Numerical investigation of electromagnetic pulse welding for aluminium-steel tubular joints

Electromagnetic pulse welding (EMPW) enables solid-state joining of dissimilar metals such as aluminium and stainless steel in tubular configurations, offering significant advantages for lightweight components in automotive drive shafts, cryogenic couplings, and energy bus-bars. Conventional fusion welding induces brittle intermetallic compounds due to thermal mismatch, whereas EMPW avoids bulk melting but is hindered by slow industrial adoption owing to extensive trial-and-error optimisation of discharge energy, coil design, air gap, and geometry. This work develops a coupled electromagnetic–structural axisymmetric finite-element model for driverless aluminium-to-stainless-steel tubular EMPW. Under experimental discharge conditions (27.2 kJ stored energy, 212 kA peak current), the model predicts peak flyer-surface magnetic flux density of 28 T, Lorentz force density up to 1.5 × 10¹² N/m³, and central impact velocity of 328 m/s. Final radial displacements (3.2 mm free end, 1.0 mm fixed end) and conical deformation profiles agree with experimental measurements within 4%. Coil edge effects generate axial non-uniformity in flux and force (~25% reduction from center to ends), resulting in sequential collision with central contact by ~20 µs and edge closure by ~25 µs. This propagating contact front expels trapped air and contaminants, promoting oxide-free, leak-tight bonding. Parametric analysis of peak current (160–220 kA) reveals a near-linear increase in central radial displacement of 12.5 ± 0.8% per 10 kA increment, providing a practical design rule. The validated model serves as an efficient virtual tool for rapid parameter optimisation, substantially reducing reliance on physical experimentation for lightweight dissimilar tubular joints.