1974 年 23 巻 244 号 p. 33-39
In the previous report, the various factors that affect the endurance limit of induction hardened steel were examined. It was found that the microstrain and particle size are more influential than the residual stress on the endurance limit of both induction hardened smooth and notched specimens.
The present paper describes an experimental study on induction hardened smooth specimens tempered at various temperatures to find out main factors affecting the tension and compression fatigue strength and changes of the integral width and structure during fatigue. The main results are as follows:
(1) The compression and tension endurance limit decreases with rising tempering temperature. But the influence of tempering temperature on the compression and tension endurance limit is smaller than on the rotating bending and the plane bending.
(2) A linear relation exists between integral width, or micro-strain of particle size obtained from profile analysis and endurance limit.
(3) The integral width and microstructure of hardened material such as induction hardened steel change during fatigue, and the fatigue damage exists in a wide area.