Effect of an interlayer on the microstructure and mechanical properties of explosively welded aluminum alloy-cast iron joints

Joining aluminum alloys to brittle cast iron is challenging due to the high carbon content present in the form of graphite and the formation of a melting layer that degrades joint strength. In this study, an interlayer-assisted explosive welding approach was employed to mitigate these issues. The introduction of the interlayer reduced kinetic energy dissipation during impact. As a result, the interfacial bonding strength was improved. Direct welding of A5052/JIS G 5501 and A6061/JIS G 5501 resulted in shear strengths of 81 MPa and 104 MPa, respectively. The introduction of an interlayer increased the shear strength to 157 MPa and 192 MPa, corresponding to improvements of 93.8% and 84.6%. Large deformation under high pressure at extremely high strain rates is generally not expected in brittle cast iron due to its low ductility. A distinct wavy interface morphology was observed at the interlayer-cast iron interface. To investigate its formation, smoothed particle hydrodynamics (SPH) simulations were performed. The numerical results reproduced the experimentally observed interfacial features and confirmed the occurrence of significant interfacial deformation under high strain-rate conditions. Overall, the results demonstrate that the use of an interlayer is an effective strategy for enhancing the interfacial morphology and mechanical performance of aluminum alloy-cast iron explosive welds.