1977 年 26 巻 280 号 p. 68-73
The effect of the surface non-martensitic microstructure on the fatigue of gas carburized steel was investigated experimentally. The following results were obtained.
(1) The fully reversed fatigue strength of carburized steel was lowered by the surface non-martensitic layer.
(2) It was confirmed by X-ray stress measurements that the surface layer deformed plastically during the fatigue test and the residual stress developed in the direction to release the applied mean stress partially.
(3) Scanning electron micrographs revealed that internal oxides act as the defects to initiate fatigue cracks.
(4) The fatigue fracture mode of carburized steel was characterized by the transgranular fracture with a linear pattern along the direction of crack propagation.