A study on the critical wall thickness of the inner tube for magnetic pulse welding of tubular Al–Fe parts

•The critical non-dimensional thickness of the inner tube for MPW is proposed.•The critical thickness of inner tube of Al–Fe welding structure is studied by combining theory calculate and technological test.•The relationship between voltage and the critical thickness of the inner tube is investigated.

Microstructure and mechanical properties of the welding zone highly depend on the thickness of inner tube for jointing two tubes using magnetic pulse welding (MPW). In this study, the critical thickness of inner 20Fe tube for the Al–Fe welding tubes is investigated by combining the theoretical calculation and experiments. Theoretical analysis demonstrates that plastic deformation zone of the inner tube expands from its inner surface to its outer surface. With equilibrium equations and modified Tresca yield criterion, the critical thicknesses of inner tube under various collision velocities are derived so as to assure the high quality of the welding. The results show that the critical thickness of inner tube increases linearly with the discharge voltage. With the discharge voltage increases by every 2 kV, the critical thickness increases by 0.5 mm accordingly. The theoretical predictions agree well experiments with an error of less than 2.5%. Furthermore, effects of thickness of inner tube on the mechanical properties of welding zone are also investigated.

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