Martensitic Transformation from Nanostructured Metastable Austenitic Steels

研究了用累积滚压(ARB)工艺制备的超细晶(UFG)奥氏体在亚稳奥氏体合金中的马氏体相变。UFG奥氏体相变后的马氏体具特征的形态和织构。ARB循环后，马氏体相变开始温度(Ms)升高，这与ARB过程早期引入的低角度晶界等形核中心数量增加有关。相反，随着ARB循环次数的增加，ms温度降低。Ms温度的降低可能与奥氏体细化强化有关。

Martensitic transformation from ultrafine grained (UFG) austenite fabricated by accumulative roll bonding (ARB) process in a metastable austenitic alloy was studied. The martensite transformed from the UFG austenite showed characteristic morphology and texture. The martensite transformation starting (Ms) temperature increased after 1 cycle ARB, which was related to increasing amount of nucleation sites, such as low angle boundaries, introduced during early stage of ARB process. In contrast, by increasing the ARB cycles, Ms temperature decreased. The decrease in the Ms temperature could be correlated to strengthening of austenite by grain refinement.