塑性疲労強度の温度依存性に関する研究

抄録

Strain-controlled low cycle fatigue tests were conducted at four temperature levels; room temperature, 150°C, 300°C and 450°C. The temperature dependence of fatigue strength of low carbon steel was discussed with reference to the result of the tension tests at elevated temperatures.
The conclusions obtained are as follows:
(1) The stress range increased continuously at 300°C until the specimen failed, while it held almost constant within other temperature levels.
(2) The mean stress range had its peak value near 300°C just like tensile strength.
(3) The number of cycles to failure of the material decreased with temperature when the test results were plotted both by the total and the plastic strain range.
(4) The plastic work, no matter whether per unit cycle or total, was not effective for the arrangement of low cycle fatigue date, though such equivalent plastic work as defined in the study was found fairly effective.
(5) The modified Larson-Miller method was applicable to estimation of failure life of low cycle fatigue at elevated temperature: Good correlation was found between the parameter P'=T(logN+C') and the total strain range Δε except for the case of room temperature.