Experimental and numerical study of high-strength steel butt weld with softened HAZ

Abstract

Static tensile tests were conducted on 26 butt welded joints on base steel of Q690 grade high-strength steel, which exhibits softening behaviour in the heat-affected zone (HAZ). Considering the challenges involved in simulating the butt weld with the HAZ, a new method was proposed for calibrating the true stress–strain relationship based on a trial-and-error approach using simulation through comparing the load–deformation response for three materials (base metal, weld metal and HAZ) in a butt weld. Good consistency on the load–deformation response between the simulation and the test was observed, validating the proposed method. Parametric study showed that the relative width of the softened zone and matching ratio have a significant influence on the ultimate strength of the butt weld and BS EN 1993-1-12 cannot be used directly to design a butt weld with a soft interlayer in the HAZ of high-strength steel.