Surface Roughness Evolution in Surface Nanocrystallization and Hardening (SNH) Process

摘要

Surface severe-plastic-deformation-based processes, such as surface mechanical attrition (SMA), surface nanocrystallization (SNC), and surface nanocrystallization and hardening (SNH), have been developed to impart metallic engineering components with a nanocrystalline surface and coarse-grained interior. Such a microstructural gradient, achieved via impacting metallic components repeatedly with high-energy balls, is expected to render the components with superior fatigue and wear resistances. However, surface roughness induced by repeated impacts of balls may degrade the performance of the components. In this study, surface roughness evolution of Ti-6Al-4V alloy as a function of the impacting intensity is evaluated via non-contact 3D profilometry. Comparisons between the experimental results and analytical models are conducted and the implication of this study on the optimization of the SNH process is discussed.