Effects of microshot peening on surface characteristics of high-speed tool steel

The effects of microshot peening on the surface characteristics of high-speed tool steel were investigated. Shot peening is widely used in automotive industry to enhance fatigue life and the surface characteristics of machine parts. More recently, new shot media have been developed to enhance the peening effect. New media is smaller and harder than the conventional one. The use of new media is effective in improving the surface of tool steels. The aim of this paper is to present the enhanced peening effect for the high-speed tool steel. In the present study, a compressed air-type microshot peening apparatus with a heating furnace was produced experimentally. Peening microshot was made of cemented carbide, and the workpiece was the high-speed tool steel. Surface roughness, compressive residual stress, and hardness of the peened workpieces were measured. The distribution of residual stress in the thickness direction was obtained from the X-ray diffraction method. The effects of processing temperature on the surface characteristics and the effect of microshot peening on fatigue characteristic were also examined. The use of hard microshots was shown to cause a significantly enhanced peening effect for high-speed tool steel.