2001 Volume 19 Issue 3 Pages 547-555
Welded joint generally has heterogeneity of strength, material, and fracture toughness. It is important to understand the characteristics of material strength and fracture of welded joint considering heterogeneous effect. Furthermore, material behavior becomes more complicated when the welded joint is subjected to dynamic loading like as earthquake. In this paper, characteristics of strength and fracture of an undermatched joint under dynamic loading is studied by round-bar tension tests and thermal elastic-plastic analyses. The results show that the strength and fracture of the undermatched joints should be evaluated based on the effects of the strain rate and the temperature including temperature rise during the dynamic loading. Tensile strength and yield stress of the undermatched joints increase with strain rate and with decreasing temperature. The strength of the soft layer approaches to that of the base metal when the thickness of the soft layer becomes smaller, and does not depend on strain rate. Finally, it is found that the stress-strain distribution affects the fracture characteristics like such as ductile-to-brittle transition behavior. The fracture characteristics are well precisely explained from the results obtained by numerical analysis.