采用分阶段拉伸、XRD、EBSD、SEM、TEM等实验手段,研究了TRIP钢奥氏体的力学稳定性.结果表明:拉伸变形初期奥氏体转变较快,拉伸变形后期奥氏体转变较慢;奥氏体的含碳量不同,在相同的拉伸变形阶段奥氏体转化率的增加速率不同;处于铁素体、贝氏体晶界或者相界面1um以上大颗粒奥氏体几乎在变形初期就全部发生相变,而晶粒小于1um的残余奥氏体在变形后期发生相变,缓解相界面局部应力集中对TRIP效应有较大贡献;铁素怀晶粒内部奥氏体力学稳定性较好不易发生相变,少量较大的颗粒拉伸后会形成M-A岛.%Mechanical stability of austenite in TRIP steels was studied using techniques such as tension test, XRD, EBSD, SEM, TEM. The results showed that austenite converted fast at early tension, and slow at upper tension. With the different carbon content, the increasing rate of convention percent of austenite was different in the same tension stage. Austenite which dimension exceed 1μm and allocated on grain boundary or phase boundary almost completely transformed to martensite at early tension, while austenite which dimension less than 1μm would transform to martensite at upper tension, which could release the stress concentration on grain or phase boundary and contributed a lot to TRIP effect. Austenite which allocated in ferrite was of good mechanical stability and not liable to transform to martensite in the whole tension test, and some big dimension austenite would transform to M-A island.
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