Influence on sampling direction for fatigue strength of shot peened carburized steel

Abstract

In this study, plane bending fatigue tests were conducted for shot peened vacuum carburized SCM420H steel sampled from the rolling direction (RD) and transverse direction (TD). The results showed that the fatigue limit of the carburized steel without shot peening was approximately 32% higher in the RD direction than the TD direction. Most fractures in TD samples were generated from elongated inclusions. On the other hand, fractures in RD samples were generated from outside of nonmetallic inclusions. The low fatigue limit of TD samples was due to the presence of rolling-induced elongated inclusions along the direction of maximum principal stress.