EVALUATION OF RESISTANCE TO DUCTILE FRACTURE OF WELDMENTS FROM THE SIMPLE TENSILE TEST: TEN YEARS OF THE RBR PARAMETERS

摘要

In 1992, Ray, Bhaduri and Rodriguez proposed an empirical method for characterizing the resistance to ductile fracture of materials from the simple tensile test of smooth (unnotched) specimens. Two empirical ductile fracture toughness parameters Γ_f and η_f were proposed based on the consideration that the post-necking regime during tensile deformation is dominated by microvoid growth and coalescence processes, and therefore the energy absorbed in this regime can be used to estimate the resistance of the necked region to ductile fracture. The method of computing the RBR parameters Γ_f and η_f, from tensile data is described. Over the last ten years the method has been extensively applied to evaluate the resistance to ductile fracture of three dissimilar welds, namely Alloy 800/ 2.25Cr-1Mo steel and Alloy 800/9Cr-1Mo steel and Alloy 800/ 316 LN SS. The method has been successfully used to optimise their post-weld heat treatments and to evaluate the effects of ageing treatments chosen to simulate their service life. Some of the typical results are presented and discussed demonstrating the efficacy of the RBR parameters and their superiority over conventional parameters from the tensile tests.