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

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 parame ter and the lower bound values of fracture toughness parameters such a s the fracture load, the energy absorbed, and the crack opening displa cement. 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 microstr ucture of the weakest zone where cleavage cracking is initiated.