Fracture performance testing and modeling of butt weld metal

Weld joints necessary for various structures are heterogeneous and anisotropic which are known to be high-risk due to inevitable defects. The location dependence of material properties in the weld joint means Linear Elastic Fracture Mechanics (LEFM) limited to homogeneous and isotropic materials may not be appropriate. In this paper, the weld metal of Q235 steel butt weld joint was taken as an object, and Boundary Effect Model (BEM) was introduced to deduce the fracture toughness K_IC of weld metal from the yield load P_y, which bypassed the stringent LEFM requirements on material homogeneity, specimen size, and initial crack/notch length. 68 three-point bending (3-p-b) specimens with different initial notches were tested, and consistent fracture toughness K_IC and yield strength σ_y of the weld metal were determined through curve-fitting based on BEM. Furthermore, these results were verified via specification-compliant tensile and Charpy impact tests respectively, demonstrating that the boundary effect model can be applied to determine the location-dependent material properties in welded sections of steel structures.