To investigate the influence of bainitic transformation temperature on microstructure and mechanical property of hot rolled medium carbon-TRIP steels, a series of experiments, such as scanning electron microscopy ( SEM ) , X-Ray diffraction ( XRD ) and High Resolution Transmission Electron Microscopy ( HRTEM) , were conducted. The results show that the bainitic transformation temperature have a significantly effects on retained austenite contents and mechanical properties of TRIP steels, and the optimal bainitic transformation temperature is 400℃, at which the retained austenite contents and the balance of strength and ductility were 28. 2% and 31. 14 GPa·%, respectively. Furthermore, it was found that the morphology of retained austenite consisted of Block type, Irregular type and Film type, and Film type austenite exhibited the kurdjumov-Sachs and Nishiyama-Wasserman orientation relationship with ferrite matrix, simultaneously. In addition, HRTEM analysis showed that Mo can incorporate into TiC to form ( Ti, Mo) C particle, which can obviously improve the strength of experimental steels.%为研究贝氏体相变温度对中碳热轧TRIP钢组织与性能的影响，采用扫描电镜（ SEM）、X射线衍射（ XRD）与高分辨透射电镜（ HRTEM）对含Ti与Mo的中碳热轧TRIP钢进行了显微组织观察、残余奥氏体含量测定以及析出相的表征与分析．结果表明：在400℃贝氏体相变温度下，试验钢的残奥含量与强塑积均达到最大值，分别为28．2％和31．14 GPa·％；同时在钢中发现了呈块状、无规则形状以及片层状形貌分布的残余奥氏体，对衍射斑标定后显示，片层状残余奥氏体与铁素体基体同时满足kurdjumov-Sachs （ K-S）与Nishiyama-Wasserman （ N-W）位向关系；HRTEM分析显示，Mo可以溶入TiC而生成（ Ti，Mo） C粒子，而纳米级的（ Ti，Mo） C粒子可以显著提高钢的沉淀析出强化效果．
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