Experimental and numerical investigation of fracture in fillet welds by cross joint specimens

Abstract

The load capacity of fillet welds is investigated experimentally and numerically in cross joint specimens with the objective of calibrating multiple failure criteria for the ductile fracture of weld metal. The cross joint specimens are composed of mild shipbuilding steel with plate thicknesses of 20 mm and 30 mm respectively. The fillet welds are manually produced by flux-cored arc welding, using the filler metal Elgacore MXX100. To achieve different stress states in the weld joints, forces in two different directions and moments about two different axes are applied separately on various specimens. A uniquely designed specimen is employed for each load scenario. For the numerical investigations, an appropriate discretization of the weld joints is established by taking into account the distribution of the metallographic structure with the weld metal and the heat-affected zone. The distribution of the different materials is determined by a macrosection of a weld joint. The material behavior, in terms of true stress-strain curves for the weld metal and the material of the heat-affected zone, is identified by hardness measurements. With the established discretization of the weld joints and true stress-strain curves of the different materials, the experimentally determined force-displacement curves are reproduced in finite element analyses. Furthermore, the Gurson (1977) damage model are successfully calibrated for the weld metal.