Affiliation:
1. Graduate School of Advanced Science and Engineering Hiroshima University Higashi‐hiroshima Japan
2. Mazda Motor Corporation Technical Research Center Hiroshima Japan
3. Faculty of Engineering Okayama University Kita‐ku Japan
4. Joining and welding research institute Osaka University Ibaraki Japan
Abstract
AbstractIn this study, the effects of variations in the weld rip diameter on fatigue properties were investigated based on the fatigue fracture mechanism using tensile peeling‐type friction stir spot welding (FSSW) joints. The results of the fatigue test showed that the high and low applied force ranges exhibited base metal fracture and weld area fracture, respectively, and the difference in the weld rip diameter hardly affected the fatigue life. In contrast, in the middle‐applied force range, the fracture morphology changes as the weld rip diameter decreases, and it is apparent that joints exhibiting weld area fracture decrease the fatigue life. The fatigue fracture morphology of the tensile peeling‐type FSSW joints can be described by a competing risk model between the weld rip diameter. Increasing the heat input during joining, thereby increasing the crack propagation resistance at the pressure fusion interface, can suppress weld area fracture.