冷間工具鋼の表面特性および疲労強度に及ぼす
マイクロショットピーニングの影響

抄録

Shot peening is a surface treatment that improves the performance of engineering components. In conventional shot peening, the medium consists of small spheres, which are usually made of high-carbon cast steel; the diameter of the spheres is in the range from 0.3 to 1.2 mm. More recently, however, a new type of microshot has been developed to enhance the peening effect. The diameter of the spheres in the new medium is in the range from 0.02 to 0.15 mm. In this study, the effects of microshot peening on the surface characteristics and fatigue strength of cold tool steel were investigated. The projective method of the microshot was of the compressed air type. The peening microshots of 0.1 mm diameter were cemented carbide, and the workpiece used was the commercially cold tool steel JIS-SKD11. The surface roughness, hardness, compressive residual stress and fatigue strength of the peened workpieces were measured. The surface layer of the workpieces was sufficiently deformed by microshot peening. A high hardness or residual stress was observed near the surface. Also, the process improved the fatigue life of the workpieces at all stress amplitudes. The use of hard microshots such as cemented carbide was found to cause a significantly enhanced peening effect for cold tool steel.