Real-time electrical resistance monitoring for quality control in titanium Grade2-Aluminum 7075 dissimilar joints through electrically assisted joining

This study establishes electrical resistance monitoring as a real-time quality control method for titanium-aluminum dissimilar joints produced via Electrically Assisted Joining (EAJ). Experiments systematically varied power (5–7 kW) and heating duration (0.1–1.4 s) to correlate electrical resistance signatures with joint mechanical properties. At 5 kW, maximum shear force, elongation at rupture, bonded area, and electrical resistance all increased approximately linearly with heating time, indicating steady joint development. At 7 kW, both maximum shear force and electrical resistance exhibited distinctive bilinear behavior with a critical inflection point at 0.3 s—corresponding to peak shear strength of 85.5 MPa. Resistance decreased sharply until 0.3 s, then exhibited a knee followed by more gradual decline. Continued heating beyond this inflection point increased total force (reaching 5.5 kN at 1.4 s) but decreased normalized shear strength due to material expulsion and defect formation. Strong quantitative correlation between electrical resistance evolution and joint quality (r = − 0.935, R² = 0.874) establishes a reliable foundation for real-time quality prediction and intelligent closed-loop process control, eliminating destructive post-process testing while ensuring consistent joint integrity in production environments.