Effect of Stress Concentration on Fatigue Strength in Hot-rolled Sheet Steel with High Tensile Strength

Effect of stress concentration of fatigue strength of hot-rolled sheet steel with high tensile strength was discussed. As a result, fatigue strength reduction factors (β) of notched specimens was equal to the stress concentration factors (α) that were less than 3.0. It was supposed that gradient of stress distribution near the notch root was one of the important factors for fatigue limit. β of lap-joint specimen with machined toe was smaller than that of the notched specimen with the same α. Residual stress introduced welding process was supposed to affect the fatigue limit of the lap joint.