Abstract
Shot peening is a mechanical surface treatment that is widely used in the automotive industry to improve the fatigue life and surface characteristics of machine parts. To enhance the peening effect, warm peening and double peening are effective. These processes have recently received considerable attention. Our aim in this study is to investigate the effect of warm double peening on the surface layer characteristics of high speed steel. This peening process is a combination of double peening and warm peening. The first peening was conducted in the warm state using large steel media. Then, the second peening was conducted at room temperature using microshot media. In the present study, a compressed-air-type shot peening apparatus with a heating furnace was produced experimentally. The workpiece was made of the high speed steel JIS-SKH51. The surface roughness, hardness, compressive residual stress, and fatigue strength of the peened workpieces were measured. We found that the warm double-peening method causes a significantly enhanced peening effect for high speed steel.
