The Effect of the Surface Working Process on the Patigue Strength of Carburized Steels

Abstract

The effect of surface working (shot peening) and additional post working heat treatment on the fatigue properties of carburized steel with surface structure anomalies was evaluated through rotating bending fatigue tests. Smooth specimens with various surface roughness and notched specimens were gas carburized and shot peened. Some smooth specimens were tempered after shot peening to examine the effect of post working heat treatment. Hardness, residual stress and the amount of retained austenite near the surface of the carburized and shot peened specimens were measured. The fatigue strength of all of the shot peened specimens increased and was as much as 90% higher than that of carburized specimens. The smooth specimen tempered at 100°C after shot peening gave the highest fatigue strength among all samples tested in this study.