Cladding of aluminum alloy 6061-T6 to mild steel by an electromagnetic tube bulging process: finite element modeling

Bimetal tubes have useful applications in various industries where service conditions demand more different requirements in the tube core than its outside surface. The recent use of electromagnetic forces to deform or join metallic workpieces at high speeds has undergone rapid growth for materials processing. However, to date, no sufficient systematic understanding of the underlying principles of a subsequent high-speed electromagnetic tube bulging process to manufacture bimetal tubes has been gained. In this work, magnetic pulse cladding of Al/Fe clad bimetal tubes was analyzed by finite element modeling (FEM) using ANSYS software. The validity of FEM analyses was first confirmed by experiments in terms of the deformed shape. Second, the effect of cladding parameters (such as axial feeding being the dominant factor in the multi-step process) on the bulging and thinning behavior of the Al clad tube was presented in detail. Both the numerical simulation and experimental results show that no more than 70% of the bulging-coil length is an appropriate amount for the feeding length to prevent defects from being introduced by non-uniform deformation in the transition zone of the Al clad tube. The distributions of the magnetic flux line, magnetic force, and plastic strain in different cladding steps were then analyzed. It was concluded that during the multi-step cladding process, there was an uneven distribution of the magnetic field force along the transition zone. Consequently, inharmonious plastic deformation behavior occurs, which results in a limited acceleration of the transition zone to a certain impact velocity.