Relation between Residual Stress and Fatigue Strength for Electron Beam Welded Joints of Sheet Metal

Residual stresses in welds significantly affect the fatigue strength and stress corrosion crack resistance of the weld joint, and therefore, numerous studies have been made about the effects. The residual stress induced by electron beam welding (EBW) has also been researched in various approaches, but many of the study reports dealt with thick plates (50 mm or thicker) only.1–5) This was because the EBW process was costly, and thus studies were focused on thick plate materials for such specific applications as observed in the nuclear-power and space-related fields that require extremely high qualities for the weldments. In these times, however, there have been many cases where the EBW processes are employed in such general applications as autos, electric machinery and apparatuses, and industrial tools. This is owing to reduction in the processing cost through usage expansion of the equipment and corporate efforts by job shops. In particular, EBW is applied for partial penetration welding of parts with a plate thickness of 3–15 mm as observed in car gears and gauge diaphragms. While EBW has lately been expanded in such sheet metal applications, there are little reports of in-depth research on this field. Taking this into consideration, the authors have researched the residual stress characteristics in the partial penetration EBW welds of sheet metals. For the first study report,6) the effects of beam power Relation between Residual Stress and Fatigue Strength for Electron Beam Welded Joints of Sheet Metal