Humid-Sensitivity of Fatigue Strength of Maraging Steel and Its Improvement by Shot Peening

Author:  N. Kawagoishi, T. Nagano, Y. Kobayashi
Source:  ICSP-13
Doc ID:  2017041
Year of Publication:  2017
Abstract:  
Introduction: Maraging steel is an ultra-high strength steel which is strengthened by means of many strengthening mechanisms such as precipitation strengthening, solution hardening, grain refinement strengthening and so on. However, the fatigue strength is very lower than expected from its static strength similar to other high strength steels. Main reasons for low resistance to fatigue are caused by their high susceptibilities for notch and humidity. For the reasons, many methods such as modifying microstructure, surface treatment and so on have been developed to improve fatigue properties of maraging steel. Shot peening is one of the useful technologies which is strengthened by hardening and compressive residual stress formed at the peened surface layer. However, studies about effect of corrosive environments on fatigue properties of maraging steel, especially effect of humidity on fatigue properties of shot peened one, were very limited in comparison with those about the resistance to stress corrosion cracking of the steel. In the present study, rotating bending fatigue tests were carried out to investigate the effect of shot peening on humid-sensitivity in fatigue of maraging steel.