High temperature (1050 °C) carburizing of SAE 1020 steel and its effect on fatigue failure

Abstract

In this work, the mechanism of fatigue failure and the method of increasing fatigue strength have been summarized. Also, it has been dwelled on the surface hardening treatments. The work has aimed to find out whether the fatigue strength is increased by the application of carburizing in liquid salt bath (NaCN+NaCO3+NaCl), widely used in practice. In particular, the carburizing at high temperature (1050 °C) at which carburizing time can considerably be reduced, and the residual stress on the case has been evaluated. In the experiments, SAE 1020 steel was used. As a result, the carburizing at 1050 °C has reduced the heat treatment time by 55% for 12% case depth/section thickness ratio in 6 mm diameter specimen, and has increased the fatigue strength by 10% for 6% ratio of case depth and section thickness.