炭素鋼S45Cの中高温度域における高サイクル疲労特性の速度効果
1988 年 37 巻 414 号 p. 261-266
詳細
1988 年 37 巻 414 号 p. 261-266
In order to clarify the frequency effect on high cycle fatigue properties at intermediate temperatures, rotating bending fatigue tests were carried out on a carbon steel S45C at 200, 300, 400 and 500°C with frequencies of 10 and 1Hz.
The conclusions obtained were as follows:
(1) The fatigue strength at 300°C was larger than that at 200°C, and a negative frequency effect on fatigue strength was observed at this temperature range. At above 400°C, the fatigue strength decreased with increasing test temperature and a positive frequency effect was observed.
(2) The frequency dependence of fatigue strength corresponded with that of deformation stress. The negative frequency dependence of fatigue strength observed at 300°C was considered as the result of decreasing cyclic plastic strain at the surface of specimen with decreasing frequency by hardening on account of dynamic strain aging.
(3) The positive frequency dependence of fatigue strength observed at 500°C was considered as the result of increasing cyclic plastic strain at the surface of specimen with decreasing frequency by creep deformation and by softening on account of tempering effect.
