This study examines the effect of hybrid surface modification by vacuum carburizing and fine particle peening on fatigue strength behaviors of SCM 415 material. We used quenched vacuum carburized and hybrid, vacuum carburized and fine particle peened, specimen made of SCM 415 and measured their hardness distribution, mechanical properties, fatigue strength and crack propagation. In terms of the fatigue behaviors, we investigated the relationship between the crack propagation rate da/dN and stress intensity factor range △K, da/dN and effective stress intensity factor range △Keff, as well as the fatigue crack initiation life Ni and crack failure life Nf of specimens. The results show specimens with hybird surface modification are effective in the prevention of fatigue crack initiation and fatigue crack propagation.
