The Effects Of Shot-peening On Residual Stresses And Fatigue Strength Of Carburized Gear Steels

Author:  Hashimoto, Shiratori, Nagashima
Source:  Conf Proc: ICSP-4, (p.495-504)
Doc ID:  1990087
Year of Publication:  1990
Abstract:  
In order to clarify precisely the effects of shot-peening on the fatigue strength of carburized gear steels, residual stresses, retained austenite and hardness in the surface layers before and after shot-peening were investigated in detail and fatigue tests were also conducted using fillet type specimens as a model of gear with two kinds of steels of as carburized and shot-peened. As the results, it is found that tensile residual stresses are formed by oxidation during carburizing treatment. The residual stresses change to compressive one through shot-peening. The maximum values of the compressive residual stresses as well as hardness near the surface layer increase by increasing duration of shot-peening. And it was also found that the fatigue strength is improved remarkably by shot-peening because of the increases of the compressive residual stresses and hardness near the surface layer. The estimated expression for the fatigue limits in the both cases of as carburized and shot-peened is proposed. It is confirmed that the estimated values of the fatigue limits agree well with the experimental ones. Descriptors: Carburized gear; Shot-peening; Fatigue strength; Residual stress; Retained austenite; Hardness