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通过相变点测定、相图计算、组织观察、XRD分析及EBSD取向成像技术研究了室温下含两种马氏体及奥氏体的18Mn钢在100—500℃间进行温变形时的组织、相结构变化及马氏体逆相变行为.结果表明,在300℃以上压缩变形时,TRIP效应消失,马氏体减少,出现逆相变;形变加速了扩散型逆相变,bcc马氏体或铁素体以扩散方式转变成奥氏体,奥氏体不需要重新形核;形变使奥氏体出现机械稳定化并出现大尺寸的形变孪晶,抑制了随后冷却过程中的马氏体相变;压缩形变时,最后残留的马氏体多出现在{110}和{100}取向的奥氏体晶粒中.bcc马氏体周围难以观察到hcp马氏体.分析认为,hcp马氏体以切变方式逆相变.
The microstructure of 18Mn steel with two types of martensite and austenite at room temperature under 100-500 ℃ was studied by phase transformation point measurement, phase diagram calculation, microstructure observation, XRD analysis and EBSD orientation imaging. Phase transformation and martensitic transformation.The results show that the TRIP effect disappears and the martensite decreases and reverse phase changes when the compressive deformation is above 300 ℃ .The deformation accelerates the diffusion reverse phase transformation and the bcc martensite Or ferrite is transformed into austenite in a diffusion manner. Austenite does not need to be re-nucleated. Deformation causes the mechanical stabilization of austenite and the occurrence of large-size deformation twins, inhibiting the subsequent cooling of the martensite In the compressive deformation, the residual martensite appears in the {110} and {100} orientated austenite grains, hcp martensite is hardly observed around the bcc martensite.Analysis shows that the hcp horse Anti-phase transformation of the body to shear mode.