameter was 4 mm. In order to achieve selective heating, a 1 kW fiber laser was attached to a 3-axis stepper motor driven CNC milling machine. The results show that the applied heating increased the maximum achievable wall angle of aluminum and copper products. However, for the steel sheets the local heating reduced the maximum achievable wall angle and increased the surface roughness.

  14. High heat loading properties of vacuum plasma spray tungsten coatings on reduced activation ferritic/martensitic steel

    Science.gov (United States)

    Tokunaga, K.; Hotta, T.; Araki, K.; Miyamoto, Y.; Fujiwara, T.; Hasegawa, M.; Nakamura, K.; Ezato, K.; Suzuki, S.; Enoeda, M.; Akiba, M.; Nagasaka, T.; Kasada, R.; Kimura, A.

    2013-07-01

    High density W coatings on reduced activation ferritic martensitic steel (RAF/M) have been produced by Vacuum Plasma Spraying technique (VPS) and heat flux experiments on them have been carried out to evaluate their possibility as a plasma-facing armor in a fusion device. In addition, quantitative analyses of temperature profile and thermal stress have been carried out using the finite element analysis (FEA) to evaluate its thermal properties. No cracks or exfoliation has been formed by steady state and cyclic heat loading experiments under heat loading at 700 °C of surface temperature. In addition, stress distribution and maximum stress between interface of VPS-W and RAF/M have been obtained by FEA. On the other hand, exfoliation has occurred at interlayer of VPS-W coatings near the interface between VPS-W and RAF/M at 1300 °C of surface temperature by cyclic heat loading.

  15. MORPHOLOGY MODIFICATION OF CARBON CHROME MOLYBDENUM STEEL STRUCTURE INFLUENCED BY HEAT TREATMENT

    Directory of Open Access Journals (Sweden)

    V. A. Lutsenko

    2011-01-01

    Full Text Available The influence of temperature and time parameters of thermal treatment on structural change and properties of carbon chromium molybdenum steel has been studied. It has been shown that there are considerable areas with grainy morphology of cementite after high temperature tempering in the structure of steel. It assures reduction of steel microhardness by 25%, and there are no substantial structural changes after medium temperature tempering.

  16. Diurnal gradual heat stress affects antioxidant enzymes, proline ...

    African Journals Online (AJOL)

    USER

    2010-02-15

    Feb 15, 2010 ... 45°C heat stress. As for the amount of total chlorophyll content, a slight increase at plants treated with. 38°C temperature was observed. Furthermore, the ... dismutase (SOD), which were associated with heat stress response in other plants was also ... to non-toxic levels by catabolizing it to water and oxygen.

  17. Diurnal gradual heat stress affects antioxidant enzymes, proline ...

    African Journals Online (AJOL)

    Even though high temperatures significantly reduce both vegetative growth and yield in cotton, very little is known about the effects of heat stress on cotton antioxidant system. Thus, the effects of gradual heat stress on cotton growth in controlled conditions were investigated in the present study. At squaring stage, cotton ...

  18. Effect of Carbon Content on Microstructure and Mechanical Properties of 9 to 12 pct Cr Ferritic/Martensitic Heat-Resistant Steels

    Science.gov (United States)

    Yin, Feng-Shi; Tian, Li-Qian; Xue, Bing; Jiang, Xue-Bo; Zhou, Li

    2012-07-01

    Two heats of 9 to 12 pct Cr ferritic/martensitic heat-resistant steels were prepared. One has an ultralow carbon content of 0.01 wt pct, whereas another heat has a normal carbon content of 0.09 wt pct. The effect of carbon content on microstructure and mechanical properties of 9 to 12 pct Cr ferritic/martensitic heat-resistant steels was studied. The results show that the ultralow-carbon steel contains bimodal, nanosized MX precipitates with high density in the matrix but few M23C6 carbide particles in the normalized-and-tempered state. The smaller nanosized MX precipitates have two kinds of typical morphology: One is cubic and another is rectangular. The cubic MX precipitate contains Nb, Ti, and V, whereas the rectangular one only contains Nb and V. The normal carbon steel has abundant M23C6 carbide particles along the grain and lath boundaries and much less density of nanosized MX precipitates after the same heat treatments. After long-term aging at 923 K (650 °C) for 10,000 hours, the stress rupture properties of the ultralow carbon content steel degrades more significantly. The strength degradation mechanism of the 9 to 12 pct Cr ferritic/martensitic heat-resistant steels is discussed in this article.

  19. Development and Demonstration of a High Efficiency, Rapid Heating, Low NOx Alternative to Conventional Heating of Round Steel Shapes, Steel Substrate (Strip) and Coil Box Transfer Bars

    Energy Technology Data Exchange (ETDEWEB)

    Kurek, Harry; Wagner, John

    2010-01-25

    Direct Flame Impingement involves the use of an array of very high-velocity flame jets impinging on a work piece to rapidly heat the work piece. The predominant mode of heat transfer is convection. Because of the locally high rate of heat transfer at the surface of the work piece, the refractory walls and exhaust gases of a DFI furnace are significantly cooler than in conventional radiant heating furnaces, resulting in high thermal efficiency and low NOx emissions. A DFI furnace is composed of a successive arrangement of heating modules through or by which the work piece is conveyed, and can be configured for square, round, flat, and curved metal shapes (e.g., billets, tubes, flat bars, and coiled bars) in single- or multi-stranded applications.

  20. Investigation of intercritical heat treatment temperature effect on microstructure and mechanical properties of dual phase (DP steel

    Directory of Open Access Journals (Sweden)

    Mohammad Davari

    2017-06-01

    Full Text Available In the present study, the effect of intercritical heat treatment temperature on the tensile properties and work hardening behavior of ferritic-martensitic dual-phase steel have been investigated utilizing tensile test, microhardness measurement and microscopic observation. Plain carbon steel sheet with a thickness of 2 mm was heat treated at 760, 780, 800, 820 and 840 °C intercritical temperatures. The results showed that martensite volume fraction (Vm increases from 32 to 81%with increasing temperature from 760 to 840 °C. The mechanical properties of samples were examined by tensile and microhardness tests. The results revealed that yield strength was increased linearly with the increase in Vm, but the ultimate strength was increased up to 55% Vm and then decreased afterward. Analyzing the work hardening behavior in term of Hollomon equation showed that in samples with less than 55% Vm, the work hardening took place in one stage and the work hardening exponent increased with increasing Vm. More than one stage was observed in the work hardening behavior when Vm was increased. The results of microhardness test showed that microhardness of the martensite is decreased by increase in heat treatment temperature while the ferrite microhardness is nearly constant for all heat-treated samples.

  1. Prolonged self-paced exercise in the heat - environmental factors affecting performance

    DEFF Research Database (Denmark)

    Junge, Nicklas; Jørgensen, Rasmus; Flouris, Andreas D

    2016-01-01

    In this review we examine how self-paced performance is affected by environmental heat stress factors during cycling time trial performance as well as considering the effects of exercise mode and heat acclimatization. Mean power output during prolonged cycling time trials in the heat (≥30°C) was ...

  2. Influence of Heat Treatment on Content of the Carbide Phases in the Microstructure of High-Speed Steel

    Directory of Open Access Journals (Sweden)

    Jaworski J.

    2017-09-01

    Full Text Available This article presents the results of investigations of the effect of heat treatment temperature on the content of the carbide phase of HS3-1-2 and HS6-5-2 low-alloy high-speed steel. Analysis of the phase composition of carbides is carried out using the diffraction method. It is determined that with increasing austenitising temperature, the intensification of dissolution of M6C carbide increases. As a result, an increase in the grain size of the austenite and the amount of retained austenite causes a significant reduction in the hardness of hardened steel HS3-1-2 to be observed. The results of diffraction investigations showed that M7C3 carbides containing mainly Cr and Fe carbides and M6C carbides containing mainly Mo and W carbides are dissolved during austenitisation. During austenitisation of HS3-1-2 steel, the silicon is transferred from the matrix to carbides, thus replacing carbide-forming elements. An increase in a degree of tempering leads to intensification of carbide separation and this process reduce the grindability of tested steels.

  3. Optimization of Heat Treatment in Aspect of Production’s Costs Reducing and Improving of Casting Quality from Duplex Cast Steel

    Directory of Open Access Journals (Sweden)

    D. Dyja

    2007-07-01

    Full Text Available The paper determines possibilities of cost optimisation in the production of GX2CrNiMoCu25-6-3-3 type duplex cast steel castings through selection of appropriate solution heat treatment temperature, which value depends on the content of alloying elements. Metallographic analysis was carried out for as-cast and heat treated cast steel. Hardness and impact strength of the cast steel were determined, which were correlated with the volume fraction of phases determined by means of ImagePro computer image analyser. It has been shown that increased carbon content creates a need to use higher treatment temperatures, thereby increasing the production cost. With increasing carbon content the cast steel hardness after solution heat treatment increases, however, crack resistance decreases

  4. Influence of long-lasting heat treatments on the structure and properties of the zirconium-steel bond

    Science.gov (United States)

    Prażmowski, Mariusz; Paul, Henryk; Najwer, Michał; Pocica, Anna

    2017-10-01

    The explosive welding technology is related to the dynamic impact of the clad onto base material. These results in significant microstructural changes of the bonded materials, the increase of internal stresses and the strain hardening of layers near the interface. In order to eliminate these unfavorable effects, it is advisable to carry out proper heat treatment. The paper presents the results of structural examinations and mechanical properties of bimetal zirconium - carbon steel, after long-lasting heat treatment. Bimetallic samples were annealed at 600oC for 1, 10, 100, 500, 1000 hours. Microscopic examination were used to the analysis of microstructural changes, whereas systematic microhardness measurements and static tensile test to evaluation of the mechanical properties. It was found that the temperature has a beneficial effect on the changes in the bond zone and for longer annealing times a systematic decrease of the strength properties of the tested bimetal was observed. However, essential for the clad mechanical properties changes were observed in carbon steel plate. After short annealing (times of 1h and 10h) only small microstructural changes due to processes of recovery and recrystallization were observed in layers near the interface. The increase of annealing time was conducive to grain growth and carbon diffusion in the interfacial layer from steel towards zirconium.

  5. Integration of Heat Treatment with Shot Peening of 17-4 Stainless Steel Fabricated by Direct Metal Laser Sintering

    Science.gov (United States)

    AlMangour, Bandar; Yang, Jenn-Ming

    2017-11-01

    Direct metal laser sintering (DMLS) is a promising powder-based additive manufacturing process for fabrication of near-net-shape parts. However, the typically poor fatigue performance of DMLS parts must be addressed for use in demanding industrial applications. Post-treatment can be applied to enhance the performance of such components. Earlier attempts at inducing grain refinement through severe plastic deformation of part surfaces using shot peening improved the physical and mechanical properties of metals without chemical alteration. However, heat treatment can modify the surface-hardening effects attained by shot peening. Hence, we examined the feasibility of applying shot peening combined with heat treatment to improve the performance of DMLS-fabricated 17-4 stainless steel parts through microstructural evolution studies and hardness measurements. Compared to a specimen treated only by shot peening, the sample exposed to additional heat treatment showed increased hardness due to aging of the dominant phase.

  6. Effect of Impurity Tin on the Creep Properties of a P91 Heat-Resistant Steel

    Science.gov (United States)

    Song, S.-H.; Xu, Y.-W.; Yang, H.-F.

    2014-09-01

    The creep properties of P91 steel specimens undoped and doped with 0.058 wt pct tin, which was normalized from 1328 K (1055 °C) and tempered at 1033 K (760 °C), were examined under different engineering stresses (150 to 210 MPa) and temperatures [873 K to 923 K (600 °C to 650 °C)]. The creep behavior followed the temperature-compensated power law and Monkman-Grant equations. In the temperature-compensated power law equation, the apparent activation energy and stress exponent for creep were approximately 541 kJ/mol and 12 for the undoped steel and 527 kJ/mol and 11 for the Sn-doped one, respectively. In the Monkman-Grant relation, the values of constants m and C were around 1.062 and 0.0672 for the undoped steel, and 1.012 and 0.0650 for the Sn-doped one, respectively. The 100 MPa stress creep lifetime at 873 K (600 °C) was estimated as 100641 hours for the undoped steel and 35290 hours for the Sn-doped steel, respectively. These indicated that Sn substantially deteriorated the creep properties of the steel. It was found that grain or subgrain boundary segregation of Sn could promote the nucleation of cavities or microcracks, thereby leading to the deterioration of the steel creep properties.

  7. The influence of manual metal arc multiple repair welding of long operated waterwall on the structure and hardness of the heat affected zone of welded joints

    Directory of Open Access Journals (Sweden)

    Pikuła J.

    2017-03-01

    Full Text Available Welded installations failures of power plants, which are often result from a high degree of wear, requires suitable repairs. In the case of cracks formed in the weld bead of waterwall, weld bead is removed and new welded joint is prepared. However, it is associated with consecutive thermal cycles, which affect properties of heat affected zone of welded joint. This study presents the influence of multiple manual metal arc welding associated with repair activities of long operated waterwall of boiler steel on properties of repair welded joints. The work contains the results of macro and microscopic metallographic examination as well as the results of hardness measurements.

  8. Physical and numerical modelling of heat treatment the precipitation-hardening complex-phase steel (CP

    Directory of Open Access Journals (Sweden)

    B. Koczurkiewicz

    2013-01-01

    Full Text Available The article presents the results of physical and numerical modeling of the processes of thermo- plastic treatment of an experimental complex-phase (CP steel. Numerical tests were carried out using a commercial software program, ThermoCalc. Based on the obtained test results, the austenitization temperature was established. Physical modeling was performed using a DIL 805A/D dilatometer and the Gleeble 3800 system. The characteristic temperatures of the steel and the primary austenite grain size were determined. The test pieces were also subjected to metallographic examinations and Vickers hardness tests. The obtained results served for building an actual CCT diagram for the steel tested.

  9. Influence of cooling rate and tempering on precipitation and hardness of vanadium microalloyed steel

    Energy Technology Data Exchange (ETDEWEB)

    Guenduez, S. [Karabuek Technical Education Faculty, Zonguldak Karaelmas University, 78200 Karabuek (Turkey)]. E-mail: sgunduz@hotmail.com; Cochrane, R.C. [Department of Materials, School of Process, Environmental and Materials Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom)]. E-mail: mtlrcc@ecu-01.novell.leeds.ac.uk

    2005-07-01

    In the present work precipitate distributions in a C-Mn-Al-V-N microalloyed steel and hardness were examined for as-received, heat-treated and heat-treated and tempered samples. Examination of as-received and heat-treated samples from the vanadium microalloyed steels using transmission electron microscopy revealed quite different precipitate distributions. The type and sizes of the precipitate particles and also hardness of the steel samples were markedly affected as the austenitisation time and cooling rates were changed. Tempering steel samples after air cooling produced fine matrix precipitates which are closely spaced, obstruct moving dislocations and hence make the steel harder.

  10. Atmospheric composition affects heat- and mass-transfer processes

    Science.gov (United States)

    Blakely, R. L.; Nelson, W. G.

    1970-01-01

    For environmental control system functions sensitive to atmospheric composition, components are test-operated in helium-oxygen and nitrogen-oxygen mixtures, pure oxygen, and air. Transient heat- and mass-transfer tests are conducted for carbon dioxide adsorption on molecular sieve and for water vapor adsorption on silica gel.

  11. Heat Shock Factor 1 Deficiency Affects Systemic Body Temperature Regulation.

    Science.gov (United States)

    Ingenwerth, Marc; Noichl, Erik; Stahr, Anna; Korf, Horst-Werner; Reinke, Hans; von Gall, Charlotte

    2016-01-01

    Heat shock factor 1 (HSF1) is a ubiquitous heat-sensitive transcription factor that mediates heat shock protein transcription in response to cellular stress, such as increased temperature, in order to protect the organism against misfolded proteins. In this study, we analysed the effect of HSF1 deficiency on core body temperature regulation. Body temperature, locomotor activity, and food consumption of wild-type mice and HSF1-deficient mice were recorded. Prolactin and thyroid-stimulating hormone levels were measured by ELISA. Gene expression in brown adipose tissue was analysed by quantitative real-time PCR. Hypothalamic HSF1 and its co-localisation with tyrosine hydroxylase was analysed using confocal laser scanning microscopy. HSF1-deficient mice showed an increase in core body temperature (hyperthermia), decreased overall locomotor activity, and decreased levels of prolactin in pituitary and blood plasma reminiscent of cold adaptation. HSF1 could be detected in various hypothalamic regions involved in temperature regulation, suggesting a potential role of HSF1 in hypothalamic thermoregulation. Moreover, HSF1 co-localises with tyrosine hydroxylase, the rate-limiting enzyme in dopamine synthesis, suggesting a potential role of HSF1 in the hypothalamic control of prolactin release. In brown adipose tissue, levels of prolactin receptor and uncoupled protein 1 were increased in HSF1-deficient mice, consistent with an up-regulation of heat production. Our data suggest a role of HSF1 in systemic thermoregulation. © 2015 S. Karger AG, Basel.

  12. Influence of Column Axial Load and Heat Affected Zone on the Strength of Aluminium Column Web in Tension

    Directory of Open Access Journals (Sweden)

    Gianfranco De Matteis

    2014-05-01

    Full Text Available The component method for aluminium joints has been recently introduced in some codes and guidelines. Nevertheless, it is still in need of some development and improvement, as in some cases it was obtained by adapting the existing formulations that are valid for steel. The current paper presents the main outcomes of a parametric analysis carried out by means of finite element (FE numerical models for determining the influence of both column axial load and heat affected zone—in the case of welded details—on the structural response of the column web in a tension component. The proposed study integrates previous research carried out by the authors, where the influence of the assumed alloy was investigated and interpreted by corrective parameters expressed as a function of both the material strain hardening and ductility.

  13. Influence of Heating Rate on Ferrite Recrystallization and Austenite Formation in Cold-Rolled Microalloyed Dual-Phase Steels

    Science.gov (United States)

    Philippot, C.; Bellavoine, M.; Dumont, M.; Hoummada, K.; Drillet, J.; Hebert, V.; Maugis, P.

    2017-11-01

    Compared with other dual-phase (DP) steels, initial microstructures of cold-rolled martensite-ferrite have scarcely been investigated, even though they represent a promising industrial alternative to conventional ferrite-pearlite cold-rolled microstructures. In this study, the influence of the heating rate (over the range of 1 to 10 K/s) on the development of microstructures in a microalloyed DP steel is investigated; this includes the tempering of martensite, precipitation of microalloying elements, recrystallization, and austenite formation. This study points out the influence of the degree of ferrite recrystallization prior to the austenite formation, as well as the importance of the cementite distribution. A low heating rate giving a high degree of recrystallization, leads to the formation of coarse austenite grains that are homogenously distributed in the ferrite matrix. However, a high heating rate leading to a low recrystallization degree, results in a banded-like structure with small austenite grains surrounded by large ferrite grains. A combined approach, involving relevant multiscale microstructural characterization and modeling to rationalize the effect of the coupled processes, highlights the role of the cold-worked initial microstructure, here a martensite-ferrite mixture: recrystallization and austenite formation commence in the former martensite islands before extending in the rest of the material.

  14. Effect of heat treatment on mechanical properties and microstructure of selective laser melting 316L stainless steel

    Science.gov (United States)

    Kamariah, M. S. I. N.; Harun, W. S. W.; Khalil, N. Z.; Ahmad, F.; Ismail, M. H.; Sharif, S.

    2017-10-01

    Selective Laser Melting (SLM) has been one of the preferred Additive Manufacturing process to fabricate parts due to its merits in terms of design freedom, lower material waste and faster production when compare to the conventional manufacturing processes. However, due to the thermal gradient experienced during the process, the parts are exposed to the residual stress that leads to parts distortion. This work presents the effect of heat treatments on the micro-hardness of 316L stainless steel parts. In current study, SLM has been employed to fabricate 316L stainless steel compacts. Different heat treatments of 650°C, 950°C, and 1100°C for 2 hours were applied on the compacts. Hardness test were performed on the as-built and heat-treated compacts. The relationship between the microstructures and micro-hardness were discussed in this paper. The results revealed that the micro-hardness of the as-built compacts is between 209.0 and 212.2 HV, which is much higher than the heattreated compacts.

  15. Physical and numerical modelling of heat treatment the precipitation-hardening complex-phase steel (CP)

    OpenAIRE

    B. Koczurkiewicz; H. Dyja; Rapalska-Nowakowska, J.; A. Kawałek

    2013-01-01

    The article presents the results of physical and numerical modeling of the processes of thermo- plastic treatment of an experimental complex-phase (CP) steel. Numerical tests were carried out using a commercial software program, ThermoCalc. Based on the obtained test results, the austenitization temperature was established. Physical modeling was performed using a DIL 805A/D dilatometer and the Gleeble 3800 system. The characteristic temperatures of the steel and the primary austenite grain si...

  16. Creep properties of advanced heat-resistant martensitic steels strengthened by L1{sub 0} type ordered intermetallic phase

    Energy Technology Data Exchange (ETDEWEB)

    Igarashi, M.; Muneki, S.; Abe, F. [National Res. Inst. for Metals, Tsukuba (Japan). Frontier Res. Center for Struct. Mater.

    2000-07-01

    Creep properties of advanced heat-resistant martensitic steels with the compositions of 0.08C-0.3Si-0.5Mn-9Cr-3.3W-(0/3)Pd-0.2V-0.05Nb-0.05N-Fe (in mass%) have been studied to explore the fundamental guiding principles for the development of new steels with improved creep strength at higher temperatures over 650 C. The steel with 3%Pd exhibits higher creep strength than that of the base steel, in particular, at higher temperatures. The microstructure of the steel with Pd is characterized by fine precipitation of a FePd based L1{sub 0} type ordered phase, {alpha}{sup ''} phase. The {alpha}{sup ''} phase forms in the tempered martensitic matrix, {alpha}, along with the existing phases such as MX (M; V, Nb, X; C, N) carbonitride and M{sub 23}C{sub 6} (M; Cr, Fe, W) carbide after normalizing at 1100 C and tempering at 770 C. A detailed TEM observation has shown that the {alpha}{sup ''} phase precipitates in a plate-shaped with the habit plane parallel to {l_brace}001{r_brace}{sub {alpha}} and with a crystallographic orientation relationship with the matrix, {l_brace}001{r_brace}{sub {alpha}}//{l_brace}001{r_brace}{sub {alpha}{sup ''}} and left angle 100 right angle {sub {alpha}}// left angle 110 right angle {sub {alpha}{sup ''}}. The {alpha}{sup ''} phase is found to be a most effective precipitate to increase creep resistance of the steel in terms of the inter-particle spacing estimated. The {alpha}{sup ''} phase is stable even after aging at 700 C and hence is more useful at higher temperatures. It is thus concluded that the creep resistance of the ferritic steels can be increased further by optimizing the combination of fine precipitation such as the {alpha}{sup ''} phase and MX carbonitride. (orig.)

  17. Modelling fracture in ferritic steel

    CERN Document Server

    Smith, G

    2002-01-01

    Results from mathematical models and computer simulations of fracture in polycrystalline steels are presented for a range of temperatures. The proportions of intergranular and intragranular failure predicted are compared with experimental results for brittle fracture, ductile fracture and in the transition region. Interactive software to create two-dimensional polycrystalline models, which allow a range of physical to be varied independently, is described. The results include those for model materials chosen to match steels used by the power generation industry. The models simulate segregation and cavitation effects in steel and fracture of weldments and their associated heat-affected zones.

  18. Role of steel slags on biomass/carbon dioxide gasification integrated with recovery of high temperature heat.

    Science.gov (United States)

    Sun, Yongqi; Liu, Qianyi; Wang, Hao; Zhang, Zuotai; Wang, Xidong

    2017-01-01

    Disposal of biomass in the agriculture and steel slags in the steel industry provides a significant solution toward sustainability in China. Herein these two sectors were creatively combined as a novel method, i.e., biomass/CO 2 gasification using waste heat from hot slags where the influence of chemical compositions of steel slags, characterized as iron oxide content and basicity, on gasification thermodynamics, was systemically reported for the first time. Both the target gases of CO, H 2 and CH 4 and the polluted gases of NH 3 , NO and NO 2 were considered. It was first found that an increasing iron content and slag basicity continuously improved the CO yield at 600-1000°C and 800-1000°C, respectively; while the effect on polluted gas releases was limited. Moreover, the solid wastes after gasification could be utilized to provide nutrients and improve the soil in the agriculture, starting from which an integrated modern system was proposed herein. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. A mechanism for corrosion product deposition on the carbon steel piping in the residual heat removal system of BWRs

    Energy Technology Data Exchange (ETDEWEB)

    Aizawa, Motohiro; Chiba, Yoshinori [Hitachi Engineering Co., Ltd., Nuclear Power Plant Engineering Dept., Hitachi, Ibaraki (Japan); Hosokawa, Hideyuki [Hitachi Ltd., Power and Industrial Systems R and D Laboratory, Hitachi, Ibaraki (Japan); Ohsumi, Katsumi [Hitachi Ltd., Power and Industrial Systems Nuclear Systems Division, Hitachi, Ibaraki (Japan); Uchida, Shunsuke [Tohoku Univ., Graduate School of Engineering, Dept. of Quantum Science and Energy Engineering, Sendai, Miyagi (Japan); Ishizawa, Noboru [Tokyo Electric Power Company, Kashiwazaki-Kariwa Nuclear Power Station, Kashiwazaki, Niigata (Japan)

    2002-10-01

    The dose rate of the residual heat removal (RHR) piping has been considered to be caused by accumulation of insoluble (crud) radioactive corrosion products on carbon steel surfaces. Soft shutdown procedures (i.e., plant shutdown with moderate coolant temperature reduction rate) used to be applied to reduce crud radioactivity release from the fuel surface, but these are no longer used because of the need for shorter plant shutdown times. In order to apply other suitable countermeasures to reduce RHR dose rate, assessment of plant data, experiments on deposition of crud and ion species on carbon steel, and mass balance evaluation of radioactive corrosion products based on plant and laboratory data were carried out and the following findings were made. (1) Deposits of ion species on carbon steel surfaces of the RHR piping was much more numerous than for crud. (2) Ion species accumulation behavior on RHR piping, which is temperature dependent, can be evaluated with the calculation model used for the dehydration reaction of corrosion products generated during the wet lay-up period. (3) Deposition amounts could be reduced to 1/2.5 when the starting RHR system operation temperature was lowered from 155degC to 120degC. (author)

  20. Estimation of early fatigue damage in heat treated En-8 grade steel

    Science.gov (United States)

    Talukdar, P.; Sen, S. K.; Ghosh, A. K.

    1998-08-01

    Generally, the failure of major machinery parts is due to fatigue damage. Because of the structural inhomogeneity of metals, fatigue damage may sometimes occur significantly below the yield strength of the material due to microplastic deformation at low stress levels. Commercial En-8 grade steel (widely used for making secondary metalworking products) was used to estimate the fatigue damage response during cyclic loading nearer to the fatigue endurance limit. Estimation of fatigue damage was carried out with the aid of a nondestructive testing (NDT) method, that is, Elastosonic measurement of fatigue damping coefficient and slope of fatigue damping curves. Results indicate that fatigue damage increases in annealed En-8 steel with an increase in peak stress and with an increase in the number of cycles. However, for hardened and tempered En-8 steel, experimental results may not provide a true indication of fatigue damage during fatigue loading nearer to the endurance limit, most likely due to the more homogeneous structure. Generally, fatigue failure occurs in this grade of steel due to microcrack generation in the cementite of the pearlite phase of annealed steel.

  1. Effect of temperature and heat fluxes on the corrosion's damage nature for mild and stainless steels in neutral chloride solutions

    Energy Technology Data Exchange (ETDEWEB)

    Kaluzhina, S.A. [Voronezh State University, University Sq.1, 394006 Voronezh (Russian Federation); Malygin, A.V. [JSC Voronezhsynthezkauchuk, Leninsky Av. 2, 394014 Voronezh (Russian Federation); Vigdorovitch, V.V. [Derzhavin State University, International St. 33, 392622 Tambov (Russian Federation)

    2004-07-01

    The detail research of the corrosion-electrochemical behavior of two types steels - mild steel (0.1%C) and stainless steel 12FeCr18Ni10Ti in series chloride solutions under elevated temperature and heat flux on interface has been carried out in the present work using the special plant and the complex electrochemical and microscopic methods. The comparative data has shown that the temperature increase is stimulating as the active alloy's corrosion (mild steel), so the passive alloy's corrosion (12FeCr18Ni10Ti).However at the last case the temperature effect is being higher because the thermal de-passivation of the stainless steel which undergoes pit corrosion under t > 50 deg C. The heat-transfer role in the studied systems is ambiguous. The corrosion rate of heat-transferring electrode from mild steel exceeds the thermo-equilibrium with solution electrode's corrosion rate because of intensification of the oxygen reduction cathodic process. The opposite effect has been established for steel 12FeCr18Ni10Ti where the oxygen flux's strengthening from cold solution to the heated surface transfers the alloy to the most stable passive state and increases its resistance to general and local corrosion. The experimental results demonstrates that the thermal condition's influence on the nature and corrosion intensity of the investigated steels is being commensurable by effect's degree with their composition and showing strictly individually. (authors)

  2. Influence of the welding parameters on the heat affected zone for aluminium welding

    Directory of Open Access Journals (Sweden)

    Meseguer-Valdenebro José L.

    2016-01-01

    Full Text Available This work analyzes the Heat Affected Zone in an aluminum alloy welded assembly using the Metal Inert Gas welding technique. Making use of numerical simulations of the involved thermal processes, the aluminum alloy cooling curve is calculated and the extension of the Heat Affected Zone is evaluated. The connection between this last parameter, the cooling rate, and the maximum obtained temperature is assessed. Additionally, the response surface method is exploited to fit the dependence of the Heat Affected Zone with the welding parameters and to optimize these parameters in order to minimize that region.

  3. Effect of Post-Weld Heat Treatment on Creep Rupture Properties of Grade 91 Steel Heavy Section Welds

    Energy Technology Data Exchange (ETDEWEB)

    Li, Leijun

    2012-11-02

    This project will conduct a systematic metallurgical study on the effect of post-weld heat treatment (PWHT) on the creep rupture properties of P91 heavy section welds. The objective is to develop a technical guide for selecting PWHT parameters, and to predict expected creep-rupture life based on the selection of heat treatment parameters. The project consists of four interdependent tasks: Experimentally and numerically characterize the temperature fields of typical post-weld heat treatment procedures for various weld and joint configurations to be used in Gen IV systems. Characterize the microstructure of various regions, including the weld fusion zone, coarse-grain heat-affected zone, and fine-grain heat affected zone, in the welds that underwent the various welding and PWHT thermal histories. Conduct creep and creep-rupture testing of coupons extracted from actual and physically simulated welds. Establish the relationship among PWHT parameters, thermal histories, microstructure, creep, and creep-rupture properties.

  4. Study of Secondary Phase Particle Dissolution and Austenite Grain Growth on Heating Fine-Grained High-Strength IF-Steel

    Science.gov (United States)

    Jia, Hong-bin; Zhang, Hong-mei; Sun, Cheng-qian

    2016-09-01

    Dissolution of particles of second phase and growth of austenite grains in high-strength fine-grained IF-steel (0.0057% C, 0.0023% N) on heating is studied. Metallographic analysis of flat steel specimens cut from plates prepared by hot and cold rolling is performed. Steel structure is studied after holding for 10 - 60 min at different temperatures and water quenching. The quenching parameters at which the microalloying elements (Ti, Nb) dissolve completely with retention of fine-grained austenite are determined. Amathematical model of austenite grain growth is developed by nonlinear regression analysis of experimental data.

  5. Corrosion Process of Stainless Steel 441 with Heated Steam at 1,000 °C

    Science.gov (United States)

    Chen, Zhiyuan; Wang, Lijun; Yu, Ziyou; Li, Fushen; Sun, Zaihong; Zhao, Hailei; Chou, Kuo Chih

    2017-07-01

    Stainless steel 441 was oxidized in water vapor containing atmospheres at 1,000 °C to study the contrary effects of water vapor on the oxidization process. The steel in 3.5 vol. % H2O containing atmosphere exhibited an relatively strong protective behavior. The reason was that the densification of the chromium oxide scale was promoted due to the sintering of the oxide grains via Cr-containing species vapor. But the oxidation of the steel in 11.5 15.6 vol. % H2O containing atmosphere followed a non-protective breakaway oxidation due to the breakage of the dense scale by "bubbles" and the formation of iron-rich oxides layer. Experimental result shows that the growth stress increased about 2 GPa during the first 70 ks in wet oxidizing atmosphere. The relatively slow increase of the oxides scale growth stress could be release in water vapor containing atmosphere.

  6. Cast, heat-resistant austenitic stainless steels having reduced alloying element content

    Energy Technology Data Exchange (ETDEWEB)

    Muralidharan, Govindarajan [Knoxville, TN; Sikka, Vinod Kumar [Oak Ridge, TN; Maziasz, Philip J [Oak Ridge, TN; Pankiw, Roman I [Greensburg, PA

    2010-07-06

    A cast, austenitic steel composed essentially of, expressed in weight percent of the total composition, about 0.4 to about 0.7 C, about 20 to about 30 Cr, about 20 to about 30 Ni, about 0.5 to about 1 Mn, about 0.6 to about 2 Si, about 0.05 to about 1 Nb, about 0.05 to about 1 W, about 0.05 to about 1.0 Mo, balance Fe, the steel being essentially free of Ti and Co, the steel characterized by at least one microstructural component selected from the group consisting of MC, M.sub.23C.sub.6, and M(C, N).

  7. Cast, heat-resistant austenitic stainless steels having reduced alloying element content

    Energy Technology Data Exchange (ETDEWEB)

    Muralidharan, Govindarajan [Knoxville, TN; Sikka, Vinod Kumar [Oak Ridge, TN; Maziasz, Philip J [Oak Ridge, TN; Pankiw, Roman I [Greensburg, PA

    2011-08-23

    A cast, austenitic steel composed essentially of, expressed in weight percent of the total composition, about 0.4 to about 0.7 C, about 20 to about 30 Cr, about 20 to about 30 Ni, about 0.5 to about 1 Mn, about 0.6 to about 2 Si, about 0.05 to about 1 Nb, about 0.05 to about 1 W, about 0.05 to about 1.0 Mo, balance Fe, the steel being essentially free of Ti and Co, the steel characterized by at least one microstructural component selected from the group consisting of MC, M.sub.23C.sub.6, and M(C, N).

  8. Influence of heat treatment on microstructure and properties of GX12CrMoVNbN9-1 cast steel

    Directory of Open Access Journals (Sweden)

    G. Golański

    2010-07-01

    Full Text Available The paper presents results of research on the influence of multistage heat treatment on microstructure and properties of high-chromiummartensitic GX12CrMoVNbN9 – 1 (GP91 steel. The material under investigation were samples taken out from a test coupon. Heattreatment of GP91 cast steel was performed at the parameters of temperature and time typical of treatment for multi-ton steel casts. The research has proved that in the as-received condition (as-cast state GP91 cast steel was characterized by a coarse grain, martensitic microstructure which provided the required standard mechanical properties. The heat treatment of GP91 cast steel contributed to obtainment of a fine grain microstructure of high tempered martensite with numerous precipitations of carbides of diverse size. The GP91 cast steel structure received through heat treatment made it possible to obtain high plastic properties, particularly impact strength, maintaining strength properties on the level of the required minimum.

  9. The Wear Characteristics of Heat Treated Manganese Phosphate Coating Applied to AlSi D2 Steel with Oil Lubricant

    Directory of Open Access Journals (Sweden)

    Venkatesan Alankaram

    2012-12-01

    Full Text Available Today, in the area of material design conversion coatings play an important role in the applications where temperature, corrosion, oxidation and wear come in to play. Wear of metals occurs when relative motion between counter-surfaces takes place, leading to physical or chemical destruction of the original top layers. In this study, the tribological behaviour of heat treated Manganese phosphate coatings on AISI D2 steel with oil lubricant was investigated. The Surface morphology of manganese phosphate coatings was examined by Scanning Electron Microscope (SEM and Energy Dispersive X-ray Spectroscopy (EDX .The wear tests were performed in a pin on disk apparatus as per ASTM G-99 Standard. The wear resistance of the coated steel was evaluated through pin on disc test using a sliding velocity of 3.0m/s under Constant loads of 40 N and 100 N with in controlled condition of temperature and humidity. The Coefficient of friction and wear rate were evaluated. Wear pattern of Manganese phosphate coated pins with oil lubricant, Heat treated Manganese phosphate coated pins with oil lubricant were captured using Scanning Electron Microscope (SEM. The results of the wear test established that the heat treated manganese phosphate coating with oil lubricant exhibited the lowest average coefficient of friction and the lowest wear loss up to 6583 m sliding distance under 40 N load and 3000 m sliding distance even under 100 N load respectively. The Wear volume and temperature rise in heat treated Manganese Phosphate coated pins with oil lubricant is lesser than the Manganese Phosphate coated pins with oil lubricant

  10. Development of heat-resistant cast steel for exhaust manifolds. Exhaust manifold yo tainetsu chuko no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Ike, M.; Akiyama, K. (Nissan Motor Co. Ltd., Tokyo (Japan)); Otsuka, K.; Ito, K. (Hitachi Metals, Ltd., Tokyo (Japan))

    1991-07-01

    Any exhaust manifold is exposed to the severer thermal cycle condition by exhasut gas of the maximum temperature reaching near 1273K and therefore the thermal resistance reliability should be improved. A new cast heat resistant steel for the exhaust manifold which had better thermal fatigue resistance and oxidation resistance than conventional Ni-resist cast iron was developed this time. The developed material was based on the 18Cr ferritic heat resistant steel of low coefficent of thermal expansion and the oxidation resistance was improved, and further the thermal fatigue life was improved by aiming at the structural stability through elevating the transformation point to the upper limit of service temperature or more. These requirements were achieved by grasping the above mentioned characteristics of the part material and by studying the effect of main composing elements, C, N, Cr, Nb, Mo, on these characteristics. The cheaper exhaust manifold of higher thermal resistant reliability than conventional one could be put into practical use by using a newly developed casting process in addition to the use of this developed material. 7 refs., 11 figs., 5 tabs.

  11. Energy Saving Melting and Revert Reduction (E-SMARRT): Optimization of Heat Treatments on Stainless Steel Castings for Improved Corrosion Resistance and Mechanical Properties

    Energy Technology Data Exchange (ETDEWEB)

    John N. DuPont; Jeffrey D. Farren; Andrew W. Stockdale; Brett M. Leister

    2012-06-30

    It is commonly believed that high alloy steel castings have inferior corrosion resistance to their wrought counterparts as a result of the increased amount of microsegregation remaining in the as-cast structure. Homogenization and dissolution heat treatments are often utilized to reduce or eliminate the residual microsegregation and dissolve the secondary phases. Detailed electron probe microanalysis (EPMA) and light optical microscopy (LOM) were utilized to correlate the amount of homogenization and dissolution present after various thermal treatments with calculated values and with the resultant corrosion resistance of the alloys.The influence of heat treatment time and temperature on the homogenization and dissolution kinetics were investigated using stainless steel alloys CN3MN and CK3MCuN. The influence of heat treatment time and temperature on the impact toughness and corrosion reistance of cast stainless steel alloys CF-3, CF-3M, CF-8, and CF-8M was also investigated.

  12. Mathematical Simulation of Heat Transfer in Heterogenous Forest Fuel Layer Influenced by Heated Up to High Temperatures Steel Particle

    Directory of Open Access Journals (Sweden)

    Baranovskiy Nikolay V.

    2014-01-01

    Full Text Available Heterogeneity of forest fuel layer renders the important influence on forest fire occurrence processes. One of sources of the raised temperature on forested territories is metal particles heated up to high temperatures. Such particles can be formed as a result of welding of metals on forested territories. The present paper represents the heat transfer research in forest fuel at the influence of metal particle heated up to high temperatures. The heterogonous forest fuel layer with inclusions of small wooden branches and chips is considered. Such object research is urgent especially at fire forecasting on forest cutting. The technology of mathematical simulation is used. The two-dimensional problem of heat transfer in forest fuel layer structure with wood inclusions is solved.

  13. Applicability of steel tube qualities in district heating grid construction; Anwendbarkeit von Stahlrohrqualitaeten im Fernwaermeleitungsbau. Sicherheitskonzept

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, Ingo [Enercity Netzgesellschaft mbH, Hannover (Germany); Besier, Rolf [AGFW Der Energieeffizienzverband fuer Waerme, Kaelte und KWK e.V., Frankfurt am Main (Germany)

    2010-07-15

    In the construction of district heating grids, different specifications concerning product quality and safety must be observed. The authors present the relevant standards and rules and discuss the consequences for stee pipes for rigid and flexible district heating pipelines. (orig.)

  14. The Assessment Of The Structure And Properties Of High-Carbon Steel Wires After The Process Of Patenting With Induction Heating

    Directory of Open Access Journals (Sweden)

    Wiewiórowska S.

    2015-06-01

    Full Text Available One of the most important types of heat treatment that high-carbon steel wires are subjected to is the patenting treatment. This process is conducted with the aim of obtaining a fine-grained uniform pearlitic structure which will be susceptible to plastic deformation in drawing processes. Patenting involves two-stage heat treatment that includes heating the wire up to the temperature above Ac3 in a continuous heating furnace (in the temperature range of 850÷1050°C followed by a rapid cooling in a tank with a lead bath down to the temperature range of 450÷550°C. The patenting process is most significantly influenced by the chemistry of the steel being treated, as well as by the temperature and the rate of heating and cooling of the wire rod or wire being patented.

  15. Creep strength and microstructural evolution of 9-12% Cr heat resistant steels during creep exposure at 600 C and 650 C

    Energy Technology Data Exchange (ETDEWEB)

    Mendez Martin, Francisca [Graz Univ. of Technology (Austria). Inst. for Materials Science and Welding; Panait, Clara Gabriela [MINES ParisTech, UMR CNRS, Evry (France). Centre des Materiaux; V et M France CEV, Aulnoye-Aymeries (France); Bendick, Walter [Salzgitter Mannesmann Forschung GmbH (SZMF), Duisburg (DE)] (and others)

    2010-07-01

    9-12% Cr heat resistant steels are used for applications at high temperatures and pressures in steam power plants. 12% Cr steels show higher creep strength and higher corrosion resistance compared to 9% Cr steels for short term creep exposure. However, the higher creep strength of 12 %Cr steels drops increasingly after 10,000-20,000 h of creep. This is probably due to a microstructural instability such as the precipitation of new phases (e.g. Laves phases and Z-phases), the growth of the precipitates and the recovery of the matrix. 9% Cr and 12% Cr tempered martensitic steels that have been creep tested for times up to 50,000 h at 600 C and 650 C were investigated using Transmission Electron Microscopy (TEM) on extractive replicas and thin foils together with Backscatter Scanning Electron Microscopy (BSE-SEM) to better understand the different creep behaviour of the two different steels. A significant precipitation of Laves phase and low amounts of Z-phase was observed in the 9% Cr steels after long-term creep exposure. The size distribution of Laves phases was measured by image analysis of SEM-BSE images. In the 12% Cr steel two new phases were identified, Laves phase and Z-phase after almost 30,000 h of creep test. The quantification of the different precipitated phases was studied. (orig.)

  16. Nondestructive evaluation for remanent life of aged 12Cr ferrite heat resisting steel by reversible permeability

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Kwon-Sang, E-mail: ryuks@kriss.re.kr [Korea Research Institute of Standards and Science, Centre for Materials Measurement, Doryong Dong, Yuseong-Gu, Daejeon 305-340 (Korea, Republic of); Kim, Chung-Seok [Automotive Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Baek, Un-bong [Korea Research Institute of Standards and Science, Centre for Materials Measurement, Doryong Dong, Yuseong-Gu, Daejeon 305-340 (Korea, Republic of); Lee, Jong Suk [Gangneung-Wonju National University, Wonju 220-711 (Korea, Republic of)

    2013-01-15

    We present a magnetic and nondestructive method to evaluate the remanent life of advanced ferritic steel using the value of reversible permeability. The method to measure reversible permeability is based on the theory that the value of reversible permeability is the same differential of the hysteresis loop. The measurement principle is based on the foundation of harmonics voltage induced in a sensing coil using a lock-in amplifier tuned to the frequency of the exciting one. Results obtained for reversible permeability, Vickers hardness, and tensile strength on the aged samples show that the peak interval of reversible permeability, Vickers hardness and tensile strength decrease as aging time increases. We could estimate the remanent life of advanced ferritic steel by using the relationship between the peak interval of reversible permeability and the Larson-Miller parameter, non-destructively. - Highlights: Black-Right-Pointing-Pointer Magnetic, nondestructive evaluation method of remanent life of 12Cr ferritic steel is presented. Black-Right-Pointing-Pointer Peak interval of reversible permeability decreases with the increase of aging time. Black-Right-Pointing-Pointer Mechanical properties decrease with the increase of aging time. Black-Right-Pointing-Pointer Magnetic and mechanical properties are decreased with increase of Larson-Miller parameter. Black-Right-Pointing-Pointer Reversible permeability is nondestructively used to estimate remanent life of 12Cr ferrite steel.

  17. Plasma nitriding of AISI 52100 ball bearing steel and effect of heat ...

    Indian Academy of Sciences (India)

    friction, generates noise/vibration and necessitates an early replacement, which causes premature failure. To meet ... such as surface hardness, wear resistance, corrosion resis- tance, and fatigue strength of various ... to enhance the wear resistance, surface hardness and service life of the bearing steels (Zaitsev et al 1990; ...

  18. A Simple Experiment To Measure the Content of Oxygen in the Air Using Heated Steel Wool

    Science.gov (United States)

    Vera, Francisco; Rivera, Rodrigo; Nunez, Cesar

    2011-01-01

    The typical experiment to measure the oxygen content in the atmosphere uses the rusting of steel wool inside a closed volume of air. Two key aspects of this experiment that make possible a successful measurement of the content of oxygen in the air are the use of a closed atmosphere and the use of a chemical reaction that involves the oxidation of…

  19. Heat treatment and effects of Cr and Ni in low alloy steel

    Indian Academy of Sciences (India)

    Administrator

    Materials and Metallurgical Engineering Department, Bangladesh University of Engineering and Technology. (BUET), Bangladesh. MS received 1 March 2010; revised 14 February 2011. Abstract. The effects of Cr and Ni on low carbon steel was observed. Undissolved carbide particles refine the austenite grain size.

  20. DEVELOPMENT OF THE COMPLEX-ALLOYED STEEL OF INCREASED HARDENABILITY, VISCOSITY AND HEAT-RESISTANCE FOR CUTTING PARTS OF HIGH-SPEED INSTRUMENT, OPERATING IN CONDITIONS OF HEATING UP AND DYNAMIC LOADS

    Directory of Open Access Journals (Sweden)

    V. N. Fedulov

    2006-01-01

    Full Text Available The theoretical aspects of development of the complex-alloyed steel compounds for cutting parts of high-speed instrument, particularly influence of alloying elements on its structure and characteristics are considered. It is shown that combined alloying of steel by carbon, chrome, silicon, manganese, vanadium and molybdenum in a certain proportion allows to reach the intended aim, achieving at the same time increase of solidity, impact elasticity and heat stability.

  1. Experimental modeling of weld thermal cycle of the heat affected zone (HAZ

    Directory of Open Access Journals (Sweden)

    J. Kulhánek

    2016-10-01

    Full Text Available Contribution deals with experimental modeling of quick thermal cycles of metal specimens. In the introduction of contribution will be presented measured graphs of thermal cycle of heat affected zone (HAZ of weld. Next will be presented experimental simulation of measured thermal cycle on the standard specimens, useable for material testing. This approach makes possible to create material structures of heat affected zone of weld, big enough for standard material testing.

  2. Metallurgical and Corrosion Characterization of POST Weld Heat Treated Duplex Stainless Steel (uns S31803) Joints by Friction Welding Process

    Science.gov (United States)

    Asif M., Mohammed; Shrikrishna, Kulkarni Anup; Sathiya, P.

    2016-02-01

    The present study focuses on the metallurgical and corrosion characterization of post weld heat treated duplex stainless steel joints. After friction welding, it was confirmed that there is an increase in ferrite content at weld interface due to dynamic recrystallization. This caused the weldments prone to pitting corrosion attack. Hence the post weld heat treatments were performed at three temperatures 1080∘C, 1150∘C and 1200∘C with 15min of aging time. This was followed by water and oil quenching. The volume fraction of ferrite to austenite ratio was balanced and highest pit nucleation resistance were achieved after PWHT at 1080∘C followed by water quench and at 1150∘C followed by oil quench. This had happened exactly at parameter set containing heating pressure (HP):40 heating time (HT):4 upsetting pressure (UP):80 upsetting time (UP):2 (experiment no. 5). Dual phase presence and absence of precipitates were conformed through TEM which follow Kurdjumov-Sachs relationship. PREN of ferrite was decreasing with increase in temperature and that of austenite increased. The equilibrium temperature for water quenching was around 1100∘C and that for oil quenching was around 1140∘C. The pit depths were found to be in the range of 100nm and width of 1.5-2μm.

  3. Carbide Precipitation in 2.25 Cr-1 Mo Bainitic Steel: Effect of Heating and Isothermal Tempering Conditions

    Science.gov (United States)

    Dépinoy, Sylvain; Toffolon-Masclet, Caroline; Urvoy, Stéphane; Roubaud, Justine; Marini, Bernard; Roch, François; Kozeschnik, Ernst; Gourgues-Lorenzon, Anne-Françoise

    2017-05-01

    The effect of the tempering heat treatment, including heating prior to the isothermal step, on carbide precipitation has been determined in a 2.25 Cr-1 Mo bainitic steel for thick-walled applications. The carbides were identified using their amount of metallic elements, morphology, nucleation sites, and diffraction patterns. The evolution of carbide phase fraction, morphology, and composition was investigated using transmission electron microscopy, X-ray diffraction, as well as thermodynamic calculations. Upon heating, retained austenite into the as-quenched material decomposes into ferrite and cementite. M7C3 carbides then nucleate at the interface between the cementite and the matrix, triggering the dissolution of cementite. M2C carbides precipitate separately within the bainitic laths during slow heating. M23C6 carbides precipitate at the interfaces (lath boundaries or prior austenite grain boundaries) and grow by attracting nearby chromium atoms, which results in the dissolution of M7C3 and, depending on the temperature, coarsening, or dissolution of M2C carbides, respectively.

  4. Effect of Heat Input During Disk Laser Bead-On-Plate Welding of Thermomechanically Rolled Steel on Penetration Characteristics and Porosity Formation in the Weld Metal

    Directory of Open Access Journals (Sweden)

    Lisiecki A.

    2016-03-01

    Full Text Available The paper presents a detailed analysis of the influence of heat input during laser bead-on-plate welding of 5.0 mm thick plates of S700MC steel by modern Disk laser on the mechanism of steel penetration, shape and depth of penetration, and also on tendency to weld porosity formation. Based on the investigations performed in a wide range of laser welding parameters the relationship between laser power and welding speed, thus heat input, required for full penetration was determined. Additionally the relationship between the laser welding parameters and weld quality was determined.

  5. Effect of Filler and Heat Treatment on the Physical and Mechanical Properties of the Brazed Joint between Carbide Tip and Steel

    Science.gov (United States)

    Winardi, Y.; Triyono; Wijayanta, A. T.

    2017-02-01

    In this study, the effect of filler and heat treatment on the physical and mechanical properties of the brazed joint carbide tip and steel was investigated. Tip carbide YG6 and low carbon steel (SS400) is joining by torch brazing with two filler metals, silver, and copper filler. Heat treatment was performed in induction furnace. Microstructure and shear strength of the brazed joint have been investigated. Many silver filler layer are formed on the surface of the base metal rather then using copper filler. The highest shear strength is achieved using a silver filler metal at temperatur 725°C. The highest shear load is 18.62 kN.

  6. FACTORS AFFECTING HEAT TOLERANCE IN CROSSBRED CATTLE IN CENTRAL BRAZIL

    Directory of Open Access Journals (Sweden)

    Concepta Margaret McManus

    2014-06-01

    Full Text Available This study compared the adaptation traits in common crosses of crossbred dairy cattle in central Brazil. Twenty animals of each of three genetic groups were used: zebu (Bos indicus, Simmental x Zebu (SZ and Holstein x Zebu (HZ. The test measured variations in rectal temperature (RT, respiration rate (RR and heart rate (HR of animals in the shade and after exposure to the sun, as well as mean daily milk production throughout the lactation period. The procedure was repeated three times. There were significant interactions between test group and genetic group for the traits investigated and the correlations among traits were low. The RR of the crossbred groups may be controlling body temperature in such a way as not to cause an increase in RT. Milk production influenced RR in crossbred cows exposed to the sun, confirming their poorer adaptation in comparison with zebu cows. We observed that the adaptation can be measured in terms of production within the same genetic group. In conclusion, the crosses with European breeds produced more milk than zebu, although they were influenced by heat/solar radiation.

  7. Effects of Heat Treatment on the Microstructure and Mechanical Properties of Low-Carbon Steel with Magnesium-Based Inclusions

    Science.gov (United States)

    Zhang, Jian; Feng, Pei-Hsien; Pan, Yan-Chi; Hwang, Weng-Sing; Su, Yen-Hao; Lu, Muh-Jung

    2016-10-01

    The effects of heat treatment on the microstructure and mechanical properties of Mg-containing (7 ppm), low-carbon commercial steel (SS400) were investigated. Twenty different heat treatment paths were performed using a Gleeble 1500 thermomechanical simulator. It was observed by using an optical microscope that as the cooling rate increased and holding temperature decreased, the volume fractions of pearlite, Widmanstätten ferrite, and grain boundary allotriomorphs ferrite fell, whereas that of acicular ferrite (AF) increased. Quantifying the fractions of AF and other phases by using electron backscatter diffraction shows that the heat treatment path with a cooling rate of 20 K/s and holding temperature of 723 K (450 °C) induced the highest volume fraction (44 pct) of AF. As such, the toughness of the sample was increased 12.4 times compared with that observed in the sample containing 4 pct AF. Typical inclusions were analyzed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy. The results showed that the magnesium-based complex inclusions could act as nucleation sites of AF. Inclusions with a size of about 5 μm can serve as heterogeneous nucleation sites for AF. Mg-containing SS400 steel also has excellent hot-ductility in the temperature range of 973 K to 1273 K (700 °C to 1000 °C), and the minimum percentage reduction in area (R.A pct) value of around 63 pct at 1073 K (800 °C).

  8. Effect of post-boronizing heat treatment on wear behaviour and pit formation in AISI-8620 gear steel

    Energy Technology Data Exchange (ETDEWEB)

    Aydin, H.; Sevim, V.; Demirci, A.H. [Uludag Univ., Gorukle-Bursa (Turkey)

    2007-07-01

    In this study the effect of post-boronizing heat treatment on wear behaviour and pit formation on a starter motor pinion gear, made from AISI-8620 steel, was investigated. This involved using a rotary wear test, where the number of cycles at a fixed load and a fixed rotational speed were varied. Boronizing was performed on starter motor pinion gears (test specimens) in a solid medium consisting of B{sub 4}C, SiC, KBF{sub 4} at a temperature of 900 C for 4 h. Following boronizing, test specimens were quenched in water at room temperature from the boronizing temperature and were subsequently tempered at 180 C for 1, 2 and 3 hours. As part of this investigation, microstructure and microhardness distribution of the boride layer and wear resistance and pitting damage rate of the specimens were examined for each of the tempering heat treatments. Morphology of the boride layer and pit formation were characterized using optical microscopy. Wear and pitting evaluations were carried out using a wear test apparatus made for this purpose, which simulates the pinion and flywheel starter ring gear pair. For each wear test the number of cycles was 25 x 10{sup 5}, inspected at 5 x 10{sup 5}-cycle intervals. It was concluded from these examinations that tempering heat treatments following boronizing contribute to the increase of microhardness alongside the surface layer, as well as an increase in wear resistance and pitting damage. (orig.)

  9. Study of heat treatment parameters for large-scale hydraulic steel gate track

    Directory of Open Access Journals (Sweden)

    Ping-zhou Cao

    2013-10-01

    Full Text Available In order to enhance external hardness and strength, a large-scale hydraulic gate track should go through heat treatment. The current design method of hydraulic gate wheels and tracks is based on Hertz contact linear elastic theory, and does not take into account the changes in mechanical properties of materials caused by heat treatment. In this study, the heat treatment parameters were designed and analyzed according to the bearing mechanisms of the wheel and track. The quenching process of the track was simulated by the ANSYS program, and the temperature variation, residual stress, and deformation were obtained and analyzed. The metallurgical structure field after heat treatment was predicted by the method based on time-temperature-transformation (TTT curves. The results show that the analysis method and designed track heat treatment process are feasible, and can provide a reference for practical projects.

  10. Study on the effect of post weld heat treatment parameters on the relaxation of welding residual stresses in electron beam welded P91 steel plates

    OpenAIRE

    Venkata, K. Abburi; Kumar, S.; Dey, H.C.; Smith, D. J.; Bouchard, P J; Truman, C.E

    2014-01-01

    Residual stresses are created by localised heating effects that occur during the welding process. Post weld heat treatment (PWHT) is the most convenient method for stress relief of welds. But PWHT cannot completely eliminate the residual stresses. So, it is essential to determine the influence of PWHT parameters like holding temperature and time on the stress relaxation for optimising the process. The selected material is modified 9Cr-1Mo (Grade 91) steel in the form of plates welded together...

  11. Effect of normalizing temperature on the strength of 9Cr–3W–3Co martensitic heat resistant steel

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Peng, E-mail: maxeric@163.com [Key Laboratory of Advanced Materials of Ministry of Education of China, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Institute for Special Steels, China Iron and Steel Research Institute, Beijing 100081 (China); Liu, Zhengdong; Bao, Hansheng [Institute for Special Steels, China Iron and Steel Research Institute, Beijing 100081 (China); Weng, Yuqing [Key Laboratory of Advanced Materials of Ministry of Education of China, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Liu, Wei, E-mail: liuw@mail.tsinghua.edu.cn [Key Laboratory of Advanced Materials of Ministry of Education of China, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2014-03-01

    Microstructure and room temperature strength of 9Cr–3W–3Co martensitic heat resistant steel after normalizing at 900–1200 °C for 1 h and then tempering at 750 °C for 1 h have been experimentally investigated using optical microscope (OM), field emission scanning electron microscope (FESEM), electron back-scattered diffraction (EBSD), field emission transmission electron microscope (FETEM) and tensile tests. The results show that with increasing normalizing temperature, the strength of the 9Cr–3W–3Co steel increases from 900 °C to 1000 °C, then keeps almost the same from 1000 °C to 1100 °C and finally increases again from 1100 °C to 1200 °C. The change in the room temperature strength can mainly be attributed to the change in precipitation strengthening. The size and the amount of particles after tempering are mainly due to the re-dissolution of particles during normalization. The higher the normalizing temperature is, the more the coarse particles formed during manufacturing will be re-dissolved, and then the larger the amount of fine particles precipitated during tempering is.

  12. Novel scanning dc-susceptometer for characterization of heat-resistant steels with different states of aging

    Science.gov (United States)

    Pereira, João M. B.; Pacheco, Clara Johanna; Arenas, Monica P.; Araujo, Jefferson F. D. F.; Pereira, Gabriela R.; Bruno, Antonio C.

    2017-11-01

    We have built a scanning dc-susceptometer for magnetic characterization of millimeter-scale samples. Using samples with few millimeter-thick slabs, the setup used is able to apply perpendicularly to the sample uniform dc magnetic fields up to 500 mT. It has a scanning range of 100 mm × 100 mm with micrometer resolution. In the present configuration, the dc-susceptometer is equipped with a pair of commercial Hall effect sensors forming an axial gradiometer. The measured output noise at 6.0 Hz is about 1.0 μTrms/√Hz in an unshielded environment and the magnetic moment sensitivity is 8.8 × 10-11 Am2. In particular, we used it to characterize heat-resistant steels, used as radiant tubes in steam reformer furnaces. We measured the cross-section of tube samples with progressing states of aging from as-cast to state VI. Measuring their susceptibilities, we detected a ferromagnetic layer at the external tube wall on aged samples. We were able to establish a relation between the magnetic response and the microstructural change of the steel.

  13. Effect of sanitizer combined with steam heating on the inactivation of foodborne pathogens in a biofilm on stainless steel.

    Science.gov (United States)

    Ban, Ga-Hee; Kang, Dong-Hyun

    2016-05-01

    The combined effect of chemical sanitizers including sodium hypochlorite, hydrogen peroxide, iodophor, and benzalkonium chloride with steam heating on the inactivation of biofilms formed by Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on stainless steel was investigated. Six day old biofilms, comprised of a mixture of three strains each of three foodborne pathogens, were produced on stainless steel coupons at 25 °C and treated with each sanitizer alone (for 5, 15, and 30 s), steam alone (for 5, 10, and 20 s), and the combination. There was a synergistic effect of sanitizer and steam on the viability of biofilm cells of the three pathogens as evidenced by plating counts and imaging. The combination treatment achieved an additional 0.01 to 2.78 log reduction compared to the sum of each individual treatment. The most effective combination for reducing levels of biofilm cells was the combination of steam and iodophor; steam for 20 s and merely 20 ppm iodophor for 30 s reduced cell numbers to below the detection limit (biofilm cells in food processing facilities as a potential intervention. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Microstructural evolution and change in hardness of S30432 heat-resistant steel during creep at 650 c

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, L.H.; Zhang, Y.J. [School of Materials Science and Engineering, Shanghai University (China); Wang, Q.J.; Xu, S.Q. [Baoshan Iron and Steel Co., Ltd. Shanghai (China)

    2010-04-15

    The microstructural evolution of S30432 heat-resistant steel during creep at 650 C and its effect on the change in hardness was investigated. The change of hardness during creep of S30432 at 650 C can be divided into three stages. These are related to the precipitation and coarsening of {epsilon}-Cu and M{sub 23}C{sub 6} carbides, decrease in the number of twins and increase in grain size. The precipitation of {epsilon}-Cu dominantly contributes to the significant hardening at stage I, and the coarsening of {epsilon}-Cu is the key factor to decrease the hardness at stage II. At stage III, the hardness hardly changes since the microstructure of S30432 tends to be stable in the long-term creep range. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  15. Factors affecting the strength of multipass low-alloy steel weld metal

    Science.gov (United States)

    Krantz, B. M.

    1972-01-01

    The mechanical properties of multipass high-strength steel weld metals depend upon several factors, among the most important being: (1) The interaction between the alloy composition and weld metal cooling rate which determines the as-deposited microstructure; and (2) the thermal effects of subsequent passes on each underlying pass which alter the original microstructure. The bulk properties of a multipass weld are therefore governed by both the initial microstructure of each weld pass and its subsequent thermal history. Data obtained for a high strength low alloy steel weld metal confirmed that a simple correlation exists between mechanical properties and welding conditions if the latter are in turn correlated as weld cooling rate.

  16. Structural Aspects of Railway Truss Bridges Affecting Transverse Shear Forces in Steel-Concrete Composite Decks

    Directory of Open Access Journals (Sweden)

    Siekierski Wojciech

    2015-03-01

    Full Text Available At the steel-concrete interface, the horizontal shear forces that are transverse to cross beams occur due to joint action of the steel-concrete composite deck and the truss girders. Numerical analysis showed that values of the forces are big in comparison to the longitudinal shear forces. In both cases extreme force values occur near side edges of a slab. The paper studies possibilities of reduction of these shear forces by structural alterations of the following: rigidity of a concrete slab, arrangement of a wind bracing, arrangement of concrete slab expansion joints. An existing railway truss bridge span has been analysed. Numerical analysis shows that it is possible to reduce the values of shear forces transverse to cross beams. It may reach 20% near the side edges of slabs and 23% in the centre of slab width.

  17. Effect of higher heating rate during continuous annealing on microstructure and mechanical properties of cold-rolled 590 MPa dual-phase steel

    Directory of Open Access Journals (Sweden)

    Deng Yonggang

    2015-01-01

    Full Text Available In this presentation, the effect of higher heating rate in continuous annealing on microstructure and mechanical properties of a cold-rolled 590 MPa ferrite-martensite dual-phase steel were investigated by using microstructural observation and mechanical property measurement. The results show that compared with the conventional continuous annealed steels heated at a rate of 5 ∘C/s (CA, the average ferrite grain sizes heated at a higher rate (300 ∘C/s, HRA was obviously refined from 15.6 μm to 5.3 μm. The morphology of martensite is observed to shift from network along ferrite grain boundaries to uniformly dispersed in the final DP590 microstructure. Twinned substructure of martensite can be found when heated at a higher heating rate in continuous annealing. EBSD orientation maps show that the fraction of low angle grain boundary is increased in HRA sample compared to CA sample. The HRA sample has excellent mechanical properties when compared to the CA sample. The variations of strength, elongation, strain hardening behavior and fracture mechanism of the this DP590 steel with different heating routine were further discussed in relation to microstructural features.

  18. Dry heat treatment affects wheat bran surface properties and hydration kinetics.

    Science.gov (United States)

    Jacobs, Pieter J; Hemdane, Sami; Delcour, Jan A; Courtin, Christophe M

    2016-07-15

    Heat stabilization of wheat bran aims at inactivation of enzymes which may cause rancidity and processability issues. Such treatments may however cause additional unanticipated phenomena which may affect wheat bran technological properties. In this work, the impact of toasting on wheat bran hydration capacity and hydration kinetics was studied. Hydration properties were assessed using the Enslin-Neff and drainage centrifugation water retention capacity methods, thermogravimetric analysis and contact angle goniometry, next to more traditional methods. While equilibrium hydration properties of bran were not affected by the heat treatment, the rate at which the heat treated bran hydrated was, however, very significantly reduced compared to the untreated bran. This phenomenon was found to originate from the formation of a lipid coating during the treatment rendering the bran surface hydrophobic. These insights help to understand and partially account for the modified processability of heat treated bran in food applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Changes in the state of heat-resistant steel induced by repeated hot deformation

    Science.gov (United States)

    Lyubimova, Lyudmila L.; Fisenko, Roman N.; Tashlykov, Alexander A.; Tabakaev, Roman B.

    2018-01-01

    This work deals with the problems of structural regeneration by thermal restoration treatment (TRT). These include the lack of a structural sign showing that TRT is possible, a consensus on TRT modes, the data on the necessary relaxation depth of residual stresses, or criteria of structural restoration. Performing a TRT without solving these problems may deteriorate the properties of steel or even accelerate its destruction. With this in view, the purpose of this work is to determine experimentally how the residual stress state changes under thermal and mechanical loads in order to specify the signs of the restoration of structure and structural stability. The object of this research is unused 12Cr1MoV steel that has been aged naturally for 13 years. Using X-ray dosimetry with X-ray spectral analysis, we study the distribution of internal residual stresses of the first kind during the repeated hot deformation. After repeated thermal deformation, the sample under study transforms from a viscoelastic Maxwell material into a Kelvin-Voigt material, which facilitates structural stabilization. A sign of this is the relaxation limit increase, prevention of continuous decay of an α-solid solution of iron and restoration of the lattice parameter.

  20. Study on characteristics of Mod.9Cr-1Mo-V.Nb steel and W-added T92 steel for liquid metal reactor heat transfer tube materials

    Energy Technology Data Exchange (ETDEWEB)

    Han, Chang Sik; Song, Byung Jun; Park, Kwang Seok; Kim, Seong Ho [Korea Atomic Energy Research Institute, Taejon (Korea)

    1999-01-01

    Mod.9Cr-1Mo-V.Nb steel and T92 steel (9Cr-1Mo-1.9W) have been investigated to identify the microstructure and mechanical properties with normalizing and tempering temperature. Microhardness does not change with normalizing temperature in Mod.9Cr-1Mo-V.Nb steel because carbides have been dissolved completely after normalizing at 900 deg C. Microhardness decreased rapidly with increasing tempering temperature because of carbide precipitation and dislocation recovery in both Mod.9Cr-1Mo-V.Nb steel and T92 steel. Transmission electron microscopy (TEM) also revealed that the evolution of substructures(cell structures) was delayed by the W addition. High-temperature strength of the T92 steel is superior to that of Mod.9Cr-1Mo-V.Nb steel which is mainly attributed to the retardation of dislocation recovery and the stabilization of carbide precipitates, caused by the W addition. Charpy impact test results at 25 deg C showed that ductile fracture observed in Mod.9Cr-1Mo-V.Nb steel tempered at 700 deg C. (author). 19 refs., 41 figs., 2 tabs.

  1. Hot Stamping of Boron Steel Using Partition Heating for Tailored Properties: Experimental Trials and Numerical Analysis

    Science.gov (United States)

    Mu, Yanhong; Wang, Baoyu; Zhou, Jing; Huang, Xu; Li, Xuetao

    2017-11-01

    Hot-stamped components with tailored properties are becoming popular for their better performance in collision. In this article, an M-shaped part with varying properties was formed by hot stamping using partition heating. Different soaking temperatures induce different austenite fractions at the different regions of the blank, resulting in the partitioned microstructure and mechanical properties in a single part. In the high-temperature region, the average tensile strength and elongation are 1565 MPa and 8.65 pct, respectively, and the average tensile strength and elongation are 626 MPa and 24.37 pct, respectively, in the low-temperature region. A finite element model of hot stamping using partition heating was established based on the relationship of austenite fraction with heating temperature determined by the dilatometer test and the stress-strain curve of 22MnB5 with different austenite fractions acquired from the hot tensile test.The differences of temperature, thickness, and Vickers hardness in different zones of the M-shaped part during forming and quenching stages were analyzed. The effects of hot stamping parameters, such as stamping velocity and heating temperature, on the forming and mechanical properties of the tailored M-shaped part were investigated, providing theoretical guidance for the production of tailored hot-stamped components using partition heating.

  2. Experimental studies of parameters affecting the heat generation in friction stir welding process

    Directory of Open Access Journals (Sweden)

    Mijajlović Miroslav M.

    2012-01-01

    Full Text Available Heat generation is a complex process of transformation of a specific type of energy into heat. During friction stir welding, one part of mechanical energy delivered to the welding tool is consumed in the welding process, another is used for deformational processes etc., and the rest of the energy is transformed into heat. The analytical procedure for the estimation of heat generated during friction stir welding is very complex because it includes a significant number of variables and parameters, and many of them cannot be fully mathematically explained. Because of that, the analytical model for the estimation of heat generated during friction stir welding defines variables and parameters that dominantly affect heat generation. These parameters are numerous and some of them, e. g. loads, friction coefficient, torque, temperature, are estimated experimentally. Due to the complex geometry of the friction stir welding process and requirements of the measuring equipment, adequate measuring configurations and specific constructional solutions that provide adequate measuring positions are necessary. This paper gives an overview of the process of heat generation during friction stir welding, the most influencing parameters on heat generation, constructional solutions for the measuring equipment needed for these experimental researches and examples of measured values.

  3. Application of Cold Formed Steel Framing Structures for Construction in Zones Affected by Land Subsidence

    Directory of Open Access Journals (Sweden)

    Correa L.-O.

    2012-09-01

    Full Text Available The main objective of this research project is to study the application of structural systems based on light gauge cold-formed steel framing to housing in subsidence zones, having the following scopes: characterize the typical settlements in a discontinuity due to subsidence, to build a laboratory facility to simulate these settlements, to simulate and to evaluate numerically and in laboratory in a full scale model the structural performance of a house subjected to settlements due to subsidence, in terms of its stresses and strains and, eventually, its capacity of retrieval to its nondeformed shape.

  4. Effect of Heat Treatment on Microstructure and Mechanical Properties of Laser Additively Manufactured AISI H13 Tool Steel

    Science.gov (United States)

    Chen, ChangJun; Yan, Kai; Qin, Lanlan; Zhang, Min; Wang, Xiaonan; Zou, Tao; Hu, Zengrong

    2017-11-01

    The effect of heat treatment on microstructure and mechanical properties (microhardness, wear resistance and impact toughness) of laser additively manufactured AISI H13 tool steel was systemically investigated. To understand the variation of microstructure and mechanical properties under different heat treatments, the as-deposited samples were treated at 350, 450, 550, 600 and 650 °C/2 h, respectively. Microstructure and phase transformation were investigated through optical microscopy, scanning electron microscope and transmission electron microscope. The mechanical properties were characterized by nanoindentation tests, Charpy tests and high-temperature wear tests. The microstructure of as-deposited samples consisted of martensite, ultrafine carbides and retained austenite. After the tempering treatment, the martensite was converted into tempered martensite and some fine alloy carbides which precipitated in the matrix. When treated at 550 °C, the greatest hardness and nanohardness were 600 HV0.3 and 6119.4 MPa due to many needle-like carbides precipitation. The value of hardness increased firstly and then decreased when increasing the temperature. When tempered temperatures exceeded 550 °C, the carbides became coarse, and martensitic matrix recrystallized at the temperature of 650 °C. The least impact energy was 6.0 J at a temperature of 550 °C. Samples tempered at 550 °C had larger wear volume loss than that of others. Wear resistances of all samples under atmospheric condition at 400 °C showed an oxidation mechanism.

  5. Experimental study on critical heat flux on a downward-facing stainless steel disk in confined space

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Y.W. [State Key Laboratory of Multiphase Flow in Power Engineering, Department of Nuclear Science and Technology, Xi' an Jiaotong University, Xi' an City 710049 (China); Su, G.H., E-mail: ghsu@mail.xjtu.edu.cn [State Key Laboratory of Multiphase Flow in Power Engineering, Department of Nuclear Science and Technology, Xi' an Jiaotong University, Xi' an City 710049 (China); Sugiyama, K., E-mail: k-sugi@eng.hokudai.ac.jp [Faculty of Engineering, Hokkaido University, Kita 13 Jo, Nishi 8 Chome, Kita-Ku, Sapporo 060-8628 (Japan)

    2011-02-15

    Critical heat flux (CHF) is experimentally studied on a relatively large downward-facing surface with a heated stainless steel disk diameter of D = 300 mm in confined space at atmospheric pressure using water as the working fluid. The bulk working fluid is subcooled. The gap size s can be adjusted to 0.9, 2.2, 2.6, 3.0, 3.2, 5.0, 7.0, 10.0, 13.0, 15.6, 19.5, 25.0, 36.0, 51.0 and 77 mm. We found that the average CHF under the present condition is approximately 0.25 MW/m{sup 2} which is only about 23% of which occurs on an upward-facing surface without confined space in pool boiling. The CHF increases with the increase of the gap size when the gap size is smaller than 7 mm and it is a function of Bond and Jakob numbers when the gap size is larger than 7 mm.

  6. Developmental acclimation to low or high humidity conditions affect starvation and heat resistance of Drosophila melanogaster.

    Science.gov (United States)

    Parkash, Ravi; Ranga, Poonam; Aggarwal, Dau Dayal

    2014-09-01

    Several Drosophila species originating from tropical humid localities are more resistant to starvation and heat stress than populations from high latitudes but mechanistic bases of such physiological changes are largely unknown. In order to test whether humidity levels affect starvation and heat resistance, we investigated developmental acclimation effects of low to high humidity conditions on the storage and utilization of energy resources, body mass, starvation survival, heat knockdown and heat survival of D. melanogaster. Isofemale lines reared under higher humidity (85% RH) stored significantly higher level of lipids and showed greater starvation survival hours but smaller in body size. In contrast, lines reared at low humidity evidenced reduced levels of body lipids and starvation resistance. Starvation resistance and lipid storage level were higher in females than males. However, the rate of utilization of lipids under starvation stress was lower for lines reared under higher humidity. Adult flies of lines reared at 65% RH and acclimated under high or low humidity condition for 200 hours also showed changes in resistance to starvation and heat but such effects were significantly lower as compared with developmental acclimation. Isofemale lines reared under higher humidity showed greater heat knockdown time and heat-shock survival. These laboratory observations on developmental and adult acclimation effects of low versus high humidity conditions have helped in explaining seasonal changes in resistance to starvation and heat of the wild-caught flies of D. melanogaster. Thus, we may suggest that wet versus drier conditions significantly affect starvation and heat resistance of D. melanogaster. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. Are adult life history traits in oriental fruit moth affected by a mild pupal heat stress?

    Science.gov (United States)

    Zheng, Jincheng; Cheng, Xiongbin; Hoffmann, Ary A; Zhang, Bo; Ma, Chun-Sen

    2017-10-01

    Thermal stress at one life stage can affect fitness at a later stage in ectotherms with complex life cycles. Most relevant studies have focused on extreme stress levels, but here we also show substantial fitness effects in a moth when pupae are exposed to a relatively mild and sublethal heat stress. We consider the impact of a 35°C heat stress of 2h in three geographically separate populations of the oriental fruit moth (OFM, Grapholita molesta) from northern, middle and southern China. Heat stress negatively affected fecundity but increased adult heat resistance and adult longevity. Fitness effects were mostly consistent across populations but there were also some population differences. In the Shenyang population from northern China, there was a hormetic effect of heat on female longevity not evident in the other populations. Adults from all populations had higher LT 50 s due to heat stress after pupal exposure to the sublethal stress. These results highlight that the pupal stage is a particularly sensitive window for development and they have implications for seasonal adaptation in uncertain environments as well as changes in pest dynamics under climate warming. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Effects of Induction Heat Bending and Heat Treatment on the Boric Acid Corrosion of Low Alloy Steel Pipe for Nuclear Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki-Tae; Kim, Young-Sik [Andong National University, Gyeongbuk (Korea, Republic of); Chang, Hyun-Young; Park, Heung-Bae [KEPCO EandC, Gyeongbuk (Korea, Republic of); Sung, Gi-Ho; Shin, Min-Chul [Sungil SIM Co. Ltd, Busan (Korea, Republic of)

    2016-11-15

    In many plants, including nuclear power plants, pipelines are composed of numerous fittings such as elbows. When plants use these fittings, welding points need to be increased, and the number of inspections also then increases. As an alternative to welding, the pipe bending process forms bent pipe by applying strain at low or high temperatures. This work investigates how heat treatment affects on the boric acid corrosion of ASME SA335 Gr. P22 caused by the induction heat bending process. Microstructure analysis and immersion corrosion tests were performed. It was shown that every area of the induction heat bent pipe exhibited a high corrosion rate in the boric acid corrosion test. This behavior was due to the enrichment of phosphorous in the ferrite phase, which occurred during the induction heat bending process. This caused the ferrite phase to act as a corrosion initiation site. However, when re-heat treatment was applied after the bending process, it enhanced corrosion resistance. It was proved that this resistance was closely related to the degree of the phosphorus segregation in the ferrite phase.

  9. Mechanical properties of heat influenced steel 10 CrMo 9 10; Mekaniska egenskaper hos vaermepaaverkat staal 10 CrMo 9 10

    Energy Technology Data Exchange (ETDEWEB)

    Storesund, Jan; Nilsson, Henrik

    2005-04-01

    At ageing and overheating of steel the microstructure degenerates continuously resulting in a reduction of the strength. For ferritic steels there are at least three pieces of work where the spheroidization and precipitation during heat treatment has been studied resulting in a classification of the microstructure degeneration. These classifications are quite similar to each other. In life time assessments and failure analysis of components operating at high temperatures such classifications are widely used to describe the extent of the microstructure degeneration in replicas or samples from the components. It is not possible to give quantitative estimations of the strength reduction in the material by use of these classifications. However, it would be useful to make it possible to do that since overheating of components in plant occurs quite frequently. The present project aims to study the relationship between strength and the degeneration of the microstructure and is performed by mechanical testing on different degrees of heat exposure of a ferritic steel. The influence of heat exposure on microstructure, hardness and tensile strength in a 10 CrMo 9 10 steel has been studied. Heat treatments were mainly performed at 720 deg C in a series of times up to 1000 hours. In addition, one sample each was heat treated at 600 and 620 deg C for 3000 h and 1000 h, respectively. The Larson-Miller Parameter, which is a widely applied time-temperature parameter, was used to describe the extent of the heat influence. The measured macro-hardness correlated well with the Larson-Miller Parameter. That was also the case for the micro-hardness and the tensile properties with exception to the samples heat treated at 600 and 620 deg C. These samples deviated to an amount of approximately 15 MPa which is suggested to be due to the solution hardening element molybdenum in the steel that has been shown to gather into the carbides in a much larger extent for heat treatments at around 600

  10. Thermally activated formation of martensite in Fe-C alloys and Fe-17%Cr-C stainless steels during heating from boiling nitrogen temperature

    DEFF Research Database (Denmark)

    Villa, Matteo; Hansen, Mikkel Fougt; Somers, Marcel A. J.

    2016-01-01

    The thermally activated austenite-to-martensite transformation was investigated by magnetometry in three Fe-C alloys and in two 17%Cr stainless steels. After quenching to room temperature, samples were immersed in boiling nitrogen and martensite formation was followed during subsequent (re)heating......-dependent transformation curve. Moreover, magnetometry showed that the heating rate had an influence on the fraction of martensite formed during sub-zero Celsius treatment. The activation energy for thermally activated martensite formation was quantified in the range 11‒21 kJ/mol by a Kissinger-like method....... to room temperature. Different tests were performed applying heating rates from 0.5 K/min to 10 K/min. An additional test consisted in fast (re)heating the samples by immersion in water. Thermally activated martensite formation was demonstrated for all investigated materials by a heating rate...

  11. Different types of stainless steel used in equipment in meat plants do not affect the initial microbial transfer, including pathogens, from pork skin.

    Science.gov (United States)

    Larivière-Gauthier, Guillaume; Quessy, Sylvain; Fournaise, Sylvain; Letellier, Ann; Fravalo, Philippe

    2015-07-01

    This study describes and measures the impact of different compositions and finishes of stainless steel used in equipment in the meat industry on the transfer of natural flora and selected pathogens from artificially contaminated pork skin. It is known that the adhesion to surfaces of Listeria monocytogenes and Salmonella, 2 pathogens frequently found in contaminated pork meat, depends on the nature and roughness of the surface. Our results show no statistically significant differences in microbial transfer regardless of the types of stainless steel considered, with the highest measured transfer difference being 0.18 log colony-forming units (CFUs)/800 cm(2). Moreover, no differences in total microbial community were observed after transfer on the 5 types of stainless steel using single-strand conformation polymorphism (SSCP). It was concluded that the different characteristics of the stainless steel tested did not affect the initial bacterial transfer in this study.

  12. Influence of Tool Rotational Speed and Post-Weld Heat Treatments on Friction Stir Welded Reduced Activation Ferritic-Martensitic Steel

    Science.gov (United States)

    Manugula, Vijaya L.; Rajulapati, Koteswararao V.; Reddy, G. Madhusudhan; Mythili, R.; Bhanu Sankara Rao, K.

    2017-08-01

    The effects of tool rotational speed (200 and 700 rpm) on evolving microstructure during friction stir welding (FSW) of a reduced activation ferritic-martensitic steel (RAFMS) in the stir zone (SZ), thermo-mechanically affected zone (TMAZ), and heat-affected zone (HAZ) have been explored in detail. The influence of post-weld direct tempering (PWDT: 1033 K (760 °C)/ 90 minutes + air cooling) and post-weld normalizing and tempering (PWNT: 1253 K (980 °C)/30 minutes + air cooling + tempering 1033 K (760 °C)/90 minutes + air cooling) treatments on microstructure and mechanical properties has also been assessed. The base metal (BM) microstructure was tempered martensite comprising Cr-rich M23C6 on prior austenite grain and lath boundaries with intra-lath precipitation of V- and Ta-rich MC precipitates. The tool rotational speed exerted profound influence on evolving microstructure in SZ, TMAZ, and HAZ in the as-welded and post-weld heat-treated states. Very high proportion of prior austenitic grains and martensite lath boundaries in SZ and TMAZ in the as-welded state showed lack of strengthening precipitates, though very high hardness was recorded in SZ irrespective of the tool speed. Very fine-needle-like Fe3C precipitates were found at both the rotational speeds in SZ. The Fe3C was dissolved and fresh precipitation of strengthening precipitates occurred on both prior austenite grain and sub-grain boundaries in SZ during PWNT and PWDT. The post-weld direct tempering caused coarsening and coalescence of strengthening precipitates, in both matrix and grain boundary regions of TMAZ and HAZ, which led to inhomogeneous distribution of hardness across the weld joint. The PWNT heat treatment has shown fresh precipitation of M23C6 on lath and grain boundaries and very fine V-rich MC precipitates in the intragranular regions, which is very much similar to that prevailed in BM prior to FSW. Both the PWDT and PWNT treatments caused considerable reduction in the hardness of SZ

  13. Tool steels

    DEFF Research Database (Denmark)

    Højerslev, C.

    2001-01-01

    On designing a tool steel, its composition and heat treatment parameters are chosen to provide a hardened and tempered martensitic matrix in which carbides are evenly distributed. In this condition the matrix has an optimum combination of hardness andtoughness, the primary carbides provide...... resistance against abrasive wear and secondary carbides (if any) increase the resistance against plastic deformation. Tool steels are alloyed with carbide forming elements (Typically: vanadium, tungsten, molybdenumand chromium) furthermore some steel types contains cobalt. Addition of alloying elements...... serves primarily two purpose (i) to improve the hardenabillity and (ii) to provide harder and thermally more stable carbides than cementite. Assuming proper heattreatment, the properties of a tool steel depends on the which alloying elements are added and their respective concentrations....

  14. Design of heat treatments for 9-12%Cr steels to optimise creep resistance for power plant applications

    Energy Technology Data Exchange (ETDEWEB)

    Morris, P.F.; Sachadel, U.A.; Clarke, P.D. [Tata Steel Europe, Rotherham (United Kingdom). Swinden Technology Centre; CRD and T, IJmuiden (Netherlands)

    2010-07-01

    Optimisation of the creep rupture properties of Steel 92 (9%Cr, 0.5%Mo, 2%W) by modification of heat treatment and C:N ratio has been studied. It was shown that a higher austenization temperature and double tempering at lower temperature can significantly extend creep life of the standard composition. The increase in austenization temperature from 1060 C and double tempering at 660 C/3h instead of single tempering at 780 C/2h resulted in the increase of stress rupture life from 1,734 to 6,179h at 650 C/110MPa. Even greater improvement in creep life was achieved by the combination of the modified heat treatment and decreased C:N ratio. In this case the creep life was extended to 10,255 h at 650 C/110MPa. A further increase in austenitization temperature to 1200 C for the decreased C:N ratio variant extended the rupture life to 17,118h. Initial results indicate that this modified heat treatment schedule does not result in notch brittle behaviour and most of the improvement in creep strength remains after a simulated post weld heat treatment at 740 C. The stress rupture programme is continuing and at 600 C test durations are approaching 60,000h. To explain the effect on rupture life thermodynamic calculations, microscopic investigations and a literature study were performed. Electron metallography investigations revealed that the lower tempering temperature resulted in a finer distribution of nano-size particles. Calculations show that increasing the austenitization temperature gave more dissolved B, N, C, Nb and V. The lower C:N ratio resulted in a higher atomic fraction of N in nano-size particles on subsequent tempering. Dissolved B should stabilize M{sub 23}M{sub 6} and dissolved N, C, Nv, and V should allow precipitation of a higher volume fraction of nano-size carbo-nitrides during tempering. Literature data suggest that lower tempering temperatures could also change their type from MX to M{sub 2}X. (orig.)

  15. Retained Austenite Transformation during Heat Treatment of a 5 Wt Pct Cr Cold Work Tool Steel

    Science.gov (United States)

    Rehan, M. Arbab; Medvedeva, Anna; Svensson, Lars-Erik; Karlsson, Leif

    2017-11-01

    Retained austenite transformation was studied for a 5 wt pct Cr cold work tool steel tempered at 798 K and 873 K (525 °C and 600 °C) followed by cooling to room temperature. Tempering cycles with variations in holding times were conducted to observe the mechanisms involved. Phase transformations were studied with dilatometry, and the resulting microstructures were characterized with X-ray diffraction and scanning electron microscopy. Tempering treatments at 798 K (525 °C) resulted in retained austenite transformation to martensite on cooling. The martensite start ( M s ) and martensite finish ( M f ) temperatures increased with longer holding times at tempering temperature. At the same time, the lattice parameter of retained austenite decreased. Calculations from the M s temperatures and lattice parameters suggested that there was a decrease in carbon content of retained austenite as a result of precipitation of carbides prior to transformation. This was in agreement with the resulting microstructure and the contraction of the specimen during tempering, as observed by dilatometry. Tempering at 873 K (600 °C) resulted in precipitation of carbides in retained austenite followed by transformation to ferrite and carbides. This was further supported by the initial contraction and later expansion of the dilatometry specimen, the resulting microstructure, and the absence of any phase transformation on cooling from the tempering treatment. It was concluded that there are two mechanisms of retained austenite transformation occurring depending on tempering temperature and time. This was found useful in understanding the standard tempering treatment, and suggestions regarding alternative tempering treatments are discussed.

  16. Heat Transfer Affected by Transverse Magnetic Field using 3D Modeling of Arc Plasma

    Science.gov (United States)

    Maeda, Yoshifumi; Tanaka, Tatsuro; Yamamoto, Shinji; Iwao, Toru

    2016-10-01

    Gas shielded metal arc welding is used to join the various metal because this is the high quality joining technology. Thus, this welding is used for a welding of large buildings such as bridges and LNG tanks. However, the welding defect caused by the heat transfer decrement may occur with increasing the wind velocity. This is because that the convection loss increases because the arc deflects to leeward side with increasing the wind velocity. In order to prevent from the arc deflection, it is used that the transverse magnetic field is applied to the arc. However, the arc deflection occurs with increasing the transverse magnetic field excessively. The energy balance of the arc is changed with increasing the convection loss caused by the arc deflection, and the heat transfer to the anode decreases. Therefore, the analysis including the arc and anode is necessary to elucidate the heat transfer to the anode. In this paper, the heat transfer affected by the transverse magnetic field using 3D modeling of the arc plasma is elucidated. The heat transfer to the anode is calculated by using the EMTF(electromagnetic thermal fluid) simulation with increasing the transverse magnetic field. As a result, the heat transfer decreased with increasing the transverse magnetic field.

  17. Comparison of Heat Treatments on the Toughness of 1.7Ni-1.5Cu-0.5Mo Pre-alloyed P/M Steels

    Science.gov (United States)

    Güral, Ahmet; Türkan, Mustafa

    2015-05-01

    Effects of quenching plus tempering and intercritical annealing plus quenching heat treatments on the impact toughness properties of 1.7Ni-1.5Cu-0.5Mo pre-alloyed powder metallurgy steels with 0.2 (in mass%) graphite were investigated. Specimens were prepared by pressing at 670 MPa and sintering at 1250 °C. Different heat treatments, namely quenching and tempering, directly intercritically annealing and fully austenization plus intercritically annealing were carried out on the sintered specimens. The results showed that the impact toughness decreased with increasing intercritical annealing temperature in ferrite plus martensite dual phase powder metallurgy steels and with increasing tempering temperature in the quenched plus tempered specimens. Besides, impact toughness of fully austenizated plus intercritically annealed specimens was higher than those of quenched plus tempered and directly intercritically annealed specimens at the same hardness levels.

  18. Microgalvanic corrosion of laser-welded HSLA steels

    NARCIS (Netherlands)

    De Wit, J.H.; Looi, Y.M.

    Laser welding of galvanized high strength low alloy (HSLA) steels leads to the evaporation of zinc at the weld and the formation of a heat-affected-zone (HAZ). High heat input due to welding generates macro galvanic coupling between the weld and the parent metal as well as micro galvanic corrosion

  19. Microgalvanic corrosion of laser-welded HSLA steels

    NARCIS (Netherlands)

    Looi, Y.M.

    2008-01-01

    Laser welding of galvanized high strength low alloy (HSLA) steels leads to the evaporation of zinc at the weld and the formation of a heat-affected-zone (HAZ). High heat input due to welding generates macro galvanic coupling between the weld and the parent metal as well as micro galvanic corrosion

  20. Biofilms affecting progression of mild steel corrosion by Gram positive Bacillus sp.

    Science.gov (United States)

    Lin, Johnson; Madida, Bafana B

    2015-10-01

    The biodeterioration of metals have detrimental effects on the environment with economic implications. The deterioration of metals is of great concern to industry. In this study, mild steel coupons which were immersed in a medium containing Gram-positive Bacillus spp. and different nutrient sources were compared with the control in sterile deionized water. The weight loss of the coupons in the presence of Bacillus spp. alone was lower than the control and was further reduced when additional carbon sources, especially fructose, were added. The level of metal corrosion was significantly increased in the presence of nitrate with or without bacteria. There was a significant strong correlation between the weight loss and biofilm level (r =  0.64; p biofilms on the coupons and resulted in greater weight loss compared to that with Bacillus spp. only under the same conditions. However, Bacillus spp. enriched with carbon sources formed less biofilms and results in lower weight loss compared to that with Bacillus spp. only. The production of biofilm by Bacillus spp. influences the level of metal corrosion under different environmental conditions, thereby, supporting the development of a preventive strategy against corrosion. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Niobium carbo-nitride precipitation behavior in a high nitrogen 15Cr-15Ni heat resistant austenitic stainless steel

    Science.gov (United States)

    Ha, Vu The; Jung, Woo Sang

    2011-10-01

    A high nitrogen 15Cr-15Ni niobium-stabilized austenitic alloy has been produced and subjected to a special heat treatment consisting of 5 hours of solution treatment at 1270 °C followed by hot rolling, quenching and subsequent aging at temperatures of 700 °C to 800 °C. It was found that fine dispersion of nano-sized thermally stable primary Nb(C,N) precipitates had already formed in the as-cast condition. The particles were presented at all examined stages of the TMT process (as-homogenized, as-solution treated and as-aged conditions). Secondary precipitates Nb(C,N) were densely formed during subsequent aging; these precipitates had sizes of 4 nm to 5 nm. Both the primary and secondary Nb(C,N) particles showed excellent thermal stability within the temperature range of 700 °C to 800 °C. The creep properties of the studied alloy at 750 °C were superior when compared to those of commercial type 347 stainless steel.

  2. Characterization of thick plasma spray tungsten coating on ferritic/martensitic steel F82H for high heat flux armor

    Science.gov (United States)

    Yahiro, Y.; Mitsuhara, M.; Tokunakga, K.; Yoshida, N.; Hirai, T.; Ezato, K.; Suzuki, S.; Akiba, M.; Nakashima, H.

    2009-04-01

    Two types of plasma spray tungsten coatings on ferritic/martensitic steel F82H made by vacuum plasma spray technique (VPS) and air plasma spray technique (APS) were examined in this study to evaluate the possibility as plasma-facing armor. The VPS-W/F82H showed superior properties. The porosity of the VPS-W coatings was about 0.6% and most of the pores were smaller than 1-2 μm and joining of W/F82H and W/W was fairly good. Thermal load tests indicated high potential of this coating as plasma-facing armor under thermal loading. In case of APS-W/F82H, however, porosity was 6% and thermal load properties were much worse than VPS-W/F82H. It is likely that surface oxidation during plasma spray process reduced joining properties. Remarkably, both coatings created soft ferrite interlayer after proper heat treatments probably due to high residual stress at the interfaces after the production. This indicates the potential function of the interlayer as stress relieve and possible high performance of such coating component under thermal loads.

  3. Precipitation behavior and martensite lath coarsening during tempering of T/P92 ferritic heat-resistant steel

    Science.gov (United States)

    Xu, Lin-qing; Zhang, Dan-tian; Liu, Yong-chang; Ning, Bao-qun; Qiao, Zhi-xia; Yan, Ze-sheng; Li, Hui-jun

    2014-05-01

    Tempering is an important process for T/P92 ferritic heat-resistant steel from the viewpoint of microstructure control, as it facilitates the formation of final tempered martensite under serving conditions. In this study, we have gained deeper insights on the mechanism underlying the microstructural evolution during tempering treatment, including the precipitation of carbides and the coarsening of martensite laths, as systematically analyzed by optical microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy. The chemical composition of the precipitates was analyzed using energy dispersive X-ray spectroscopy. Results indicate the formation of M3C (cementite) precipitates under normalized conditions. However, they tend to dissolve within a short time of tempering, owing to their low thermal stability. This phenomenon was substantiated by X-ray diffraction analysis. Besides, we could observe the precipitation of fine carbonitrides (MX) along the dislocations. The mechanism of carbon diffusion controlled growth of M23C6 can be expressed by the Zener's equation. The movement of Y-junctions was determined to be the fundamental mechanism underlying the martensite lath coarsening process. Vickers hardness was estimated to determine their mechanical properties. Based on the comprehensive analysis of both the micro-structural evolution and hardness variation, the process of tempering can be separated into three steps.

  4. Data demonstrating the effects of build orientation and heat treatment on fatigue behavior of selective laser melted 17–4 PH stainless steel

    OpenAIRE

    Yadollahi, Aref; Simsiriwong, Jutima; Thompson, Scott M.; Shamsaei, Nima

    2016-01-01

    Axial fully-reversed strain-controlled ( R = ? 1 ) fatigue experiments were performed to obtain data demonstrating the effects of building orientation (i.e. vertical versus horizontal) and heat treatment on the fatigue behavior of 17?4 PH stainless steel (SS) fabricated via Selective Laser Melting (SLM) (Yadollahi et al., submitted for publication [1]). This data article provides detailed experimental data including cyclic stress-strain responses, variations of peak stresses during cyclic def...

  5. Inhibitory effects of UV treatment and a combination of UV and dry heat against pathogens on stainless steel and polypropylene surfaces.

    Science.gov (United States)

    Bae, Young-Min; Lee, Sun-Young

    2012-01-01

    Pathogens that contaminate the surfaces of food utensils may contribute to the occurrence of foodborne disease outbreaks. We investigated the efficacy of UV treatment combined with dry heat (50 °C) for inhibiting 5 foodborne pathogens (Escherichia coli O157:H7, Salmonella Typhimurium, Pseudomonas aeruginosa, Listeria monocytogenes, and Staphylococcus aureus) on stainless steel and polypropylene surfaces in this study. We inoculated substrates with each of the 5 foodborne pathogens cultured on agar surface and then UV treatment alone or a combination of both UV and dry heat (50 °C) was applied for 30 min, 1 h, 2 h, and 3 h. The initial populations of the 5 pathogens before treatment were 8.02 to 9.18 and 8.73 to 9.16 log₁₀ CFU/coupon on the surfaces of stainless steel and polypropylene coupons, respectively. UV treatments for 3 h significantly inhibited S. Typhimurium, L. monocytogenes, and S. aureus on the stainless steel by 3.06, 2.18, and 2.70 log₁₀ CFU/coupon, and S. aureus on the polypropylene by 3.11 log₁₀ CFU/coupon, respectively. The inhibitory effects of the combined UV and dry heat treatment (50 °C) increased as treatment time increased, yielding significant reductions in all samples treated for 3 h, with the exception of S. aureus on polypropylene. The reduction level of E. coli O157:H7 treated for 3 h on the surface of stainless steel and polypropylene treated was approximately 6.00 log₁₀ CFU/coupon. These results indicate that combined UV and dry heat (50 °C) treatments may be effective for controlling microbial contamination on utensils and cooking equipment surfaces as well as in other related environments. © 2011 Institute of Food Technologists®

  6. Cast Steels for Creep-resistant Parts Used in Heat Treatment Plants

    Directory of Open Access Journals (Sweden)

    A. Drotlew

    2012-12-01

    Full Text Available Creep-resistant parts of heat treatment furnaces are in most cases made from high-alloyed chromium-nickel and nickel-chromium ironalloys, both cast and wrought. This paper presents the types of casting alloys used for this particular purpose, since the majority of furnace components are made by the casting process. Standards were cited which give symbols of alloy grades used in technical specifications by the domestic industry. It has been indicated that castings made currently are based on a wider spectrum of the creep-resistant alloy grades than the number of alloys covered by the standards. Alloy grades recommended by the technical literature for individual parts of the furnace equipment were given. The recommendations reflect both the type of the technological process used and the technical tasks performed by individual parts of the furnace equipment. Comments were also made on the role of individual alloying elements in shaping the performance properties of castings.

  7. Cast Steels for Creep-Resistant Parts Used in Heat Treatment Plants

    Directory of Open Access Journals (Sweden)

    Drotlew A.

    2012-12-01

    Full Text Available Creep-resistant parts of heat treatment furnaces are in most cases made from high-alloyed chromium-nickel and nickel-chromium iron alloys, both cast and wrought. This paper presents the types of casting alloys used for this particular purpose, since the majority of furnace components are made by the casting process. Standards were cited which give symbols of alloy grades used in technical specifications by the domestic industry. It has been indicated that castings made currently are based on a wider spectrum of the creep-resistant alloy grades than the number of alloys covered by the standards. Alloy grades recommended by the technical literature for individual parts of the furnace equipment were given. The recommendations reflect both the type of the technological process used and the technical tasks performed by individual parts of the furnace equipment. Comments were also made on the role of individual alloying elements in shaping the performance properties of castings.

  8. Influence of Austenitizing Heat Treatment on the Properties of the Tempered Type 410-1Mo Stainless Steel

    Science.gov (United States)

    Mabruri, E.; Syahlan, Z. A.; Sahlan; Prifiharni, S.; Anwar, M. S.; Chandra, S. A.; Romijarso, T. B.; Adjiantoro, B.

    2017-05-01

    The modified 410-1Mo stainless steel has been developed with higher tensile strength and elongation compared to the standard 410 stainless steel. This paper reports the influence of austenitizing temperature on the microstructure, hardness, impact resistance and corrosion resistance of the modified 410-1Mo steel. The steel samples were prepared by a process sequence of induction melting, hot forging, annealing, hardening, and tempering. The microstructure of the tempered steels revealed additional phase of delta ferrite at pre-austenitizing temperatures of 950 to 1050 °C and disappeared at a temperature of 1100 °C. The steels which underwent pre-austenitizing at 1100 °C showed the largest sized lath martensite and the largest amount of retained austenite. The tempered steels maintained hardness at austenitizing temperatures of 950 °C to 1000 °C and showed an increasing hardness at austenitizing temperatures from 1000 to 1100 °C. At a range of austenitizing temperatures, it was investigated that the steels exhibited higher impact resistance at 1050 °C. The tempered steels that were pre-austenitized at 950 °C and 1100 °C showed the lowest pitting potential due to the existence of carbides and coarse-high carbon martensite, respectively.

  9. Evolution of phases in P91 steel in various heat treatment conditions and their effect on microstructure stability and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Chandan, E-mail: chandanpy.1989@gmail.com; Giri, Anoj; Mahapatra, M.M.

    2016-05-10

    To achieve high thermal efficiency, modern day thermal power plants operate at higher operating temperature and pressure which necessitates use of steels with high creep rupture strength such as modified 9Cr-1Mo steels. In the present study, the evolution of phases in modified 9Cr-1Mo P91 steel and their effects on microstructural stability and mechanical properties have been studied for specimens that were subjected to different thermal heat treatment conditions. The main focus has been to study the effect of heat treatment temperature ranging from 623 K to 1033 K (350–760 °C) on P91 steel. Further, the effect of furnace cooling, water quenching, tempering at 1273 K (1000 °C) and austenitizing on the mechanical properties and microstructure has been studied. The techniques used for material characterization were scanning electron microscopy (SEM), optical microscopy (OM) and X-ray diffraction. For low tempering temperature, i.e. 623 K (350 °C), M{sub 23}C{sub 6}, M{sub 3}C, M{sub 7}C{sub 3,} and MX precipitates have been observed with high yield strength (YS), tensile strength (UTS), hardness and low toughness. In the high temperature range, 923–1033 K (650–760 °C), fine MX, M{sub 7}C{sub 3}, M{sub 23}C{sub 6}, M{sub 2}X, and M{sub 3}C precipitates have been observed with low YS, UTS, hardness and high toughness. The steel tempered at 1033 K (760 °C) was observed to be having best combination of YS, UTS, hardness, toughness and ductility.

  10. Effect of Continuous Galvanizing Heat Treatments on the Microstructure and Mechanical Properties of High Al-Low Si Transformation Induced Plasticity Steels

    Science.gov (United States)

    Bellhouse, E. M.; McDermid, J. R.

    2010-02-01

    Heat treatments were performed using an isothermal bainitic transformation (IBT) temperature compatible with continuous hot-dip galvanizing on two high Al-low Si transformation induced plasticity (TRIP)-assisted steels. Both steels had 0.2 wt pct C and 1.5 wt pct Mn; one had 1.5 wt pct Al and the other had 1 wt pct Al and 0.5 wt pct Si. Two different intercritical annealing (IA) temperatures were used, resulting in intercritical microstructures of 50 pct ferrite (α)-50 pct austenite (γ) and 65 pct α-35 pct γ. Using the IBT temperature of 465 °C, five IBT times were tested: 4, 30, 60, 90, and 120 seconds. Increasing the IBT time resulted in a decrease in the ultimate tensile strength (UTS) and an increase in the uniform elongation, yield strength, and yield point elongation. The uniform elongation was higher when using the 50 pct α-50 pct γ IA temperature when compared to the 65 pct α-35 pct γ IA temperature. The best combinations of strength and ductility and their corresponding heat treatments were as follows: a tensile strength of 895 MPa and uniform elongation of 0.26 for the 1.5 pct Al TRIP steel at the 50 pct γ IA temperature and 90-second IBT time; a tensile strength of 880 MPa and uniform elongation of 0.27 for the 1.5 pct Al TRIP steel at the 50 pct γ IA temperature and 120-second IBT time; and a tensile strength of 1009 MPa and uniform elongation of 0.22 for the 1 pct Al-0.5 pct Si TRIP steel at the 50 pct γ IA temperature and 120-second IBT time.

  11. Laboratory Studies of Technological Strength of Heat-Resistant Steels 15H1N1F Using the Small Sample Tests with Artificial Cooling

    Directory of Open Access Journals (Sweden)

    V. S. Drizhov

    2015-01-01

    Full Text Available The aim of the work is to develop a technique to research a damage of the welded structures from thermostable steels under reiterated heating.Damage of welded structures under reiterated heating depends on numerous processes, proceeding both in welding and under reiterated heating. This circumstance makes it necessary to analyze the reasons and conditions of emerging damage on the basis of numerous statistical materials. This problem can be solved only if simple and effective research methods are used to conduct tests.The paper uses theoretical and experimental methods of research. Theoretical researches are based on the calculation analysis of proceeding internal welding stresses in the welded structures from thermostable steels. For analysis the calculation method of solving a problem was applied taking into account heterogeneity of phase dilatation in different zones of the welded structure.Experimental researches were conducted on the small welded samples in conditions of isothermal relaxation of stresses. Using the artificial heat sink, when welding is a feature of these researches. These welding conditions allowed us to reproduce thermal cycles of welding on small samples, taking place in welding of the thick-walled welded units. Experimental researches of metal damage nature of the welded structures under reiterated heating were conducted on the welded samples, which were welded both by non-consumable electrode and by consumable one. In analysis the influence of stress concentrator on emerging damage was also taken into account.As a result of research a technique has been offered to study damage of welded structures under reiterated heating on the small samples used for tests.The metallography analysis of the metal damage nature of welded structures at small sample tests confirmed damage identity at tests and in practice during heat treatment of weldments from thermostable steels.The conducted experimental analysis of emerging damage

  12. Thermal creep and stress-affected precipitation of 20% cold-worked 316 stainless steel

    Science.gov (United States)

    Puigh, R. J.; Lovell, A. J.; Garner, F. A.

    1984-05-01

    Measurements of the thermal creep of 20% cold-worked 316 stainless stpel have been performed for temperatures from 593 to 760°C, stress levels as high as 138 MPa and exposure times as long as 15,000 hours. The creep strains exhibit a complex behavior arising from the combined action of true creep and stress-affected precipitation of intermetallic phases. The latter process is suspected to be altered by neutron irradiation.

  13. 46 CFR 54.25-20 - Low temperature operation-ferritic steels with properties enhanced by heat treatment (modifies...

    Science.gov (United States)

    2010-10-01

    ... welding procedures, welders and weld-production testing for the steels of Table 54.25-20(a) must conform..., steel conforming to the specifications of Table 54.25-20(a) may be used in the fabrication of pressure... applicable specification and shall be suitable for the design stress levels adopted. The service temperature...

  14. Transient heat transfer behavior of water spray evaporative cooling on a stainless steel cylinder with structured surface for safety design application in high temperature scenario

    Science.gov (United States)

    Aamir, Muhammad; Liao, Qiang; Hong, Wang; Xun, Zhu; Song, Sihong; Sajid, Muhammad

    2017-02-01

    High heat transfer performance of spray cooling on structured surface might be an additional measure to increase the safety of an installation against any threat caused by rapid increase in the temperature. The purpose of present experimental study is to explore heat transfer performance of structured surface under different spray conditions and surface temperatures. Two cylindrical stainless steel samples were used, one with pyramid pins structured surface and other with smooth surface. Surface heat flux of 3.60, 3.46, 3.93 and 4.91 MW/m2 are estimated for sample initial average temperature of 600, 700, 800 and 900 °C, respectively for an inlet pressure of 1.0 MPa. A maximum cooling rate of 507 °C/s was estimated for an inlet pressure of 0.7 MPa at 900 °C for structured surface while for smooth surface maximum cooling rate of 356 °C/s was attained at 1.0 MPa for 700 °C. Structured surface performed better to exchange heat during spray cooling at initial sample temperature of 900 °C with a relative increase in surface heat flux by factor of 1.9, 1.56, 1.66 and 1.74 relative to smooth surface, for inlet pressure of 0.4, 0.7, 1.0 and 1.3 MPa, respectively. For smooth surface, a decreasing trend in estimated heat flux is observed, when initial sample temperature was increased from 600 to 900 °C. Temperature-based function specification method was utilized to estimate surface heat flux and surface temperature. Limited published work is available about the application of structured surface spray cooling techniques for safety of stainless steel structures at very high temperature scenario such as nuclear safety vessel and liquid natural gas storage tanks.

  15. Effects of heat treatment on the intermetallic compounds and mechanical properties of the stainless steel 321-aluminum 1230 explosive-welding interface

    Science.gov (United States)

    Shiran, Mohammadreza Khanzadeh Gharah; Khalaj, Gholamreza; Pouraliakbar, Hesam; Jandaghi, Mohammadreza; Bakhtiari, Hamid; Shirazi, Masoud

    2017-11-01

    The effects of heat treatment on the microstructure and mechanical properties of intermetallic compounds in the interface of stainless steel 321 explosively bonded to aluminum 1230 were investigated in this study. Experimental investigations were performed by optical microscopy, scanning electron microscopy, and microhardness and shear tensile strength testing. Prior to heat treatment, increasing the stand-off distance between samples from 1 to 2.5 mm caused their interface to become wavy and the thickness of intermetallic layers to increase from 3.5 to 102.3 μm. The microhardness increased from HV 766 in the sample prepared at a stand-off distance of 1 mm to HV 927 in the sample prepared at a stand-off distance of 2.5 mm; in addition, the sample strength increased from 103.2 to 214.5 MPa. Heat treatment at 450°C for 6 h increased the thickness of intermetallic compound layers to 4.4 and 118.5 μm in the samples prepared at stand-off distances of 1 and 2.5 mm, respectively. These results indicated that increasing the duration and temperature of heat treatment decreased the microhardness and strength of the interface of explosively welded stainless steel 321-Al 1230 and increased the thickness of the intermetallic region.

  16. Effect of Heat Treatment on Low Temperature Toughness of Reduced Pressure Electron Beam Weld Metal of Type 316L Stainless Steel

    Science.gov (United States)

    Nakagawa, H.; Fujii, H.; Tamura, M.

    2006-03-01

    Austenitic stainless steels are considered to be the candidate materials for liquid hydrogen vessels and the related equipments, and those welding parts that require high toughness at cryogenic temperature. The authors have found that the weld metal of Type 316L stainless steel processed by reduced pressure electron beam (RPEB) welding has high toughness at cryogenic temperature, which is considered to be due to the single-pass welding process without reheating effect accompanied by multi-pass welding process. In this work, the effect of heat treatment on low temperature toughness of the RPEB weld metal of Type 316L was investigated by Charpy impact test at 77K. The absorbed energy decreased with higher temperature and longer holding time of heat treatment. The remarkable drop in the absorbed energy was found with heat treatment at 1073K for 2 hours, which is as low as that of conventional multi-pass weld metal such as tungsten inert gas welding. The observations of fracture surface and microstructure revealed that the decrease in the absorbed energy with heat treatment resulted from the precipitation of intermetallic compounds near delta-ferrite phase.

  17. Effects of Cryogenic Treatment on the Strength Properties of Heat Resistant Stainless Steel (07X16H6)

    Science.gov (United States)

    Nadig, D. S.; Bhat, M. R.; Pavan, V. K.; Mahishi, Chandan

    2017-09-01

    Cryogenic treatment on metals is a well known technology where the materials are exposed to cryogenic temperature for prolonged time duration. The process involves three stages viz. slow cooling, holding at cryogenic temperature and warming to room temperature. During this process, hard and micro sized carbide particles are released within the steel material. In addition, soft and unconverted austenite of steel changes to strong martensite structure. These combined effects increase the strength and hardness of the cryotreated steel. In this experimental study, the effects of cryogenic treatment, austenitising and tempering on the mechanical properties of stainless steel (07X16H6) have been carried. After determining the strength properties of the original material, the specimens were cryotreated at 98K for 24 hours in a specially developed cryotreatment system. The effects of austenitising prior to cryogenic treatment and tempering post cryotreatment on the mechanical properties of steel samples have been experimentally determined and analysed.

  18. Effect of Reinforcement Using Stainless Steel Mesh, Glass Fibers, and Polyethylene on the Impact Strength of Heat Cure Denture Base Resin - An In Vitro Study.

    Science.gov (United States)

    Murthy, H B Mallikarjuna; Shaik, Sharaz; Sachdeva, Harleen; Khare, Sumit; Haralur, Satheesh B; Roopa, K T

    2015-06-01

    The impact strength of denture base resin is of great concern and many approaches have been made to strengthen acrylic resin dentures. The objective of this study was to compare the impact strength of the denture base resin with and without reinforcement and to evaluate the impact strength of denture base resin when reinforced with stainless steel mesh, glass fiber, and polyethylene fibers in the woven form. The specimens (maxillary denture bases) were fabricated using a standard polyvinylsiloxane mold with conventional heat cured polymethyl methacrylate resin. The specimens were divided into four groups (n = 10). Group I specimens or control group were not reinforced. Group II specimens were reinforced with stainless steel mesh and Group III and Group IV specimens were reinforced with three percent by weight of glass fibers and polyethylene fibers in weave form respectively. All the specimens were immersed in water for 1-week before testing. The impact strength was measured with falling weight impact testing machine. One-way analysis of variance and Tukey's post-hoc test were used for statistical analysis. Highest impact strength values were exhibited by the specimens reinforced with polyethylene fibers followed by glass fibers, stainless steel mesh, and control group. Reinforcement of maxillary complete dentures showed a significant increase in impact strength when compared to unreinforced dentures. Polyethylene fibers exhibit better impact strength followed by glass fibers and stainless steel mesh. By using pre-impregnated glass and polyethylene fibers in woven form (prepregs) the impact strength of the denture bases can be increased effectively.

  19. Effect of chemical compositions and heat treatment on IGSCC resistance for strain hardened low carbon austenitic stainless steels in oxygenated water

    Energy Technology Data Exchange (ETDEWEB)

    Yonezawa, T. [FRRI, Graduate School of Engineering, Tohoku University (Japan); Kanasaki, H.; Fujimoto, K.; Taneike, M. [Takasago R-D Center, Mitsubishi Heavy Industries (Japan); Ooki, S.; Sueishi, Y.; Tezuka, H.; Takamori, K.; Suzuki, S. [Materials Engineering Center, R-D Center, Tokyo Electric Power Company (Japan)

    2011-07-01

    In order to develop the highly resistant alternative materials to intergranular stress corrosion cracking (IGSCC) for the non-sensitized and strain hardened low carbon austenitic stainless steel in oxygenated water, the effects of chemical compositions and heat treatment conditions on the IGSCC resistance and stacking fault energy (SFE) values were studied for 33 laboratory melted steels and commercial type 310S stainless steel. The IGSCC resistance for test materials was compared by the maximum crack length, average crack length and cracked area in fatigue pre-cracked CT specimens after SCC test in oxygenated high temperature water. SFE values for these test materials were measured by the transmission electron microscopy on the width of isolated extended dislocations under g-3g weak beam condition for thin foils taken from the test materials, in this study. From these experiments, the effects of the chromium, molybdenum, nitrogen, silicon and manganese contents on the SCC resistance for non-aged materials were not so pronounced in this study. It is strongly suggested that the SFE value is a key parameter for the IGSCC resistance of the aged or non-aged and strain hardened low carbon austenitic stainless steels. (authors)

  20. Optimal welding technology of high strength steel S690QL

    Directory of Open Access Journals (Sweden)

    Dusan Arsic

    2015-02-01

    Full Text Available In this paper is presented the detailed procedure for defining the optimal technology for welding the structures made of the high strength steel S690QL. That steel belongs into a group of steels with exceptional mechanical properties. The most prominent properties are the high tensile strength and impact toughness, at room and at elevated temperatures, as well. However, this steel has a negative characteristic - proneness to appearance of cold cracks.  That impedes welding and makes as an imperative to study different aspects of this steel's properties as well as those of eventual filler metal. Selection and defining of the optimal welding technology of this high strength steel is done for the purpose of preserving the favorable mechanical properties once the welded joint is realized; properties of the welded metal and the melting zone, as well as in the heat affected zone, which is the most critical zone of the welded joint.

  1. Analytical model for the extent of the heat-affected zone occurring during overlap laser welding of dissimilar materials

    Science.gov (United States)

    Jarwitz, M.; Weber, R.; Graf, T.

    2017-10-01

    An analytical model to predict the extent of the heat-affected zone in laser-welded dissimilar materials with strongly differing thermal properties is presented. The model applies to the joining of two materials, where the heat-affected zone occurs in the joining partner with low thermal responsivity. Heat is supplied to the joining partner with high thermal responsivity and heat conduction is the only mechanism of heat transfer. The model is applied to the laser welding of solid nickel sheets to sheets of nickel foam. With a deviation of less than 1.5%, the extent of the heat-affected zone predicted by the model is in excellent agreement with the ones determined experimentally.

  2. Microstructural evolution of delta ferrite in SAVE12 steel under heat treatment and short-term creep

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shengzhi, E-mail: lishengzhi@sjtu.edu.cn [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Eliniyaz, Zumrat; Zhang, Lanting; Sun, Feng [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Shen, Yinzhong [School of Nuclear Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Shan, Aidang, E-mail: adshan@sjtu.edu.cn [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2012-11-15

    This research focused on the formation and microstructural evolution of delta ferrite phase in SAVE12 steel. The formation of delta ferrite was due to the high content of ferrite forming alloy elements such as Cr, W, and Ta. This was interpreted through either JMatPro-4.1 computer program or Cr{sub eq} calculations. Delta ferrite was found in bamboo-like shape and contained large amount of MX phase. It was surrounded by Laves phases before creep or aging treatment. Annealing treatments were performed under temperatures from 1050 Degree-Sign C to 1100 Degree-Sign C and various time periods to study its dissolution kinetics. The result showed that most of the delta ferrite can be dissolved by annealing in single phase austenitic region. Dissolution process of delta ferrite may largely depend on dissolution kinetic factors, rather than on thermodynamic factors. Precipitation behavior during short-term (1100 h) creep was investigated at temperature of 600 Degree-Sign C under a stress of 180 MPa. The results demonstrated that delta ferrite became preferential nucleation sites for Laves phase at the early stage of creep. Laves phase on the boundary around delta ferrite showed relatively slower growth and coarsening rate than that inside delta ferrite. - Highlights: Black-Right-Pointing-Pointer Delta ferrite is systematically studied under heat treatment and short-term creep. Black-Right-Pointing-Pointer Delta ferrite contains large number of MX phase and is surrounded by Laves phases before creep or aging treatment. Black-Right-Pointing-Pointer Formation of delta ferrite is interpreted by theoretical and empirical methods. Black-Right-Pointing-Pointer Most of the delta ferrite is dissolved by annealing in single phase austenitic region. Black-Right-Pointing-Pointer Delta ferrite becomes preferential nucleation sites for Laves phase at the early stage of creep.

  3. Microstructure and properties degradation of P/T 91, 92 steels weldments in creep conditions

    OpenAIRE

    Falat L.; Homolová V.; Kepič J.; Svoboda M; Výrostková A.

    2012-01-01

    The studies were performed on dissimilar ferritic/austenitic weldments between 9Cr tempered martensitic steels of the grades either P/T 91 or 92 and unstabilised AISI316H austenitic steel. The welded joints were fabricated using the fusion welding by tungsten inert gas (TIG) method with Ni-based filler metal. Microstructural analyses were performed using light and electron microscopy. Microstructural gradient in heat-affected zone (HAZ) of 9Cr steels remained preserved during creep expo...

  4. Microstructural, Mechanical, and Electrochemical Analysis of Duplex and Superduplex Stainless Steels Welded with the Autogenous TIG Process Using Different Heat Input

    Directory of Open Access Journals (Sweden)

    Gláucio Soares da Fonseca

    2017-12-01

    Full Text Available Duplex Stainless Steels (DSS and Superduplex Stainless Steels (SDSS have a strong appeal in the petrochemical industry. These steels have excellent properties, such as corrosion resistance and good toughness besides good weldability. Welding techniques take into account the loss of alloying elements during the process, so this loss is usually compensated by the addition of a filler metal rich in alloying elements. A possible problem would be during the welding of these materials in adverse conditions in service, where the operator could have difficulties in welding with the filler metal. Therefore, in this work, two DSS and one SDSS were welded, by autogenous Tungsten Inert Gas (TIG, i.e., without addition of a filler metal, by three different heat inputs. After welding, microstructural, mechanical, and electrochemical analysis was performed. The microstructures were characterized for each welding condition, with the aid of optical microscopy (OM. Vickers hardness, Charpy-V, and cyclic polarization tests were also performed. After the electrochemical tests, the samples were analyzed by scanning electron microscopy (SEM. The SDSS welded with high heat input kept the balance of the austenite and ferrite, and toughness above the limit value. The hardness values remain constant in the weld regions and SDSS is the most resistant to corrosion.

  5. The presence of heat-stable conformers of ovalbumin affects properties of thermally formed aggregates.

    Science.gov (United States)

    de Groot, Jolan; de Jongh, Harmen H J

    2003-12-01

    The aim of this work was to study the effect of the formation of more heat-stable conformers of chicken egg ovalbumin during incubation at basic pH (9.9) and elevated temperature (55 degrees C) on the protein aggregation properties at neutral pH. Native ovalbumin (N-OVA) is converted on the hours time-scale into more heat-stable forms denoted I- (intermediate) and S-OVA, that have denaturation temperatures 4.8 and 8.4 degrees C, respectively, higher than that of N-OVA. The conversions most likely proceed via I-OVA, but direct conversion of N-OVA into S-OVA with slower kinetics can not be excluded. It is demonstrated that both I- and S-OVA have similar denaturation characteristics to N-OVA, except that higher temperatures are required for denaturation. The presence of even small contributions of I-OVA does, however, reduce the Stokes radius of the aggregates formed upon heat treatment of the material at 90 degrees C about 2-fold. This affects the gel network formation considerably. Since many (commercial) preparations of ovalbumin contain varying contributions of the more heat-stable forms mentioned, proper characterization or standardization of the isolation procedure of the material is essential to control or predict the industrial application of this protein.

  6. The Effect of Heat Treatment on the Properties of Zirconium - Carbon Steel Bimetal Produced By Explosion Welding

    Directory of Open Access Journals (Sweden)

    Prażmowski M.

    2014-10-01

    Full Text Available This paper assesses the effect of various values of detonation velocity on the quality of the bond zone, and thus the properties of bimetal zirconium (Zr 700 - steel (P355NL. The research was carried out for as-bonded welds, i.e. immediately following explosion welding. The results of shearing, peeling and tensile tests as well as macro-scale structural analyses were presented. In order to determine the changes in the value of strain hardening, the microhardness measurements across the interface were carried out. Based on the performed analyses it can be claimed that, depending on the applied technological settings of welding, most cases displayed wavy bond with highly diversified parameters of the wave. The changes observed with the detonation velocity are non-monotonic. High detonation velocities favored the formation of waves with large height and length and strongly affect the increase of the volume of brittle melted zones. Increased volume of the melted regions results in strong decrease of strength properties of the clad. The analysis of strength test results allows claiming that a small volume of melted regions in the bond considerably improves the strength of the bond.

  7. Denaturation and Oxidative Stability of Hemp Seed (Cannabis sativa L.) Protein Isolate as Affected by Heat Treatment.

    Science.gov (United States)

    Raikos, Vassilios; Duthie, Garry; Ranawana, Viren

    2015-09-01

    The present study investigated the impact of heat treatments on the denaturation and oxidative stability of hemp seed protein during simulated gastrointestinal digestion (GID). Heat-denatured hemp protein isolate (HPI) solutions were prepared by heating HPI (2 mg/ml, pH 6.8) to 40, 60, 80 and 100 °C for 10 min. Heat-induced denaturation of the protein isolates was monitored by polyacrylamide gel electrophoresis. Heating HPI at temperatures above 80 °C significantly reduced solubility and led to the formation of large protein aggregates. The isolates were then subjected to in vitro GID and the oxidative stability of the generated peptides was investigated. Heating did not significantly affect the formation of oxidation products during GID. The results suggest that heat treatments should ideally remain below 80 °C if heat stability and solubility of HPI are to be preserved.

  8. Assessment of Negligible Creep, Off-Normal Welding and Heat Treatment of Gr91 Steel for Nuclear Reactor Pressure Vessel Application

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Weiju [ORNL; Terry, Totemeier [Idaho National Laboratory (INL)

    2006-10-01

    Two different topics of Grade 91 steel are investigated for Gen IV nuclear reactor pressure vessel application. On the first topic, negligible creep of Grade 91 is investigated with the motivation to design the reactor pressure vessel in negligible creep regime and eliminate costly surveillance programs during the reactor operation. Available negligible creep criteria and creep strain laws are reviewed, and new data needs are evaluated. It is concluded that modifications of the existing criteria and laws, together with their associated parameters, are needed before they can be reliably applied to Grade 91 for negligible creep prediction and reactor pressure vessel design. On the second topic, effects of off-normal welding and heat treatment on creep behavior of Grade 91 are studied with the motivation to better define the control over the parameters in welding and heat treatment procedures. The study is focused on off-normal austenitizing temperatures and improper cooling after welding but prior to post-weld heat treatment.

  9. Variation of mechanical properties with addition of Al in low activity ferritic/martensitic heat resistant steels

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S. H.; Song, B. J.; Ryu, W. S. [KAERI, Taejon (Korea, Republic of)

    2003-10-01

    The effect of aluminum on mechanical properties in low activation martensitic steel has been studied. Impact test and tensile test were performed at high temperature. Aluminum is in solid solution state after normalizing so the grain size of prior austenite was not changed. AlN was precipitated during tempering treatment. The size of Cr{sub 2}N precipitates were decreased due to the precipitation of AlN in 0.10wt.%N steel. But the precipitation of nitride such as V(C,N) and Cr{sub 2}N was suppressed by the formation of AlN in 0.08wt.%N steel. The addition of aluminum have little effect on the impact properties such as DBTT and upper shelf energy. The increase of tensile strength and yield strength by addition of aluminum appeared in 0.10wt.%N steel, but not in 0.08wt.%N steel. But the tensile and yield strength of aluminum added 0.10wt.%N steel is not higher than that of 0.08wt.%N steel.

  10. High-plasticity heat-resistant 03Kh14G16N6Yu-type steels with heat-and deformation-resistant austenite

    Science.gov (United States)

    Blinov, V. M.; Bannykh, I. O.; Zvereva, T. N.

    2008-08-01

    The structure and mechanical properties of 03Kh14G16N6Yu-type austenitic steels alloyed by molybdenum, tungsten, vanadium, and zirconium are studied after normalization at 1075°C and long-term holding at 500 700°C. The chemical composition of these steels ensures the resistance of their austenite to the martensitic transformation in the temperature range from 1200 to -196°C and during cold plastic deformation at a reduction of up to 60%. The best combination of the mechanical and technological properties is achieved in a 03Kh15G17N6YuVF steel with 0.08% W and 0.12% V. Long-term (up to 1000 h) holdings at 550 750°C do not cause the precipitation of carbide, nitride, and intermetallic phases in this steel. The long-term strength of the 03Kh15G17N6YuVF steel at temperatures up to 650°C is comparable with and its plasticity and impact toughness are higher than those of high-nickel Kh16N9M2 and Kh16N12M2 steels, which are applied in the main parts of electric power installations.

  11. J-R fracture characteristics of ferritic steels for RPVs and RCS piping of nuclear power plants

    Science.gov (United States)

    Yoon, Ji-Hyun; Lee, Bong-Sang; Hong, Jun-Hwa

    2001-10-01

    J-R fracture resistance tests have been performed on 3 heats of SA508-Gr.3 nuclear reactor pressure vessel (RPV) steel as well as 2 heats of SA516-Gr.70 and a heat of SA508-Gr.1a steels for nuclear reactor coolant system (RCS) piping. For the latter two steels, dynamic in addition to static J-R fracture resistances were investigated. From the test results of the SA508-Gr.3 steels, the J-R fracture resistance was superior in the following order: Si-killing steel, modified VCD steel and VCD steel. Microstructural analyses were carried out to correlate J-R fracture resistances with microstructural characteristics. According to the test results for SA508-Gr.1a and SA516-Gr.70 steels, all of the tested steels showed steep drops in fracture resistance at certain temperature and loading rate combinations. One heat of SA516-Gr.70 steel was very sensitive to dynamic strain aging and its fracture resistance was significantly low. It was concluded that microstructural and chemical factors affect the J-R fracture and DSA characteristics of SA516-Gr.70 steels.

  12. Study of the Impact of Heat Treatment Modes on Formation of Microstructure and a Given Set of Mechanical Properties of High-Strength Flat Products with Guaranteed Hardness (400 to 450 HB) from Low-Alloyed Steel

    Science.gov (United States)

    Matrosov, M. Yu; Martynov, P. G.; Goroshko, T. V.; Zvereva, M. I.; Mitrofanov, A. V.; Barabash, K. Yu

    2017-12-01

    The results of the study of influence of heat treatment modes on microstructure, size and shape of grains, mechanical properties of high-strength flat products from low-alloyed C-Mn-Cr-Si-Mo steel microalloyed by boron are presented. Heat treatment modes, which provide a combination of high impact viscosity at negative temperatures and guaranteed hardness, are determined.

  13. Effects of the ageing of microporous heat-insulating materials on temperature control in steel casting ladles; Auswirkungen der Alterung von mikroporoesen Waermedaemmstoffen auf die Temperaturfuehrung von Stahlgiesspfannen

    Energy Technology Data Exchange (ETDEWEB)

    Buhr, A.; Felsch, T.; Hoever, P. [Thyssen Krupp Stahl AG, Dortmund (Germany); Bauer, W. [Duisburg Univ. (Gesamthochschule) (Germany). Fachbereich Huettentechnik und Giessereitechnik; Feja, D. [Muenster Univ. (Germany). Inst. fuer Mineralogie

    1998-12-15

    With steel casting ladles developing from pure transfer vessels into metallurgical reactors, the exact control of the melt temperature in the ladles has become co-decisive for the production of high-grade quality steel. A thermal model used for such temperature control was to undergo verification by comparing the shell temperature calculated and measured for high-alumina- and basic-lined steel casting ladles. The shell temperature calculated in the thermal model for the steel casting ladles during circulation was verified by infrared thermography. While there is a good concurrence for high-alumina-lined steel casting ladles, with maximum variations of 15 K emerging, appreciable variations as great as some 45 K were found for basic-lined ladles. The cause of these variations lies in material changes in the form of shrinkage, carbon deposits and single particle growth of the microporous panels utilised for heat insulation. This results in increased thermal conductivity. The variations are reduced to a maximum of 8 K, also for basic-lined ladles, with corrected material data. Given the progressive ageing of the insulating panels in the permanent safety lining, it appears advisable to set a maximum operating time as a function of the conditions prevailing in the steel plant in each case so as to avoid excessive heat losses. (orig.) [Deutsch] Mit der Entwicklung der Stahlgiesspfanne vom reinen Transportgefaess zum metallurgischen Reaktor wurde die exakte Temperaturfuehrung der Schmelze in der Pfanne mitentscheidend fuer die Erzeugung qualitativ hochwertigen Stahls. Ein zur Temperaturfuehrung eingesetztes waermetechnisches Modell sollte durch Vergleich von berechneter und gemessener Manteltemperatur von aluminareich und basisch zugestellten Stahlgiesspfannen ueberprueft werden. Die im waermetechnischen Modell berechnete Manteltemperatur der Stahlgiesspfannen waehrend des Umlaufs wurde mit Infrarotthermografie ueberprueft. Waehrend bei aluminareich zugestellten

  14. A RSM-based predictive model to characterize heat treating parameters of D2 steel using combined Barkhausen noise and hysteresis loop methods

    Science.gov (United States)

    Kahrobaee, Saeed; Hejazi, Taha-Hossein

    2017-07-01

    Austenitizing and tempering temperatures are the effective characteristics in heat treating process of AISI D2 tool steel. Therefore, controlling them enables the heat treatment process to be designed more accurately which results in more balanced mechanical properties. The aim of this work is to develop a multiresponse predictive model that enables finding these characteristics based on nondestructive tests by a set of parameters of the magnetic Barkhausen noise technique and hysteresis loop method. To produce various microstructural changes, identical specimens from the AISI D2 steel sheet were austenitized in the range 1025-1130 °C, for 30 min, oil-quenched and finally tempered at various temperatures between 200 °C and 650 °C. A set of nondestructive data have been gathered based on general factorial design of experiments and used for training and testing the multiple response surface model. Finally, an optimization model has been proposed to achieve minimal error prediction. Results revealed that applying Barkhausen and hysteresis loop methods, simultaneously, coupling to the multiresponse model, has a potential to be used as a reliable and accurate nondestructive tool for predicting austenitizing and tempering temperatures (which, in turn, led to characterizing the microstructural changes) of the parts with unknown heat treating conditions.

  15. Temperature of Heating and Cooling of Massive, Thin, and Wedge-Shaped Plates from Hard-to-Machine Steels During Their Grinding

    Science.gov (United States)

    Dement‧ev, V. B.; Ivanova, T. N.; Dolginov, A. M.

    2017-01-01

    Grinding of flat parts occurs by solid abrasive particles due to the physicomechanical process of deformation and to the action of a process liquid at high temperatures in a zone small in volume and difficult for observation. The rate of heating and cooling depends on the change in the intensity of the heat flux and in the velocity and time of action of the heat source. A study has been made of the regularities of the influence of each of these parameters on the depth and character of structural transformations during the grinding of flat parts from hard-to-machine steels. A procedure to calculate temperature in grinding massive, thin, and wedge-shaped parts has been developed with account taken of the geometric and thermophysical parameters of the tool and the treated part, and also of cutting regimes. The procedure can be used as a constituent part in developing a system for automatic design of the technological process of grinding of flat surfaces. A relationship between the temperature in the grinding zone and the regimes of treatment has been established which makes it possible to control the quality of the surface layer of massive, thin, and wedge-shaped plates from hard-to-machine steels. The rational boundaries of shift of cutting regimes have been determined.

  16. Improved life of die casting dies of H13 steel by attaining improved mechanical properties and distortion control during heat treatment. Year 1 report, October 1994--September 1995

    Energy Technology Data Exchange (ETDEWEB)

    Wallace, J.F.; Schwam, D. [Case Western Reserve Univ., Cleveland, OH (United States)

    1995-03-01

    Optimum heat treatment of dies (quenching) is critical in ensuring satisfactory service performance: rapid cooling rates increase the thermal fatigue/heat checking resistance of the steel, although very fast cooling rates can also lead to distortion and lower fracture toughness, increasing the danger of catastrophic fracture. Goal of this project is to increase die life by using fast enough quenching rates (> 30 F/min ave cooling rate from 1750 to 550 F, 1/2 in. below working surfaces) to obtain good toughness and fatigue resistance in Premium grade H-13 steel dies. An iterative approach of computer modeling validated by experiment was taken. Cooling curves during gas quenching of H-13 blocks and die shapes were measured under 2, 5, and 7.5 bar N2 and 4 bar Ar. Resulting dimensional changes and residual stresses were determined. To facilitate the computer modeling work, a database of H-13 mechanical and physical properties was compiled. Finite element analysis of the heat treated shapes was conducted. Good fit of modeled vs measured quenched rates was demonstrated for simple die shapes. The models predict well the phase transformation products from the quench. There is good fit between predicted and measured distortion contours; however magnitude of predicted distortion and residual stresses does not match well the measured values. Further fine tuning of the model is required.

  17. Precipitation Kinetics of M23C6 Carbides in the Super304H Austenitic Heat-Resistant Steel

    Science.gov (United States)

    Zhou, Qingwen; Ping, Shaobo; Meng, Xiaobo; Wang, Ruikun; Gao, Yan

    2017-11-01

    The precipitation kinetics of M23C6 carbides in Super304H and TP304H steels were investigated using the selective-etching method, SEM backscattered electron images and Image-Pro-Plus 6.0 software. Precipitation-temperature-time (PTT) diagrams of M23C6 carbides in the as-received Super304H (fine grains), coarsened Super304H (coarse grains) and TP304H (coarse grains) steels all show the typical C-shaped character with nose temperature range from 800 to 850 °C. Compared with the TP304H steel, the same trend is found of the PTT curve of M23C6 carbides for both kinds of Super304H steels, but their start lines move to the right and finish lines to the left. The preferential formation of Nb(C,N) phase at grain boundaries in the Super304H steels inhibited the nucleation of M23C6 carbides in the early stage of precipitation, causing the right shift of the start line of PTT curve. The main reason for the left shift of the finish line of the two Super304H steels was the quicker growing and coarsening rate of M23C6 in the later precipitation stage due to their higher C content than in TP304H. For the difference in PPT curves between the two grain sizes of the Super304H steel, the lower diffusion rate of atoms in the coarse-grained Super304H steel may explain its righter finish line than the fine-grained counterpart, while the reason for its lefter start line is due to the higher solute segregation along coarse-grained boundaries.

  18. Beneficial effect of Re on the long-term creep strength of high Cr ferritic heat resistant steels

    Energy Technology Data Exchange (ETDEWEB)

    Hashizume, Ryokichi; Tamura, Osam [The Kansai Electric Power Company Inc., Amagasaki (Japan); Miki, Kazuhiro; Azuma, Tsukasa [The Japan Steel Works, Ltd., Muroran (Japan). Muroran Research Lab.; Ishiguro, Tohru [The Japan Steel Works, Ltd., Muroran (Japan). Muroran Plant; Murata, Yoshinori; Morinaga, Masahiko [Nagoya Univ. (Japan). Dept. of Materials Science and Engineering

    2010-07-01

    9-12%Cr ferritic steels were designed by using the d-electrons concept for the use of steam turbine rotors operated in the USC power plants at the steam temperature of 620 C to 650 C. The crucial issue for the design is to suppress the deterioration of the long-term creep strength by alloying. First, the Re addition was found to give a beneficial effect on the creep strength of a 10%Cr-4%W steel. Then, the creep tests were performed with the six Re-free and 3.5%W ferritic steels to get an optimum Cr content in the range of 8.5% to 11.5%. As a result, it was found that an excess amount of Cr yielded a detrimental effect on the creep properties, and 9%Cr steel was the best in view of the very long-term creep strength tested in the condition of 650 C, 98 MPa. Subsequently, a series of creep tests was conducted with the steels by fixing at 9%Cr, but by varying the W content from 2% to 4% and the Re content from 0% to 0.5%. From the prolonged creep tests and creep rate tests for more than 30,000-40,000 hours, it was shown that the 9Cr-4W without Re steel had the long creep rupture life for more than 32,000 hours at 650 C 0,98 MPa and the 9Cr-4W-0.5Re steel had the longer one for more than 43,000 hours. It was the longest creep rupture life among all the tested steels. (orig.)

  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...... measurements of the hydrogen uptake by cathodically protected steel exposed in heavy clay and peat type soils....

  20. Characterization and Performance of Laser Alloyed Commercial Tool Steels

    Directory of Open Access Journals (Sweden)

    Miroslaw Sebastian Bonek

    2013-07-01

    Full Text Available The paper presents the effect of alloying with tungsten carbide on properties of the X40CrMoV5-1 steel surface layer, using the high power diode laser (HPDL. Selection of laser operating conditions is discussed, as well as alloying material, and their influence on structure and chemical composition of the steel. Analysis of the process conditions influence on thicknesses of the alloyed layer and heat-affected zone is presented.

  1. Analysis of Heat Affected Zone in Welded Aluminum Alloys Using Inverse and Direct Modeling

    Science.gov (United States)

    Zervaki, A. D.; Haidemenopoulos, G. N.; Lambrakos, S. G.

    2008-06-01

    The concept of constructing parameter spaces for process control and the prediction of properties within the heat affected zone (HAZ) of welds using inverse modeling is examined. These parameter spaces can be, in principle, either independent or a function of weld process conditions. The construction of these parameter spaces consists of two procedures. One procedure entails calculation of a parameterized set of temperature histories using inverse heat transfer analysis of the heat deposition occurring during welding. The other procedure entails correlating these temperature histories with either a specific process control parameter or physical property of the weld that is measurable. Two quantitative case study analyses based on inverse modeling are presented. One analysis examines the calculation of temperature histories as a function of process control parameters. For this case, the specific process control parameter adopted as prototypical is the electron beam focal point. Another analysis compares some general characteristics of inverse and direct modeling with respect to the prediction of properties of the HAZ for deep penetration welding of aluminum alloys. For this case, the specific property adopted as prototypical is hardness. This study provides a foundation for an examination of the feasibility of constructing a parameter space for the prediction of weld properties using weld cross-section measurements that are independent of weld process conditions.

  2. A study on heat-flow analysis of friction stir welding on a rotation affected zone

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Sung Wook; Jang, Beom Seon [Seoul National University, Seoul (Korea, Republic of); Kim, Jae Woong [Daewoo Shipbuilding and Marine Engineering Co., Soeul (Korea, Republic of)

    2014-09-15

    In recent years, as interest in environmental protection and energy conservation rose, technological development for lightweight efficiency of transport equipment, such as aircrafts, railcars, automobiles and vessels, have been briskly proceeding. This has led to an expansion of the application of lightweight alloys such as aluminum and magnesium. For the welding of these lightweight alloys, friction stir welding has been in development by many researchers. Heat-flow analysis of friction stir welding is one such research. The flow and energy equation is solved using the computational fluid dynamic commercial program 'Fluent'. In this study, a rotation affected zone concept is imposed. The rotation affected zone is a constant volume. In this volume, flow is rotated the same as the tool rotation speed and so plastic dissipation occurs. Through this simulation, the temperature distribution results are calculated and the simulation results are compared with the experimental results.

  3. Data demonstrating the effects of build orientation and heat treatment on fatigue behavior of selective laser melted 17–4 PH stainless steel

    Directory of Open Access Journals (Sweden)

    Aref Yadollahi

    2016-06-01

    Full Text Available Axial fully-reversed strain-controlled (R=−1 fatigue experiments were performed to obtain data demonstrating the effects of building orientation (i.e. vertical versus horizontal and heat treatment on the fatigue behavior of 17–4 PH stainless steel (SS fabricated via Selective Laser Melting (SLM (Yadollahi et al., submitted for publication [1]. This data article provides detailed experimental data including cyclic stress-strain responses, variations of peak stresses during cyclic deformation, and fractography of post-mortem specimens for SLM 17–4 PH SS.

  4. Effect of Heat Treatment on the Microstructure and Mechanical Properties of Nitrogen-Alloyed High-Mn Austenitic Hot Work Die Steel

    Directory of Open Access Journals (Sweden)

    Yi Zhang

    2017-03-01

    Full Text Available In view of the requirements for mechanical properties and service life above 650 °C, a high-Mn austenitic hot work die steel, instead of traditional martensitic hot work die steel such as H13, was developed in the present study. The effect of heat treatment on the microstructure and mechanical properties of the newly developed work die steel was studied. The results show that the microstructure of the high-Mn as-cast electroslag remelting (ESR ingot is composed of γ-Fe, V(C,N, and Mo2C. V(C,N is an irregular multilateral strip or slice shape with severe angles. Most eutectic Mo2C carbides are lamellar fish-skeleton-like, except for a few that are rod-shaped. With increasing solid solution time and temperature, the increased hardness caused by solid solution strengthening exceeds the effect of decreased hardness caused by grain size growth, but this trend is reversed later. As a result, the hardness of specimens after various solid solution heat treatments increases first and then decreases. The optimal combination of hardness and austenitic grain size can be obtained by soaking for 2 h at 1170 °C. The maximum Rockwell hardness (HRC is 47.24 HRC, and the corresponding austenite average grain size is 58.4 μm. When the solid solution time is 3 h at 1230 °C, bimodality presented in the histogram of the austenite grain size as a result of further progress in secondary recrystallization. Compared with the single-stage aging, the maximum impact energy of the specimen after two-stage aging heat treatment was reached at 16.2 J and increased by 29.6%, while the hardness decreased by 1–2 HRC. After two-stage aging heat treatment, the hardness of steel reached the requirements of superior grade H13, and the maximum impact energy was 19.6% higher than that of superior grade H13, as specified in NADCA#207-2003.

  5. OPTIMIZATION OF TEMPERATURE HARDENING FOR IMPROVING THE HEAT RESISTANCE OF TOOL STEEL 4X5MФ1С IN VARIOUS WORKPIECES Part 1. INFLUENCE OF HEATING TEMPERATURE 1040 °С IN THE OIL HARDENING AND HARDERING ON THE HARDNESS AND STRUCTURE OF FORGINGS AND CASTINGS MADE OF STEEL 4X5MФ1C

    Directory of Open Access Journals (Sweden)

    V. N. Fedulov

    2017-01-01

    Full Text Available Influence of the oil quenching temperature with the heating 1040 °С near 1 hour of tool steel 4X5МФ1С forgings and castings on the microstructure and the ability to hardening after high temperature tempering at 500–650 °C for 1, 5 hours. It was shown that increase of hardening level in comparison with the required index has not been achieved.

  6. Assessing Heat-to-Heat Variations Affecting Mechanism Based Modeling of Hydrogen Environment Cracking (HEAC) in High Strength Alloys for Marine Applications: Monel K-500

    Science.gov (United States)

    2016-01-28

    shafts, oil-well tools and instruments, surgical blades and scrapers, springs, valve trim, fasteners, and marine propeller shafts. These Ni-based...34Assessing Heat-to-Heat Variations Affecting Mechanism Based Modeling of Hydrogen Environment Cracking (HEAC) in High Strength Alloys for Marine ...Environment Cracking (HEAC) in High Strength Alloys for Marine Applications: Monel K-500 5a. CONTRACT NUMBER N00014-12-1-0506 5b. GRANT NUMBER N/A 5c

  7. The Effect of the Production Process and Heat Processing Parameters on the Fatigue Strength of High-Grade Medium-Carbon Steel

    Directory of Open Access Journals (Sweden)

    T. Lipiński

    2012-04-01

    Full Text Available The experimental material consisted of semi-finished products of high-grade, medium-carbon constructional steel with: manganese, chromium, nickel, molybdenum and boron. The experimental material consisted of steel products obtained in three metallurgical processes: electric and desulfurized (E, electric and desulfurized with argon-refined (EA and oxygen converter with vacuum degassed of steel (KP. The production process involved two melting technologies: in a 140-ton basic arc furnace with desulphurisation and argon refining variants, and in a 100-ton oxygen converter. Billet samples were collected to analyze: relative volume of impurities, microstructure and fatigue tests. The samples were quenched and austenitized at a temperature of 880oC for 30 minutes. They were then cooled in water and tempered by holding the sections at a temperature of 200, 300, 400, 500 and 600oC for 120 minutes and air-cooled. Fatigue tests were performed with the use of a rotary bending machine at a frequency of 6000 cpm. The results were statistical processed and presented in graphic form. This paper discusses the results of microstructural analyses, the distribution of the relative volume of impurities in different size ranges, the fatigue strength characteristics of different production processes, the average number of sample- damaging cycles and the average values of the fatigue strength coefficient for various heat processing options.

  8. Establishment of Heat Treatment Process for Modified 440A Martensitic Stainless Steel Using Differential Scanning Calorimetry and Thermo-Calc Calculation

    Directory of Open Access Journals (Sweden)

    Huei-Sen Wang

    2015-12-01

    Full Text Available To provide a suitable microstructure and mechanical properties for modified Grade 440A martensitic stainless steel (MSS, which could facilitate the further cold deformation process (e.g., cold rolling, this work used differential scanning calorimetry (DSC and Thermo-Calc software to determine three soaking temperatures for annealing heat treatment processes (HT1, HT2 and HT3. To verify the feasibility of the proposed annealing heat treatment processes, the as-received samples were initially heated to 1050 °C (similar to the on-line working temperature for 30 min and air quenched to form a martensitic structure. The air-quenched samples were then subjected to three developed annealing heat treatment conditions. The microstructure and mechanical properties of the heat-treated samples were then investigated. Test results showed that considering the effects of the microstructure and the hardness, the HT1, the HT2 or the soaking temperatures between the HT1 and HT2 were the most recommended processes to modified Grade 440A MSS. When using the recommended processes, their carbides were fine and more evenly distributed, and the microhardness was as low as 210 Hv, which can be applied to the actual production process.

  9. In processing of a spheroidized medium carbon steel, modelling with regression analysis of cutting forces and surface roughness affected by cutting parameters

    Directory of Open Access Journals (Sweden)

    Hüdayim Başak

    2016-08-01

    Full Text Available In this study, different spheronization heat treatment applied on a mild carbon steel during the machining was created main cutting forces and surface roughness value, were modeled by using multiple linear regression analysis. Main cutting force and surface roughness value which are dependent variable are described respectively rate of 94.6% and 94.2% by independent variables. The ANOVA significance test were used to determine dependent and independent variables correlations. Also, processing parameters variations such as effects on the feed rate, depth of cut and cutting force changes effect on surface roughness and main cutting force general effects were plotted to discuss.

  10. Ground-water heat pumps: an examination of hydrogeologic, environmental, legal, and economic factors affecting their use

    Energy Technology Data Exchange (ETDEWEB)

    Armitage, D M; Bacon, D J; Massey-Norton, J T; Miller, J D

    1980-11-12

    Groundwater is attractive as a potential low-temperature energy source in residential space-conditioning applications. When used in conjuncton with a heat pump, ground water can serve as both a heat source (for heating) and a heat sink (for cooling). Major hydrogeologic aspects that affect system use include groundwater temperature and availability at shallow depths as these factors influence operational efficiency. Ground-water quality is considered as it affects the performance and life-expectancy of the water-side heat exchanger. Environmental impacts related to groundwater heat pump system use are most influenced by water use and disposal methods. In general, recharge to the subsurface (usually via injection wells) is recommended. Legal restrictions on system use are often stricter at the municipal and county levels than at state and Federal levels. Although Federal regulations currently exist, the agencies are not equipped to regulate individual, domestic installations. Computer smulations indicate that under a variety of climatologic conditions, groundwater heat pumps use less energy than conventional heating and cooling equipment. Life-cycle cost comparisons with conventional equipment depend on alternative system choices and well cost options included in the groundwater heat pump system.

  11. Sensitivities Affecting Heat and Urban Heat Island Effect on Local Scale Projected to Neighborhood Scale in Baltimore, Maryland

    Science.gov (United States)

    Sze, C.; Zaitchik, B. F.; Scott, A.

    2015-12-01

    Urban regions are often impacted more by heat than adjacent rural areas, which is a phenomenon known as the urban heat island (UHI) effect. Urban areas are also highly heterogeneous and notoriously difficult to monitor using standard meteorological protocols—the hottest microclimates within a city often occur in locations that lack open, representative installation sites that are an adequate distance from buildings and direct heat sources. To investigate the challenges of monitoring urban heat, this study examines the sensitivity of temperature and humidity sensors currently used in a Baltimore UHI monitoring network to differences in sun exposure, material on which the data collecting instrument is attached, and land cover class of the vicinity. Sensitivity to sun exposure and attachment site can be interpreted as sources of uncertainty for urban heat monitoring, while sensitivity to land cover may reflect a true source of local temperature and humidity variability. In this study, we present results from a test deployment designed to assess the sensitivity of heat measurements to each of these three factors. We then apply these results to interpret measurements taken across the entire Baltimore UHI monitoring network. These results can then be used to improve heat measurements and more accurately represent and quantify the UHI effect on a broader scale, such as in neighborhoods or urban centers.

  12. Material property evaluations of bimetallic welds, stainless steel saw fusion lines, and materials affected by dynamic strain aging

    Energy Technology Data Exchange (ETDEWEB)

    Rudland, D.; Scott, P.; Marschall, C.; Wilkowski, G. [Battelle Memorial Institute, Columbus, OH (United States)

    1997-04-01

    Pipe fracture analyses can often reasonably predict the behavior of flawed piping. However, there are material applications with uncertainties in fracture behavior. This paper summarizes work on three such cases. First, the fracture behavior of bimetallic welds are discussed. The purpose of the study was to determine if current fracture analyses can predict the response of pipe with flaws in bimetallic welds. The weld joined sections of A516 Grade 70 carbon steel to F316 stainless steel. The crack was along the carbon steel base metal to Inconel 182 weld metal fusion line. Material properties from tensile and C(T) specimens were used to predict large pipe response. The major conclusion from the work is that fracture behavior of the weld could be evaluated with reasonable accuracy using properties of the carbon steel pipe and conventional J-estimation analyses. However, results may not be generally true for all bimetallic welds. Second, the toughness of austenitic steel submerged-arc weld (SAW) fusion lines is discussed. During large-scale pipe tests with flaws in the center of the SAW, the crack tended to grow into the fusion line. The fracture toughness of the base metal, the SAW, and the fusion line were determined and compared. The major conclusion reached is that although the fusion line had a higher initiation toughness than the weld metal, the fusion-line J-R curve reached a steady-state value while the SAW J-R curve increased. Last, carbon steel fracture experiments containing circumferential flaws with periods of unstable crack jumps during steady ductile tearing are discussed. These instabilities are believed to be due to dynamic strain aging (DSA). The paper discusses DSA, a screening criteria developed to predict DSA, and the ability of the current J-based methodologies to assess the effect of these crack instabilities. The effect of loading rate on the strength and toughness of several different carbon steel pipes at LWR temperatures is also discussed.

  13. Effects of N/C Ratio on Solidification Behaviors of Novel Nb-Bearing Austenitic Heat-Resistant Cast Steels for Exhaust Components of Gasoline Engines

    Science.gov (United States)

    Zhang, Yinhui; Li, Mei; Godlewski, Larry A.; Zindel, Jacob W.; Feng, Qiang

    2017-03-01

    In order to comply with more stringent environmental and fuel consumption regulations, novel Nb-bearing austenitic heat-resistant cast steels that withstand exhaust temperatures as high as 1,323 K (1,050 °C) is urgently demanded from automotive industries. In the current research, the solidification behavior of these alloys with variations of N/C ratio is investigated. Directional solidification methods were carried out to examine the microstructural development in mushy zones. Computational thermodynamic calculations under partial equilibrium conditions were performed to predict the solidification sequence of different phases. Microstructural characterization of the mushy zones indicates that N/C ratio significantly influenced the stability of γ-austenite and the precipitation temperature of NbC/Nb(C,N), thereby altering the solidification path, as well as the morphology and distribution of NbC/Nb(C,N) and γ-ferrite. The solidification sequence of different phases predicted by thermodynamic software agreed well with the experimental results, except the specific precipitation temperatures. The generated data and fundamental understanding will be helpful for the application of computational thermodynamic methods to predict the as-cast microstructure of Nb-bearing austenitic heat-resistant steels.

  14. The specific heat loss combined with the thermoelastic effect for an experimental analysis of the mean stress influence on axial fatigue of stainless steel plain specimens

    Directory of Open Access Journals (Sweden)

    G. Meneghetti

    2014-10-01

    Full Text Available The energy dissipated to the surroundings as heat in a unit volume of material per cycle, Q, was recently proposed by the authors as fatigue damage index and it was successfully applied to correlate fatigue data obtained by carrying out fully reversed stress- and strain-controlled fatigue tests on AISI 304L stainless steel plain and notched specimens. The use of the Q parameter to analyse the experimental results led to the definition of a scatter band having constant slope from the low- to the high-cycle fatigue regime. In this paper the energy approach is extended to analyse the influence of mean stress on the axial fatigue behaviour of unnotched cold drawn AISI 304L stainless steel bars. In view of this, stress controlled fatigue tests on plain specimens at different load ratios R (R=-1; R=0.1; R=0.5 were carried out. A new energy parameter is defined to account for the mean stress effect, which combines the specific heat loss Q and the relative temperature variation due to the thermoelastic effect corresponding to the achievement of the maximum stress level of the stress cycle. The new two-parameter approach was able to rationalise the mean stress effect observed experimentally. It is worth noting that the results found in the present contribution are meant to be specific for the material and testing condition investigated here.

  15. Stability of Retained Austenite in High-Al, Low-Si TRIP-Assisted Steels Processed via Continuous Galvanizing Heat Treatments

    Science.gov (United States)

    McDermid, J. R.; Zurob, H. S.; Bian, Y.

    2011-12-01

    Two galvanizable high-Al, low-Si transformation-induced plasticity (TRIP)-assisted steels were subjected to isothermal bainitic transformation (IBT) temperatures compatible with the continuous galvanizing (CGL) process and the kinetics of the retained austenite (RA) to martensite transformation during room temperature deformation studied as a function of heat treatment parameters. It was determined that there was a direct relationship between the rate of strain-induced transformation and optimal mechanical properties, with more gradual transformation rates being favored. The RA to martensite transformation kinetics were successfully modeled using two methodologies: (1) the strain-based model of Olsen and Cohen and (2) a simple relationship with the normalized flow stress, ( {{{σ_{{flow}} - σ_{YS} }/{σ_{YS }}}} ) . For the strain-based model, it was determined that the model parameters were a strong function of strain and alloy thermal processing history and a weak function of alloy chemistry. It was verified that the strain-based model in the present work agrees well with those derived by previous workers using TRIP-assisted steels of similar composition. It was further determined that the RA to martensite transformation kinetics for all alloys and heat treatments could be described using a simple model vs the normalized flow stress, indicating that the RA to martensite transformation is stress-induced rather than strain-induced for temperatures above the Ms^{σ }.

  16. Downward Heat Penetration below Seasonal Thermocline and its Impact on Sea Surface Temperature Variation Affected by Net Heat Flux during Summer Season

    Science.gov (United States)

    Hosoda, S.; Nonaka, M.; Tomita, T.; Taguchi, B.; Tomita, H.; Iwasaka, N.

    2016-02-01

    Oceanic heat capacity of the upper layer is a key of the change in the sea surface temperature (SST) affecting air-sea heat exchange and of the temporal scale of SST variability. In the past, studies of SST variability associated with the air-sea heat exchange have mainly focused on the conditions during the winter, because wintertime deep mixed layer (ML) accumulates a huge amount of heat to the atmosphere. On the contrary, ML during the warming season is thinner than it is during the cooling season, being only a few tens of meters deep at mid- and high- latitudes, bounded by a shallow and sharp seasonal thermocline. Since the ML that directly communicates with the atmosphere is thin, the ocean has been considered to play a passive role in air-sea interactions during the warming season. In this study, we clarified that subsurface ocean plays an important role to seasonal changes of SST and heat capacity during the warming season using observational data of Argo and J-OFURO2, which is net heat flux (Qnet) data from satellites. To clarify the role of upper ocean to the Qnet during summer, we introduce a concept of heat penetration depth (HPD), defined as the depth to which Qnet distinctly penetrates below the seasonal thermocline. Then we assume vertical one dimensional process between Qnet and temporal heat content (HC) change integrating temperature from surface to HPD. The vertical one dimensional process can be assumed in almost mid- and high-latitude NP, and we successfully characterize the heat capacity in terms of the HC above the HPD. The downward heat penetration below the shallow seasonal thermocline is widely found throughout the NP. On the basis of a simple estimation that the amount of heat accumulated by summer Qnet in the NP, about two-thirds of Qnet penetrates below the shallow seasonal thermocline. The effect of heat penetration also makes a magnitude of seasonal change in SST to be smaller, at least a half of that the magnitude under the assumption

  17. Micromechanics-based modeling of stress–strain and fracture behavior of heat-treated boron steels for hot stamping process

    Energy Technology Data Exchange (ETDEWEB)

    Srithananan, P.; Kaewtatip, P.; Uthaisangsuk, V., E-mail: vitoon.uth@kmutt.ac.th

    2016-06-14

    In the automotive industry, hot stamped parts with tailored properties have shown advantageous safety performance. Such components are produced by applying different heat treatment conditions after forming for different zones in order to obtain various combinations of hard and soft microstructures. In this work, pure martensitic, pure bainitic, and three martensitic/bainitic phase microstructures were initially generated from the boron steel grade 22MnB5 by a two-step quenching procedure in which different holding times in the bainitic temperature range were varied. Increased phase fraction of bainite due to longer holding time led to decreased yield and tensile strength; however, elongation and resulting energy absorbability became significantly higher. To describe mechanical properties and failure behavior of hot stamped parts containing multiphase microstructures, influences of microstructure characteristics should be considered on the micro-scale. Using modeling, 2-D representative volume elements (RVE) were generated from observed real microstructures and flow curves of the individual single phases were defined, taking into account a dislocation theory based model and local chemical compositions. Then, effective stress–strain curves of the heat-treated boron steels were calculated by using the isostrain and non-isostrain methods and compared with tensile test results. Regarding fracture behavior, damage curves of fully martensitic and bainitic structures were determined by means of tensile tests of different notched samples and a hybrid digital image correlation (DIC)–finite element (FE) approach. 2-D RVE simulations of a martensite/bainite mixture were carried out under various states of stress, in which the obtained damage curves were individually applied for each phase. The predicted damage curve from RVE simulations for two-phase boron steel fairly agreed with experimental fracture strains. Moreover, correspondingly normalized Lode angle could be

  18. Water color affects the stratification, surface temperature, heat content, and mean epilimnetic irradiance of small lakes

    Science.gov (United States)

    Houser, J.N.

    2006-01-01

    The effects of water color on lake stratification, mean epilimnetic irradiance, and lake temperature dynamics were examined in small, north-temperate lakes that differed widely in water color (1.5-19.8 m -1). Among these lakes, colored lakes differed from clear lakes in the following ways: (i) the epilimnia were shallower and colder, and mean epilimnetic irradiance was reduced; (ii) the diel temperature cycles were more pronounced; (iii) whole-lake heat accumulation during stratification was reduced. The depth of the epilimnion ranged from 2.5 m in the clearest lake to 0.75 m in the most colored lake, and 91% of the variation in epilimnetic depth was explained by water color. Summer mean morning epilimnetic temperature was ???2??C cooler in the most colored lake compared with the clearest lake. In clear lakes, the diel temperature range (1.4 ?? 0.7??C) was significantly (p = 0.01) less than that in the most colored lake (2.1 ?? 1.0??C). Change in whole-lake heat content was negatively correlated with water color. Increasing water color decreased light penetration more than thermocline depth, leading to reduced mean epilimnetic irradiance in the colored lakes. Thus, in these small lakes, water color significantly affected temperature, thermocline depth, and light climate. ?? 2006 NRC.

  19. Prediction of laser cutting heat affected zone by extreme learning machine

    Science.gov (United States)

    Anicic, Obrad; Jović, Srđan; Skrijelj, Hivzo; Nedić, Bogdan

    2017-01-01

    Heat affected zone (HAZ) of the laser cutting process may be developed based on combination of different factors. In this investigation the HAZ forecasting, based on the different laser cutting parameters, was analyzed. The main goal was to predict the HAZ according to three inputs. The purpose of this research was to develop and apply the Extreme Learning Machine (ELM) to predict the HAZ. The ELM results were compared with genetic programming (GP) and artificial neural network (ANN). The reliability of the computational models were accessed based on simulation results and by using several statistical indicators. Based upon simulation results, it was demonstrated that ELM can be utilized effectively in applications of HAZ forecasting.

  20. 3D modelling of a multi pass dissimilar tube welding and post weld heat treatment of nickel based alloy and chromium steel

    Energy Technology Data Exchange (ETDEWEB)

    Kumar-Krishnasamy, Ram, E-mail: ram.kumar.krishnasamy@iwm.fraunhofer.d [Fraunhofer Institute for Mechanics of Materials, Woehlerstrasse 11, 79108 Freiburg (Germany); Siegele, Dieter [Fraunhofer Institute for Mechanics of Materials, Woehlerstrasse 11, 79108 Freiburg (Germany)

    2010-11-15

    A dissimilar tube welding is performed between the nickel based Alloy617 and creep resistant steel VM12 using the former as the weld material. SYSWELD welding software is used to model the thermal and mechanical analysis. A readily available thermal history is used to calibrate the heat source input for the thermal analysis to generate the adequate thermal cycle by fitting the welding velocity, heat intensity factor of the GOLDAK heat source and the length of molten zone. The transient temperature field is then incorporated as the input for the mechanical analysis to obtain the residual stresses in which the phase transformation of the materials during welding is taken into account. Subsequently, the weld materials are characterized by using the Norton's creep law to determine the Norton parameters based on relaxation experiments. The residual stresses generated after the multi pass welding by SYSWELD is transferred into ABAQUS as the initial condition for the post weld heat treatment (PWHT) simulation. The simulations show that the residual stresses reduce in magnitude but still present even after PWHT.

  1. Impact of the surface roughness of AISI 316L stainless steel on biofilm adhesion in a seawater-cooled tubular heat exchanger-condenser.

    Science.gov (United States)

    García, Sergio; Trueba, Alfredo; Vega, Luis M; Madariaga, Ernesto

    2016-11-01

    The present study evaluated biofilm growth in AISI 316L stainless steel tubes for seawater-cooled exchanger-condensers that had four different arithmetic mean surface roughness values ranging from 0.14 μm to 1.2 μm. The results of fluid frictional resistance and heat transfer resistance regarding biofilm formation in the roughest surface showed increases of 28.2% and 19.1% respectively, compared with the smoothest surface. The biofilm thickness taken at the end of the experiment showed variations of up to 74% between the smoothest and roughest surfaces. The thermal efficiency of the heat transfer process in the tube with the roughest surface was 17.4% greater than that in the tube with the smoothest surface. The results suggest that the finish of the inner surfaces of the tubes in heat exchanger-condensers is critical for improving energy efficiency and avoiding biofilm adhesion. This may be utilised to reduce biofilm adhesion and growth in the design of heat exchanger-condensers.

  2. Bacterial and osteoblast behavior on titanium, cobalt-chromium alloy and stainless steel treated with alkali and heat: a comparative study for potential orthopedic applications.

    Science.gov (United States)

    Hu, Xuefeng; Neoh, Koon Gee; Zhang, Jieyu; Kang, En-Tang

    2014-03-01

    Anatase-modified titanium (Ti) substrates have been found to possess antibacterial properties in the absence of ultraviolet irradiation, but the mechanism is not known. We hypothesize that this is due to the bactericidal effects of reactive oxygen species (ROS) generated by the surface anatase. Alkali and heat treatment was used to form anatase on Ti surface. The generation of ROS, and the behavior of bacteria and osteoblasts on the anatase-modified Ti were investigated. Cobalt-chrome (Co-Cr) alloys and stainless steel (SS) were similarly treated with alkali and heat, and their surface properties and effects on bacteria and osteoblasts were compared with the results obtained with Ti. The anatase-functionalized Ti substrates demonstrated significant bactericidal effects and promoted apoptosis in osteoblasts, likely a result of ROS generated by the anatase. The alkali and heat-treated Co-Cr and SS substrates also reduced bacterial adhesion but were not bactericidal. This effect is likely due to an increase in hydrophilicity of the surfaces, and no significant ROS were generated by the alkali and heat-treated Co-Cr and SS substrates. The treated Co-Cr and SS substrates did not induce significant apoptosis in osteoblasts, and thus with these properties, they may be promising for orthopedic applications. Copyright © 2013 Elsevier Inc. All rights reserved.

  3. Analysis of reverse heat transfer for conventional and optimized lubri-cooling methods during tangential surface grinding of ABNT 1020 steel

    Directory of Open Access Journals (Sweden)

    Henrique Cotait Razuk

    Full Text Available Abstract A numerical thermal model was developed to evaluate the heat flux which is conducted to a rectangular workpiece of steel plate ABNT 1020, thus making it possible to compute the maximum temperature in the grinding surface, taking into account the rectangular distribution of heat flux, the thermal properties of the grinding wheel conventional Al2O3, the piece to be machined and the lubri-refrigerating fluid. The finite volume method was employed for the discretization of the direct thermal problem from the heat diffusion equation associated with the two-dimensional problem of heat conduction in transient regime. The inverse thermal problem was solved by the Golden Section technique. The thermal flux, when compared to the conventional technique of method of application fluid, was reduced by 84.0% in the practices performed with cutting depth of 30µm, at 74.0% in practices with cutting depth of 45µm and 61.2% in the aggressive practices of 60µm, thus demonstrating the applicability of the optimized method for fluid application.

  4. Mechanical Properties of Steel P92 Welded Joints Obtained By TIG Technology

    Science.gov (United States)

    Mohyla, P.; Havelka, L.; Schmidová, E.; Vontorová, J.

    2017-11-01

    Mechanical properties of P92 steel welded joints obtained using the TIG (141) technology have been studied upon post-welding heat treatment (PWHT). The microhardness, tensile strength, and impact toughness of metal in the weld and heat-affected zone are determined. The PWHT is shown to be obligatory.

  5. How do rain drops affect atmospheric radiative fluxes and heating rates?

    Science.gov (United States)

    Hill, Peter; Chiu, Christine; Chern, Jiun-Dar; Allan, Richard; Hill, Adrian

    2017-04-01

    General circulation model (GCM) radiation schemes are becoming increasingly sophisticated; the treatment of clouds has become more refined while the number of gases and aerosol species that are represented continues to rise. However, all GCMs continue to ignore the radiative effect of precipitating liquid water (rain). The resulting biases are expected to be small, but they have yet to be quantified. This study aims to provide a first estimate of how rain affects the atmospheric radiation budget at a range of temporal and spatial scales. This is a necessary first step towards determining whether GCM radiation schemes should include rain. We define the rain radiative effect here as the difference between radiative fluxes calculated with and without rain. We perform calculations using the SOCRATES (Suite Of Community Radiative Transfer codes based on Edwards-Slingo) radiative tranfser scheme. Input atmospheric profiles are taken from two weeks (one week during boreal winter and the other during boreal summer) of a Goddard multiscale modelling framework (MMF) simulation. Based on these calculations, we shall quantify and explain how rain affects the transfer of radiation through the atmosphere and thus radiative heating rates and fluxes at both the surface and top of atmosphere.

  6. A study of factors affecting the performance of micro square endmills in milling of hardened tool steels

    NARCIS (Netherlands)

    Li, P.; Aristimuno, P.X.; Arrazola, P.J.; Hoogstrate, A.M.; Oosterling, J.A.J.; Langen, H.H.

    2008-01-01

    Proper setting of cutting conditions is critical for the performance of micro endmills in micro milling of hardened tool steels. In this paper, the influence of the cutting parameters on the wear behaviour of micro square endmills is presented. The selected parameters are cutting speed, depth of

  7. THE ESTIMATION OF EFFICIENCY OF THE LADLES HEATING PROCESS

    OpenAIRE

    Wnęk, Mariusz; Rozpondek, Maciej

    2016-01-01

    The paper presents a system of drying and heating the metallurgical ladles. The ladle heating parameters significantly affect the metallurgical processes. The heating process target of the ceramic ladle lining can reduce the steel temperature in the furnace. It resulted in reduction of energy consumption what is an economic benefit. Adopted drying and heating rate of the ladle depends on the ladle refractory lining - an alkaline or an aluminosilicate. The temperature field uniformity of ceram...

  8. Evolution of microstructure of the new heat resistant 9 - 11 % Cr steels as a function of long term creep stressing

    Energy Technology Data Exchange (ETDEWEB)

    Kauffmann, F. [Stuttgart Univ. (Germany). MPA; Kern, T.U. [Siemens AG, Muehlheim (Germany). Energy Sector; Straub, S. [ALSTOM Power Systems GmbH, Mannheim (Germany); Mayer, K.H. [ALSTOM Power Systems GmbH, Nuernberg (Germany)

    2010-07-01

    The development of new creep resistant materials for higher temperatures in the field of energy generation is a key topic with high technological, economical and environmental interest. The strength and usability of typical materials in this area are 9 - 11 % Cr steels additional alloyed with Mo, W, V, Nb, N and B, which are governed by their microstructural features such as precipitations in the sub-micron range, the dislocation density, the subgrain sizes and in unfavorable cases with the formation of boride-particles. The evaluation of these features and the understanding of their correlation with the long-time creep properties is of pivotal interest in the development of improved materials. This paper will focus on two aspects: the correlation of the microstructure after long testing times with the corresponding creep properties and the measurement and possible quantification of borides in these steels. (orig.)

  9. Behavioural responses to thermal conditions affect seasonal mass change in a heat-sensitive northern ungulate.

    Directory of Open Access Journals (Sweden)

    Floris M van Beest

    Full Text Available BACKGROUND: Empirical tests that link temperature-mediated changes in behaviour (activity and resource selection to individual fitness or condition are currently lacking for endotherms yet may be critical to understanding the effect of climate change on population dynamics. Moose (Alces alces are thought to suffer from heat stress in all seasons so provide a good biological model to test whether exposure to non-optimal ambient temperatures influence seasonal changes in body mass. Seasonal mass change is an important fitness correlate of large herbivores and affects reproductive success of female moose. METHODOLOGY/PRINCIPAL FINDINGS: Using GPS-collared adult female moose from two populations in southern Norway we quantified individual differences in seasonal activity budget and resource selection patterns as a function of seasonal temperatures thought to induce heat stress in moose. Individual body mass was recorded in early and late winter, and autumn to calculate seasonal mass changes (n = 52 over winter, n = 47 over summer. We found large individual differences in temperature-dependent resource selection patterns as well as within and between season variability in thermoregulatory strategies. As expected, individuals using an optimal strategy, selecting young successional forest (foraging habitat at low ambient temperatures and mature coniferous forest (thermal shelter during thermally stressful conditions, lost less mass in winter and gained more mass in summer. CONCLUSIONS/SIGNIFICANCE: This study provides evidence that behavioural responses to temperature have important consequences for seasonal mass change in moose living in the south of their distribution in Norway, and may be a contributing factor to recently observed declines in moose demographic performance. Although the mechanisms that underlie the observed temperature mediated habitat-fitness relationship remain to be tested, physiological state and individual variation in

  10. Microbial-Influenced Corrosion of Corten Steel Compared with Carbon Steel and Stainless Steel in Oily Wastewater by Pseudomonas aeruginosa

    Science.gov (United States)

    Mansouri, Hamidreza; Alavi, Seyed Abolhasan; Fotovat, Meysam

    2015-07-01

    The microbial corrosion behavior of three important steels (carbon steel, stainless steel, and Corten steel) was investigated in semi petroleum medium. This work was done in modified nutrient broth (2 g nutrient broth in 1 L oily wastewater) in the presence of Pseudomonas aeruginosa and mixed culture (as a biotic media) and an abiotic medium for 2 weeks. The behavior of corrosion was analyzed by spectrophotometric and electrochemical methods and at the end was confirmed by scanning electron microscopy. The results show that the degree of corrosion of Corten steel in mixed culture, unlike carbon steel and stainless steel, is less than P. aeruginosa inoculated medium because some bacteria affect Corten steel less than other steels. According to the experiments, carbon steel had less resistance than Corten steel and stainless steel. Furthermore, biofilm inhibits separated particles of those steels to spread to the medium; in other words, particles get trapped between biofilm and steel.

  11. Thermally Stable Ni-rich Austenite Formed Utilizing Multistep Intercritical Heat Treatment in a Low-Carbon 10 Wt Pct Ni Martensitic Steel

    Science.gov (United States)

    Jain, Divya; Isheim, Dieter; Zhang, Xian J.; Ghosh, Gautam; Seidman, David N.

    2017-08-01

    Austenite reversion and its thermal stability attained during the transformation is key to enhanced toughness and blast resistance in transformation-induced-plasticity martensitic steels. We demonstrate that the thermal stability of Ni-stabilized austenite and kinetics of the transformation can be controlled by forming Ni-rich regions in proximity of pre-existing (retained) austenite. Atom probe tomography (APT) in conjunction with thermodynamic and kinetic modeling elucidates the role of Ni-rich regions in enhancing growth kinetics of thermally stable austenite, formed utilizing a multistep intercritical ( Quench- Lamellarization- Tempering (QLT)-type) heat treatment for a low-carbon 10 wt pct Ni steel. Direct evidence of austenite formation is provided by dilatometry, and the volume fraction is quantified by synchrotron X-ray diffraction. The results indicate the growth of nm-thick austenite layers during the second intercritical tempering treatment (T-step) at 863 K (590 °C), with austenite retained from first intercritical treatment (L-step) at 923 K (650 °C) acting as a nucleation template. For the first time, the thermal stability of austenite is quantified with respect to its compositional evolution during the multistep intercritical treatment of these steels. Austenite compositions measured by APT are used in combination with the thermodynamic and kinetic approach formulated by Ghosh and Olson to assess thermal stability and predict the martensite-start temperature. This approach is particularly useful as empirical relations cannot be extrapolated for the highly Ni-enriched austenite investigated in the present study.

  12. Microstructures and High-Temperature Mechanical Properties of a Martensitic Heat-Resistant Stainless Steel 403Nb Processed by Thermo-Mechanical Treatment

    Science.gov (United States)

    Chen, Liqing; Zeng, Zhouyu; Zhao, Yang; Zhu, Fuxian; Liu, Xianghua

    2013-11-01

    Thermo-mechanical treatments (TMT) at different rolling deformation temperatures were utilized to process a martensitic heat-resistant stainless steel 403Nb containing 12 wt pct Cr and small additions of Nb and V. Microstructures and mechanical properties at room and elevated temperatures were characterized by scanning electron microscopy, transmission electron microscopy, and hardness, tensile, and creep tests. The results showed that high-temperature mechanical behavior after TMT can be greatly improved and microstructures with refined martensitic lath and finely dispersed nanosized MX carbides could be produced. The particle sizes of M23C6 and MX carbides in 403Nb steel after conventional normalizing and tempering (NT) treatments are about 50 to 160 and 10 to 20 nm, respectively, while those after TMT at 1123 K (850 °C) and subsequent tempering at 923 K (650 °C) for 2 hours reach about 25 to 85 and 5 to 10 nm, respectively. Under the condition of 260 MPa and 873 K (600 °C), the tensile creep rupture life of 403Nb steel after TMT at 1123 K (850 °C) is 455 hours, more than 3 times that after conventional NT processes. The mechanisms for improving mechanical properties at elevated temperature were analyzed in association with the existence of finely dispersed nanosized MX particles within martensitic lath. It is the nanosized MX particles having the higher stability at elevated temperature that assist both dislocation hardening and sub-grain hardening for longer duration by pinning the movement of dislocations and sub-grain boundary migration.

  13. STUDY OF THE INFLUENCE OF THE HEAT INPUT ON MECHANICAL PROPERTIES OF C-Mn STEEL WELD METALS OBTAINED BY SUBMERGED ARC PROCESS

    Directory of Open Access Journals (Sweden)

    Erick de Sousa Marouço

    2013-06-01

    Full Text Available The present work is part of a research program that aims to evaluate the technical feasibility of increasing productivity in the manufacturing of tubular components for offshore oil industry, which are fully welded by automatic submerged arc welding process, with high heat input, but with no impairment on the impact toughness of the weld metal. Multipass welds were produced by the submerged arc welding process, with a combination of F7A4-EM12K (wire/flux, by using a 3.2 mm-diameter wire, preheating at 80°C, with direct current, in flat position, with heat input varying from 3.5 kJ/mm to 12 kJ/mm. After welding, tensile tests and Charpy-V impact tests at –60°C, –40°C, –20°C, 0°C and 20°C were carried out, as well as metallographic examination by both optical (OM and scanning electron microscopy (SEM, of specimens obtained entirely from the weld metal, allowing the discussion over the toughness X microstructure relationship. The weld metals have shown higher toughness levels in relation to the minimum required for use with low-alloy C-Mn steels welding with requirements of impact toughness of 27 J at 0°C for heat input up to 12 kJ/mm allowing an increase in productivity of 58% on the effective manufacturing time.

  14. Factors affecting hydrogen-assisted cracking in a commercial tempered martensitic steel: Mn segregation, MnS, and the stress state around abnormal cracks

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, Daisuke [Graduate School of Kyushu University, Fukuoka 819-0395 (Japan); Koyama, Motomichi [Department of Mechanical Engineering, Faculty of Engineering, Kyushu University, 744 Moto-oka, Nishi-ku Fukuoka 819-0395 (Japan); Noguchi, Hiroshi, E-mail: nogu@mech.kyushu-u.ac.jp [Department of Mechanical Engineering, Faculty of Engineering, Kyushu University, 744 Moto-oka, Nishi-ku Fukuoka 819-0395 (Japan)

    2015-07-29

    The purpose of this paper is to reveal the dominant factors affecting tensile fracture under a hydrogen gas atmosphere. Tensile tests were conducted in hydrogen gas with circumferentially-notched specimens of a commercial tempered martensitic steel. Two specimens were exposed to hydrogen gas for 48 h before tensile testing; the other two specimens were not pre-charged. Longitudinal cracks along the loading direction and a transverse crack perpendicular to the loading direction were observed on a cross section of the non-charged specimen, but there was only one small crack on a cross section of the pre-charged specimen. Electron back scatter diffraction, energy dispersive X-ray spectrometry and finite element method analyses were applied to clarify the relationships among the longitudinal crack, Mn segregation, microstructures of martensitic steel and hydrogen. As a result, it has been demonstrated that Mn segregation and MnS promote hydrogen-assisted cracking in the tempered martensitic steel, causing the longitudinal cracking which is a mechanically non-preferential direction in homogeneous situations. More specifically, we have shown that the role of the Mn segregation is to promote the hydrogen-enhanced decohesion effect (HEDE), which is particularly important for crack propagation in the present case. These considerations indicate that the presence of Mn is crucially important for hydrogen-assisted cracking associated with hydrogen-enhanced localized plasticity (HELP) as well as HEDE.

  15. Experimental investigation of MHD heat transfer in a vertical round tube affected by transverse magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Melnikov, I.A., E-mail: corpuskula@gmail.com; Sviridov, E.V.; Sviridov, V.G.; Razuvanov, N.G.

    2016-11-15

    Highlights: • Local and averaged heat transfer coefficient are measured. • Free convection influence on MHD-flow is investigated. • The region with the free convection effect of MHD-heat transfer is found. • Temperature low-frequency fluctuations of abnormally high amplitude are detected. • Analysis of the MHD-heat transfer experimental data is performed. - Abstract: The article is devoted to the results of experimental investigation of heat transfer for a downward mercury flow in a vertical round tube in the presence of a transverse magnetic with non-uniform heat flux along the tube circumference.

  16. Effect of heat treatments on hardness and precipitation in 2.25Cr-1Mo-NiNb stabilized ferritic steel

    Energy Technology Data Exchange (ETDEWEB)

    Akhter, J.I.; Ahmad, M.; Shaikh, M.A. [Paakistan inst. of Nuclear Science and Technology, Islamabad (pakistan). Nuclear Physics Div.; Ehrlich, K. [Kernforschungszentrum Karlsruhe GmbH (Germany). Inst. fuer Material- und Festkoerperforschung 1 - Teilinstitut Kernbrennstoffe

    1996-05-15

    Investigations have been carried out in order to specify a heat treatment for the Nb stabilised 2.25Cr-1Mo steel and to study the effects of aging at 475{sup o}C, the temperature at which embrittlement occurs in the unstabilised material. Samples were austenised at temperatures over the range 950-1150{sup o}C for 1hr and 10hrs and then air cooled; tempering was carried out in the range 470-800{sup o}C for 1-100hrs and aging at 475{sup o}C for up to 1000hrs. Electron micrographs and summarised results of grain size measurements, Vicker`s hardness, and quantitative analyses of precipitates are presented. No segregation was observed of those trace elements such as P and S which cause embrittlement in the unstabilised material. Segregation might occur, however, with longer aging and a higher temperature, as has been observed by previous authors in 2.25Cr-1Mo-V steel. (UK).

  17. Hybrid friction diffusion bonding of 316L stainless steel tube-to-tube sheet joints for coil-wound heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Haneklaus, Nils; Cionea, Cristian; Reuven, Rony; Frazer, David; Hosemann, Peter; Peterson, Per F. [Dept of Nuclear Engineering, University of California, Berkeley (United States)

    2016-11-15

    Hybrid friction diffusion bonding (HFDB) is a solid-state bonding process first introduced by Helmholtz-Zentrum Geesthacht to join aluminum tube-to-tube sheet joints of Coil-wound heat exchangers (CWHE). This study describes how HFDB was successfully used to manufacture 316L test samples simulating tube-to-tube sheet joints of stainless steel CWHE for molten salt coolants as foreseen in several advanced nuclear- and thermal solar power plants. Engineering parameters of the test sample fabrication are presented and results from subsequent non-destructive vacuum decay leak testing and destructive tensile pull-out testing are discussed. The bonded areas of successfully fabricated samples as characterized by tube rupture during pull-out tensile testing, were further investigated using optical microscopy and scanning electron microscopy including electron backscatter diffraction.

  18. Microstructure of Welded Joints of X5CrNiCuNb16-4 (17-4 PH Martensitic Stainlees Steel After Heat Treatment

    Directory of Open Access Journals (Sweden)

    Ziewiec A.

    2014-10-01

    Full Text Available The paper presents rezults of microstructure (LM, TEM investigation and hardness measurments of welded joints in martensitic precipitation hardened stainless steel containing copper, subjected to heat treatment. For the aging temperature up to 540 °C even for the very long times, the microstructure of the welded joints is similar to this one at lower temerature aging. After aging at 620 °C a distinct change of the microstructure was observed. Non-equilibrium solidification conditions of the weld metal, segregation and the diffusion of copper and the elements stablilizing the austenite cause the occurrence of the reverse transformation of the martensite into austenite as fast as just 1 hour at 620 °C. TEM investigations revealed the differences in dispersion of hardening copper precipitates after aging at temperature 620 °C for 1 and 4 hours.

  19. Structure-mechanical function relations at nano-scale in heat-affected human dental tissue.

    Science.gov (United States)

    Sui, Tan; Sandholzer, Michael A; Le Bourhis, Eric; Baimpas, Nikolaos; Landini, Gabriel; Korsunsky, Alexander M

    2014-04-01

    The knowledge of the mechanical properties of dental materials related to their hierarchical structure is essential for understanding and predicting the effect of microstructural alterations on the performance of dental tissues in the context of forensic and archaeological investigation as well as laser irradiation treatment of caries. So far, few studies have focused on the nano-scale structure-mechanical function relations of human teeth altered by chemical or thermal treatment. The response of dental tissues to thermal treatment is thought to be strongly affected by the mineral crystallite size, their spatial arrangement and preferred orientation. In this study, synchrotron-based small and wide angle X-ray scattering (SAXS/WAXS) techniques were used to investigate the micro-structural alterations (mean crystalline thickness, crystal perfection and degree of alignment) of heat-affected dentine and enamel in human dental teeth. Additionally, nanoindentation mapping was applied to detect the spatial and temperature-dependent nano-mechanical properties variation. The SAXS/WAXS results revealed that the mean crystalline thickness distribution in dentine was more uniform compared with that in enamel. Although in general the mean crystalline thickness increased both in dentine and enamel as the temperature increased, the local structural variations gradually reduced. Meanwhile, the hardness and reduced modulus in enamel decreased as the temperature increased, while for dentine, the tendency reversed at high temperature. The analysis of the correlation between the ultrastructure and mechanical properties coupled with the effect of temperature demonstrates the effect of mean thickness and orientation on the local variation of mechanical property. This structural-mechanical property alteration is likely to be due to changes of HAp crystallites, thus dentine and enamel exhibit different responses at different temperatures. Our results enable an improved understanding of

  20. Development and Study of Hard-Facing Materials on the Base of Heat-Resisting High-Hardness Steels for Plasma-Jet Hard- Facing in Shielding-Doping Nitrogen Atmosphere

    Science.gov (United States)

    Malushin, N. N.; Kovalev, A. P.; Valuev, D. V.; Shats, E. A.; Borovikov, I. F.

    2016-08-01

    The authors develop hard-facing materials on the base of heat-resisting highhardness steels for plasma-jet hard-facing in nitrogen atmosphere for manufacturing parts of mining and metallurgic equipment which significantly simplify the production process and effect a saving when producing bimetallic parts and tools.

  1. Utility of bromide and heat tracers for aquifer characterization affected by highly transient flow conditions

    Science.gov (United States)

    Ma, Rui; Zheng, Chunmiao; Zachara, John M.; Tonkin, Matthew

    2012-08-01

    A tracer test using both bromide and heat tracers conducted at the Integrated Field Research Challenge site in Hanford 300 Area (300A), Washington, provided an instrument for evaluating the utility of bromide and heat tracers for aquifer characterization. The bromide tracer data were critical to improving the calibration of the flow model complicated by the highly dynamic nature of the flow field. However, most bromide concentrations were obtained from fully screened observation wells, lacking depth-specific resolution for vertical characterization. On the other hand, depth-specific temperature data were relatively simple and inexpensive to acquire. However, temperature-driven fluid density effects influenced heat plume movement. Moreover, the temperature data contained "noise" caused by heating during fluid injection and sampling events. Using the hydraulic conductivity distribution obtained from the calibration of the bromide transport model, the temperature depth profiles and arrival times of temperature peaks simulated by the heat transport model were in reasonable agreement with observations. This suggested that heat can be used as a cost-effective proxy for solute tracers for calibration of the hydraulic conductivity distribution, especially in the vertical direction. However, a heat tracer test must be carefully designed and executed to minimize fluid density effects and sources of noise in temperature data. A sensitivity analysis also revealed that heat transport was most sensitive to hydraulic conductivity and porosity, less sensitive to thermal distribution factor, and least sensitive to thermal dispersion and heat conduction. This indicated that the hydraulic conductivity remains the primary calibration parameter for heat transport.

  2. The effect of heat treatment and test parameters on the aqueous stress corrosion cracking of D6AC steel

    Science.gov (United States)

    Gilbreath, W. P.; Adamson, M. J.

    1974-01-01

    The crack growth behavior of D6AC steel as a function of stress intensity, stress and corrosion history and test technique, under sustained load in natural seawater, 3.3 percent NaCl solution, distilled water, and high humidity air was investigated. Reported investigations of D6AC were considered with emphasis on thermal treatment, specimen configuration, fracture toughness, crack-growth rates, initiation period, threshold, and the extension of corrosion fatigue data to sustained load conditions. Stress history effects were found to be most important in that they controlled incubation period, initial crack growth rates, and apparent threshold.

  3. Fatigue-Crack Growth in D6AC Steel Heat-Treated to Different Values of Fracture Toughness,

    Science.gov (United States)

    1979-04-01

    with a cyclic Kmx of - 15 MPa.m * applied for 5 to 10 x 104 cycles. 2.4.2 Test Atmospere A constant environment was preserved by maintaining a flow of...Director 59 C.S. I. R.O. Materials Science Division. Director 60 Qantas , Library 61 Trans Australia Airlines. Library 62 Gas and Fuel Corporation of...204 Calspan Corporation, Professor H. Johnson 205 Rockwell International , Dr H. L. Marcus 206 U.S. Steel Applied Research Labs, J. M. Barsom 207 U.S

  4. A Study on Structural, Corrosion, and Sensitization Behavior of Ultrafine and Coarse Grain 316 Stainless Steel Processed by Multiaxial Forging and Heat Treatment

    Science.gov (United States)

    Kiahosseini, Seyed Rahim; Mohammadi Baygi, Seyyed Javad; Khalaj, Gholamreza; Khoshakhlagh, Ali; Samadipour, Razieh

    2018-01-01

    Cubic specimens from AISI 316 stainless steel were multiaxially forged to 15 passes and annealed at 1200 °C for 1, 2, and 3 h and finally sensitized at 700 °C for 24 h. Examination of samples indicated that the hardness of the annealed samples was reduced from 153 to 110, 81, and 74 HV for as-received sample and under 1, 2, and 3 h of annealing, and increased from 245 to 288 HV for samples forged at 3 and 7 passes. However, no significant changes were observed in a large number of passes and at about 300 HV. Degree of sensitization of samples was increased to approximately 27.3% at 3-h annealing but reduced to 1.23% by 15 passes of MF. The potentiodynamic polarization test shows that the breakdown potentials decreased with annealing time from 0.6 to - 102 (mV/SCE) for as-received and 3-h annealed specimen. These potentials increased to approximately - 16.5 mV with the increase in MF passes to 15. These observations indicated that the chromium carbide deposition affects Cr-depleted zone, which can subsequently affect the degree of sensitization and pitting corrosion resistance of AISI 316 austenitic stainless steel.

  5. Surface composition effect of nitriding Ni-free stainless steel as bipolar plate of polymer electrolyte fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Yang; Shironita, Sayoko [Nagaoka University of Technology, 1603-1, Kamitomioka, Nagaoka, Niigata 940-2188 (Japan); Nakatsuyama, Kunio [Nakatsuyama Heat Treatment Co., Ltd., 1-1089-10, Nanyou, Nagaoka, Niigata 940-1164 (Japan); Souma, Kenichi [Nagaoka University of Technology, 1603-1, Kamitomioka, Nagaoka, Niigata 940-2188 (Japan); Hitachi Industrial Equipment Systems Co., Ltd., 3 Kanda Neribei, Chiyoda, Tokyo 101-0022 (Japan); Umeda, Minoru, E-mail: mumeda@vos.nagaokaut.ac.jp [Nagaoka University of Technology, 1603-1, Kamitomioka, Nagaoka, Niigata 940-2188 (Japan)

    2016-12-01

    Graphical abstract: The anodic current densities in the passive region of nitrided SUS445-N stainless steel are lower than those of a non heat-treated SUS445 stainless steel and heat-treated SUS445-Ar stainless steel under an Ar atmosphere. It shows a better corrosion resistance for the SUS445 stainless steel after the nitriding heat treatment. - Highlights: • The nitriding heat treatment was carried out using Ni-free SUS445 stainless steel. • The corrosion resistance of the nitrided SUS445-N stainless steel was improved. • The structure of the nitrided SUS445-N stainless steel changed from α-Fe to γ-Fe. • The surface elemental components present in the steels affect the corrosion resistance. - Abstract: In order to increase the corrosion resistance of low cost Ni-free SUS445 stainless steel as the bipolar plate of a polymer electrolyte fuel cell, a nitriding surface treatment experiment was carried out in a nitrogen atmosphere under vacuum conditions, while an Ar atmosphere was used for comparison. The electrochemical performance, microstructure, surface chemical composition and morphology of the sample before and after the electrochemical measurements were investigated using linear sweep voltammetry (LSV), X-ray diffraction (XRD), glow discharge optical emission spectroscopy (GDS) and laser scanning microscopy (LSM) measurements. The results confirmed that the nitriding heat treatment not only increased the corrosion resistance, but also improved the surface conductivity of the Ni-free SUS445 stainless steel. In contrast, the corrosion resistance of the SUS445 stainless steel decreased after heat treatment in an Ar atmosphere. These results could be explained by the different surface compositions between these samples.

  6. Heat exchange modeling in a multilayered karst aquifer affected by seawater intrusion

    OpenAIRE

    Luca Vettorello; Roberto Pedron; Andrea Sottani; Michele Chieco

    2015-01-01

    A Feflow thermohaline model has been implemented in order to study borehole heat exchangers (BHEs) activity in a coastal aquifer in the South of Italy (Province of Lecce, Puglia Region). The modeled closed-loop system consists of two double u-pipe heat exchangers, installed in 200 meters deep boreholes. The main purpose of numerical modeling was to forecast thermal plume extension in groundwater after a long period of heat exchange, calculating temperature trends in observation points during ...

  7. Progress in thermomechanical control of steel plates and their commercialization

    Directory of Open Access Journals (Sweden)

    Kiyoshi Nishioka and Kazutoshi Ichikawa

    2012-01-01

    Full Text Available The water-cooled thermomechanical control process (TMCP is a technology for improving the strength and toughness of water-cooled steel plates, while allowing control of the microstructure, phase transformation and rolling. This review describes metallurgical aspects of the microalloying of steel, such as niobium addition, and discusses advantages of TMCP, for example, in terms of weldability, which is reduced upon alloying. Other covered topics include the development of equipment, distortions in steel plates, peripheral technologies such as steel making and casting, and theoretical modeling, as well as the history of property control in steel plate production and some early TMCP technologies. We provide some of the latest examples of applications of TMCP steel in various industries such as shipbuilding, offshore structures, building construction, bridges, pipelines, penstocks and cryogenic tanks. This review also introduces high heat-affected-zone toughness technologies, wherein the microstructure of steel is improved by the addition of fine particles of magnesium-containing sulfides and magnesium- or calcium-containing oxides. We demonstrate that thanks to ongoing developments TMCP has the potential to meet the ever-increasing demands of steel plates.

  8. Progress in thermomechanical control of steel plates and their commercialization

    Science.gov (United States)

    Nishioka, Kiyoshi; Ichikawa, Kazutoshi

    2012-04-01

    The water-cooled thermomechanical control process (TMCP) is a technology for improving the strength and toughness of water-cooled steel plates, while allowing control of the microstructure, phase transformation and rolling. This review describes metallurgical aspects of the microalloying of steel, such as niobium addition, and discusses advantages of TMCP, for example, in terms of weldability, which is reduced upon alloying. Other covered topics include the development of equipment, distortions in steel plates, peripheral technologies such as steel making and casting, and theoretical modeling, as well as the history of property control in steel plate production and some early TMCP technologies. We provide some of the latest examples of applications of TMCP steel in various industries such as shipbuilding, offshore structures, building construction, bridges, pipelines, penstocks and cryogenic tanks. This review also introduces high heat-affected-zone toughness technologies, wherein the microstructure of steel is improved by the addition of fine particles of magnesium-containing sulfides and magnesium- or calcium-containing oxides. We demonstrate that thanks to ongoing developments TMCP has the potential to meet the ever-increasing demands of steel plates.

  9. Heat

    CERN Document Server

    Lawrence, Ellen

    2016-01-01

    Is it possible to make heat by rubbing your hands together? Why does an ice cube melt when you hold it? In this title, students will conduct experiments to help them understand what heat is. Kids will also investigate concepts such as which materials are good at conducting heat and which are the best insulators. Using everyday items that can easily be found around the house, students will transform into scientists as they carry out step-by-step experiments to answer interesting questions. Along the way, children will pick up important scientific skills. Heat includes seven experiments with detailed, age-appropriate instructions, surprising facts and background information, a "conclusions" section to pull all the concepts in the book together, and a glossary of science words. Colorful, dynamic designs and images truly put the FUN into FUN-damental Experiments.

  10. Ruminal biohydrogenation kinetics of defatted flaxseed and sunflower is affected by heat treatment

    DEFF Research Database (Denmark)

    Lashkari, Saman; Hymøller, Lone; Jensen, Søren Krogh

    2017-01-01

    and partly defatted flaxseed (DF) and partly defatted sunflower (DS) as test feeds. Feeds were heated in a laboratory oven at 110 °C for 0 (unheated), 45, or 90 min. Michaelis–Menten kinetics was applied for quantifying biohydrogenation rate. The DF heated for 90 min showed the lowest biohydrogenation rate...

  11. Pre-natal heat load affects bacterial levels and innate immunity in neonatal calves

    Science.gov (United States)

    Heat stress suppresses immunity, making animals more susceptible to bacterial infections. Additionally, field observations suggest that calves have greater morbidity and mortality when they are born after a heat event. However, scientific evidence is still lacking, limiting the development of target...

  12. Ruminal Biohydrogenation Kinetics of Defatted Flaxseed and Sunflower Is Affected by Heat Treatment.

    Science.gov (United States)

    Lashkari, Saman; Hymøller, Lone; Jensen, Søren Krogh

    2017-10-11

    The effect of heat treatment on biohydrogenation of linoleic acid (LA) and linolenic acid (LNA) and formation of stearic acid (SA), cis-9, trans-11 conjugated LA (CLA), trans-10, cis-12 CLA and trans-vaccenic acid (VA) was studied in in vitro incubations with diluted rumen fluid as inoculum and partly defatted flaxseed (DF) and partly defatted sunflower (DS) as test feeds. Feeds were heated in a laboratory oven at 110 °C for 0 (unheated), 45, or 90 min. Michaelis-Menten kinetics was applied for quantifying biohydrogenation rate. The DF heated for 90 min showed the lowest biohydrogenation rate of LNA and LA, indicated by the lowest Vmax value (P < 0.04 and P < 0.03, respectively). The DS heated for 45 min had the lowest biohydrogenation rate of LNA, indicated by the lowest Vmax value (P < 0.04). In conclusion, heat treatment decreased biohydrogenation of LA and LNA in DF and LNA in DS.

  13. Effect of post-weld heat treatments on strength and toughness behavior of T-250 maraging steel welded by laser beam

    Energy Technology Data Exchange (ETDEWEB)

    Li, Kun [Laser Processing Research Center, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Shan, Jiguo, E-mail: shanjg@mail.tsinghua.edu.cn [Laser Processing Research Center, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Key Laboratory for Advanced Materials Professing Technology, Ministry of Education, Tsinghua University, Beijing 100084 (China); Wang, Chunxu; Tian, Zhiling [Institute for Special Steel, Central Iron & Steel Research Institute, Beijing 100081 (China)

    2016-04-29

    This paper elucidates here the strength and toughness behavior of T-250 maraging steel welded by laser beam under different approaches of three post-weld heat treatments, i.e. aging (A), solutionizing+aging (SA) and homogenizing+solutionizing+aging (HSA). The microstructures of the weld metals with A and SA processes both comprised of finely dispersive Ni{sub 3}(Ti, Mo) precipitates, small martensite lath and reverted austenite along the grain boundary. However, in the weld metal with HSA process, it exhibited the same Ni{sub 3}(Ti, Mo) precipitate with the large martensite lath and the absence of reverted austenite. The ultimate tensile strength and static toughness of the welded joint with HSA process were 1350.6 MPa and 63.8 MJ m{sup −3}, respectively. The static toughness has been remarkably improved from 71% to 91% of the applied parent metal compared with that of the welded joint with A process. The present study underscores that the Ni{sub 3}(Ti, Mo) precipitate and martensite are significant to ensure the high strength of welded joints. Due to its inconsistent deformation with the matrix of martensite, the reverted austenite has a notable influence on the toughness of welded joints. It shows that the post-weld heat treatments of HSA process can influence the mechanical behavior of welded joints by eliminating the reverted austenite.

  14. Effect of Q&P heat treatment on fine microstructure and mechanical properties of a low-alloy medium-carbon steel

    Science.gov (United States)

    Jafari, Rahim; Kheirandish, Shahram; Mirdamadi, Shamsoddin

    2018-01-01

    The current research investigates the effect of ultrafine microstructure resulted from Quench and Partitioning (Q&P) process on obtaining ultra-high strengths in a low-alloy steel with 4wt.% carbon. The purpose of Q&P heat treatment is to enrich the austenite with carbon by partitioning of carbon from supersaturated martensite to austenite, in order to stabilize it to the room temperature. The microstructure, consequently, is consists of martensite, retained austenite and in some conditions bainite. Two-step Q&P heat treatment with quench and partitioning temperatures equal to 120°C and 300°C respectively were applied to the samples at different times. Mechanical behavior was studied by tensile test. The microstructure of the samples was observed using SEM, and TEM and to quantify the amount of retained austenite X-ray diffraction was used. The retained austenite grain size was estimated to be about 0.5 µm and the highest amount of retained austenite obtained was 10 vol%. All samples showed a yield strength and a tensile strength of above 900MPa and 1500MP respectively. The yield strength increased with increase in partitioning time, whereas tensile strength showed an inverse behavior. The elongation in samples varied from 5% to 9% which seemed to not have a direct connection with the amount of retained austenite, but instead it was related to the ferritic structures formed during partitioning such as coalesced martensite, bainite and tempered martensite.

  15. Full-scale experimental and numerical study about structural behaviour of a thin-walled cold-formed steel building affected by ground settlements due to land subsidence

    Directory of Open Access Journals (Sweden)

    J. A. Ortiz

    2015-11-01

    Full Text Available Land subsidence due to ground water withdrawal is a problem in many places around the world (Poland, 1984. This causes differential ground settlements that affect masonry structures, because these structural materials do not exhibit an adequate performance beyond a certain level of angular distortion. This work presents the experimental and numerical results about a study regarding the performance of a full-scale thin-walled cold-formed steel building affected by ground differential settlements due to land subsidence. The experimental stage consisted in the construction of a test-building to be subjected to differential settlements in laboratory. The numerical stage consisted in performing a numerical non-linear static pull-down analysis simulating the differential ground settlements of the test-building. The results show that the structural performance of the tested building was very suitable in terms of ductility.

  16. Effect of Welding Consumables on Fatigue Performance of Shielded Metal Arc Welded High Strength, Q&T Steel Joints

    Science.gov (United States)

    Magudeeswaran, G.; Balasubramanian, V.; Madhusudhan Reddy, G.

    2009-02-01

    Quenched and Tempered (Q&T) steels are widely used in the construction of military vehicles due to their high strength-to-weight ratio and high hardness. These steels are prone to hydrogen-induced cracking in the heat affected zone (HAZ) after welding. The use of austenitic stainless steel consumables to weld the above steel was the only remedy because of higher solubility for hydrogen in austenitic phase. Recent studies proved that high nickel steel and low hydrogen ferritic steel consumables can be used to weld Q&T steels, which can give very low hydrogen levels in the weld deposits. In this investigation an attempt has been made to study the effect of welding consumables on high cycle fatigue properties of high strength, Q&T steel joints. Three different consumables namely (i) austenitic stainless steel, (ii) low hydrogen ferritic steel, and (iii) high nickel steel have been used to fabricate the joints by shielded metal arc (SMAW) welding process. The joints fabricated using low hydrogen ferritic steel electrodes showed superior fatigue properties than other joints.

  17. Influence of the chemical composition, heat and surface treatment in the biofouling of austenitic stainless steels; Influencia de la composicion quimica, del tratamiento termico y del acabado supreficial en el bioensuciamiento de aceros inoxidables austeniticos

    Energy Technology Data Exchange (ETDEWEB)

    Sarro, M. I.; Aleman, O.; Moreno, D. A.; Roso, M.; Ranninger, C.

    2004-07-01

    The main objective of this study was to analyse the biofouling processes in the kinds of stainless steels used normally in industry (UNS S30400, UNS S30403 and UNS S31600), with different surface treatments after grinding and polishing. The study was developed using two microscopy techniques. Scanning Electron Microscopy (SEM) was used to evaluate the microorganisms distribution in the materials, and Epi fluorescence Microscopy was used to evaluate the viability of cells in the biofilm. The results revealed the influence of the material, heat treatment, surface treatment and roughness in the biofouling processes in the stainless steel assays. (Author) 33 refs.

  18. Braze alloy spreading on steel

    Science.gov (United States)

    Siewert, T. A.; Heine, R. W.; Lagally, M. G.

    1978-01-01

    Scanning electron microscopy (SEM) and Auger electron microscopy (AEM) were employed to observe elemental surface decomposition resulting from the brazing of a copper-treated steel. Two types of steel were used for the study, stainless steel (treated with a eutectic silver-copper alloy), and low-carbon steel (treated with pure copper). Attention is given to oxygen partial pressure during the processes; a low enough pressure (8 x 10 to the -5th torr) was found to totally inhibit the spreading of the filler material at a fixed heating cycle. With both types of steel, copper treatment enhanced even spreading at a decreased temperature.

  19. Textural and rheological properties of Pacific whiting surimi as affected by nano-scaled fish bone and heating rates.

    Science.gov (United States)

    Yin, Tao; Park, Jae W

    2015-08-01

    Textural and rheological properties of Pacific whiting (PW) surimi were investigated at various heating rates with the use of nano-scaled fish bone (NFB) and calcium chloride. Addition of NFB and slow heating improved gel strength significantly. Activity of endogenous transglutaminase (ETGase) from PW surimi was markedly induced by both NFB calcium and calcium chloride, showing an optimal temperature at 30°C. Initial storage modulus increased as NFB calcium concentration increased and the same trend was maintained throughout the temperature sweep. Rheograms with temperature sweep at slow heating rate (1°C/min) exhibited two peaks at ∼ 35°C and ∼ 70°C. However, no peak was observed during temperature sweep from 20 to 90°C at fast heating rate (20°C/min). Protein patterns of surimi gels were affected by both heating rate and NFB calcium concentration. Under slow heating, myosin heavy chain intensity decreased with NFB calcium concentration, indicating formation of ε-(γ-glutamyl) lysine cross-links by ETGase and NFB calcium ion. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. BAG3 affects the nucleocytoplasmic shuttling of HSF1 upon heat stress

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Young-Hee [Department of Biochemistry, Dongguk University College of Oriental Medicine, Gyeongju 780-714 (Korea, Republic of); Ahn, Sang-Gun [Department of Pathology, Chosun University College of Dentistry, Gwangju 501-759 (Korea, Republic of); Kim, Soo-A., E-mail: ksooa@dongguk.ac.kr [Department of Biochemistry, Dongguk University College of Oriental Medicine, Gyeongju 780-714 (Korea, Republic of)

    2015-08-21

    Bcl2-associated athoanogene (BAG) 3 is a member of the co-chaperone BAG family. It is induced by stressful stimuli such as heat shock and heavy metals, and it regulates cellular adaptive responses against stressful conditions. In this study, we identified a novel role for BAG3 in regulating the nuclear shuttling of HSF1 during heat stress. The expression level of BAG3 was induced by heat stress in HeLa cells. Interestingly, BAG3 rapidly translocalized to the nucleus upon heat stress. Immunoprecipitation assay showed that BAG3 interacts with HSF1 under normal and stressed conditions and co-translocalizes to the nucleus upon heat stress. We also demonstrated that BAG3 interacts with HSF1 via its BAG domain. Over-expression of BAG3 down-regulates the level of nuclear HSF1 by exporting it to the cytoplasm during the recovery period. Depletion of BAG3 using siRNA results in reduced nuclear HSF1 and decreased Hsp70 promoter activity. BAG3 in MEF(hsf1{sup −/−}) cells actively translocalizes to the nucleus upon heat stress suggesting that BAG3 plays a key role in the processing of the nucleocytoplasmic shuttling of HSF1 upon heat stress. - Highlights: • The expression level of BAG3 is induced by heat stress. • BAG3 translocates to the nucleus upon heat stress. • BAG3 interacts with HSF1 and co-localizes to the nucleus. • BAG3 is a key regulator for HSF1 nuclear shuttling.

  1. Characterization by transmission electron microscopy of a JRQ steel subjected to different heat treatments; Caracterizacion por microscopia electronica de transmision de un acero JRQ sometido a diferentes tratamientos termicos

    Energy Technology Data Exchange (ETDEWEB)

    Moreno G, N.

    2014-07-01

    In this work a study was conducted on the steel Astm A-533, Grade B, Class 1 of reference JRQ, for the purpose of carrying out a study by transmission electron microscopy on the size and distribution of precipitates in steel samples JRQ previously subjected to heat treatments. This because the reactor vessels of the nuclear power plant of Laguna Verde, are made of a steel Astm A-533 Grade B, Class 1. It is known that the neutron radiation causes damage primarily embrittlement in materials that are exposed to it. However, observable damage through mechanical tests result from microstructural defects and atomic, induced by the neutron radiation. In previous studies hardening by precipitation of a JRQ steel (provided by the IAEA) was induced by heat treatments, finding that the conditions of heat treatment that reproduce the hardness and stress mechanical properties of a steel Astm A-533, Grade B, Class 1 irradiated for 8 years to a fluence of 3.5 x 10 {sup 17} neutrons/cm{sup 2} and to a temperature of 290 grades C are achieved with annealing treatments at 550 grades C. In the studied samples it was found that the more hardening phase both the heat treatments as the neutron radiation, is the bainite, being the ferrite practically unchanged. Which it gave the tone to believe that the ferrite is the phase that provides at level macro the mechanical properties in stress, since in the irradiated samples such properties remained unchanged with respect to the non-irradiated material, however changes were observed in material ductility, which may be attributable to the change of hardness in the bainite, which opens a possibility for modeling the micromechanical behavior of this material. (Author)

  2. Effect of Reheating Temperature and Cooling Treatment on the Microstructure, Texture, and Impact Transition Behavior of Heat-Treated Naval Grade HSLA Steel

    Science.gov (United States)

    Sk, Md. Basiruddin; Ghosh, A.; Rarhi, N.; Balamuralikrishnan, R.; Chakrabarti, D.

    2017-07-01

    In order to achieve the desired mechanical properties [YS > 390 MPa, total elongation >16 pct and Charpy impact toughness of 78 J at 213 K (-60 °C)] for naval application, samples from a low-carbon microalloyed steel have been subjected to different austenitization (1223 K to 1523 K) (950 °C to 1250 °C) and cooling treatments (furnace, air, or water cooling). The as-rolled steel and the sample air cooled from 1223 K (950 °C) could only achieve the required tensile properties, while the sample furnace cooled from 1223 K (950 °C) showed the best Charpy impact properties. Water quenching from 1223 K (950 °C) certainly contributed to the strength but affected the impact toughness. Overall, predominantly ferrite matrix with fine effective grain size and intense gamma-fiber texture was found to be beneficial for impact toughness as well as impact transition behavior. Small size and fraction of precipitates (like TiN, Nb, and V carbonitrides) eliminated the possibility of particle-controlled crack propagation and grain size-controlled crack propagation led to cleavage fracture. A simplified analytical approach has been used to explain the difference in impact transition behavior of the investigated samples.

  3. Steels from materials science to structural engineering

    CERN Document Server

    Sha, Wei

    2013-01-01

    Steels and computer-based modelling are fast growing fields in materials science as well as structural engineering, demonstrated by the large amount of recent literature. Steels: From Materials Science to Structural Engineering combines steels research and model development, including the application of modelling techniques in steels.  The latest research includes structural engineering modelling, and novel, prototype alloy steels such as heat-resistant steel, nitride-strengthened ferritic/martensitic steel and low nickel maraging steel.  Researchers studying steels will find the topics vital to their work.  Materials experts will be able to learn about steels used in structural engineering as well as modelling and apply this increasingly important technique in their steel materials research and development. 

  4. Testing of intergranular and pitting corrosion in sensitized welded joints of austenitic stainless steel

    Directory of Open Access Journals (Sweden)

    Bore V. Jegdic

    2017-06-01

    Full Text Available Pitting corrosion resistance and intergranular corrosion of the austenitic stainless steel X5Cr Ni18-10 were tested on the base metal, heat affected zone and weld metal. Testing of pitting corrosion was performed by the potentiodynamic polarization method, while testing of intergranular corrosion was performed by the method of electrochemical potentiokinetic reactivation with double loop. The base metal was completely resistant to intergranular corrosion, while the heat affected zone showed a slight susceptibility to intergranular corrosion. Indicators of pitting corrosion resistance for the weld metal and the base metal were very similar, but their values are significantly higher than the values for the heat affected zone. This was caused by reduction of the chromium concentration in the grain boundary areas in the heat affected zone, even though the carbon content in the examined stainless steel is low (0.04 wt. % C.

  5. Analysis of Leaf Heat Balance Affected by Operation of a Frost Protective Fan in Tea Fields

    National Research Council Canada - National Science Library

    KIMURA, Kensuke; MARUO, Kyosuke; OOKI, Takahiro; NAKAZONO, Kentaro; MATSUO, Kiyoshi; KITANO, Masaharu

    2016-01-01

    .... The method for quantifying the thermal effect brought by operation of frost protection methods was newly developed based on analysis of leaf heat balance, where leaf boundary layer conductance...

  6. Heat exchange modeling in a multilayered karst aquifer affected by seawater intrusion

    National Research Council Canada - National Science Library

    Vettorello, Luca; Pedron, Roberto; Sottani, Andrea; Chieco, Michele

    ...) activity in a coastal aquifer in the South of Italy (Province of Lecce, Puglia Region). The modeled closed-loop system consists of two double u-pipe heat exchangers, installed in 200 meters deep boreholes...

  7. Methods of making bainitic steel materials

    Energy Technology Data Exchange (ETDEWEB)

    Bakas, Michael Paul; Chu, Henry Shiu-Hung; Zagula, Thomas Andrew; Langhorst, Benjamin Robert

    2018-01-16

    Methods of making bainitic steels may involve austenitizing a quantity of steel by exposing the quantity of steel to a first temperature. A composition of the quantity of steel may be configured to impede formation of non-bainite ferrite, pearlite, and Widmanstatten ferrite. The quantity of steel may be heat-treated to form bainite by exposing the quantity of steel to a second, lower temperature. The second, lower temperature may be stabilized by exposing the quantity of steel to the second, lower temperature in the presence of a thermal ballast.

  8. Stahlschüssel key to steel

    CERN Document Server

    Wegst, W S

    2016-01-01

    The Key to Steel (Stahlschlüssel/Stahlschluessel) cross reference book will help you to decode / decipher steel designations and find equivalent materials worldwide. The 2016 edition includes more than 70,000 standard designations and trade names from approximately 300 steelmakers and suppliers. Presentation is trilingual: English, French, and German. Materials covered include structural steels, tool steels, valve steels, high temperature steels and alloys, stainless and heat-resisting steels, and more. Standards and designations from 25 countries are cross-referenced.

  9. Section 3: Optimization of a 550/690-MPa high-performance bridge steel

    Energy Technology Data Exchange (ETDEWEB)

    Magee, A.B.; Gross, J.H.; Stout, R.D. [and others

    1997-04-01

    This project to develop a high-performance bridge steel was intended to avoid susceptibility of the steel to weld heat-affected-zone cracking and therefore minimize the requirement for preheat, and to increase its fracture toughness at service temperatures. Previous studies by the Lehigh University Center for Advanced Technology for Large Structural Systems have suggested that a Cu-Ni steels with the following composition was an excellent candidate for such a bridge steel: C/0.070; Mn/1.50; P/0.009; S/0.005; Si/0.25; Cu/1.00; Ni/0.75; Cr/0.50; Mo/0.50; V/0.06; Cb/0.010. To confirm that observation, 227-kg heats of the candidate steel were melted and processed to 25- and 50-mm-thick plate by various thermomechanical practices, and the weldability and mechanical properties determined. To evaluate the feasibility of reduced alloy content, two 227-kg heats of a lower hardenability steel were melted with C reduced to 0.06, Mn to 1.25, and Mo to 0.25 and similarly processed and tested. The results indicate that the steels were not susceptible to hydrogen-induced weld-heat-affected-zone cracking when welded without preheat. Jominy end-quench tests of the higher-hardenability steel indicate that a minimum yield-strength of 690 MPa should be readily attainable in thicknesses through 50 mm and marginally at 100 mm. The toughness of the steel readily met AASHTO specifications for Zone 3 in all conditions and thicknesses, and may be sufficiently tough so that the critical crack size will minimize fatigue-crack-extension problems.

  10. Microstructural Characterization and Mechanical Properties of Electron Beam Welded Joint of High Strength Steel Grade S690QL

    Directory of Open Access Journals (Sweden)

    Błacha S.

    2016-06-01

    Full Text Available In the paper the results of metallographic examination and mechanical properties of electron beam welded joint of quenched and tempered steel grade S690QL are presented. Metallographic examination revealed that the concentrated electron beam significantly affect the changes of microstructure in the steel. Parent material as a delivered condition (quenched and tempered had a bainitic-martensitic microstructure at hardness about 290 HV0.5. After welding, the microstructure of heat affected zone is composed mainly of martensite (in the vicinity of the fusion line of hardness 420 HV0.5. It should be noted, however, that the microstructure of steel in the heat affected zone varies with the distance from the fusion line. The observed microstructural changes were in accordance with the CCT-S transformation diagram for the examined steel.

  11. Heat exchange modeling in a multilayered karst aquifer affected by seawater intrusion

    Directory of Open Access Journals (Sweden)

    Luca Vettorello

    2015-11-01

    Full Text Available A Feflow thermohaline model has been implemented in order to study borehole heat exchangers (BHEs activity in a coastal aquifer in the South of Italy (Province of Lecce, Puglia Region. The modeled closed-loop system consists of two double u-pipe heat exchangers, installed in 200 meters deep boreholes. The main purpose of numerical modeling was to forecast thermal plume extension in groundwater after a long period of heat exchange, calculating temperature trends in observation points during a 10 years transport simulation. The complex geological structure, including calcarenites, fractured limestones and a deep karst aquifer, has been translated into a multilayered model, with a depth-related parameter distribution, assigning different values of hydraulic, thermal and chemical properties to each layer. In particular saltwater concentration has been taken into account, considering the influence of seawater intrusion on the heat transport density-dependent model. Parameters assignment was based on experimental datasets collected during initial field investigations, including thermal characterization of soil samples and GRTs, together with historical hydrogeological and hydrochemical measures and previous groundwater surveys. After model structure configuration and aquifers parameterization, a sensitivity analysis on porosity and heat dispersivity has been conducted, to evaluate their influence on thermal transport phenomena with a multiple scenarios approach, considering in particular the uncertainty related to secondary porosity in karst systems. Feflow simulation represented the first step in environmental compatibility evaluation for the BHE plant, waiting for the necessary model calibration with groundwater temperature monitoring trends.

  12. Probability of US Heat Waves Affected by a Subseasonal Planetary Wave Pattern

    Science.gov (United States)

    Teng, Haiyan; Branstator, Grant; Wang, Hailan; Meehl, Gerald A.; Washington, Warren M.

    2013-01-01

    Heat waves are thought to result from subseasonal atmospheric variability. Atmospheric phenomena driven by tropical convection, such as the Asian monsoon, have been considered potential sources of predictability on subseasonal timescales. Mid-latitude atmospheric dynamics have been considered too chaotic to allow significant prediction skill of lead times beyond the typical 10-day range of weather forecasts. Here we use a 12,000-year integration of an atmospheric general circulation model to identify a pattern of subseasonal atmospheric variability that can help improve forecast skill for heat waves in the United States. We find that heat waves tend to be preceded by 15-20 days by a pattern of anomalous atmospheric planetary waves with a wavenumber of 5. This circulation pattern can arise as a result of internal atmospheric dynamics and is not necessarily linked to tropical heating.We conclude that some mid-latitude circulation anomalies that increase the probability of heat waves are predictable beyond the typical weather forecast range.

  13. Effects of heat treatment on microstructure and mechanical properties of Ni60/h-BN self-lubricating anti-wear composite coatings on 304 stainless steel by laser cladding

    Science.gov (United States)

    Lu, Xiao-Long; Liu, Xiu-Bo; Yu, Peng-Cheng; Zhai, Yong-Jie; Qiao, Shi-Jie; Wang, Ming-Di; Wang, Yong-Guang; Chen, Yao

    2015-11-01

    Laser clad Ni60/h-BN self-lubricating anti-wear composite coating on 304 stainless steel were heat treated at 600 °C (stress relief annealing) for 1 h and 2 h, respectively. Effects of the phase compositions, microstructure, microhardness, nano-indentation and tribological properties of the composite coatings with and without heat treatment had been investigated systemically. Results indicated that three coatings mainly consist of the matrix γ-(Ni, Fe) solid solution, the CrB ceramic phases and the h-BN lubricating phases. The maximum microhardness of the coatings was first increased from 667.7 HV0.5 to 765.0 HV0.5 after heat treatment for 1 h, and then decreased to 698.3 HV0.5 after heat treatment for 2 h. The hardness of γ-(Ni, Fe) solid solution without heat treatment and after heat treatment 1 h and 2 h were 5.09 GPa, 7.20 GPa and 3.77 GPa, respectively. Compared with the coating without heat treatment, the friction coefficients of the coating after heat treatment were decreased obviously. Effects of the heat treatment time on friction coefficient were negligible, but were significant on wear volume loss. Comparatively speaking, the laser clad self-lubricating anti-wear composite coating after heat treatment for 1 h presented the best anti-wear and friction reduction properties.

  14. Initial Evaluation of the Heat-Affected Zone, Local Embrittlement Phenomenon as it Applies to Nuclear Reactor Vessels

    Energy Technology Data Exchange (ETDEWEB)

    McCabe, D.E.

    1999-09-01

    The objective of this project was to determine if the local brittle zone (LBZ) problem, encountered in the testing of the heat-affected zone (HAZ) part of welds in offshore platform construction, can also be found in reactor pressure vessel (RPV) welds. Both structures have multipass welds and grain coarsening along the fusion line. Literature was obtained that described the metallurgical evidence and the type of research work performed on offshore structure welds.

  15. Heterogeneities in local plastic flow behavior in a dissimilar weld between low-alloy steel and stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Mas, Fanny [Université Grenoble Alpes, SIMAP, 38000 Grenoble (France); CNRS, SIMAP, 38000 Grenoble (France); Martin, Guilhem, E-mail: guilhem.martin@simap.grenoble-inp.fr [Université Grenoble Alpes, SIMAP, 38000 Grenoble (France); CNRS, SIMAP, 38000 Grenoble (France); Lhuissier, Pierre; Bréchet, Yves; Tassin, Catherine [Université Grenoble Alpes, SIMAP, 38000 Grenoble (France); CNRS, SIMAP, 38000 Grenoble (France); Roch, François [Areva NP, Tour Areva, 92084 Paris La Défense (France); Todeschini, Patrick [EDF R& D, Avenue des Renardières, 77250 Moret-sur-Loing (France); Simar, Aude [Institute of Mechanics, Materials and Civil Engineering (iMMC), Université catholique de Louvain, 1348 Louvain-la-Neuve (Belgium)

    2016-06-14

    In dissimilar welds between low-alloy steel and stainless steel, the post-weld heat-treatment results in a high variety of microstructures coexisting around the fusion line, due to carbon diffusion and carbides dissolution/precipitation. The local constitutive laws in the vicinity of the fusion zone were identified by micro tensile specimens for the sub-millimeter sized zones, equivalent bulk materials representing the decarburized layer using both wet H{sub 2} atmosphere and diffusion couple, and nano-indentation for the carburized regions (i.e. the martensitic band and the austenitic region). The decarburized zone presents only 50% of the yield strength of the low-alloy steel heat affected zone and a ductility doubled. The carburized zones have a yield strength 3–5 times higher than that of the low-alloy steel heat affected zone and have almost no strain hardening capacity. These properties result in heterogeneous plastic deformation happening over only millimeters when the weld is loaded perpendicularly to the weld line, affecting its overall behavior. The constitutive laws experimentally identified were introduced as inputs into a finite elements model of the transverse tensile test performed on the whole dissimilar weld. A good agreement between experiments and simulations was achieved on the global stress-strain curve. The model also well predicts the local strain field measured by microscale DIC. A large out-of-plane deformation due to the hard carburized regions has also been identified.

  16. Magnetic nanowires and hyperthermia: How geometry and material affect heat production efficiency

    KAUST Repository

    Contreras, Maria F.

    2015-05-01

    Magnetic hyperthermia, which refers to the production of heat by magnetic nanostructures under an alternating magnetic field (AMF), has been previously investigated with superparamagnetic nanobeads as a cancer therapy method. Magnetic nanowires (NWs) used in hyperthermia can be very promising, as it has been shown that they have a larger magnetic moment per unit of volume compared to the nanobeads. Moreover, Fe NWs proved to have a higher heating efficiency compared to Fe nanobeads, when exposed to an AMF at the same concentration [1].

  17. Strength Evaluation of Heat Affected Zone in Electron Beam Welded ARAA for HCCR TBM in ITER

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, J. S.; Kim, S. K.; Jin, H. G.; Lee, E. H.; Lee, D. W. [KAERI, Daejeon (Korea, Republic of); Cho, S. [National Fusion Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    The Korean helium cooled ceramic reflector (HCCR) test blanket module (TBM) has been developed for ITER, and Korean reduced activation ferritic martensitic (RAFM) steel, called advanced reduced activation alloy (ARAA), has also been developed for a structural material of the HCCR TBM. One case of limited optimized electron beam (EB) welding conditions was selected based on previous work, and the weldability of an EB weld was evaluated for TBM fabrication. The micro-hardness was measured from the base to the weld region, and the microstructures were also observed. A small punch (SP) test considering the HAZ was carried out at room and high (550 .deg. C) temperatures. The empirical mechanical properties of HAZ in the EB weld were evaluated, and the fracture behavior was investigated after the SP test. The SP results show that the estimated yield and tensile strength of the HAZ were higher than the base metal at both temperatures. Korean RAFM steel, ARAA, was developed as a TBM structural material. Using one of the program alloys in ARAA (F206), one case of a limited optimized EB welding condition was selected based on previous works, and the weldability of an EB weld using the SP test was evaluated for TBM fabrication at room and high (550 .deg. C) temperatures. From a micro-Vickers hardness evaluation, the HAZ gave the highest values compared with the other regions. The irregular grain boundaries in the HAZ were observed, but its width was narrower than the TIG weld from the previous results. The optimized welding methods such as the TIG, EB, and laser weld, and the welding procedure considering the PWHT are being established, and the weldability evaluation is also progressing according to the development of the ARAA for the fusion material application in Korea.

  18. Dietary heme adversely affects experimental colitis in rats, despite heat-shock protein induction

    NARCIS (Netherlands)

    Schepens, Marloes A. A.; Vink, Carolien; Schonewille, Arjan J.; Dijkstra, Gerard; van der Meer, Roelof; Bovee-Oudenhoven, Ingeborg M. J.

    Objective: Research on dietary modulation of inflammatory bowel disease is in its infancy. Dietary heme, mimicking red meat, is cytotoxic to colonic epithelium and thus may aggravate colitis. Alternatively, heme-induced colonic stress might also result in potential protective heat-shock proteins

  19. The presence of heat-stable conformers of ovalbumin affects properties of thermally formed aggregates

    NARCIS (Netherlands)

    Groot, J.de; Jongh, H.H.J.de

    2003-01-01

    The aim of this work was to study the effect of the formation of more heat-stable conformers of chicken egg ovalbumin during incubation at basic pH (9.9) and elevated temperature (55°C) on the protein aggregation properties at neutral pH. Native ovalbumin (N-OVA) is converted on the hours time-scale

  20. Factors affecting gas migration and contaminant redistribution in heterogeneous porous media subject to electrical resistance heating.

    Science.gov (United States)

    Munholland, Jonah L; Mumford, Kevin G; Kueper, Bernard H

    2016-01-01

    A series of intermediate-scale laboratory experiments were completed in a two-dimensional flow cell to investigate gas production and migration during the application of electrical resistance heating (ERH) for the removal of dense non-aqueous phase liquids (DNAPLs). Experiments consisted of heating water in homogeneous silica sand and heating 270 mL of trichloroethene (TCE) and chloroform (CF) DNAPL pools in heterogeneous silica sands, both under flowing groundwater conditions. Spatial and temporal distributions of temperature were measured using thermocouples and observations of gas production and migration were collected using front-face image capture throughout the experiments. Post-treatment soil samples were collected and analyzed to assess DNAPL removal. Results of experiments performed in homogeneous sand subject to different groundwater flow rates showed that high groundwater velocities can limit subsurface heating rates. In the DNAPL pool experiments, temperatures increased to achieve DNAPL-water co-boiling, creating estimated gas volumes of 131 and 114 L that originated from the TCE and CF pools, respectively. Produced gas migrated vertically, entered a coarse sand lens and subsequently migrated laterally beneath an overlying capillary barrier to outside the heated treatment zone where 31-56% of the original DNAPL condensed back into a DNAPL phase. These findings demonstrate that layered heterogeneity can potentially facilitate the transport of contaminants outside the treatment zone by mobilization and condensation of gas phases during ERH applications. This underscores the need for vapor phase recovery and/or control mechanisms below the water table during application of ERH in heterogeneous porous media during the co-boiling stage, which occurs prior to reaching the boiling point of water. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Effect of welding processes and consumables on fatigue crack growth behaviour of armour grade quenched and tempered steel joints

    Directory of Open Access Journals (Sweden)

    G. Magudeeswaran

    2014-03-01

    Full Text Available Quenched and Tempered (Q&T steels are widely used in the construction of military vehicles due to its high strength to weight ratio and high hardness. These steels are prone to hydrogen induced cracking (HIC in the heat affected zone (HAZ after welding. The use of austenitic stainless steel (ASS consumables to weld the above steel was the only available remedy because of higher solubility for hydrogen in austenitic phase. The use of stainless steel consumables for a non-stainless steel base metal is not economical. Hence, alternate consumables for welding Q&T steels and their vulnerability to HIC need to be explored. Recent studies proved that low hydrogen ferritic steel (LHF consumables can be used to weld Q&T steels, which can give very low hydrogen levels in the weld deposits. The use of ASS and LHF consumables will lead to distinct microstructures in their respective welds. This microstructural heterogeneity will have a drastic influence in the fatigue crack growth resistance of armour grade Q&T steel welds. Hence, in this investigation an attempt has been made to study the influence of welding consumables and welding processes on fatigue crack growth behaviour of armour grade Q&T Steel joints. Shielded metal arc welding (SMAW and Flux cored arc welding (FCAW were used for fabrication of joints using ASS and LHF consumables. The joints fabricated by SMAW process using LHF consumable exhibited superior fatigue crack growth resistance than all other joints.

  2. Heat treatments in a conventional steel to reproduce the microstructure of a nuclear grade steel; Tratamientos termicos en un acero convencional para reproducir la microestructura de un acero grado nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Rosalio G, M.

    2014-07-01

    The ferritic steels used in the manufacture of pressurized vessels of Boiling Water Reactors (BWR) suffer degradation in their mechanical properties due to damage caused by the neutron fluxes of high energy bigger to a Mega electron volt (E> 1 MeV) generated in the reactor core. The materials with which the pressurized vessels of nuclear reactors cooled by light water are built correspond to low alloy ferritic steels. The effect of neutron irradiation on these steels is manifested as an increase in hardness, mechanical strength, with the consequent decrease in ductility, fracture toughness and an increase in temperature of ductile-brittle transition. The life of a BWR is 40 years, its design must be considered sufficient margin of safety because pressure forces experienced during operation, maintenance and testing of postulated accident conditions. It is necessary that under these conditions the vessel to behave ductile and likely to propagate a fracture is minimized. The vessels of light water nuclear reactors have a bainite microstructure. Specifically, the reactor vessels of the nuclear power plant of Laguna Verde (Veracruz, Mexico) are made of a steel Astm A-533, Grade B Class 1. At present they are carrying out some welding tests for the construction of a model of a BWR, however, to use nuclear grade steel such as Astm A-533 to carry out some of the welding tests, is very expensive; perform these in a conventional material provides basic information. Although the microstructure present in the conventional material does not correspond exactly to the degree of nuclear material, it can take of reference. Therefore, it is proposed to conduct a pilot study to establish the thermal treatment that reproduces the microstructure of nuclear grade steel, in conventional steel. The resulting properties of the conventional steel samples will be compared to a JRQ steel, that is a steel Astm A-533, Grade B Class 1, provided by IAEA. (Author)

  3. Influence of different cyclic intercritical heat treatment schedules on the microstructure and mechanical behaviour of a medium carbon low alloy steel

    Directory of Open Access Journals (Sweden)

    K. K. Alaneme

    2013-06-01

    Full Text Available In the present research, the prospect of optimizing high strength and formability in medium carbon low alloy steel via different cyclic intercritical treatment procedures was investigated. Three intercritical treatment schedules (Route A - cyclic intercritical annealing only, Route B - cold rolling followed by cyclic intercritical annealing, and Route C - cyclic cold rolling and intercritical annealing operations performed at 770o C were utilized in this research work. For each treatment route, a maximum of three heating cycles was used. Microstructural examination, hardness measurement and tensile properties evaluation were used as basis to assess the mechanical behaviour of the dual phase structures produced. The results show that for Route A and B, grain refinement and homogeneous distribution of ferrite and martensite was obtained for specimens subjected to two cycles of intercritical annealing. This resulted in peak strength, toughness and hardness in comparison to specimens subjected to one or three cycles of intercritical annealing. For Route C, the same properties were impoverished with increase in intercritical annealing cycles. The best combination of hardness, strength, toughness and strain to fracture was achieved with the use of an initial cold rolling and two cycles of intercritical annealing at 770o C.

  4. Application of Response Surface Methodology for Modeling of Postweld Heat Treatment Process in a Pressure Vessel Steel ASTM A516 Grade 70.

    Science.gov (United States)

    Peasura, Prachya

    2015-01-01

    This research studied the application of the response surface methodology (RSM) and central composite design (CCD) experiment in mathematical model and optimizes postweld heat treatment (PWHT). The material of study is a pressure vessel steel ASTM A516 grade 70 that is used for gas metal arc welding. PWHT parameters examined in this study included PWHT temperatures and time. The resulting materials were examined using CCD experiment and the RSM to determine the resulting material tensile strength test, observed with optical microscopy and scanning electron microscopy. The experimental results show that using a full quadratic model with the proposed mathematical model is YTS = -285.521 + 15.706X1 + 2.514X2 - 0.004X1(2) - 0.001X2(2) - 0.029X1X2. Tensile strength parameters of PWHT were optimized PWHT time of 5.00 hr and PWHT temperature of 645.75°C. The results show that the PWHT time is the dominant mechanism used to modify the tensile strength compared to the PWHT temperatures. This phenomenon could be explained by the fact that pearlite can contribute to higher tensile strength. Pearlite has an intensity, which results in increased material tensile strength. The research described here can be used as material data on PWHT parameters for an ASTM A516 grade 70 weld.

  5. Application of in-service temperature lowering to reduce radioactivity corrosion product deposition on carbon steel piping of BWR residual heat removal system

    Energy Technology Data Exchange (ETDEWEB)

    Aizawa, Motohiro; Chiba, Yoshinori [Hitachi Engineering Co., Ltd., Nuclear Power Plant Engineering Dept., Hitachi, Ibaraki (Japan); Ohsumi, Katsumi [Hitachi Ltd., Power and Industrial Systems Nuclear Systems Division, Hitachi, Ibaraki (Japan); Uchida, Shunsuke [Tohoku Univ., Graduate School of Engineering, Dept. of Quantum Science and Energy Engineering, Sendai, Miyagi (Japan); Takahashi, Toshihiko; Saitoh, Takeshi [Hokuriku Electric Power Company, Shika Nuclear Power Station, Radiation Safety and Chemistry Section, Shika, Ishikawa (Japan)

    2002-10-01

    Assessment of plant data and experiments on deposition of ion species on carbon steel were carried out in order to develop suitable countermeasures to reduce RHR (residual heat removal) piping dose rate. It was thought that radioactivity deposits on the RHR piping were mainly from radioactive ion species in the coolant and they were enhanced by the dehydration reaction of corrosion products on the piping. From an evaluation for temperature dependence of the dehydration reaction, it was proposed to lower the start-up temperature of RHR operation as a way to reduce radioactivity deposition. Feasibility studies of improved RHR operation were conducted and test operations were carried out in the Shika Nuclear Power Station Unit 1. Application of the improved RHR operation resulted in a temperature reduction from 150degC to 110degC, and a radioactivity deposition reduction on the RHR piping to one-fifth of that in conventional RHR operation. The improved RHR operation has now been applied to more than fifteen Japanese BWRs and significant suppression effects of radioactivity deposition have been observed. (author)

  6. Effect of Stress Relief Annealing on Microstructure & Mechanical Properties of Welded Joints Between Low Alloy Carbon Steel and Stainless Steel

    Science.gov (United States)

    Nivas, R.; Das, G.; Das, S. K.; Mahato, B.; Kumar, S.; Sivaprasad, K.; Singh, P. K.; Ghosh, M.

    2017-01-01

    Two types of welded joints were prepared using low alloy carbon steel and austenitic stainless steel as base materials. In one variety, buttering material and weld metal were Inconel 82. In another type, buttering material and weld metal were Inconel 182. In case of Inconel 82, method of welding was GTAW. For Inconel 182, welding was done by SMAW technique. For one set of each joints after buttering, stress relief annealing was done at 923 K (650 °C) for 90 minutes before further joining with weld metal. Microstructural investigation and sub-size in situ tensile testing in scanning electron microscope were carried out for buttered-welded and buttered-stress relieved-welded specimens. Adjacent to fusion boundary, heat-affected zone of low alloy steel consisted of ferrite-pearlite phase combination. Immediately after fusion boundary in low alloy steel side, there was increase in matrix grain size. Same trend was observed in the region of austenitic stainless steel that was close to fusion boundary between weld metal-stainless steel. Close to interface between low alloy steel-buttering material, the region contained martensite, Type-I boundary and Type-II boundary. Peak hardness was obtained close to fusion boundary between low alloy steel and buttering material. In this respect, a minimum hardness was observed within buttering material. The peak hardness was shifted toward buttering material after stress relief annealing. During tensile testing no deformation occurred within low alloy steel and failure was completely through buttering material. Crack initiated near fusion boundary between low alloy steel-buttering material for welded specimens and the same shifted away from fusion boundary for stress relieved annealed specimens. This observation was at par with the characteristics of microhardness profile. In as welded condition, joints fabricated with Inconel 82 exhibited superior bond strength than the weld produced with Inconel 182. Stress relief annealing

  7. Influence of Normalizing Temperature on the Microstructure and Hardness of 9Cr-1Mo ODS Steel

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Ki Nam; Kim, Tae Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Kyu Tae [Dongguk University, Gyeongju (Korea, Republic of)

    2016-10-15

    Oxide dispersion strengthened(ODS) steel has superior high-temperature strength and creep properties because fine oxide particles having an excellent stability at high temperatures are uniformly distributed in the matrix. ODS steel has being developed for structure materials of sodium fast cooled reactor(SFR) because of its excellent irradiation resistance and mechanical properties. 9Cr-1Mo ODS steel has better high temperature strength and irradiation resistance than common 9Cr-1Mo steel because Y{sub 2}O{sub 3} nano-sized particles which interrupt dislocation movement and grain boundary slip are uniformly dispersed in the martensite matrix. The mechanical properties of the ODS steels are mainly determined by their microstructures, and the microstructure is considerably decided by the heat-treatment conditions. This study focused on the effect of normalizing temperature on microstructure and hardness of 9Cr-1Mo martensitic ODS steel so as to optimize the heat-treatment condition. In this study, the effect of normalizing temperature on mechanical property and microstructures of 9Cr-1Mo martensitic ODS steel was investigated. It was shown that the microhardness was steadily increased with increasing of the normalizing temperature. According to TEM observation, mechanical property of 9Cr-1Mo ODS steel was significantly affected by lath width. These observations, could be useful to understand the relationship between normalizing temperature and microstructure.

  8. Fiber laser welding of austenitic steel and commercially pure copper butt joint

    Science.gov (United States)

    Kuryntsev, S. V.; Morushkin, A. E.; Gilmutdinov, A. Kh.

    2017-03-01

    The fiber laser welding of austenitic stainless steel and commercially pure copper in butt joint configuration without filler or intermediate material is presented. In order to melt stainless steel directly and melt copper via heat conduction a defocused laser beam was used with an offset to stainless steel. During mechanical tests the weld seam was more durable than heat affected zone of copper so samples without defects could be obtained. Three process variants of offset of the laser beam were applied. The following tests were conducted: tensile test of weldment, intermediate layer microhardness, optical metallography, study of the chemical composition of the intermediate layer, fractography. Measurements of electrical resistivity coefficients of stainless steel, copper and copper-stainless steel weldment were made, which can be interpreted or recalculated as the thermal conductivity coefficient. It shows that electrical resistivity coefficient of cooper-stainless steel weldment higher than that of stainless steel. The width of intermediate layer between stainless steel and commercially pure copper was 41-53 μm, microhardness was 128-170 HV0.01.

  9. Autodeformation of Carburized Steel during Tempering

    Directory of Open Access Journals (Sweden)

    Regita BENDIKIENĖ

    2013-03-01

    Full Text Available The article analyses the results of autodeformation registered during tempering of carburized steel. Test pieces for the tests were carburized till the different depth in order to examine influence of depth of carburization on the deformation of steel during heat treatment operation. Carburization was performed on the one surface of test pieces seeking to analyze extent of acted normal stresses to autodeformation of steel. Different bending loads were applied for analyzed steel from 5 MPa to 100 MPa. Deflection of test pieces was analyzed. The obtained results proved that size and direction of deflection were affected by depth of carburization. Particular results of stretched and compressed surface examination showed different behavior of test pieces during tempering process. Test pieces, which undergo deformation at the beginning of martensitic transformation, after unloading bend further. When tempered test pieces with assimetrically carburized layer bend during hardening, its direction and extent of autodeformation depend on depth of carburization and tempering temperature. Kinetics of autodeformation (during tempering is affected by difference of volume changes in the carburized part and in the unaffected low carbon part of specimen, and similarly by decomposition of retained austenite in the carburized part.DOI: http://dx.doi.org/10.5755/j01.ms.19.1.3820

  10. Concentration of plasticizers applied during heat-moisture treatment affects properties of the modified canna starch.

    Science.gov (United States)

    Juansang, Juraluck; Puncha-Arnon, Santhanee; Uttapap, Dudsadee; Puttanlek, Chureerat; Rungsardthong, Vilai; Watcharatewinkul, Yanika

    2017-04-15

    Effects of the concentration of plasticizers applied during heat-moisture treatment (HMT) on the properties of canna starch were investigated. The modified starches were prepared by soaking starch in 0 (water), 1, 3, 5, 10, 20 and 30% w/w glycerol or sorbitol solution for 24h and adjusting the moisture content to 25% before HMT (100°C, 1h). Changes in the pasting profiles of heat-moisture treated starches were more obvious when glycerol solutions were used instead of water. An increase in the concentration of glycerol solution from 1% to 5% resulted in a progressive decrease in paste viscosity; paste viscosity then increased as the glycerol concentration rose from 10 to 30%. A similar trend was observed when sorbitol was used as a plasticizer, but with a lesser effect. A scheme for arrangements of the molecular structure of starch during the process of HMT was suggested. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Factors which affect heat rejection system design for lunar production systems

    Science.gov (United States)

    Wong-Swanson, Belinda

    This paper presents a radiation model of radiators on the surface moon. The driving factors on radiator area are the operating temperature and solar radiation. In addition, five types of radiators are examined. Heat pipe radiators are currently the best type available due to its light mass, high reliability and wide operating temperature range. However, liquid droplet radiators show tremendous potential because of its light mass, simple design and immunity to meteoroid puncture.

  12. Preferences for heat, cold, or contrast in patients with knee osteoarthritis affect treatment response

    Directory of Open Access Journals (Sweden)

    Craig R Denegar

    2010-07-01

    Full Text Available Craig R Denegar, Devon R Dougherty, Jacob E Friedman, Maureen E Schimizzi, James E Clark, Brett A Comstock, William J KraemerHuman Performance Laboratory and Physical Therapy Program, Department of Kinesiology, University of Connecticut, Storrs, CT, USAObjective: This investigation assessed preferences for, and effects of, 5 days of twice daily superficial heat, cold, or contrast therapy applied with a commercially available system ­permitting the circulation of water through a wrap-around garment, use of an electric heating pad, or rest for patients with level II–IV osteoarthritis (OA of the knee.Methods: We employed a within subject, randomized order design to study 34 patients ­receiving each treatment in 1-week blocks. A knee injury and osteoarthritis outcome score (KOOS questionnaire and visual analog pain scale was completed at baseline, and twice each week. Treatment preferences were assessed in the last week of the study.Results: Treatment with the device set to warm was preferred by 48% of subjects. Near equal preferences were observed for cold (24% and contrast (24%. Pain reduction and improvements in KOOS subscale measures were demonstrated for each treatment but responses were (P < 0.05 greater with preferred treatments. Most patients preferred treatment with the water circulating garment system over a heating pad.Conclusions: We recommend that when superficial heat or cold is considered in the management of knee OA that patients experiment to identify the intervention that offers them the greatest relief and that contrast is a treatment option.Keywords: pain scales, KOOS, therapeutic agents, knee, patient preferences

  13. Factors affecting projected Arctic surface shortwave heating and albedo change in coupled climate models

    Science.gov (United States)

    Holland, Marika M.; Landrum, Laura

    2015-01-01

    We use a large ensemble of simulations from the Community Earth System Model to quantify simulated changes in the twentieth and twenty-first century Arctic surface shortwave heating associated with changing incoming solar radiation and changing ice conditions. For increases in shortwave absorption associated with albedo reductions, the relative influence of changing sea ice surface properties and changing sea ice areal coverage is assessed. Changes in the surface sea ice properties are associated with an earlier melt season onset, a longer snow-free season and enhanced surface ponding. Because many of these changes occur during peak solar insolation, they have a considerable influence on Arctic surface shortwave heating that is comparable to the influence of ice area loss in the early twenty-first century. As ice area loss continues through the twenty-first century, it overwhelms the influence of changes in the sea ice surface state, and is responsible for a majority of the net shortwave increases by the mid-twenty-first century. A comparison with the Arctic surface albedo and shortwave heating in CMIP5 models indicates a large spread in projected twenty-first century change. This is in part related to different ice loss rates among the models and different representations of the late twentieth century ice albedo and associated sea ice surface state. PMID:26032318

  14. Factors affecting projected Arctic surface shortwave heating and albedo change in coupled climate models.

    Science.gov (United States)

    Holland, Marika M; Landrum, Laura

    2015-07-13

    We use a large ensemble of simulations from the Community Earth System Model to quantify simulated changes in the twentieth and twenty-first century Arctic surface shortwave heating associated with changing incoming solar radiation and changing ice conditions. For increases in shortwave absorption associated with albedo reductions, the relative influence of changing sea ice surface properties and changing sea ice areal coverage is assessed. Changes in the surface sea ice properties are associated with an earlier melt season onset, a longer snow-free season and enhanced surface ponding. Because many of these changes occur during peak solar insolation, they have a considerable influence on Arctic surface shortwave heating that is comparable to the influence of ice area loss in the early twenty-first century. As ice area loss continues through the twenty-first century, it overwhelms the influence of changes in the sea ice surface state, and is responsible for a majority of the net shortwave increases by the mid-twenty-first century. A comparison with the Arctic surface albedo and shortwave heating in CMIP5 models indicates a large spread in projected twenty-first century change. This is in part related to different ice loss rates among the models and different representations of the late twentieth century ice albedo and associated sea ice surface state. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  15. EFFECTS OF MO ADDITION ON THE MICROSTRUCTURE AND MECHANICAL PROPERTIES OF CAST MICROALLOYED STEEL

    Directory of Open Access Journals (Sweden)

    H. Torkamani

    2017-09-01

    Full Text Available In industry, the cost of production is an important factor and it is preferred to use conventional and low cost procedures for producing the parts. Heat treatment cycles and alloying additions are the key factors affecting the microstructure and mechanical properties of the cast steels. In this study an attempt was made to evaluate the influence of minor Mo addition on the microstructure and mechanical properties of conventionally heat treated cast micro-alloyed steels. The results of Jominy and dilatometry tests and also microstructural examinations revealed that Mo could effectively increase the hardenability of the investigated steel and change the microstructure features of the air-cooled samples. Acicular microstructure was the consequence of increasing the hardenability in Mo-added steel. Besides, it was found that Mo could greatly affect the isothermal bainitic transformation and higher fraction of martensite after cooling (from isothermal temperature was due to the Mo addition. The results of impact test indicated that the microstructure obtained in air-cooled Mo-added steel led to better impact toughness (28J in comparison with the base steel (23J. Moreover, Mo-added steel possessed higher hardness (291HV, yield (524MPa and tensile (1108MPa strengths compared to the base one.

  16. Effect of post weld heat treatment on wear resistance of hot forging cast steel die coated with surfacing layer

    Directory of Open Access Journals (Sweden)

    Xu Wujiao

    2015-01-01

    Full Text Available The wear resistance capability of die surfacing layer under different Post Weld Heat Treatments (PWHT was analysed by Finite Element Method (FEM simulation and experiments. Taking the hot forging process of crankshaft as example, a wear model of hot forging die coated with surfacing layer was established by the software DEFORM-3D. The simulation results indicate that the wear resistance capability of the die surfacing layer is optimal when tempering temperature and holding time are 550 ∘C and 4h respectively. To verify the wear calculation result, 16 groups of different PWHT orthogonal wear tests were performed under atmospheric condition at 400 ∘C. The wear test result shows a good agreement with the FEM simulation result. SEM observation of the wear debris shows that oxidative wear plays a dominant role in 400 ∘C among 16 specimens. Furthermore, when tempering temperature and holding time are 550 ∘C and 4h respectively, the alloy carbide dispersively distributes in the metallographic structure, which can improve the wear resistance of the surfacing.

  17. Effect of post-welding heat treatment on wear resistance of cast-steel die with surfacing layer

    Directory of Open Access Journals (Sweden)

    Xu Wujiao

    2015-01-01

    Full Text Available The wear resistance capability of die surfacing layer under different Post-Welding Heat Treatments (PWHT was analysed by Finite Element (FE simulation and experiments. Taking hot forging process of a crankshaft as an example, a wear model of the hot forging die coated with surfacing layer was established using FE software DEFORM-3D. The simulation results indicated that the wear resistance capability of the die surfacing layer is optimal when tempering temperature and holding time are 550 °C and 4 h respectively. To verify the wear computational results, 16 groups of PWHT orthogonal wear tests were performed at a temperature of 400 °C, which is a similar temperature to that occurs in an actual hot forging die. The wear-test result showed a good agreement with the FE simulation. SEM observation of the wear debris on 16 specimens showed that oxidative wear is dominant when the temperature was in 400 °C. Furthermore, when tempering temperature and holding time were 550 °C and 4 h respectively, the carbide alloy dispersively distributes in the metallographic structure, which helps to improve the wear resistance of the surfacing layer.

  18. Induction surface hardening of hard coated steels

    DEFF Research Database (Denmark)

    Pantleon, Karen; Kessler, Olaf; Hoffmann, Franz

    1999-01-01

    -process is the high deposition temperature, consequently the properties of steel substrates are negatively influenced. Therefore, a subsequent heat treatment of the coated steels is necessary to restore the properties of steels ready for operation. Induction surface hardening is used as a method of heat treatment......, the scratch test is used to estimate critical loads for cohesive and adhesive failure of the coatings. Additionally, distortion measurements are carried out. The results emphasize the advantage of induction surface hardening as a method of subsequent heat treatment of CVD-coated steels....... after the deposition of TiN hard coatings on steel substrates. Influences of both the coating properties and the substrate properties are discussed in dependence on the parameters of induction heating. Thereby the heating time, heating atmosphere and the power input into the specimen are changed...

  19. Effect of Austenization Temperature on the Microstructure and Strength of 9% and 12% Cr Ferritic-Martensitic Steels

    Energy Technology Data Exchange (ETDEWEB)

    Terry C. Totemeier

    2004-10-01

    The effect of reduced-temperature austenization on the microstructure and strength of two ferritic-martensitic steels was studied. Prototypic 9% and 12% Cr steels, grade 91 (9Cr-1MoVNb) and type 422 stainless (12Cr-1MoVW), respectively, were austenized at 925°C and 1050°C and tempered at 760°C. The reduced austenization temperature was intended to simulate potential inadequate austenization during field construction of large structures and also the thermal cycle experienced in the Type IV region of weld heat affected zones (HAZ). The microstructure, tensile behavior, and creep strength were characterized for both steels treated at each condition. The reduced austenization temperature resulted in general coarsening of carbides in both steels and polygonization of the tempered martensite structure in type 422. For this steel, a marked reduction in microhardness was observed, while there was little change in microhardness for grade 91. Slight reductions in tensile strength were observed for both steels at room temperature and elevated temperatures of 450 and 550°C. The strength reduction was greater for type 422 than for grade 91. At 650°C the tensile strength reduction was minimal for both steels. Marked reductions in creep rupture lives were observed for both steels at 650°C; the reductions were less at 600°C and minimal at 550°C. Overall, the higher Cr content steel was observed to be more sensitive to variations in heat treatment conditions.

  20. Effect of weld heat input on toughness and structure of HAZ of a new ...

    Indian Academy of Sciences (India)

    Unknown

    lysed by using H-800 transmission electron microscope and electron diffraction technique. 3. Results and analysis. 3.1 Toughness and fracture morphology in the heat-affected zone. Effect of the weld heat input (E) on the impact energy in the HAZ of HQ130 super-high strength steel is shown in. *Author for correspondence ...

  1. How do patchy snow covers affect turbulent sensible heat fluxes? - Numerical analysis and experimental findings

    Science.gov (United States)

    Schlögl, Sebastian; Mott, Rebecca; Lehning, Michael

    2017-04-01

    The surface energy balance of a snow cover significantly changes once the snow cover gets patchy. The substantial progress in knowledge about the surface energy balance of patchy snow covers is a mandatory requirement to reduce biases in flux parameterizations in larger scale meteorological or climatological models. The aim of this project was to numerically improve energy balance calculations late in the melting season when the spatial variability of turbulent fluxes is especially high owing to the complex feedback between bare/snow-covered areas and the atmosphere above. In order to account for the feedback between the atmosphere and the patchy snow-cover we calculated three-dimensional air temperature and wind velocity fields with the non-hydrostatic atmospheric model ARPS for an idealized flat test site initialized with different snow distributions and atmospheric conditions. The physics-based surface process model Alpine3D has been forced with these atmospheric fields close to the snow surface in order to resolve the small-scale spatial variability. We further initialized the model with atmospheric fields above the blending height as a reference case. The numerical analysis shows that for simulations initialized with fully-resolved atmospheric fields below the blending height, turbulent sensible heat fluxes are up to 50 W/m2 larger than for calculations forced without resolved atmospheric fields. This difference in turbulent sensible heat fluxes over snow increase with increasing number of snow patches and decreasing snow-cover fraction. This is mainly attributed to an increase in the mean near-surface air temperature over snow due to horizontal and vertical exchange processes induced by the heterogeneous land-surface. We used flux footprint estimations to analyse turbulence data measured during three ablation periods in the Dischma valley (Switzerland). This fundamental theory was deployed for eddy-covariance measurements revealing the origin of the measured

  2. Hydrogen induced cold cracking studies on armour grade high strength, quenched and tempered steel weldments

    Energy Technology Data Exchange (ETDEWEB)

    Magudeeswaran, G.; Balasubramanian, V. [Centre for Materials Joining Research (CEMAJOR), Department of Manufacturing Engineering, Annamalai University, Annamalai Nagar 608 002, Tamil Nadu (India); Madhusudhan Reddy, G. [Metal Joining Section, Defence Metallurgical Research Laboratory (DMRL), Kanchanbagh (P.O.) Hyderabad 560 058 Andhra Pradesh (India)

    2008-04-15

    Quenched and tempered (Q and T) steels are prone to hydrogen induced cracking (HIC) in the heat affected zone after welding. The use of austenitic stainless steel (ASS) consumables to weld the above steel was the only available remedy because of higher solubility for hydrogen in austenitic phase. The use of stainless steel consumables for a non-stainless steel base metal is not economical. Hence, alternate consumables for welding Q and T steels and their vulnerability to HIC need to be explored. Recent studies proved that low hydrogen ferritic (LHF) steel consumables can be used to weld Q and T steels, which can give very low hydrogen levels in the weld deposits. In this investigation an attempt has been made to study the influence of welding consumables and welding processes on hydrogen induced cold cracking of armour grade Q and T steel welds by implant testing. Shielded metal arc welding (SMAW) and flux cored arc welding (FCAW) processes were used for making welds using ASS and LHF welding consumables. ASS welds made using FCAW process offered a higher resistance to HIC than all other welds considered in this investigation. (author)

  3. High Strength-High Ductility Combination Ultrafine-Grained Dual-Phase Steels Through Introduction of High Degree of Strain at Room Temperature Followed by Ultrarapid Heating During Continuous Annealing of a Nb-Microalloyed Steel

    Science.gov (United States)

    Deng, Yonggang; Di, Hongshuang; Hu, Meiyuan; Zhang, Jiecen; Misra, R. D. K.

    2017-07-01

    Ultrafine-grained dual-phase (UFG-DP) steel consisting of ferrite (1.2 μm) and martensite (1 μm) was uniquely processed via combination of hot rolling, cold rolling and continuous annealing of a low-carbon Nb-microalloyed steel. Room temperature tensile properties were evaluated and fracture mechanisms studied and compared to the coarse-grained (CG) counterpart. In contrast to the CG-DP steel, UFG-DP had 12.7% higher ultimate tensile strength and 10.7% greater uniform elongation. This is partly attributed to the increase in the initial strain-hardening rate, decrease in nanohardness ratio of martensite and ferrite. Moreover, a decreasing number of ferrite grains with {001} orientation increased the cleavage fracture stress and increased the crack initiation threshold stress with consequent improvement in ductility UFG-DP steel.

  4. Possible role of growth regulators in adaptation to heat stress affecting partitioning of photosynthates in tomato plants

    Directory of Open Access Journals (Sweden)

    Zofia Starck

    2014-01-01

    Full Text Available Tomato plants of two cultivars: Roma - sensitive and Robin - tolerant to heat stress were grown in greenhouse up to the flowering stage and then under controlled environmen­tal conditions. The partitioning of recently fixed 14CO2 by mature tomato leaves was examined as a posteffect of 24-h heat stress (38/25°C day/night with the interaction of growth regulators (GR sprayed on the flowers with solution of β-naphthoxyacetic (NOA and gibberellic (GA3 acid (denoted as NG, or Zeatin + NOA + GA3 (denoted as ZNG. In both cuitivars GR strongly stimulated fruit growth and transport of 14C-photosynthates to the clusters at the expense of vegetative organs. Heat stress decreased export of 14C-phoiosynthates from the blades in plants not treated with GR, but even more in cv. Roma. In Roma plants not treated with GR (with very small fruitlets and fruits the heat stress retarded 14C-transport just in the petioles, diminishing the 14C-supply to the fruits. Reduction of the current photosynthate supplied to the fruits seems to be causally connected with inhibition of the specific activity of acid invertase in that organ. Growth regulators reduced the negative effect of high temperature - they alleviated depression of 14C-export from the blades and increased invertase activity. 14C-photosynthate transport to the fruits, presumably owing to their higher sink strength, was less affected by heat stress. In Robin plants (which had bigger fruits during the experiment high temperature depressed 14C-fruit supply only in the NG-series, in contrast to enhacement of 14C-Movement to that sink in the control and ZNG-series. In spite of these facts, after heat stress, the specific activity of acid invertase decreased in all the experimental series, but much less in the GR-treated series. Therefore, in the Robin cv. there was no relation between invertase activity and 14C-mobilization by fruits, as was observed in Roma plants. The possible explanation of the different

  5. Conception rate of artificially inseminated Holstein cows affected by cloudy vaginal mucus, under intense heat conditions

    Directory of Open Access Journals (Sweden)

    Miguel Mellado

    2015-06-01

    Full Text Available The objective of this work was to obtain prevalence estimates of cloudy vaginal mucus in artificially inseminated Holstein cows raised under intense heat, in order to assess the effect of meteorological conditions on its occurrence during estrus and to determine its effect on conception rate. In a first study, an association was established between the occurrence of cloudy vaginal mucus during estrus and the conception rate of inseminated cows (18,620 services, raised under intense heat (mean annual temperature of 22°C, at highly technified farms, in the arid region of northern Mexico. In a second study, data from these large dairy operations were used to assess the effect of meteorological conditions throughout the year on the occurrence of cloudy vaginal mucus during artificial insemination (76,899 estruses. The overall rate of estruses with cloudy vaginal mucus was 21.4% (16,470/76,899; 95% confidence interval = 21.1-21.7%. The conception rate of cows with clean vaginal mucus was higher than that of cows with abnormal mucus (30.6 vs. 22%. Prevalence of estruses with cloudy vaginal mucus was strongly dependent on high ambient temperature and markedly higher in May and June. Acceptable conception rates in high milk-yielding Holstein cows can only be obtained with cows showing clear and translucid mucus at artificial insemination.

  6. FE analysis of cruciform welded joints considering different mechanical properties for base material, heat affected zone and weld metal

    Directory of Open Access Journals (Sweden)

    Pasqualino Corigliano

    2014-10-01

    Full Text Available The aim of this scientific work was to investigate the behaviour of cruciform welded joints under static loading using a full-field technique: Digital Image Correlation. The material curves, relative to different zones (base material, heat affected zone, weld, were obtained by hardness measurements, which were done by means of a fully automated hardness scanner with high resolution. This innovative technique, based on the UCI method, allowed to identify the different zones and to assess their different mechanical properties, which were considered in the finite element model. Finally the finite element model was validated experimentally, comparing the results with the measurements obtained using the Digital Image Correlation technique.

  7. Structural and mechanical properties of welded joints of reduced activation martensitic steels

    Energy Technology Data Exchange (ETDEWEB)

    Filacchioni, G. E-mail: gianni.filacchioni@casaccia.enea.it; Montanari, R.; Tata, M.E.; Pilloni, L

    2002-12-01

    Gas tungsten arc welding and electron beam welding methods were used to realise welding pools on plates of reduced activation martensitic steels. Structural and mechanical features of these simulated joints have been investigated in as-welded and post-welding heat-treated conditions. The research allowed to assess how each welding technique affects the original mechanical properties of materials and to find suitable post-welding heat treatments. This paper reports results from experimental activities on BATMAN II and F82H mod. steels carried out in the frame of the European Blanket Project - Structural Materials Program.

  8. Effect of laser processing on the microstructure of a structural low-carbon steel

    Science.gov (United States)

    Pugacheva, N. B.; Trushina, E. B.; Antenorova, N. P.

    2014-07-01

    The macro- and microstructures and the distribution of microhardness over the height and width of the remelted and heat-affected zones in structural low-carbon grade 20 steel (1020 AISI) are investigated after laser processing under various conditions, including the application of an electric arc.

  9. Measuring Dilution and Wear for Laser Cladding of Stellite 6 Produced on a P91 Steel Substrate using Two Different Heat Inputs

    Directory of Open Access Journals (Sweden)

    Kusmoko Alain

    2016-01-01

    Full Text Available Stellite 6 was deposited by laser cladding on a P91 substrate with energy inputs of 1 kW (P91-1 and 1.8 kW (P91–1.8. The chemical compositions, microstructures and surface roughnesses of these coatings were characterized by atomic absorption spectroscopy, scanning electron microscopy and atomic force microscopy. The microhardness of the coatings was measured and the wear mechanism of the coatings was evaluated using a pin-on-plate (reciprocating wear testing machine. The results showed less cracking and pore development for Stellite 6 coatings applied to the P91 steel substrate with the lower heat input (P91–1. Further, the Stellite coating for P91-1 was significantly harder than that obtained for P91–1.8. The wear test results indicated that the weight loss for P91–1 was much lower than for P91–1.8. The surface topography data indicated that the surface roughness for P91-1 was much lower than for P91–1.8. The measurements of dilution and carbon content showed that P91–1 has lower dilution and higher concentration of carbon than P91–1.8. It is concluded that the lower hardness of the coating for P91–1.8, together with the softer underlying substrate structure, markedly reduced the wear resistance of the Stellite 6 coating and the lower hardness of the coating for P91-1.8 was due to higher level of dilution and lower concentration of carbon.

  10. Improved Life of Die Casting Dies of H13 Steel by Attaining Improved Mechanical Properties and Distortion Control During Heat Treatment

    Energy Technology Data Exchange (ETDEWEB)

    J. F. Wallace; D. Schwam

    1998-10-01

    The ultimate goal of this project is to increase die casting die life by using fast enough quenching rates to obtain good toughness and fatigue resistance in premium grade H-13 steel dies. The main tasks of the project were to compile a database on physical and mechanical properties of H-13; conduct gas quenching experiments to determine cooling rates of dies in difference vacuum furnaces; measure the as-quenched distortion of dies and the residual stresses; generate finite element analysis models to predict cooling rates, distortion, and residual stress of gas quenched dies; and establish rules and create PC-based expert system for prediction of cooling rates, distortion, and residual stress in vacuum/gas quenched H-13 dies. Cooling curves during gas quenching of H-13 blocks and die shapes have been measured under a variety of gas pressure. Dimensional changes caused by the gas quenching processes have been determined by accurate mapping of all surfaces with coordinate measuring machines before and after the quench. Residual stresses were determined by the ASTM E837 hole-drilling strain gage method. To facilitate the computer modeling work, a comprehensive database of H-13 mechanical and physical properties has been compiled. Finite element analysis of the heat treated shapes has been conducted using the TRAST/ABAQUS codes. There is a good fit between the predicted and measured distortion contours. However, the magnitude of the predicted distortion and residual stresses does not match well the measured values. Further fine tuning of the model is required before it can be used to predict distortion and residual stress in a quantitative manner. This last step is a prerequisite to generating rules for a reliable expert system.

  11. Microstructure development of welding joints in high Cr ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Kubushiro, Keiji; Takahashi, Satoshi; Morishima, Keiko [IHI Corporation (Japan). Research Lab.

    2010-07-01

    Creep failure in high Cr ferritic steels welding joints are Type IV failure. Type IV-failure was ruptured in fine grained region of heat affected zone, microstructure and phase transformation process at welding in fine grained region were very important to clarify. Microstructure difference of heat affected zone was investigated in Gr.91, Gr.92, Gr.122 welding joint. The fraction of 60 degree block boundary, packet boundary, random boundary (including prior gamma boundary) length was compared in three ferritic steels by EBSP(Electron Backscatter Diffraction Pattern) analysis. HAZ was almost fully martensite phase in Gr.122 weld joint. On the other hand, HAZ in Gr.91 welding joint were some equiaxial grain and martensite structure. (orig.)

  12. Numerical investigation of MHD heat transfer in a vertical round tube affected by transverse magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Zikanov, Oleg [University of Michigan - Dearborn, MI 48128-1491 (United States); Listratov, Yaroslav [Moscow Power Engineering Institute, 14 Karsnokazarmennaya St., Moscow 111250 (Russian Federation)

    2016-12-15

    Numerical simulations of the flow of a liquid metal in a vertical pipe are performed. The configuration reproduces the test section of the recent experiment . The mean flow is directed downward, a half of the pipe's wall is heated, and a strong horizontal magnetic field perpendicular to the temperature gradient is imposed. The simulations produce results in good agreement with the experiment and lead us to an explanation of the observed phenomenon of anomalous high-amplitude temperature fluctuations. The fluctuations are caused by growth and quasi-periodic breakdown of the pairs of ascending and descending jets related to the elevator-mode thermal convection. Implications for operation of liquid metal blankets with poloidal ducts are discussed.

  13. Heat Stress Affects Pi-related Genes Expression and Inorganic Phosphate Deposition/Accumulation in Barley.

    Science.gov (United States)

    Pacak, Andrzej; Barciszewska-Pacak, Maria; Swida-Barteczka, Aleksandra; Kruszka, Katarzyna; Sega, Pawel; Milanowska, Kaja; Jakobsen, Iver; Jarmolowski, Artur; Szweykowska-Kulinska, Zofia

    2016-01-01

    Phosphorus (P) in plants is taken from soil as an inorganic phosphate (Pi) and is one of the most important macroelements in growth and development. Plants actively react to Pi starvation by the induced expression of Pi transporters, MIR399, MIR827, and miR399 molecular sponge - IPS1 genes and by the decreased expression of the ubiquitin-conjugating enzyme E2 (PHOSPHATE2 - PHO2) and Pi sensing and transport SPX-MFS genes. The PHO2 protein is involved in the degradation of Pi transporters PHT1;1 (from soil to roots) and PHO1 (from roots to shoots). The decreased expression of PHO2 leads to Pi accumulation in shoots. In contrast, the pho1 mutant shows a decreased level of Pi concentration in shoots. Finally, Pi starvation leads to decreased Pi concentration in all plant tissues. Little is known about plant Pi homeostasis in other abiotic stress conditions. We found that, during the first hour of heat stress, Pi accumulated in barley shoots but not in the roots, and transcriptomic data analysis as well as RT-qPCR led us to propose an explanation for this phenomenon. Pi transport inhibition from soil to roots is balanced by lower Pi efflux from roots to shoots directed by the PHO1 transporter. In shoots, the PHO2 mRNA level is decreased, leading to an increased Pi level. We concluded that Pi homeostasis in barley during heat stress is maintained by dynamic changes in Pi-related genes expression.

  14. Heat and water transfer at the bare soil surface : aspects affecting thermal imagery

    NARCIS (Netherlands)

    Berge, ten H.F.M.

    1986-01-01

    Surface temperature as assessed by means of thermal infra red remote sensing is affected by a number of soil properties. The sensitivity of surface temperature and surface energy fluxes to variations in physical soil properties is studied by means of a numerical simulation

  15. Long-Term Acclimation to Different Thermal Regimes Affects Molecular Responses to Heat Stress in a Freshwater Clam Corbicula Fluminea

    Science.gov (United States)

    Falfushynska, Halina I.; Phan, Tuan; Sokolova, Inna M.

    2016-12-01

    Global climate change (GCC) can negatively affect freshwater ecosystems. However, the degree to which freshwater populations can acclimate to long-term warming and the underlying molecular mechanisms are not yet fully understood. We used the cooling water discharge (CWD) area of a power plant as a model for long-term warming. Survival and molecular stress responses (expression of molecular chaperones, antioxidants, bioenergetic and protein synthesis biomarkers) to experimental warming (20-41 °C, +1.5 °C per day) were assessed in invasive clams Corbicula fluminea from two pristine populations and a CWD population. CWD clams had considerably higher (by ~8-12 °C) lethal temperature thresholds than clams from the pristine areas. High thermal tolerance of CWD clams was associated with overexpression of heat shock proteins HSP70, HSP90 and HSP60 and activation of protein synthesis at 38 °C. Heat shock response was prioritized over the oxidative stress response resulting in accumulation of oxidative lesions and ubiquitinated proteins during heat stress in CWD clams. Future studies should determine whether the increase in thermal tolerance in CWD clams are due to genetic adaptation and/or phenotypic plasticity. Overall, our findings indicate that C. fluminea has potential to survive and increase its invasive range during warming such as expected during GCC.

  16. Short communication: A comparison of biofilm development on stainless steel and modified-surface plate heat exchangers during a 17-h milk pasteurization run.

    Science.gov (United States)

    Jindal, Shivali; Anand, Sanjeev; Metzger, Lloyd; Amamcharla, Jayendra

    2018-02-02

    Flow of milk through the plate heat exchanger (PHE) results in denaturation of proteins, resulting in fouling. This also accelerates bacterial adhesion on the PHE surface, eventually leading to the development of biofilms. During prolonged processing, these biofilms result in shedding of bacteria and cross-contaminate the milk being processed, thereby limiting the duration of production runs. Altering the surface properties of PHE, such as surface energy and hydrophobicity, could be an effective approach to reduce biofouling. This study was conducted to compare the extent of biofouling on native stainless steel (SS) and modified-surface [Ni-P-polytetrafluoroethylene (PTFE)] PHE during the pasteurization of raw milk for an uninterrupted processing run of 17 h. For microbial studies, raw and pasteurized milk samples were aseptically collected from inlets and outlets of both PHE at various time intervals to examine shedding of bacteria in the milk. At the end of the run, 3M quick swabs (3M, St. Paul, MN) and ATP swabs (Charm Sciences Inc., Lawrence, MA) were used to sample plates from different sections of the pasteurizers (regeneration, heating, and cooling) for biofilm screening and to estimate the efficiency of cleaning in place, respectively. The data were tested for ANOVA, and means were compared. Modified PHE experienced lower mesophilic and thermophilic bacterial attachment and biofilm formation (average log 1.0 and 0.99 cfu/cm 2 , respectively) in the regenerative section of the pasteurizer compared with SS PHE (average log 1.49 and 1.47, respectively). Similarly, higher relative light units were observed for SS PHE compared with the modified PHE, illustrating the presence of more organic matter on the surface of SS PHE at the end of the run. In addition, at h 17, milk collected from the outlet of SS PHE showed plate counts of 5.44 cfu/cm 2 , which were significantly higher than those for pasteurized milk collected from modified PHE (4.12 log cfu/cm 2 ). This

  17. Steel making

    CERN Document Server

    Chakrabarti, A K

    2014-01-01

    "Steel Making" is designed to give students a strong grounding in the theory and state-of-the-art practice of production of steels. This book is primarily focused to meet the needs of undergraduate metallurgical students and candidates for associate membership examinations of professional bodies (AMIIM, AMIE). Besides, for all engineering professionals working in steel plants who need to understand the basic principles of steel making, the text provides a sound introduction to the subject.Beginning with a brief introduction to the historical perspective and current status of steel making together with the reasons for obsolescence of Bessemer converter and open hearth processes, the book moves on to: elaborate the physiochemical principles involved in steel making; explain the operational principles and practices of the modern processes of primary steel making (LD converter, Q-BOP process, and electric furnace process); provide a summary of the developments in secondary refining of steels; discuss principles a...

  18. Weldability of helium-containing stainless steels using a YAG laser

    Science.gov (United States)

    Kawano, S.; Nakahigashi, S.; Uesugi, K.; Nakamura, H.; Kono, W.; Fukuya, K.; Kano, F.; Hasegawa, A.; Abe, K.

    1998-10-01

    Bead-on-plate welding experiments using a 400 W YAG laser were conducted on SUS304 stainless steels implanted with helium ions of 0.5, 5 and 50 appm uniformly to a depth of 0.25 mm. High heat input welding at 20 kJ/cm caused surface grain boundary cracking in the heat-affected zone at 50 appm He. Cross-sectional observations after etching in oxalic acid solution revealed that bubble growth at grain boundaries in the heat-affected zone was enhanced at higher heat input and at higher helium concentrations. Bubble growth was negligible for the laser welding condition of 1 kJ/cm even at 50 appm He. The results suggest that YAG laser welding is a promising welding technique for stainless steels containing high amounts of helium.

  19. Joining dissimilar stainless steels for pressure vessel components

    Science.gov (United States)

    Sun, Zheng; Han, Huai-Yue

    1994-03-01

    A series of studies was carried out to examine the weldability and properties of dissimilar steel joints between martensitic and austenitic stainless steels - F6NM (OCr13Ni4Mo) and AISI 347, respectively. Such joints are important parts in, e.g. the primary circuit of a pressurized water reactor (PWR). This kind of joint requires both good mechanical properties, corrosion resistance and a stable magnetic permeability besides good weldability. The weldability tests included weld thermal simulation of the martensitic steel for investigating the influence of weld thermal cycles and post-weld heat treatment (PWHT) on the mechanical properties of the heat-affected zone (HAZ); implant testing for examining the tendency for cold cracking of martensitic steel; rigid restraint testing for determining hot crack susceptibility of the multi-pass dissimilar steel joints. The joints were subjected to various mechanical tests including a tensile test, bending test and impact test at various temperatures, as well as slow strain-rate test for examining the stress corrosion cracking tendency in the simulated environment of a primary circuit of a PWR. The results of various tests indicated that the quality of the tube/tube joints is satisfactory for meeting all the design requirements.

  20. Electroslag remelting of high-speed steel using a magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Murgas, M.

    2000-10-01

    The electroslag remelting process was studied when the consumable electrode made from the powder of M2 type high-speed steel was used and the effect of outside magnetic field was applied. The electromagnetic forces that arise from the interaction between the outside direct magnetic field and the one-phase electric current of the electroslag remelting process by a monofilar scheme alter the mechanism of the electrode remelting and thus, affect the solidification of a high-speed steel and its structure. The cast cutting tips made from ingots produced by this technology had tool life to be comparable to that of standard ones made from the wrought steel of the identical chemical composition and heat treatment. It has been shown that a magnetic field also affects both the temperature ranges and the kinetics of phase transformation in a high-speed steel. This suggestion is proved by DTA measurements. (author)

  1. Evaluation of variables affecting crack propagation by Delayed Hydride Cracking in Zr-2.5Nb with different heat treatments

    Energy Technology Data Exchange (ETDEWEB)

    Mieza, J.I., E-mail: mieza@cnea.gov.ar [CNEA, Centro Atomico Constituyentes, Dano por Hidrogeno, Av. Gral. Paz 1499, San Martin (B1650KNA), Bs. As. (Argentina); Instituto Sabato, UNSAM-CNEA, Av. Gral. Paz 1499, San Martin (B1650KNA), Bs. As. (Argentina); Vigna, G.L.; Domizzi, G. [CNEA, Centro Atomico Constituyentes, Dano por Hidrogeno, Av. Gral. Paz 1499, San Martin (B1650KNA), Bs. As. (Argentina)

    2011-04-15

    Delayed Hydride Cracking (DHC) is a failure mechanism that may occur in zirconium alloys used in nuclear reactor core components. The knowledge of the direct effects of the variables affecting the cracking velocity could be used to minimize the risk of crack propagation. In practice, most of these variables - as for example the alloy yield stress and hydrogen diffusion coefficient - are coupled and vary during reactor operation, leading to a complex variable dependence of the cracking mechanism. In order to get an insight into the relative effect of these variables, experimental data and a theoretical approach using a generally accepted DHC model were used in this work. A series of DHC velocity measurements were made in Zr-2.5Nb tube with different heat treatments. The yield stress, the Nb concentration in {beta} phase, and hydrogen solvus of the alloy were measured for different heat treatments. Niobium concentration in {beta} phase gave an indirect indication of {beta}-phase continuity and, with a proper correlation, of the hydrogen diffusion coefficient. The obtained values were used as inputs in a theoretical calculation of cracking velocity. Good agreement between experimental data and predicted values was obtained, showing that hydrogen diffusion coefficient was the most relevant variable affecting DHC velocity cracking. Furthermore, this approach has been demonstrated to be useful in estimating DHC velocity in irradiated materials.

  2. Oxy-Hydrogen Flame for Cutting of Steels

    OpenAIRE

    Tušek, J.; Šraj, M.

    2007-01-01

    The paper deals with oxy-hydrogen cutting of steel plates. The first part deals with calculation of the combustion efficiency of an oxy-hydrogen flame. A device for supply of a hydrogen-oxygen mixture is described. The main part of the paper is focused on oxy-hydrogen cutting and its advantages. The main conclusions show that the cut surface is flat and very smooth, the heat-affected zone is very narrow, and the cutting speed is relatively high.

  3. Impurity Antimony-Induced Creep Property Deterioration and Its Suppression by Rare Earth Ceriumfor a 9Cr-1Mo Ferritic Heat-Resistant Steel

    Directory of Open Access Journals (Sweden)

    Yewei Xu

    2016-08-01

    Full Text Available The high temperature creep properties of three groups of modified 9Cr-1Mo steel samples, undoped, doped with Sb, and doped with Sb and Ce, are evaluated under the applied stresses from 150 MPa to 210 MPa and at the temperatures from 873–923 K. The creep behavior follows the temperature-compensated power law as well as the Monkman-Grant relation. The creep activation energy for the Sb-doped steel (519 kJ/mol is apparently lower than that for the undoped one (541 kJ/mol, but it is considerably higher for the Sb+Ce-doped steel (621 kJ/mol. Based on the obtained relations, both the creep lifetimes under 50 MPa, 80 MPa, and 100 MPa in the range 853–923 K and the 105 h creep rupture strengths at 853 K, 873 K, and 893 K are predicted. It is demonstrated that the creep properties of the Sb-doped steel are considerably deteriorated but those of the Sb+Ce-doped steel are significantly improved as compared with the undoped steel. Microstructural and microchemical characterizations indicate that the minor addition of Ce can stabilize the microstructure of the steel by segregating to grain boundaries and dislocations, thereby offsetting the deleterious effect of Sb by coarsening the microstructure and weakening the grain boundary.

  4. Heat Stress Affects Pi-related Genes Expression and Inorganic Phosphate Deposition/Accumulation in Barley

    DEFF Research Database (Denmark)

    Pacak, Andrzej; Barciszewska-Pacak, Maria; Swida-Barteczka, Aleksandra

    2016-01-01

    and by the decreased expression of the ubiquitin-conjugating enzyme E2 (PHOSPHATE2 - PHO2) and Pi sensing and transport SPX-MFS genes. The PHO2 protein is involved in the degradation of Pi transporters PHT1;1 (from soil to roots) and PHO1 (from roots to shoots). The decreased expression of PHO2 leads to Pi......Phosphorus (P) in plants is taken from soil as an inorganic phosphate (Pi) and is one of the most important macroelements in growth and development. Plants actively react to Pi starvation by the induced expression of Pi transporters, MIR399, MIR827, and miR399 molecular sponge - IPS1 genes...... of heat stress, Pi accumulated in barley shoots but not in the roots, and transcriptomic data analysis as well as RT-qPCR led us to propose an explanation for this phenomenon. Pi transport inhibition from soil to roots is balanced by lower Pi efflux from roots to shoots directed by the PHO1 transporter...

  5. Creep properties of PWC-11 base metal and weldments as affected by heat treatment

    Energy Technology Data Exchange (ETDEWEB)

    Titran, R.H.; Moore, T.J.; Grobstein, T.L. [Lewis Research Center, Cleveland, OH (United States)

    1994-09-01

    In a preliminary study using single specimens for each condition, PWC-11 (a niobium-base alloy with a nominal composition of Nb-1%Zr-0.1%C) was creep tested at 1350 K and 40 MPa. Base metal specimens and specimens with transverse electrode beam welds were tested with and without a 1000 hr, 1350 K aging treatment prior to testing. In the annealed condition (1 hr at 1755 K + 2 hr at 1475 K), the base metal exhibited superior creep strength compared to the aged condition, reaching 1 percent strain in 3480 hr. A 1000 hr, 1350 K aging treatment prior to creep testing had a severe detrimental effect on creep strength of the base metal and transverse electron beam weldments, reducing the time to attain 1 percent strain by an order of magnitude. Extrapolated temperature compensated creep rates indicate that the present heat of PWC-11 may be four times as creep resistance as similarly tested Nb-1%Zr. The extrapolated stress to achieve 1 percent creep strain in 7 yr at 1350 K is 0.6 MPa for annealed Nb-1%Zr and 2.8 MPa for annealed and aged PWC-11 base metal with and without a transverse electron beam weld.

  6. The method for reproducing fine grained HAZ of W strengthened high Cr steel

    OpenAIRE

    Wang, Xue Z.; Xu, Qiang; Liu, Hong-wei; Shang, Wei; Ren, Yao-yao; Yu, Shu-min

    2014-01-01

    The methods for reproducing fine grained heat affected zone of high Cr steel for creep test were investigated. This research was motivated by the need for reproducing uniform FGHAZ to investigate the creep damage process and untangle the coupling between thermal aging and cavitation (nucleation, growth, and coalesce), and the influence of states of stress. The two methods for producing FGHAZ were weld simulator and heat treatment in furnace. The microstructures, hardness, and creep rupture ti...

  7. Measurement and analysis of SHCCT diagram for CLAM steel

    Energy Technology Data Exchange (ETDEWEB)

    Huang Yuming [School of Materials Science and Engineering, Jiangsu University, ZhenJiang, Jiangsu 212013 (China); Chen Xizhang, E-mail: kernel.chen@gmail.com [School of Materials Science and Engineering, Jiangsu University, ZhenJiang, Jiangsu 212013 (China); Shen Zheng [School of Materials Science and Engineering, Jiangsu University, ZhenJiang, Jiangsu 212013 (China); Madigan, Bruce [Montana Tech. of University of Montana, Butte, MT 59701 (United States); Yucheng, Lei [School of Materials Science and Engineering, Jiangsu University, ZhenJiang, Jiangsu 212013 (China); Zhou Jianzhong [School of Mechanical Engineering, Jiangsu University, ZhenJiang, Jiangsu 212013 (China)

    2013-01-15

    China Low Activation Martensitic (CLAM) steel is a leading candidate material for construction of the Chinese fusion reactor Test Blanket Module. The Simulated HAZ Continuous Cooling Transformation (SHCCT) diagram is developed via physical simulation, and the effects of thermal history on the microstructure and mechanical properties of the weld coarse-grain heat-affected zone (CGHAZ) in CLAM steel are evaluated. The results of thermal cycle simulation show that grain size increases and hardness decreases gradually with increasing heat input. Under certain conditions, especially when cooling times from 800 Degree-Sign C to 500 Degree-Sign C (T8/5) are larger than 136 s, delta ferrite may form which is deleterious for the TBM application. The amounts of delta ferrite are given under different T8/5. A SHCCT diagram of CLAM steel is developed using dilatometry and it predicts the AC1, AC3 and the Ms temperatures. With decreased cooling rate (larger T8/5), martensite laths widen and carbide precipitates grow. The results indicate that welding heat input should be taken into consideration and controlled in practical CLAM steel welding process applications.

  8. Development of novel protective high temperature coatings on heat exchanger steels and their corrosion resistance in simulated coal firing environment; Developpement de revetements pour les aciers d'echangeurs thermiques et amelioration de leur resistance a la corrosion en environnement simulant les fumees de combustion et de charbon

    Energy Technology Data Exchange (ETDEWEB)

    Rohr, V.

    2005-10-15

    Improving the efficiencies of thermal power plants requires an increase of the operating temperatures and thus of the corrosion resistance of heat exchanger materials. Therefore, the present study aimed at developing protective coatings using the pack cementation process. Two types of heat exchanger steels were investigated: a 17% Cr-13% Ni austenitic steel and three ferritic-martensitic steels with 9 (P91 and P92) and 12% Cr (HCM12A). The austenitic steel was successfully aluminized at 950 C. For the ferritic-martensitic steels, the pack cementation temperature was decreased down to 650 C, in order to maintain their initial microstructure. Two types of aluminides, made of Fe{sub 2}Al{sub 5} and FeAl, were developed. A mechanism of the coating formation at low temperature is proposed. Furthermore, combining the pack cementation with the conventional heat treatment of P91 allowed to take benefit of higher temperatures for the deposition of a two-step Cr+Al coating. The corrosion resistance of coated and uncoated steels is compared in simulated coal firing environment for durations up to 2000 h between 650 and 700 C. It is shown that the coatings offer a significant corrosion protection and, thus, an increase of the component lifetime. Finally, the performance of coated 9-12% Cr steels is no longer limited by corrosion but by interdiffusion between the coating and the substrate. (author)

  9. Effects of the heat input in the mechanical integrity of the welding joints welded by GMAW and LBW process in Transformation Induced Plasticity steel (TRIP used in the automotive industry

    Directory of Open Access Journals (Sweden)

    Victor H. López Cortéz

    2010-09-01

    Full Text Available In this work an Advanced High Strength Steel (AHSS sheet of the Transformation Induced Plasticity (TRIP type currently employed in the automotive sector was welded using a Gas Metal Arc Welding (GMAW and a CO2 Laser Beam Welding (LBW processes. The mechanical properties of welded tensile specimens including microhardness were determined and the results were related to the exhibited microstructures. It was found that LBW lead to relatively high hardness in the fusion zone (FZ indicating that the resultant microstructure was predominantly martensite. In the Heat Affected Zone (HAZ, a mixture of phases consisting of bainite and ferrite was present. Similar phase mixtures were found in the HAZ and Fusion Zone (FZ of the GMAW samples. The exhibited microstructure did not result in mechanical degradation when the GMAW specimens were tested in tension as all the fractures occurred in the BM. In contrast, the region adjacent to the HAZ of most tensile specimens welded using LBW failed by brittle cleavage. Apparently, in this region tempering effects due to heat dissipation in the LBW process promoted carbide growth and a relatively coarse microstructure. No embrittlement was found that could be associated with the development of martensite.Neste trabalho, uma chapa de aço de alta resistência (AHSS - Advanced High Strength Steel tipo TRIP (Transformation Induced Plasticity empregado atualmente no setor automotivo foi soldado usando o processo de soldagem a arco com arame solido sob proteção gasosa (GMAW e soldagem com LASER de CO2 (LBW. As propriedades mecânicas das amostras soldadas quanto a tração e microdureza foram determinadas e os resultados foram relacionados com as microestruturas apresentadas. Verificou-se que a solda com LBW chegou a valores realtivamente altos de dureza na zona fundida (ZF, indicando que a microestrutura resultante foi predominantemente de martensita. Na zona termicamente afetadas (ZTA, encontrou-se uma mistura de fases

  10. Thermally Stable Nanocrystalline Steel

    Science.gov (United States)

    Hulme-Smith, Christopher Neil; Ooi, Shgh Woei; Bhadeshia, Harshad K. D. H.

    2017-10-01

    Two novel nanocrystalline steels were designed to withstand elevated temperatures without catastrophic microstructural changes. In the most successful alloy, a large quantity of nickel was added to stabilize austenite and allow a reduction in the carbon content. A 50 kg cast of the novel alloy was produced and used to verify the formation of nanocrystalline bainite. Synchrotron X-ray diffractometry using in situ heating showed that austenite was able to survive more than 1 hour at 773 K (500 °C) and subsequent cooling to ambient temperature. This is the first reported nanocrystalline steel with high-temperature capability.

  11. A Modified HR3C Austenitic Heat-Resistant Steel for Ultra-supercritical Power Plants Applications Beyond 650 °C

    Science.gov (United States)

    Zhu, C. Z.; Yuan, Y.; Zhang, P.; Yang, Z.; Zhou, Y. L.; Huang, J. Y.; Yin, H. F.; Dang, Y. Y.; Zhao, X. B.; Lu, J. T.; Yan, J. B.; You, C. Y.

    2018-02-01

    A modified HR3C austenitic steel has been designed by optimizing the chemical composition. Compared with a commercial HR3C alloy, the modified steel has comparable oxidation resistance, yield strength, and plasticity, but higher creep rupture strength and impact toughness after long-term thermal exposure. The results suggest that the modified alloy is a promising candidate for the applications of ultra-supercritical power plants operating beyond 650 °C.

  12. The influence of electron-beam welding parameters on heat-affected-zone microfissuring in INCOLOY 903

    Science.gov (United States)

    Richards, N. L.; Nakkalil, R.; Chaturvedi, M. C.

    1994-08-01

    The microfissuring in the heat-affected zone (HAZ) of electron-beam-(EB-) welded thermomechanically processed INCOLOY 903 has been studied with a view to reducing the incidence of microfissuring and to obtaining a better understanding of the influence of EB welding parameters on it. For a given heat of material, microfissuring susceptibility has been quantitatively related to EB welding parameters and the shape of the weld pool. Fractional factorial experimental study of welding parameters showed that a reduction in welding speed and an increase in EB current for a given heat input would minimize HAZ microfissuring in the alloy. It was observed that with lower travel speeds, bccause of the shallower temperature gradients in the HAZ, the amount of liquated grain boundary area is less, thus leading to decreased microfissuring. Considerable HAZ microfissuring was observed on the coarse grain boundaries of warm-worked grains. The microfissures appeared to initiate in regions slightly removed from the fusion line. Minimal microfissuring was observed on the grain boundaries of fine recrystallized grains. These boundaries, however, had a thickened appearance bccause of the formation of Nb-enriched y phase by the process of grain boundary liquid film migration (LFM). The origin of the liquid on the grain boundaries is suggested to be due to the constitutional liquation of preexisting primary carbides (partial), fine MC carbides, and MNP-type phosphides. It is suggested that substantial occurrence of LFM in the HAZ minimizes microfissuring by decreasing the total temperature range of solidification and also by enabling the grain boundary liquid to solidify without the occurrence of low-melting terminal eutectic reaction.

  13. Effect of heat input on microstructure and properties of hybrid fiber laser-arc weld joints of the 800 MPa hot-rolled Nb-Ti-Mo microalloyed steels

    Science.gov (United States)

    Wang, X.-N.; Zhang, S.-H.; Zhou, J.; Zhang, M.; Chen, C.-J.; Misra, R. D. K.

    2017-04-01

    Hybrid fiber laser-arc welding (HLAW) process was applied to a novel hot-rolled Nb-Ti-Mo microalloyed steels of 8 mm thickness. The steel is primarily used to manufacture automotive and construction machinery components, etc. To elucidate the effect of heat input on geometry, microstructure and mechanical properties, different heat inputs (3.90, 5.20 and 7.75 kJ/cm) were used by changing the welding speeds. With increased heat input, the depth/width of penetration was decreased, and the geometry of fusion zone (FZ) changed to "wine cup-like" shape. In regard to the microstructural constituents, the martensite content was decreased, but granular bainite (GB) content was increased. The main microstructural difference was in the FZ cross-section at 7.75 kJ/cm because of the effect of thermal source on the top and bottom. The microstructure of the top part consisted of GB, grain boundary ferrite, and acicular ferrite, while the bottom part was primarily lath martensite. The hardness distribution was similar for different heat inputs. Hardness in FZ, coarse-grained HAZ and mixed-grained HAZ was higher than the base metal (BM), but for the fine-grained HAZ was similar or marginally less than the base metal (BM). Tensile strain was concentrated in the BM such that the fracture occurred in this region. In summary, the geometry, microstructure, and mechanical properties of weld joints were superior at heat input of 5.20 kJ/cm.

  14. Oral administration of γ-aminobutyric acid affects heat production in a hot environment in resting humans

    Directory of Open Access Journals (Sweden)

    Miyazawa Taiki

    2012-02-01

    Full Text Available Abstract Background Central administration of γ-amino butyric acid (GABA induces lower body temperature in animals in hot ambient air. However, it is still unknown whether oral GABA administration affects temperature regulation at rest in a hot environment in humans. Therefore, in the present study, we specifically hypothesized that systemic administration of GABA in humans would induce hypothermia in a hot environment and that this response would be observed in association with decreased heat production. Methods Eight male participants drank a 200-ml sports drink with 1 g of GABA (trial G or without GABA (trial C, then rested for 30 minutes in a sitting position in a hot environment (ambient air temperature 33°C, relative humidity 50%. Results We found that changes in esophageal temperature from before drinking the sports drink were lower in trial G than in trial C (-0.046 ± 0.079°C vs 0.001 ± 0.063°C; P 2 vs 47 ± 8 W/m2; P Conclusions In this study, we have demonstrated that a single oral administration of GABA induced a larger decrease in body core temperature compared to a control condition during rest in a hot environment and that this response was concomitant with a decrease in total heat production.

  15. Heat-Affected Zone Liquation Cracking Resistance of Friction Stir Processed Aluminum-Copper Alloy AA 2219

    Science.gov (United States)

    Karthik, G. M.; Janaki Ram, G. D.; Kottada, Ravi Sankar

    2017-04-01

    In the current work, the effect of friction stir processing on heat-affected zone (HAZ) liquation cracking resistance of aluminum-copper alloy AA 2219 was evaluated. In Gleeble hot-ductility tests and longitudinal Varestraint tests, the FSPed material, despite its very fine dynamically recrystallized equiaxed grain structure, showed considerably higher susceptibility to HAZ liquation cracking when compared to the base material. Detailed microstructural studies showed that the increased cracking susceptibility of the FSPed material is due to (i) increase in the amount of liquating θ phase (equilibrium Al2Cu) and (ii) increase in the population of grain boundary θ particles. An important learning from the current work is that, in certain materials like alloy 2219, the use of FSP as a pretreatment to fusion welding can be counterproductive.

  16. Mechanical properties of duple stainless steels laser joints; Propiedades mecanicas de las uniones por laser de aceros inoxidables duplex

    Energy Technology Data Exchange (ETDEWEB)

    Amigo, V.; Bonache, V.; Teruel, L.; Vicente, A.

    2005-07-01

    The welded joints of stainless steels always present problems for the microstructural modifications that occur in the heat affected zone. Particularly, duplex stainless steels present very important changes when the weld pool solidifies forming fundamentally ferritic structures with some austenite in grain boundaries. These microstructural modifications, and those which occur in the HAZ, justify the mechanical properties of the joint and mainly those of plasticity, being all of them influenced by the processing conditions. In this work the influence of the laser welding speed on the tensile behaviour od duplex stainless steel welded joints is presented. The microstructure of the obtained seams and of the heat affected zone will be evaluated by means of optic and scanning electron microscopy. Also, different microhardness profiles have been obtained to evaluate the modifications in the mechanical properties both in the seam and the zone of thermal affection. (Author) 23 refs.

  17. Corrosion behavior of stainless steel weldments in physiological solutions

    Science.gov (United States)

    Farooq, A.; Azam, M.; Deen, K. M.

    2018-01-01

    In this study corrosion behavior of TIG welded 316L stainless steel plates in simulated biological solutions is investigated. The mechanical testing results showed slight decrease in ductility after welding and the fracture surface represented mixed cleavage and inclusions containing dimple structure. The heat affected and weld zone (WZ) demonstrated higher corrosion potential and relatively large pitting tendency than base metal (BM) in both Hank’s and Ringer’s solution. The formation of delta (δ) ferrite in the heat affected and WZ decreased the corrosion resistance as confirmed from potentiodynamic Tafel scans. The decrease in pitting resistance and lower protection tendency of the WZ compared to BM and heat affected zone was also quantified from the cyclic polarization trends.

  18. Experiences with austenitic steels in boiling water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Wachter, O. [Preussische Elektrizitaets-AG (Preussenelektra), Hannover (Germany); Bruemmer, G. [Hamburgische Electricitaets-Werke AG., Hamburg (Germany)

    1997-05-01

    Stabilized austenitic steels are susceptible to intergranular stress corrosion cracking (IGSCC) under boiling water reactor (BWR) conditions. This important finding for the German nuclear power station industry arises from the detection of cracks during the last 3 years in reactor hot water pipes made from titanium-stabilized steel AISI 321 in six BWRs and in reactor core components made from the niobium-stabilized steel AISI 347 in one BWR. All the observed cracks had a common feature: they had their origin in the chromium carbide precipitates at the grain boundaries and in the associated chromium-depleted region near the grain boundary. These microstructural features in the heat-affected zones of the hot water pipe weldments were caused by the heat input during deposition of the root bead. The TiC partially dissolved in the region near the fusion line and the released carbon reacted to form chromium-rich M{sub 23}C{sub 6}. Regarding the cracks found in the core shroud and the core grid plates, it was shown that a sensitizing heat treatment of rings taken from the same heat of steel could give rise to a microstructure susceptible to IGSCC in the region of a weldment. High carbon contents coupled with low stabilization ratios led to sensitization. Residual stresses developed during welding provided the significant contributions to the tensile stress necessary for IGSCC. With regard to the service medium, the influence of the electrochemical corrosion potential (ECP) was recognized as a dominant factor, together with the conductivity. The corrosion potential was mainly determined by the radiolytic formation of H{sub 2}O{sub 2}; with increasing distance from the core, the H{sub 2}O{sub 2} content decreased owing to catalytic decomposition. For the pipes the problem of IGSCC could be resolved by the use of optimized steel (lower carbon content with maximum allowable stabilization ratio).

  19. Heating up Climate Literacy Education: Understanding Teachers' and Students' Motivational and Affective Response to Climate Change

    Science.gov (United States)

    Sinatra, G. M.

    2011-12-01

    Changing students' ideas about controversial scientific issues, such as human-induced climate change, presents unique challenges for educators (Lombardi & Sinatra, 2010; Sinatra & Mason, 2008). First, climate science is complex and requires "systems thinking," or the ability to think and reason abstractly about emergent systems (Goldstone & Sakamoto, 2003). Appreciating the intricacies of complex systems and emergent processes has proven challenging for students (Chi, 2005). In addition to these challenges, there are specific misconceptions that may lead thinking astray on the issue of global climate change, such as the distinction between weather and climate (Lombardi & Sinatra, 2010). As an example, when students are asked about their views on climate change, they often recall individual storm events or very cold periods and use their personal experiences and recollections of short-term temperature fluctuations to assess whether the planet is warming. Beyond the conceptual difficulties, controversial topics offer another layer of challenge. Such topics are often embedded in complex socio-cultural and political contexts, have a high degree of uncertainty, and may be perceived by individuals as in conflict with their personal or religious beliefs (Levinson, 2006, Sinatra, Kardash, Taasoobshirazi, & Lombardi, 2011). Individuals are often committed to their own views on socio-scientific issues and this commitment may serve as a motivation to actively resist new ideas (Dole & Sinatra, 1998). Individuals may also have strong emotions associated with their misconceptions (Broughton, Pekrun, & Sinatra, 2011). Negative emotions, misconceptions, and resistance do not make a productive combination for learning. Further, teachers who find human-induced climate change implausible have been shown to hold negative emotions about having to teach about climate change (Lombardi & Sinatra, in preparation), which could affect how they present the topic to students. In this

  20. Effects of Heat-Affected Zone Microstructure on Fracture Toughness of Two X70 Pipe Girth Welds

    Science.gov (United States)

    Park, Dong-Yeob; Amirkhiz, Babak Shalchi; Gravel, Jean-Philippe; Wang, Yiyu; Li, Leijun; Zavadil, Renata; Liang, Jie; Liu, Pei; He, Anqiang; Arafin, Muhammad

    2017-07-01

    In the previous study, unstable brittle crack extensions were observed during ductile tearing from all the single-edge notched bend [SE(B)] specimens with an initial crack placed in heat-affected zone (HAZ), machined from one of the two studied X70 pipe girth welds, performed at 258 K (-15 °C). Thus their microstructures and properties have been investigated using optical microscopy, microhardness measurement, and advanced scanning electron microscopy and transmission electron microscopy so as to (1) characterize their metallographic properties including crystallographic texture and (2) correlate them with the unstable brittle crack occurrence and propagation. The results suggest that HAZ softening—strength loss—is a major factor responsible for the cleavage occurrence in the given HAZ specimens as it could induce a large local strain concentration by limiting plasticity in base metal when a ductile crack crosses from the HAZ to the base metal. The HAZ softening seems to be associated with the disappearance of pearlite packets in the HAZ region, which presumably occurred during welding, for the given material. High angle grain boundaries in the fine-grained HAZ appear to affect the direction of cleavage propagation at the point of cleavage initiation ( i.e., pop-in).