1963 年 12 巻 112 号 p. 43-52
Recently much attension has come to be paid to the thermal fatigue phenomenon of materials by many investigators, because of the rapid development of machines operated at high tem perature, and a number of papers have been issued on this subject. But the thermal fatigue is considered to be one of the most complicated problems, because two important factors, strain and temperature, completely overlap in this phenomenon. Therefore, some more advanced and more systematic investigation has become necessary to obtain much more useful informations about it.
The authors, being interested in this problem, constructed for trial a new thermal fatigue testing machine in order to obtain systematic informations, because the testing equipments used by many investigators were in most cases nearly the same type as that originally made by L.F. Coffin, and no substantial development had not been made.
Main feature of this machine is, among other things, to be able to independently apply the strain cycling and the heating cycling to the specimen. So the effect of each factor can be pursued systematically with this machine. Furthermore, these two cycles can be synchronized with arbitrary phase difference, and the strain rate, heating or cooling speed and hold times may be adjusted to the desired values. Several thermal fatigue tests were carried out on the annealed high carbon steel using solid cylindrical specimens.
Test result are as follows;
(1) All performances of the machine and the controlling circuits are very satisfactory ones.
(2) Effects of specimen size on thermal fatigue life are small.
(3) Thermal fatigue life is decreased with the increase of maximum temperature when mechanical strain is maintaind constant.
(4) Effect of radial temperature distribution of solid specimen on thermal fatigue life is negligible when mechanical strain is superimposed