Abstract：
A two-step bainitic treatment with a final isothermal temperature below MS was adopted to obtain bainitic steel with abundant retained austenite (RA). Nanoindentation testing was used to investigate the stability of RA in bainite steel and clarify the effect of RA on the deformation of medium-carbon steel. The results showed that, in contrast to the traditional one-step approach, a greater amount of nanoscale RA film was obtained using the two-step treatment. This was due to a lower final bainitic transformation temperature, which induced a higher carbon concentration in the untransformed austenite in the stasis stage; this resulted in untransformed austenite with a higher carbon content existing as RA rather than forming martensite in the subsequent cooling process. In addition, it was determined that the increased stability of RA during the two-step transformation delayed the pop-in point.
摘要：
采用最终等温温度低于MS的两步贝氏体处理，以获得具有丰富残留奥氏体（RA）的贝氏体钢。采用纳米压痕试验研究了RA在贝氏体钢中的稳定性，阐明了RA对中碳钢变形的影响。结果表明,与传统的一步法相比，使用两步处理获得了更大量的纳米级RA膜。这是由于较低的最终贝氏体转变温度，在停滞阶段，未转化奥氏体中的碳浓度更高；这导致未转化奥氏体的碳含量更高，而不是在随后的冷却过程中形成马氏体。此外,确定在两步转换过程中RA的稳定性增加延迟了突出点。
