Peening Characteristics of Cemented Carbide Peening Shot & Life Improvement of Cold Forging Die

Author:  T Ito, T Mizuno, T Takahashi, J Kurosaki
Source:  Conf Proc: ICSP-7 (pg 371-377)
Doc ID:  1999050
Year of Publication:  1999
Abstract:  
Shot peening is a technology having being extensively used chiefly for improvement of fatigue strength of automobile parts, air craft parts, and various forging dies. The common peening shots having being used are steel shot, glass beads, and ceramic shot. Recently, cemented carbide shot which features high hardness (1400HV) and high specific gravity (14) also came into use. Since it generates a large plastic deformation to the surface of work piece., it subsequently provides a greater compressive residual stress to and near the surface more than the common peening shots. The application of it to cold forging die showed an extension of its life up to max. 6 times. (Steel peening shot showed max. 3 times). It indicates the cemented carbide shot provides a highly compressive residual stress to and near the surface which subsequently retard the occurrence of fatigue cracks or the growth of cracks, resulting in a greater extension of life of the die.