Effect of crack length on fracture toughness of welded joints with pronounced strength heterogeneity

摘要

The integrity assessment of repaired welds is dependent on accurate characterization of their fracture behavior and limit load estimation. The final weld consists of multiple microstructures due to different weld consumables used for repair welding. As a result, a large degree of heterogeneity is to be expected. The variation of mechanical and fracture properties within the weld influences the fracture behavior and limit load capacity of repaired weld. This motivated the authors of this work to adapt existing testing methods in order to characterize the fracture behavior of repair welds and to develop limit load solutions which include the effects of weld heterogeneity. This work focuses on the idea of implementing T-stress in characterization of fracture toughness at the onset of crack tip blunting. By normalizing J-integral by stress biaxiality coefficient β, obtained from T-stress solution, a new fracture toughness parameter is derived which tends to be dependent only on the distance from crack tip to interface between two mismatched weld materials.