采用表面机械滚压处理(SMRT)方法, 分别在室温空气中和液氮中对304L不锈钢进行处理, 制备出了纳米晶表层. 用OM, SEM, XRD和TEM对试样组织结构的演变进行了分析; 通过测定试样表层到内部的硬度研究了SMRT对试样硬度的影响. 结果表明, 试样表层形成了晶粒取向各异的纳米晶组织, 晶粒尺寸与处理环境和处理次数有关. SMRT还使试样内部产生了大量的机械孪晶和内晶界, 使试样发生了显著的马氏体相变, 硬度显著提高并随距试样表面的距离的增加减小. SMRT与传统的表面纳米化方法相比, 可以在不同的温度和介质环境下对试样进行表面纳米化, 并能形成较厚的硬化层, 而且工业化前景较好.
The mechanical property variation and micro-structure evolution of 304L stainless steel subjected to treatment of a new method, the surface mechanical rolling treatment (SMRT), were investigated in both liquid nitrogen and atmosphere at room temperature. The grain refinement, phase transition and hardness of 304L stainless steel treated by SMRT were examined using OM, SEM, XRD, TEM and Vickers hardess tester. The results show that nano-grains are created on the surface of SMRT 304L stainless steel, their sizes vary with treating conditions. Large numbers of intersections and mechanical twins are observed in the steel samples. Due to prominent martensitic transformation during SMRT, the hardness of samples is enhanced greatly and varies with increasing depth from surface. The SMRT method has its advantages compared with the traditional methods to generate thicker hardening layers than other traditional methods. It can be easily industrialized.
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