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对S30408奥氏体不锈钢进行室温应变强化,在深冷温区(77K~4.2K)进一步时效处理,利用金相显微镜、X射线衍射仪(XRD)和透射电子显微镜(TEM)研究了应变诱发和热诱发马氏体相变的微观特征,探讨了马氏体相变的微观机理。结果表明:马氏体相变的含量、微观形貌、形核特征和位错组态随着预应变量的增加和温度的降低而改变,且应变强化比温度对相变的影响要大。诱发马氏体与母相奥氏体的位相关系符合K-S关系,其相变的微观机理为γ(fcc)→ε(hcp)、γ(fcc)→α’(bcc)、γ(fcc)→ε(hcp)→α’(bcc)、γ(fcc)→形变孪晶→α’(bcc)。
S30408 austenitic stainless steel was subjected to strain hardening at room temperature and further aging treatment in the cryogenic temperature range (77K ~ 4.2K). The effects of strain-induced heat and heat were investigated by metallographic microscope, X-ray diffraction (XRD) and transmission electron microscopy Induced the microscopic characteristics of martensitic transformation and discussed the microscopic mechanism of martensitic transformation. The results show that the content of martensitic transformation, microstructure, nucleation characteristics and dislocation change with the increase of pre-strain and the decrease of temperature, and the effect of strain hardening on the transformation is greater than that of temperature. The phase relationship between induced martensite and parent austenite coincides with the KS relationship. The microscopic mechanism of phase transformation is γ (fcc) → ε (hcp), γ (fcc) → α ’(bcc), γ (fcc) → ε (hcp) → α ’(bcc), γ (fcc) → deformation twin → α’ (bcc).