表面机械滚压处理(SMRT)316L不锈钢梯度纳米层在腐蚀介质下的摩擦学行为研究

采用表面机械滚压处理(surface mechanical rolling treatment，SMRT)技术在316L奥氏体不锈钢表面构筑了梯度纳米结构层. 利用透射电子显微镜(TEM)和纳米压痕仪等分析其微观组织、力学性能等基础上，重点探讨了SMRT前后316L在1 mol/L HCl溶液(以纯水环境作为对比组)中的摩擦学行为. 结果表明:经SMRT加工后316L表面梯度纳米晶层厚度达200 μm以上，表面硬化层厚度超过1.5 mm，表面硬度提升至基体近2倍；SMRT大大减缓了材料磨损，与基体试样相比，SMRT试样在腐蚀介质下减摩效果比纯水环境更明显，且在腐蚀环境下表现出优异的耐腐蚀性能，其磨损机制由处理前伴随严重剥落特征的疲劳磨损和磨粒磨损转变为轻微疲劳磨损. 因此，316L不锈钢机械滚压梯度纳米层在腐蚀服役环境下具有较高的潜在工程应用价值. 

Tribological Behavior of Nanocrystalline Layer on 316L Stainless Steel Subjected to Surface Mechanical Rolling Treatment under Corrosion Environment

A gradient nanostructured layer was fabricated on 316L austenitic stainless steel by means of surface mechanical rolling treatment (SMRT) technology. The microstructure and mechanical properties of the surface layer were studied by transmission electron microscopy, nanoindentation tester. And on this basis, this article focused on the tribological behavior of 316L before and after SMRT in 1 mol/L HCl solution, and the pure water environment was taken as the reference group. The results showed that, a gradient nanocrystalline layer with a thickness of 200 μm was formed after SMRT processing. The surface hardening layer exceeded 1.5 mm in thickness. The surface microhardness of surface hardening layer was twice as much as that of the base metal. The surface subjected to SMRT greatly alleviated wear. Compared with the base metal, SMRT surface was effective in reducing friction under the corrosive medium than that under the pure water environment, and it exhibited excellent corrosion resistance. The wear mechanisms varied from abrasive wear and fatigue wear accompanied by severe delamination before treatment to mild fatigue wear. Therefore, the nanostructured layer of 316L subjected to SMRT is a good candidate for application.