Properties of cold work tool steel shot peened by 1200 HV-Class Fe-Cr-B gas atomized powder as shot peening media

Abstract

Shot peening is widely used for automobile parts such as springs and gears to improve fatigue strength. In general, high hardness media is required for shot peening to targets with high hardness. Recently, shot peening to various tool steels such as cold and hot tool steels and high speed tool steel has been investigated and is used in some applications, and improvements in fatigue strength and die life by the increase of compressive residual stress and hardness at their shot peened surface have been reported. In this study, the properties of cold work tool steel shot peened by Fe-8%Cr-6.5%B (mass%) gas atomized powder (FeCrB powder) with 1200HV-class Vickers hardness and long life as shot peening media were examined. Quenched and tempered JIS-SKD11 followed by shot peening by FeCrB and high speed steel powder sieved between 45 and 125 μn was used. Vickers hardness and compressive residual stress of the shot peened JIS-SKD11 surface by FeCrB powder were higher than these by high speed steel powder. As a result, JIS-SKD11 shot peened by FeCrB powder showed excellent fatigue property, Charpy impact value and wear resistance property. © 2010 The Japan Institute of Metals.