Magnetic pulse welding of AA6061 and AISI 1020 steel tubes: Numerical and experimental investigation

In the present investigation dissimilar weld joints were made between Aluminium-6061(Al) and 1020-Steel (St) tubular components using magnetic pulse welding (MPW) process under the discharge voltages of 12 to 14 kV and at a standoff distance (air gap) of 1 to 2.5 mm. The finite element modelling (FEM) based simulation and experimental approaches were used to understand the manufacturability of MPW process. The tool design and process parameters of MPW process were optimized from FEM simulation results. Defect-free Al-St tubular joints were obtained at optimized process parameters of 1 mm air gap with 12.5, 13.5 and 14 kV voltage. Detailed microstructural characterization was carried out at the interface of Al-St joint to understand the joining mechanism. Destructive evaluation of the welded samples showed that weld joint strength is higher than base metal. A maximum failure load of 42.3 kN was achieved for joint. Fractography study was carried out on the failed samples to understand the failure mechanism of the joint. Higher hardness of 734 HV was seen at 1 mm air gap and 12.5 kV voltage along the interface due to the intermetallic formation and refined grain size by severe plastic deformation. The physics of MPW process and micro mechanism of interfacial bonding was studied in detailed.