ひずみ時効能の異なる軟鋼材の繰返し塑性ひずみ振幅挙動について

概要

論文の詳細を見る
Existence of the fatigue limit in steels has been explained in connection with the change in grain size or strain ageing. In this work, the effect of strain ageing on the fatigue strength of mild steels with different sensitivities to strain ageing was investigated. In order to know the mechanism of the effect of strain ageing on fatigue, the measurement of plastic strain amplitude, ε_<pa>, and observation of slip lines on the specimen surface were performed during the high cycle fatigue test under constant stress amplitude. The important results obtained were as follows: (1) The steel wit the higher sensitivity to strain ageing had the higher fatigue strength. (2) In the steel with the high sensitivity to strain ageing, ε_<pa> increased very rapidly in the early stage of fatigue, then decreased immediately. On the other hand, in the steel with the low sensitivity, ε_<pa> increased acceleratively after some incubation time, which depends on the cyclic stress level. (3) Such a behavior of ε_<pa> is well correlated with the change in the density of slip lines during the test.
1976-09-15