AISI 52100 is a high carbon alloy steel typically used in bearings. One hardening heat treatment method for AISI 52100 is austempering, in which the steel is heated to above austenitizing temperature, cooled to just above martensite starting (Ms) temperature in quench media (typically molten salt), held at that temperature until the transformation to bainite is completed and then cooled further to room temperature. Different austempering temperatures and holding times will develop different bainite percentages in the steel and result in a variation in mechanical properties. In the present work, the bainitic transformation kinetics of AISI 52100 were investigated through experiments and simulation. Molten salt austempering trials of AISI 52100 were conducted at selected austempering temperatures and holding times. The microstructure of austempered samples were characterized with optical microscope and x-ray diffraction. The bainitic transformation kinetics were analyzed by Avrami equations using measured hardness data. The CHTE quench probe was used to measure the cooling curves in the molten salt from austenitizing temperature to the selected austempering temperatures. The heat transfer coefficient (HTC) was calculated with the measured cooling rates and used to calculate the bainitic transformation kinetics via DANTE software. The experimental results were compared with the calculated results and displayed good agreement.

AISI 52100 是一种高碳合金钢，通常用于轴承。 AISI 52100 的一种硬化热处理方法是等温淬火，其中将钢加热到奥氏体化温度以上，在淬火介质（通常是熔盐）中冷却到略高于马氏体起始 (Ms) 温度，保持在该温度直至转变为贝氏体完成后进一步冷却至室温。不同的等温回火温度和保温时间会在钢中形成不同的贝氏体百分比，并导致机械性能的变化。在目前的工作中，通过实验和模拟研究了 AISI 52100 的贝氏体转变动力学。 AISI 52100 的熔盐等温淬火试验在选定的等温淬火温度和保温时间下进行。利用光学显微镜和X射线衍射对等温淬火样品的显微组织进行了表征。使用测得的硬度数据通过 Avrami 方程分析贝氏体转变动力学。 CHTE 淬火探针用于测量熔盐中从奥氏体化温度到选定的奥氏体回火温度的冷却曲线。根据测量的冷却速率计算传热系数 (HTC)，并通过 DANTE 软件计算贝氏体转变动力学。实验结果与计算结果进行了比较，吻合良好。