Low-alloy steels were subjected to peening with fine titanium-nitride (TiN) particles under ambient conditions to form surface modified layer having TiN and improve their fatigue properties. Steels treated with fine particle peening using TiN particles (TiN-FPP) were assessed using electron probe microanalysis and X-ray diffraction to characterize the surface microstructure. Heterogeneous TiN particles transferred layer was formed on the steel surface. Rotating bending fatigue tests were performed for TiN-FPP treated steels in ambient air. It was found that TiN-FPP increased the fatigue limit due to high degree of compressive residual stress and surface hardness. In addition, the combined effects of residual stress, surface hardness and surface morphology on the fatigue limit of the TiN-FPP treated steel were quantitatively investigated based on a modified Goodman diagram considering residual stress relaxation during fatigue tests. The proposed method can achieve the fatigue limit estimation of the TiN-FPP treated steel.
