316L不锈钢在表面机械滚压处理时的形变诱导马氏体相变和组织细化过程

Processes of Deformation-induced Martensite Transformation and Microstructure Refinement of 316L Stainless Steel during Surface Mechanical Rolling Treatment

采用表面机械滚压处理（SMRT）在316L不锈钢表面制备出梯度纳米结构（GNS）表层,研究了SMRT对GNS表层中的相组成和微观组织演变的影响机制。结果表明：经SMRT后316L不锈钢表层的奥氏体相发生形变诱导马氏体相变,且马氏体含量随着SMRT压下量的增大而增多;微观组织的细化过程先后经历了高密度位错生成和交互作用、形变孪生、形变诱导马氏体相变和马氏体晶粒细化过程,最终在最表层形成以马氏体相为主、晶粒尺寸~55 nm的纳米晶组织。

A gradient and nanostructured（GNS） surface layer was formed on a 316 L stainless steel sample by using surface mechanical rolling treatment（SMRT）. The effect of SMRT on the evolution of phase composition and microstructure was studied of the GNS surface layer. The results show that deformation- induced martensite transformation occurs in the surface layer after SMRT, and the martensite amount increases with the increasing penetration depth of SMRT. The microstructural refinement mechanism includes subsequently the formation and interaction of various dislocations, deformation twinning,deformation- induced martensite transformation, and martensite refinement. Finally, nanostructure with mostly martensite and a mean grain size of ca. 55 nm was achieved in the topmost surface layer of the316 L sample.