Single Shot Peening and Composite Shot Peening for 42CrMoA Steel

42CrMoA high strength steel was strengthened by single shot peening, finishing composite shot peening, and polishing composite shot peening. The surface roughness, fatigue performance, surface residual stress, structure refinement and microhardness of the steel under different shot peening conditions were studied. The results show that shot peening methods had little effect on the maximum residual compressive stress and stress layer depth of 42CrMoA steel. The surface residual compressive stress, surface structure refinement, microhardness and fatigue limit of the steel increased in sequence after single shot peening, finishing composite shot peening, and polishing composite shot peening, while the surface roughness decreased in sequence. Composite shot peening, especially polishing composite shot peening, could reduce the shot peening surface roughness of 42CrMoA steel significantly.