Surface nanocrystallization and property of Ti6Al4V alloy induced by high pressure surface rolling

Ti6Al4V alloy was subjected to high pressure surface rolling (HPSR) deformation. Effects of initial microstructure (heat treatments) and HPSR parameter on the formation of surface nanostructure and mechanical property of Ti6Al4V were investigated. A gradient nano-microstructured surface layer was successfully produced on Ti6Al4V after HPSR, of which the thickness increases and the grain size decreases with the increase of HPSR load (F). Microhardness of HPSR samples increased with decreasing depth from the treated surface, and increased with the increase of F. Microstructure of the original sample including the morphology and size of the α and β phases was found to have evident effect on the thickness, grain size and microhardness of the surface deformed layer produced by HPSR. The HPSR sample showed good thermal stability after annealing at 700°C for 1h. The present results indicated that HPSR can be used as an effective method for controlled production of gradient surface nano-microstructure on Ti6Al4V alloy with enhanced property. [Display omitted] •Ti6Al4V alloy was subjected to high pressure surface rolling (HPSR) deformation.•A gradient nano-microstructured surface layer was successfully produced.•Effects of initial microstructure and HPSR parameter were investigated.•Microhardness after HPSR increased with decreasing depth from the treated surface.•The HPSR sample showed good thermal stability at 700°C.