Refinement mechanism of cerium addition on solidification structure and sigma phase of super austenitic stainless steel S32654

2022 ◽  
Vol 102 ◽  
pp. 105-114
Author(s):  
Shucai Zhang ◽  
Jiangtao Yu ◽  
Huabing Li ◽  
Zhouhua Jiang ◽  
Yifeng Geng ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Sigma Phase ◽  
Solidification Structure ◽  
Refinement Mechanism ◽  
Super Austenitic Stainless Steel

scholarly journals Corrosion Behaviors of Super Austenitic Stainless Steel Weld Joints in the As-Welded and Post Weld Heat Treated States

2021 ◽  
Vol 59 (6) ◽  
pp. 374-383
Author(s):  
Dong min Cho ◽  
Jin-seong Park ◽  
Won Ki Jeong ◽  
Seung Gab Hong ◽  
Sung Jin Kim
Keyword(s):  
Heat Treatment ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Pitting Corrosion ◽  
Arc Welding ◽  
Sigma Phase ◽  
Inconel 625 ◽  
Gas Tungsten Arc ◽  
Corrosion Behaviors ◽  
Super Austenitic Stainless Steel

The corrosion behaviors of a combined weld (plasma, gas tungsten arc) joint in a super austenitic stainless steel pipe were investigated using a range of experimental and analytical methods. To ensure superior corrosion resistance, a Ni-based super alloy (Inconel 625) was employed as the welding material only in the gas tungsten arc welding (GTAW). Nevertheless, pitting corrosion occurred preferentially around the sigma phase which had been precipitated in the interdendritic region of the GTAW. This indicated that the Inconel 625, which has a higher pitting resistance equivalent number (PREN), became even more susceptible to pitting corrosion than the base metal (BM). The higher Fe content in the Inconel 625 due to the dilution of Fe, supplied by the leading plasma arc welding, may increase the driving force for the precipitation of sigma phase. It was also revealed that the post weld heat treatment conducted at 1050~1150 oC effectively reduced the fraction of sigma phase precipitated in the weld. Even after such heat treatment, however, pitting corrosion occurred unexpectedly in the center region of the BM. This may be due to additional precipitation of the sigma phase in the BM, caused by inadequate control of the cooling rate during heat treatment at the industrial site.

Research on Precipitation Kinetics of Super Austenitic Stainless Steel with High Mo and N

2014 ◽  
Vol 687-691 ◽  
pp. 4197-4201
Author(s):  
Shu Cai Zhang ◽  
Hong Chun Zhu ◽  
De Gang Liu ◽  
Hao Feng ◽  
Hua Bing Li ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Grain Boundaries ◽  
Sigma Phase ◽  
Optical Microscope ◽  
Precipitation Kinetics ◽  
Incubation Periods ◽  
Austenite Grains ◽  
Super Austenitic Stainless Steel ◽  
Kinetics Of

The precipitates and precipitation kinetics of super austenitic stainless steel with high Mo and N (HHSASS) were investigated by optical microscope (OM), scanning electron microscope (SEM) and quantitative metallography method. The results show that the TTP curves are C-shaped, the “nose” temperatures of precipitation are found to be 1000°C with the incubation periods of 120s and 600s, respectively. At 1000°C, some precipitates form as ellipsoidal-shaped and connect along the grain boundaries first. Then a few precipitates start forming as needle-shaped within austenite grains. Until aging for 300min, the field is filled with needle-shaped precipitates. The main precipitates in HHSASS are Sigma phase and Chi phase that are rich in Cr and Mo. The precipitates on the grain boundaries are ellipsoidal-shaped and those in the austenite grains are needle-shaped. About the structures of precipitates need to be further researched.

Chloride- and sulphate-induced hot corrosion mechanism of super austenitic stainless steel S31254 under dry gas environment

2020 ◽  
Vol 163 ◽  
pp. 108295 ◽  
Author(s):  
Shucai Zhang ◽  
Huabing Li ◽  
Zhouhua Jiang ◽  
Binbin Zhang ◽  
Zhixing Li ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Hot Corrosion ◽  
Corrosion Mechanism ◽  
Gas Environment ◽  
Super Austenitic Stainless Steel
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