片振り繰返し引張熱応力下の熱疲れ

抄録

The test of pulsating tensile thermal stress cycling is necessary in order to know the relationship between the strength in thermal stress cycling and that of creep rupture. This is also necessary to obtain the information of strength of material subjected to both mechanical stress and cyclic thermal stress, from a practical point of view. In the present paper, strength of pulsating tensile thermal stress cycling is discussed in comparison with those of fully reversed thermal stress cycling and of static creep rupture. The following are conclusions from the present study ; (1) Lifetime for pulsating tensile thermal stress cycling is much smaller than the case of completely reversed thermal stress cycling, that is, strain amplitude for pulsating tensile thermal stress cycling is nearly one half the fully reversed thermal stress cycling for the same number of thermal strain cycles to fracture. (2) Lifetime of pulsating tensile thermal stress cycling can be predicted approximately from the test data of static creep rupture, provided that the increase in thermal stress amplitude with the number of thermal strain cycles follows the curve of strain-hardening of the material. (3) The influence of mode of temperature variation on the number or thermal strain cycles to fracture for pulsating thermal stress cycling is not observed.