Influence of Welding Residual Stresses on Fatigue Crack Initiation Life

概要

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In this study, total fatigue life (Nf) was divided into initiation life (Nc) and propagation life (Np). The influence of welding tensile residual stresses on crack initiation life (Nc) was studied experimentally. Crack initiation life (Nc) was measured by crack gage attached to location of crack initiation that was edge of open-hole on surface of welding bead. Crack gage was attached less than 0.1mm away from location of crack initiation. Therefore, crack initiation life (Nc) was measured as crack propagation less than 0.1mm. The results were as follows. 1. Crack initiation life (Nc) increases as welding tensile residual stress becomes lower. Specially, it is notable at near the fatigue limit, and influence of welding tensile residual stress becomes smaller as stress level becomes higher. 2. Influence of welding tensile residual stress on crack propagation life (Np) is smaller than that of crack initiation life (Nc). 3. Scatter of failure life (Nf) is caused by crack initiation life (Nc), and scatter of crack propagation life (Np) is little. This phenomenon is not affected by welding residual stress.
大阪大学の論文