The Experts below are selected from a list of 6000 Experts worldwide ranked by ideXlab platform
Lefu Zhang - One of the best experts on this subject based on the ideXlab platform.
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a research on the corrosion and stress corrosion Cracking Susceptibility of 316l stainless steel exposed to supercritical water
Corrosion Science, 2017Co-Authors: Kai Chen, Zhao Shen, Lefu ZhangAbstract:Abstract This study investigated the corrosion and stress corrosion Cracking Susceptibility of 316L stainless steel exposed to 550 °C and 600 °C supercritical water. XRD, SEM, EDS and EBSD analyses have been carried out to characterize the microstructure of the tested specimens. Results indicate that increasing the test temperature reduced the corrosion and SCC resistance of 316L SS. The oxide scale of corroded specimen shows a duplex structure, and the fracture analysis indicates that the formation of Fe3O4 ‘channels’ in the Fe-Cr spinel layer contributes to the intergranular and transgranular SCC of the materials in 550 °C and 600 °C SCW.
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a research on the corrosion and stress corrosion Cracking Susceptibility of 316l stainless steel exposed to supercritical water
Corrosion Science, 2017Co-Authors: Xianglong Guo, Kai Chen, Zhao Shen, Wenhua Gao, Ping Lai, Lefu ZhangAbstract:Abstract This study investigated the corrosion and stress corrosion Cracking Susceptibility of 316L stainless steel exposed to 550 °C and 600 °C supercritical water. XRD, SEM, EDS and EBSD analyses have been carried out to characterize the microstructure of the tested specimens. Results indicate that increasing the test temperature reduced the corrosion and SCC resistance of 316L SS. The oxide scale of corroded specimen shows a duplex structure, and the fracture analysis indicates that the formation of Fe 3 O 4 ‘channels’ in the Fe-Cr spinel layer contributes to the intergranular and transgranular SCC of the materials in 550 °C and 600 °C SCW.
Kai Chen - One of the best experts on this subject based on the ideXlab platform.
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a research on the corrosion and stress corrosion Cracking Susceptibility of 316l stainless steel exposed to supercritical water
Corrosion Science, 2017Co-Authors: Kai Chen, Zhao Shen, Lefu ZhangAbstract:Abstract This study investigated the corrosion and stress corrosion Cracking Susceptibility of 316L stainless steel exposed to 550 °C and 600 °C supercritical water. XRD, SEM, EDS and EBSD analyses have been carried out to characterize the microstructure of the tested specimens. Results indicate that increasing the test temperature reduced the corrosion and SCC resistance of 316L SS. The oxide scale of corroded specimen shows a duplex structure, and the fracture analysis indicates that the formation of Fe3O4 ‘channels’ in the Fe-Cr spinel layer contributes to the intergranular and transgranular SCC of the materials in 550 °C and 600 °C SCW.
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a research on the corrosion and stress corrosion Cracking Susceptibility of 316l stainless steel exposed to supercritical water
Corrosion Science, 2017Co-Authors: Xianglong Guo, Kai Chen, Zhao Shen, Wenhua Gao, Ping Lai, Lefu ZhangAbstract:Abstract This study investigated the corrosion and stress corrosion Cracking Susceptibility of 316L stainless steel exposed to 550 °C and 600 °C supercritical water. XRD, SEM, EDS and EBSD analyses have been carried out to characterize the microstructure of the tested specimens. Results indicate that increasing the test temperature reduced the corrosion and SCC resistance of 316L SS. The oxide scale of corroded specimen shows a duplex structure, and the fracture analysis indicates that the formation of Fe 3 O 4 ‘channels’ in the Fe-Cr spinel layer contributes to the intergranular and transgranular SCC of the materials in 550 °C and 600 °C SCW.
Zhao Shen - One of the best experts on this subject based on the ideXlab platform.
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a research on the corrosion and stress corrosion Cracking Susceptibility of 316l stainless steel exposed to supercritical water
Corrosion Science, 2017Co-Authors: Kai Chen, Zhao Shen, Lefu ZhangAbstract:Abstract This study investigated the corrosion and stress corrosion Cracking Susceptibility of 316L stainless steel exposed to 550 °C and 600 °C supercritical water. XRD, SEM, EDS and EBSD analyses have been carried out to characterize the microstructure of the tested specimens. Results indicate that increasing the test temperature reduced the corrosion and SCC resistance of 316L SS. The oxide scale of corroded specimen shows a duplex structure, and the fracture analysis indicates that the formation of Fe3O4 ‘channels’ in the Fe-Cr spinel layer contributes to the intergranular and transgranular SCC of the materials in 550 °C and 600 °C SCW.
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a research on the corrosion and stress corrosion Cracking Susceptibility of 316l stainless steel exposed to supercritical water
Corrosion Science, 2017Co-Authors: Xianglong Guo, Kai Chen, Zhao Shen, Wenhua Gao, Ping Lai, Lefu ZhangAbstract:Abstract This study investigated the corrosion and stress corrosion Cracking Susceptibility of 316L stainless steel exposed to 550 °C and 600 °C supercritical water. XRD, SEM, EDS and EBSD analyses have been carried out to characterize the microstructure of the tested specimens. Results indicate that increasing the test temperature reduced the corrosion and SCC resistance of 316L SS. The oxide scale of corroded specimen shows a duplex structure, and the fracture analysis indicates that the formation of Fe 3 O 4 ‘channels’ in the Fe-Cr spinel layer contributes to the intergranular and transgranular SCC of the materials in 550 °C and 600 °C SCW.
Kazuyoshi Saida - One of the best experts on this subject based on the ideXlab platform.
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theoretical approach to influence of nitrogen on solidification Cracking Susceptibility of austenitic stainless steels computer simulation of hot Cracking by solidification segregation models
Welding International, 2018Co-Authors: Tomo Ogura, Shinya Ichikawa, Kazuyoshi SaidaAbstract:The effect of nitrogen on the solidification Cracking Susceptibility of austenitic stainless steels (SUS316L and SUS310S) was quantitatively evaluated by transverse-Varestraint test. The amount of ...
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Hot Cracking Susceptibility in Duplex Stainless Steel Welds
Materials Science Forum, 2018Co-Authors: Kazuyoshi Saida, Tomo OguraAbstract:The hot Cracking (solidification Cracking) Susceptibility in the weld metals of duplex stainless steels were quantitatively evaluated by Transverse-Varestraint test with gas tungsten arc welding (GTAW) and laser beam welding (LBW). Three kinds of duplex stainless steels (lean, standard and super duplex stainless steels) were used for evaluation. The solidification brittle temperature ranges (BTR) of duplex stainless steels were 58K, 60K and 76K for standard, lean and super duplex stainless steels, respectively, and were comparable to those of austenitic stainless steels with FA solidification mode. The BTRs in LBW were 10-15K lower than those in GTAW for any steels. In order to clarify the governing factors of solidification Cracking in duplex stainless steels, the solidification segregation behaviours of alloying and impurity elements were numerically analysed during GTAW and LBW. Although the harmful elements to solidification Cracking such as P, S and C were segregated in the residual liquid phase in any joints, the solidification segregation of P, S and C in LBW was inhibited compared with GTAW due to the rapid cooling rate in LBW. It followed that the decreased solidification Cracking Susceptibility of duplex stainless steels in LBW would be mainly attributed to the suppression of solidification segregation of P, S and C.
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Quantitative evaluation of reheat Cracking Susceptibility by in situ observation and measurement using laser confocal microscope
Welding International, 2016Co-Authors: Kazuyoshi Saida, Kazutoshi Nishimoto, Yoji SakataAbstract:AbstractIn the post-weld heat treatment process, the reheat Cracking which might occur in the weldments of low-alloy steels has been a serious problem. So, it is considered to be important to predict the possibility of occurrence of reheat Cracking in these steels. It is however recognized as a time-consuming procedure to evaluate quantitatively the Susceptibility to this type of Cracking. In the present study, a new quantitative evaluation method of reheat Cracking Susceptibility by in situ observation and measurement using a laser confocal microscope has been proposed. Through this new method, the reheat Cracking Susceptibility of any kind of steels can be evaluated with the same standard. Moreover, because the position of the initial crack can be focused and the critical ductility to initiate the crack is measured by in situ observation, the reheat Cracking Susceptibility can be evaluated using only one specimen. So the newly developed method can provide efficient quantitative assessment of the reheat ...
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Evaluation of solidification Cracking Susceptibility in laser welds for type 316FR stainless steel
Welding in the World, 2016Co-Authors: Eunjoon Chun, Kazutoshi Nishimoto, Kazuyoshi SaidaAbstract:Laser beam welding (LBW) transverse-Varestraint tests were performed to quantitatively evaluate the solidification Cracking Susceptibility of laser welds of type 316FR stainless steel with two kinds of filler metal (316FR-A and 316FR-B). This found that as the welding speed increased from 1.67 to 40.0 mm/s, the increase in the solidification brittle temperature range (BTR) was greater in the case of 316FR-B (from 14 to 40 K) than 316FR-A (from 37 to 46 K). Based on theoretical calculations for the temperature range over which both solid and liquid phases coexist, for which Kurz-Giovanola-Trivedi and solidification segregation models were used, the greater increase in BTR with 316FR-B was determined to be due to a larger decrease in δ-ferrite during welding solidification than with 316FR-A. This, in turn, greatly increases the segregation of impurities, which is responsible for the greater temperature range of solid/liquid coexistence when using 316FR-B.
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development of laser beam welding transverse varestraint test for assessment of solidification Cracking Susceptibility in laser welds
Metals and Materials International, 2015Co-Authors: Eunjoon Chun, Kazutoshi Nishimoto, Hayato Baba, Kazuyoshi SaidaAbstract:In order to quantitatively evaluate the solidification Cracking Susceptibility in laser welds of type 310S stainless steel, a transverse-Varestraint testing system using a laser beam welding apparatus was newly constructed. The timing-synchronization between the laser oscillator, welding robot and hydraulic pressure devices was established by employing high-speed camera observations together with electrical signal control among the three components. Moreover, the yoke-drop time measured by the camera was used to prevent underestimation of the crack length. The laser beam melt-run welding used a variable welding speed from 10.0 to 40.0 mm/s, while the gas tungsten arc welding varied the welding speed from 1.67 to 5.00 mm/s. As the welding speed increased from 1.67 to 40.0mm/s, the solidification brittle temperature range of type 310S stainless steel welds was reduced from 146 to 120 K. It follows that employing the laser beam welding process mitigates the solidification Cracking Susceptibility for type 310S stainless steel welds.
Kazutoshi Nishimoto - One of the best experts on this subject based on the ideXlab platform.
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Quantitative evaluation of reheat Cracking Susceptibility by in situ observation and measurement using laser confocal microscope
Welding International, 2016Co-Authors: Kazuyoshi Saida, Kazutoshi Nishimoto, Yoji SakataAbstract:AbstractIn the post-weld heat treatment process, the reheat Cracking which might occur in the weldments of low-alloy steels has been a serious problem. So, it is considered to be important to predict the possibility of occurrence of reheat Cracking in these steels. It is however recognized as a time-consuming procedure to evaluate quantitatively the Susceptibility to this type of Cracking. In the present study, a new quantitative evaluation method of reheat Cracking Susceptibility by in situ observation and measurement using a laser confocal microscope has been proposed. Through this new method, the reheat Cracking Susceptibility of any kind of steels can be evaluated with the same standard. Moreover, because the position of the initial crack can be focused and the critical ductility to initiate the crack is measured by in situ observation, the reheat Cracking Susceptibility can be evaluated using only one specimen. So the newly developed method can provide efficient quantitative assessment of the reheat ...
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Evaluation of solidification Cracking Susceptibility in laser welds for type 316FR stainless steel
Welding in the World, 2016Co-Authors: Eunjoon Chun, Kazutoshi Nishimoto, Kazuyoshi SaidaAbstract:Laser beam welding (LBW) transverse-Varestraint tests were performed to quantitatively evaluate the solidification Cracking Susceptibility of laser welds of type 316FR stainless steel with two kinds of filler metal (316FR-A and 316FR-B). This found that as the welding speed increased from 1.67 to 40.0 mm/s, the increase in the solidification brittle temperature range (BTR) was greater in the case of 316FR-B (from 14 to 40 K) than 316FR-A (from 37 to 46 K). Based on theoretical calculations for the temperature range over which both solid and liquid phases coexist, for which Kurz-Giovanola-Trivedi and solidification segregation models were used, the greater increase in BTR with 316FR-B was determined to be due to a larger decrease in δ-ferrite during welding solidification than with 316FR-A. This, in turn, greatly increases the segregation of impurities, which is responsible for the greater temperature range of solid/liquid coexistence when using 316FR-B.
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development of laser beam welding transverse varestraint test for assessment of solidification Cracking Susceptibility in laser welds
Metals and Materials International, 2015Co-Authors: Eunjoon Chun, Kazutoshi Nishimoto, Hayato Baba, Kazuyoshi SaidaAbstract:In order to quantitatively evaluate the solidification Cracking Susceptibility in laser welds of type 310S stainless steel, a transverse-Varestraint testing system using a laser beam welding apparatus was newly constructed. The timing-synchronization between the laser oscillator, welding robot and hydraulic pressure devices was established by employing high-speed camera observations together with electrical signal control among the three components. Moreover, the yoke-drop time measured by the camera was used to prevent underestimation of the crack length. The laser beam melt-run welding used a variable welding speed from 10.0 to 40.0 mm/s, while the gas tungsten arc welding varied the welding speed from 1.67 to 5.00 mm/s. As the welding speed increased from 1.67 to 40.0mm/s, the solidification brittle temperature range of type 310S stainless steel welds was reduced from 146 to 120 K. It follows that employing the laser beam welding process mitigates the solidification Cracking Susceptibility for type 310S stainless steel welds.
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Influences of phosphorus and sulphur on ductility dip Cracking Susceptibility in multipass weld metal of alloy 690
Science and Technology of Welding and Joining, 2012Co-Authors: Kazuyoshi Saida, Hiroyuki Ogiwara, Y Nomoto, H Okauchi, Kazutoshi NishimotoAbstract:The influence of P and S on ductility dip Cracking Susceptibility in the reheated weld metal of alloy 690 was evaluated by the spot Varestraint test using different alloy 690 filler metals, while varying the contents of P and S. The ductility dip Cracking Susceptibility was reduced with a decrease in the content of P and S in the filler metal; the amount of (P+1·2S) in the weld metal should be limited to 30 ppm in order to prevent microCracking in the multipass weld metal. A numerical simulation of cosegregation behaviour of P and S revealed that both elements were segregated at the grain boundary in the ductility dip temperature range during multipass welding. A molecular orbital analysis has suggested that ductility dip Cracking can be attributed to grain boundary embrittlement due to grain boundary segregation of P and S.
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Hot Cracking Susceptibility of F82H with controlled Ta content
Journal of Nuclear Materials, 2011Co-Authors: Hiroyuki Ogiwara, Hiroaki Mori, Hiroki Tokuichi, Kazuyoshi Saida, Kazutoshi Nishimoto, Hiroyasu TanigawaAbstract:Abstract An important issue in current fusion materials research is finalizing the detailed manufacturing specification for ITER test blanket modules. The objective of this study is to clarify Ta effects of the hot Cracking Susceptibility of welds in F82H steels with controlled Ta contents up to 0.14%. Hot Cracking Susceptibility was evaluated with transverse-Varestraint testing. Hot cracks that occurred in the weld bead during the test were mainly solidification cracks. Maximum length slightly increased with increased Ta content. On the basis of the brittleness temperature range (BTR), evaluated by measuring maximum crack length and welding thermal cycle the BTR was slightly wider due to the increase in Ta content. However, the value of the temperature ranges was about 10 K. The hot Cracking Susceptibility of F82H steel was the same or better than commercial steels.