Mechanical properties of mismatched high strength steel butt joints with three softened/hardened strength distribution patterns

Abstract

Abstract Based on the proposed three hardness distribution patterns of butt-welded joints of high strength steel, a systematic numerical analysis considering geometric and mechanical parameters on mismatched butt joints of high strength steel is performed with a total of 938 simulated specimens. An extensive analysis of the effect of eight parameters on the mechanical behavior of mismatched butt joints is preformed, including width of weld metal, width of softened zone, width of hardened zone, the plate width-to-thickness ratio, the bevel angle, the strength of weld metal, the strength of softened zone and the strength of hardened zone. Through significance analysis, the contribution of each parameter is discussed, showing that mismatch ratio, the strength and width of SHAZ have obvious contribution on the load carrying capacity of butt-welded joints while The existence of hardened HAZ zone has negligible effect on the strength of butt joints. In addition to typical failure modes occurring at the weakest zone in most cases, a combined failure mode is observed in the test of undermatched joints with softened heat affected zone. It is found that constraint effect has significant influence on the strength and failure mode of butt joints.