THE LOCAL FRACTURE STRESS AS A FRACTURE TOUGHNESS PARAMETER TO CHARACTERIZE AN HETEROGENEOUS WELD ZONE

Abstract— The toughnesses of specimens of heterogeneous multipass weldments with various ratios of weld metal to base metal can be characterized by a single value of the local fracture stress within a narrow scatter band. Relationships were found between the normalized value of this parameter and the lower bound values of fracture toughness parameters such as the fracture load, the energy absorbed, and the crack opening displacement. These facts indicate that using such a toughness parameter, it is possible to assess a heterogeneous multipass weldment by a single value; within a narrow scatter band. Further experiments indicate that this parameter could be measured on specimens simulating the microstructure of the weakest zone where cleavage cracking is initiated.