Fatigue Behavior of 18% Ni Maraging Steels: A Review

Abstract

18% Ni maraging steels are based on the Fe-Ni-Co-Mo system with low-carbon content. They display an excellent combination of high strength and high toughness. However, they suffer from a low fatigue ratio, the ratio decreasing monotonically with increasing strength. Considering prospective applications for these steels involving fatigue loading, attempts were made by researchers to improve their fatigue life. The studies suggest that fatigue strengths higher than those realized in peak aged condition can be obtained through controlled overaging with a small amount of reversed austenite playing a critical role. Corrosion fatigue in different environments is a serious problem with these steels. Double aging seems to reduce the susceptibility to corrosion fatigue under high humidity conditions. Inclusion content has a strong influence on the fatigue life, inclusion size and type playing an important role. Surface treatments such as shot peening, laser peening, and nitriding were found to improve the fatigue life; however, it is important to optimize the process parameters. This paper attempts a critical review of studies reported in the published literature aiming to improve the fatigue life of 18% Ni maraging steels.