表面深滚处理对纯镍组织性能及残余应力分布的影响

通过一种新型表面自纳米化方法———表面深滚处理，在纯镍（N4）表面制备出晶粒尺寸小于500nm 的梯度超细晶结构，并对材料次表面微观组织结构、残余应力分布及力学性能进行了研究。结果表明：N4经过表面深滚处理，表面形成织构；由于剧烈塑性变形，位错大量产生，并出现胞状组织和高密度位错墙，这些组织经过演化形成超细晶，并在表面形成具有一定厚度的残余压应力场；与原始材料相比，经过表面深滚处理后表面组织硬度提高近一倍；通过合理选择滚压参数，其细化层厚度、硬度、表面粗糙度及残余应力分布均得到不同程度改善。

Effects of Surface Deep Rolling treatment on Mechanical Properties and Residual Stress Field in Pure Nickel

Surface self-nanocrystallization by means of surface deep rolling (SDR)was applied to produce gradient ultra-fine grain structure with the grain size less than 500 nm near the surface of pure Nickel.The subsurface microstructure,residual stress field and mechanical properties of the treated nickel were investigated.It is found that the texture structure is formed near the nickel surface after SDR treatment.Due to severe plastic deformation,a large number of dislocations,dislocation cells and high density-dislocation walls are generated,leading to the formation of ultra-fine grain structure and large compressive stress near the surface.By comparing with the as-received material,the hardness of the material is increased nearly double after SDR treatment.The thickness,hardness,surface roughness of refined layer and residual stress field within it can be adjusted through proper selection of treatment parameters.