Microstructural and mechanical enhancement of resistance spot welding with initial gap using TiO₂ and Fe nanoparticle interlayers

Abstract

The welding time, current intensity, and electrode pressure are critical parameters in resistance spot welding. The initial gap often arises during spot welding of automotive repair structures, hindering the attainment of excellent welds. These variables evidently affect welding quality, hence compromising the structural integrity and safety of the vehicle. This study's novelty lies in the use of two interlayer types in a spot-welding technique to produce microstructurally strong lap joints. It assesses the influence of interlayer composition on microstructural evolution and the formation of the weld nugget under tensile shear stress. The influence of three initial gap dimensions (0.5 mm, 1 mm, and 1.5 mm) was analyzed using two varieties of interlayer nanoparticles (iron particles and TiO₂) to fill the gaps by compaction, excluding the incorporation of filler material; the investigation evaluated the mechanical properties of the welded joints. The results demonstrated a significant increase in joint strength relative to a direct connection without an interlayer; this enhancement is influenced by the gap size and the type of nanoparticles used to fill it. At a plate gap of 0.5 mm, both iron and TiO₂ particles significantly enhance weld strength; this effect is also observable at a separation of 1 mm. Nonetheless, when the gap widened to 1.5 mm, adding an interlayer did not affect the strength of the welded plates. Results demonstrate that nanoparticle interlayers substantially affect gap size by enhancing welding conditions in vehicle repair. The study clarifies the importance of nanoparticle augmentation in closing gaps, hence enhancing joint efficacy and structural integrity.