Effects of the different frequencies and loads of ultrasonic surface rolling on surface mechanical properties and fretting wear resistance of HIP Ti–6Al–4V alloy

•Effects of MUSR frequency and load on surface properties of HIP Ti-6Al-4V investigated.•The grains in surface-modified layer were refined and appeared twins and many dense dislocations.•The hardened layer depth and surface residual stress of MUSR- treated samples were significantly improved.•MUSR- treated samples showed the good fretting friction and wear resistance.•The best microstructure and properties of surface-modified layer obtained by sample treated by 30kHz and 900N.