Microstructural Approach of Study on the Fatigue Behavior of Induction-Hardened Steel (Report 1)

抄録

In recent years it has been well known that the remarkable improvement of fatigue strength of carbon steel specimen which was induction-hardened, can be due to 1) an improvement of mechanical properties of material by rapid heating, and 2) prevention of the propagation of the fatigue crack by the residual compressive stress in the surface layer of a specimen. However, at the initiation stage of a macro-or microscopic fatigue crack, it is not yet defined what kind of role the residual compressive stress in the surface layer of specimen is to play, and what kind of effect the rapid heating has. In this paper, the fatigue behavior of induction-hardened microstructure which is free from the residual compressive stress, is investigated. Also the effect of the microstructural change of material due to induction-hardening on the fatigue strength, is observed.