2009 Volume 73 Issue 5 Pages 401-406
Shot peening is a surface treatment effective to obtain compressive residual stress on shot peened surface and to improve fatigue strength, and it is applied to automobile parts such as springs and gears. Based on recent trend for further reduction of automobile parts weight, higher hardness of automobile parts is required through various treatments such as carburizing.
In this study, the effects of the amount of B addition on properties of gas atomized Fe-8Cr-B(mass%) powders for shot peening were examined. Including Fe-8Cr-6.5B as base composition, alloys with the amount of B addition from 4 to 9.5 mass% were gas-atomized and examined. The amount of Fe2B phase and Vickers hardness increased with the increase of the amount of B addition, and high hardness of 1200HV was obtained in alloys with more than 6.5 mass% B addition. Density decreased with the increase of the amount of B addition, and 7.14 Mg/m3 was obtained in the alloy with 9.5 mass% B addition. No crack initiated near indentation by 1000 g load in the alloys with the amount of B addition from 5.5 to 6.5 mass%.
