Fatigue crack growth behavior of nodular cast iron subjected to two-step austempering

This research aimed to investigate the fatigue crack behaviorof nodular cast iron heat-treated with two-step austempering. In this study, the material was initially reheated at 260 °C for 10 minutes, and then the temperature was increased to 280 °C, 310 °C, and 340 °C with the holding time of 60 minutes and 120 minutes. The results of these treatments showed that slower fatigue crack propagation occurred at the austempering temperature of 340 °C with 60-minutes holding time than those at lower temperatures (280 °C and 310 °C) and with longer time (120 minutes). The maximum fatigue crack propagation resistance occurred at the holding time of 60 minutes compared to that at the 120 minutes holding time