表面机械研磨316L不锈钢诱导表层纳米化

采用表面机械研磨处理方法在316L不锈钢上制备出纳米结构表层,用X射线衍射和透射电镜研究横截面组织结构的演变过程,通过测定表层到内部的硬度变化研究纳米化对硬度的影响·结果表明:经过60min表面机械研磨处理后,在距样品表面约100μm深度形成高密度位错;随着应变量和应变速率的增加,在距样品表面约50μm深度诱发了机械孪生,形成了片层状孪晶,并相互交割细化组织;最终在样品表面形成了厚度约为20μm的纳米层,表层显微组织由晶粒尺寸为10～30nm的双相组织(马氏体和奥氏体)组成·表面纳米化是通过位错 孪晶及孪晶 孪晶相互作用实现晶粒细化·表面纳米化后,表层硬度显著提高·

Surface Nanocrystallization of 316L Stainless Steel Induced by Surface Mechanical Attrition Treatment

Surface nanocrystallization of 316L stainless steel was successfully realized by means of surface mechanical attrition treatment (SMAT). The microstructural evolution was examined through XRD and TEM, as well as its grain refinement behavior and hardness variation. The experimental results showed that high density dislocations form about 100 μm deep under sample surface, and then the mechanical twins are induced about 50 μm deep with increasing strain value and strain rate. The lamellar twins intercross each other to refine grain. Finally, a nanostructured surface layer about 20 μm thick forms after SMAT process, of which the microstructure consists of a mixture of both martensite and austenite phases with grain size about 10-30 nm. The realization of surface nanocrystallization is considered as resulting from the grain refinement due to dislocation-twin and twin-twin interactions, and its hardness is improved greatly after SMAT.