X線によるSM50AおよびHT80鋼の疲労破面解析(<小特集>X線材料強度小特集)

概要

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An X-ray fractographic study was made on the fatigue fracture surface of SM50A and HT 80 steels. The residual stress and the half-value breadth of X-ray diffraction profile were measured at and beneath the fracture surface. The correlation was examined between the parameters obtained from the X-ray measurements and the fracture mechanics parameter of K_<max> or ΔK at which the fracture surface had formed. The residual stress on the fracture surface was found to increase at first, reach to a maximum value at a certain value of K_<max> or ΔK and then decrease. It was also found that the residual stress was controlled by K_<max> in a low of K_<max> or ΔK region, while it was governed by of ΔK in a high of K_<max> or ΔK region. The reasons of this behavior were discussed by using the data from constant K_<max> and constant ΔK tests which were additionally planned and made in this study. The half-value breadth B, on the fracture surface was found to increase with K_<max> in the two steels used in this study. The value of B was influenced by stress ratio in HT 80, although it was not influenced in SM50A. Both of the distributions of residual stress and half-value breadth beneath the fracture surface were found to be useful for the prediction of monotonic plastic zone size or K_<max>.
1984-04-15