Ｓ４５Ｃ鋼同種摩擦圧接継手の統計的疲労特性について

Abstract

Recently the application of the friction welded butt joint to mechanical structures has come into wider use. A further increase in demand for this sort of joint is anticipated because of its utility for some engineering purposes and the technical easiness of this welding method to make the butt joint of dissimilar metallic materials. However, there exist only a few papers concerned with the fatigue strength characteristics of this type of joint, for it has been recognized empirically that the fatigue strength of the friction interface exceeds that of the base material and thus no noticable problem on this type of joint exists from the view point of fatigue strength.In the preliminary study conducted by the authors on the friction welded butt joint specimens composed of 0.23%C carbon steel, however, it was revealed that the fatigue lives of these specimens showed a considerably wide scattering in comparison with those of the base material specimens.To clarify such statistical fatigue strength characteristics of the friction welded butt joint specimens, a series of experiments were planned and conducted on the base material specimens of 0.46%C carbon steel and the friction welded butt joint specimens at several stress levels in the overstress range.Statistical discussions on the results obtained were made by accepting the Weibull distribution as the original distribution for the fatigue life. It was revealed that there existed a distinct difference in S-N relation between the base material specimen and the friction welded butt joint specimen, when the distribution of fatigue life was taken into consideration.