Effects of the secondary shot in the double shot peening process on the residual compressive stress distribution of Ti-6Al-4V.

Double shot peening is the development of shot peening by shooting large media as a first shot and re-shooting again with smaller media as a second shot in order to achieve high residual compressive stress and hardness at the surface, while the in-depth effect can still be maintained. This research aims to examine the effect of media type and media size when used in the second shot of double shot peening on hardness, roughness, and residual stress to identify the suitable conditions and compare them with single shot peening, such as conventional shot peening and fine shot peening, which was used as the first shot and second shot. Ti-6Al-4V was used as the substrate material, while various diameter sizes of silica and SUS304 media were selected as the media for the second shot in the process.