The formation of austenite during tempering of a 13Cr6Ni2Mo supermartensitic stainless steel (X2CrNiMoV13-5-2) was investigated using an in situ thermo-magnetic technique to establish the kinetics of the martensite to austenite transformation and the stability of austenite. The austenite fraction was obtained from in situ magnetization measurements. It was found that during heating to the tempering temperature 1 to 2 vol pct of austenite, retained during quenching after the austenitization treatment, decomposed between 623 K and 753 K (350 °C and 480 °C). The activation energy for martensite to austenite transformation was found by JMAK-fitting to be 233 kJ/mol. This value is similar to the activation energy for Ni and Mn diffusion in iron and supports the assumption that partitioning of Ni and Mn to austenite are mainly rate determining for the austenite formation during tempering. This also indicates that the stability of austenite during cooling after tempering depends on these elements. With increasing tempering temperature the thermal stability of austenite is decreasing due to the lower concentrations of austenite-stabilizing elements in the increased fraction of austenite. After cooling from the tempering temperature the retained austenite was further partially decomposed during holding at room temperature. This appears to be related to previous martensite formation during cooling.

利用原位热磁技术研究了13Cr6Ni2Mo超马氏体不锈钢（X2CrNiMoV13-5-2）回火过程中的奥氏体形成，以建立马氏体向奥氏体转变的动力学以及奥氏体的稳定性。奥氏体分数从原位获得磁化强度测量。发现在加热至回火温度期间，在奥氏体化处理后的淬火期间保留的奥氏体为1-2vol pct，在623 K和753 K（350°C和480°C）之间分解。通过JMAK拟合，马氏体向奥氏体转变的活化能为233 kJ / mol。该值类似于铁中Ni和Mn扩散的活化能，并支持以下假设：在回火过程中，将Ni和Mn分配给奥氏体主要是决定奥氏体形成的速率。这也表明，回火后冷却期间奥氏体的稳定性取决于这些元素。随着回火温度的升高，由于在增加的奥氏体比例中奥氏体稳定元素的浓度较低，奥氏体的热稳定性降低。从回火温度冷却后，在保持于室温的过程中，残留的奥氏体进一步分解。这似乎与冷却期间先前的马氏体形成有关。