Effects of Some Pre-cyclic Stressings on the Fatigue Strength Containing the Low Cycle Fatigue Range

Abstract

It is already known that iron and many ferrous alloys show a characteristic coaxing or understressing effect. In this report, some programmed fatigue tests were carried out to investigate the pre-stressing effect. Also, the micro Vickers hardness and macro residual stress of the specimen were examined. Experimental results are outlined, suggesting that the coaxing effect is due to the ability of steel to undergo strain hardening or strain aging especially at the crack tip area by strain cycling. It was found that only a small number of cycles of large overstressing can destroy the coaxing effects.