Fatigue Strength of Maraging Steel at Elevated Temperatures
Norio KAWAGOISHI, Teppei IWAMOTO, Takanori NAGANO and Kazuhiro MORINO
Abstract:In order to investigate fatigue properties of maraging steel at elevated temperature, rotating bending fatigue tests were carried out at room temperature, 473K and 673K in ambient air. Fatigue strength at elevated temperature was higher than that at room temperature, though static strength was decreased at elevated temperature. Endurance ratio ƒÐw/ƒÐB (ƒÐw: fatigue limit, ƒÐB : tensile strength) was increased with increasing temperature. Crack growth resistance was hardly influenced by temperature. Hardness of specimen after fatigue test was increased and the hardness was large with increasing fatigue life. That is, the high fatigue strength at elevated temperature may be explained by age hardening yielded at fatigue process at elevated temperature. This phenomena was confirmed from the results that the steel double-aged at 673K corresponding to the fatigue tested condition showed high static and fatigue strengths. Key Words:Fatigue, Maraging steel, Elevated temperature, Rotating bending, Age-hardening, Crack initiation, Crack propagation