Athermal martensite transformation of modified high Cr ferritic heat resistant steel undergoing different quenching temperatures

Abstract

The thermal dilation behaviours of modified high Cr ferritic heat resistant steel quenched at different temperatures were employed to investigate the kinetics of martensite transformation. The martensite fraction and formation rate were obtained as a function of temperature. A model considering ‘spread’ martensites was introduced to explore the influence of quenching temperatures on martensite transformation. Both onset and offset temperatures of martensite formation decrease with the increase in quenching temperatures, and the reaction rate increases rapidly at the beginning of transformation and reaches a peak when a small quantity of martensite forms. The fitted data based on the proposed phase transformation model indicated that the width/length ratio of martensite laths decreases with the increase in quenching temperatures.

Keywords:

• Quenching
• Martensite transformation
• ‘Spread’ kinetic model
• Width/length ratio

The authors are grateful to the National Natural Science Foundation of China and Shanghai Baosteel Group Company (grant no. 50834011) for the grant and financial support.