Fracture Toughness Evaluation of the Heterogeneous Bond Region in HT80 Steel Weldments

Fracture toughness tests of specimens in which the crack fronts consist of the weld metal region, the HAZ, and the base metal region have been carried out. It seems that, even in the case of the specimens, the stretched zone width can be a proper parameter of fracture toughness. It is necessary to take note of the stretched zone width in the lower toughness region in estimating the macroscopic and average value of fracture toughness of the specimen. It is satisfactory to consider that the critical COD values of the specimens used here, even though the weld metal region is away from the center of thickness, are roughly equal to those of specimens of which the crack front is completely in the weld metal.