Abstract. Shot peening is a mechanical surface treatment with a beneficial effect to generate compressive residual stress caused by plastic deformation on the surface of material. This plastic deformation can improve the surface characteristics of metallic materials, such as modification of surface morphology, surface roughness, and surface hardness. The objective of this study is to investigate the effect of shot peening in different shot distance and shot angle on surface morphology, surface roughness, and surface hardness of 316L biomaterial. Shot distance was varied at 6, 8, 10, and 12 cm and shot angle at 30, 60, and 90 o , working pressure at 7 kg/cm 2 , shot duration for 20 minutes, and using steel balls S-170 with diameter of 0.6 mm. The results present that the shot distance and shot angle of shot peening give the significant effect to improve the surface morphology, surface roughness, and surface hardness of 316 L biomaterial. Shot peening can increase the surface roughness by the increasing of shot distance and by the decreasing of shot angle. The nearest shot distance (6 cm) and the largest shot angle (90 o ) give the best results on the grain refinement with the surface roughness of 1.04 m and surface hardness of 534 kg/mm 2 .

Corrosion resistance of 316L biomaterial can be improved by mechanical surface treatment such as shot peening. Shot peening can create plastic deformation as a nanocrystal surface layer on the metal surface to protect the material from corrosion attack. This study aims to investigate the effect of shot peening on the corrosion resistance of 316L to reach the best rate of corrosion. The shot peening parameters in this research are shot distance (6, 8, 10, and 12 cm), shot angle (30, 60, and 90°), compressor pressure (7 kg/cm2), shot duration (20 minutes), and steel balls S-170 (diameter of 0.6 mm). Simulated Body Fluid (SBF) was used as a corrosion media with ion concentrations nearly equal to human blood plasma. Corrosion tests were used versaSTAT, and the data were analyzed by VersaStudio. The result shows that the shot peening can decrease the corrosion rate of the 316L biomaterial. The larger the shot angle, the lower the corrosion rate and the nearer the shot distance, the lower the corrosion rate. The nearest shot distance (6 cm) and the largest shot angle (90°) give the best result to decrease the corrosion rate from 0.8617 mpy to 0.1096 mpy.