深冷温区应变强化S30408奥氏体不锈钢马氏体相变研究

Study on martensitic transformation of strain-strengthening S30408 austenitic stainless steel at the cryogenic temperature range

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 austenitie stainless steel was strain - strengthened with different strain at room temperature, and then ag- ing treatment at the cryogenic temperature range （77K -4.2K）. Microcopic features of strain - induced and thermal - induced martensitic transformation were investigated through metallographie observation, X - ray diffraction and transmission electron mi- croscopy. The microscopic mechanism of marenscie transformation was further discussed. The results show that the volume frac- tion, morphologies, nucleation sites, disle figurations of the martensitie transformation are changed along with the in- crease of pre - strain and the decrease of tempecature. The effect of strain - strengthening on the transformation is large than cryo- genic temperature. The interface relationship between the induced martensite and the austenite phases is in accord with the K - S model. The transformation mechanisms were observed to be γ（fec）→ε（hcp）、γ（fcc）→α′（bcc）、γ（fec）→ε（hcp）→α′（bcc）、γ（fcc）→deformation→α′（bcc）