表面机械研磨诱导AISI 304不锈钢表层纳米化: Ⅰ. 组织与性能

Nanostructured surface layer was synthesized on an AISI 304 stainless steel by using surface mechanical attrition treatment (SMAT), the grain refinement behavior and the hardness variation were examined. Experimental results show that a nanostructured surface layer of about 30 μm thick forms after the SMAT, in which the microstructure changes from the martensite phase of about 10 nm in size to a mixture of the martensite and the austenite phases with a little large size. In the region from 30 to 300 μm depth, the microstructure changes from multidirectional austenite twins (the dominating phase) to one-directional ones, and the size of twin increases from submicro-scale to micron-scale. The surface nanocrystallization can be attributed to the refinement of initial coarse grains and the formation of nanoscale new phase. The hardness of the nanostructured layer is enhanced significantly after the SMAT compared with that of the initial sample.