Joining titanium grade 2 and aluminum AA7075 dissimilar sheets by electrically assisted joining: mechanical characterization

This study introduces a novel electrically assisted joining (EAJ) process for titanium-aluminum dissimilar metal joints, combining laser surface texturing with resistive heating to create strong mechanical bonds without extensive intermetallic formation. A systematic investigation using full-factorial experimental design evaluated process feasibility and optimized key parameters including power input (1.1–6.3 kW) and joining time (0.66–1.98 s). Mechanical performance assessed through single-lap shear tests revealed that untextured samples exhibited minimal strength (≤ 220 N), while laser-textured titanium substrates achieved significantly stronger joints with higher shear forces of 6.3 kN. Microstructural analysis using optical and scanning electron microscopy demonstrated that the joining mechanism relies on penetration of laser-textured titanium features into the selectively electrothermal softening aluminum surface, creating robust mechanical micro-interlocking at the interface with minimal interdiffusion. The process exhibits remarkable efficiency with joining times as short as 1.2 s. Optimization of laser texturing parameters identified that 40 laser scans with 0.3-mm hatch distance provided the optimal balance between joint strength and processing efficiency. This research establishes EAJ as a promising technique for dissimilar metal joining, particularly for titanium-aluminum combinations in aerospace and automotive applications.