Investigation of the effect of microstructure changes on the elastoplastic behavior in cross-wire welding using the finite element method

Abstract The elastoplastic behavior of dual-phase wires was investigated using both experimental methods and the explicit dynamic finite element with Johnson–Cook material model after resistance spot welding. The welded region was examined in detail using a scanning electron microscope, revealing three distinct regions: the welded zone, the heat-affected zone, and the unaffected zone. The breakage distance and displacements of the cross welded wire under load were studied for various alignment angles, electrode sizes, and wire diameters. Increasing the electrode diameter reduces the weld area’s deformation capacity by enlarging the brittle volume. At the highest wire diameter, as the electrode diameter increases, the elongation values decrease by 33.3%, 18.1%, and 7.1% for 0°, 45°, and 90°, respectively. However, due to the increase in wire diameter, the bending stress also increases, causing breakage in the WZ. The distance of the breakage is directly related to the ratio of the welding surface and the cross-sectional area of the wire. During tensile testing, the $${A}_{n}/{A}_{tr}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>A</mml:mi> <mml:mi>n</mml:mi> </mml:msub> <mml:mo>/</mml:mo> <mml:msub> <mml:mi>A</mml:mi> <mml:mrow> <mml:mi>tr</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> ratio is always below one, and damage occurs in the transition zone. In cross-tensile testing, the area ratio is above one, and rupture can occur in the welded zone, depending on the amount of bending stress.