Enhanced constraint-based resistance model for welded HSS joints with HAZ influence

In order to analyze the effects of HAZ softening on the resistance of welded HSS joints, experimental and numerical investigations were conducted on single-sided welded T-joints as part of the IGF-FOSTA research project P1453. The experimental investigations of the study focused on specimen preparation, manufacturing, experimental execution, HAZ expansion evaluations, and the analysis of load-bearing capacity tests on two thermomechanically rolled HSS S700MC steels. The numerical investigations focused on further analyses of the resistances of T-joints with HAZ failure, highlighting the influence of different tensile-strength mismatching ratios between the base material, weld metal, and HAZ, as well as the impact of different geometric HAZ expansions on the tensile resistance of butt and fillet welds. This article combines the results of experimental and numerical investigations to enhance and modify an existing constraint-based resistance model from the literature. Based on the numerical results, the original model is extended to include fillet welds and modified to predict a more reliable overall resistance behavior of full-strength welded joints with HAZ failure. A comparison with the experimental results shows that the enhanced resistance model can accurately calculate the test data for single-sided welded T-joints within a 5% tolerance. Further validation of the resistance model was conducted using an existing experimental database containing HAZ failure tests of HSS butt welds. The comparison between the experimentally determined load-resistances and the values calculated by the model demonstrates good agreement within a tolerance limit of 10%.