σ-Phase Precipitation Mechanism of 15Cr-15Ni Titanium-Modified Austenitic Stainless Steel During Long-Term Thermal Exposure

• 来源期刊: 金属学报（英文版）
• 年，卷（期）: 2018,（3）
• 页码范围: 281-289
• 页数: 9页
• 语种: 英文

摘要

The σ-phase precipitation in 20％ cold-worked 15Cr-15Ni titanium-modified austenitic stainless steel was studied during long-term aging treatment.During the isothermal aging stage,the amount of σ-phase was significantly increased at beginning and gradually became constant.The aging time only slightly affected the size and morphology of the σ-phase.Conversely,during the isochronal aging stage,the amount of σ-phase grew rapidly with the increase in the aging temperature.The σ-phase with a large amount of stacking faults was prone to nucleate around the (Ti,Mo)C particles or at the grain boundaries.The (Ti,Mo)C particles can act as effective nucleation sites,where the σ-phase directly precipitates from the austenitic matrix.From this work,the growth of σ-phase is found to be influenced by the aging temperature,and a new mechanism of σ-phase precipitation from austenite has been proposed.