Effect of Grain Size and Cooling Rate on the Martensite Start Temperature of Stainless Steel

• Published in: Steel research international 2022-08, Vol.93 (8), p.n/a
• Main Authors: Liu, Chengcheng, Huang, Minping, Ren, Qiang, Ren, Ying, Zhang, Lifeng
• Format: Article
• Language: English
• Subjects: Austenite; Austenitic stainless steels; Cooling rate; cooling rates; Grain boundary migration; Grain size; grain sizes; Martensite; martensite start temperatures; Martensitic stainless steels; Quenching; Residual stress
• ISSN: 1611-3683; 1869-344X
• DOI: 10.1002/srin.202200044

Herein, the transformation process of the martensitic stainless steel under different austenite temperatures, holding times, and cooling rates were in situ observed using the confocal laser scanning microscope. The grain boundary migration energy of the austenite grain was 241.51 kJ mol−1. The grain size at different temperatures and holding times was predicted, agreeing well with measured values. The relationship between the martensite start temperature and the grain size is proposed. The martensitic start temperature was significantly influenced by the cooling rate. With the increase of the cooling rate, the martensitic start temperature first decreased then rose up due to the quenching vacancy and internal stress, respectively. The transformation process of martensitic stainless steel under different austenite temperatures, holding times, and cooling rates is observed in situ by a confocal laser scanning microscope. Then the effects of grain size and cooling rate on martensite starting temperature (Ms) are analyzed. The Ms formula, which is of certain significance for the prediction of Ms, is discussed.