2015 年 64 巻 12 号 p. 1026-1033
Fatigue tests were conducted on 90°V-shape bending-worked cold rolled steel sheet specimens under fully-reversed out-of-plane bending to investigate the fatigue strength of bending-worked plates. The tests were also performed on low-temperature annealed specimens with no work-hardened layer formed by the bending-work. For annealed specimens, the fatigue strength decreased with reduction in radius of curvature of bending. The fatigue life can be estimated with sufficient accuracy taking account of the influence of elastic-plastic stress concentration at critical location. For bending-worked specimens without annealing, the fatigue strength was relatively higher than those of annealed bent specimens in relation to the existence of work-hardened layer. The increase of fatigue strength due to work-hardening was estimated based on the difference in S-N diagrams of both specimens. Consequently, the fatigue life of bending-worked specimens without annealing can be evaluated taking the effects of stress concentration and work-hardening into consideration.