In the present study, quenching and partitioning (Q & P) treatment of a medium-carbon silicon-rich steel was processed by a dilatometer. The volume fraction of the retained austenite at different partitioning times was determined by X-ray diffraction (XRD). The metastable austenite transformation process after different partitioning times was studied by a combination of dilatometry, XRD, and transmission electron microscopy (TEM). Analysis of the transformation kinetics of metastable austenite during partitioning by means of dilatometry and the Johnson–Mehl–Avrami–Kolmogorov (JMAK) equation was carried out. The results show that the volume fraction of retained austenite increases first and then decreases with the increase of the partitioning time. The transformation active energy Q = 141 kJ·mol⁻¹ and the Avrami exponent n = 1. The transformation product of metastable austenite is needle-like bainite, which grows perpendicularly towards the boundary of the austenite. Finally, the blocky austenite was divided into lath-shaped forms.

中文翻译：

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Q＆P分离过程中中碳富硅钢的亚稳态奥氏体转变动力学

在本研究中，通过膨胀计对中碳富硅钢进行淬火和分配（Q＆P）处理。通过X射线衍射（XRD）确定在不同分配时间的残余奥氏体的体积分数。通过膨胀计，X射线衍射和透射电子显微镜（TEM）的组合研究了不同分配时间后的亚稳态奥氏体转变过程。利用膨胀法和Johnson-Mehl-Avrami-Kolmogorov（JMAK）方程分析了亚稳奥氏体在分配过程中的转变动力学。结果表明，随着分配时间的增加，残余奥氏体的体积分数先增大，然后减小。转变有功能量Q = 141 kJ·mol ^-1亚稳指数为avrami指数n =1。亚稳奥氏体的相变产物为针状贝氏体，其垂直于奥氏体边界生长。最后，块状奥氏体被分为板条形。