2016 Volume 34 Issue 4 Pages 274-284
Mechanical and physical properties of the explosive welded joint are often decreased by an intermediate layer (IML) formed at the joint interface. Local melting due to the local temperature increase at the joint interface is one of the possible reasons of the IML formation. However, it is difficult to investigate experimentally the temperature change at the joint interface directly during the explosive welding. In the present study, the explosive welded Cu/Al joint, which is prone to form IML at the joint interface, was selected for the research. Wavy interface formation, temperature change at and near the joint interface and melting temperature change by high pressure collision were examined by using SPH simulation. The simulation results were compared to the interface microstructure of the explosive welded Cu/Al joint. The large and rapid temperature increase was observed at the joint interface, in particular, at the vortex zone with the wavy interface formation. The temperature increase was localized near the joint interface, and no temperature increase was observed in the region 500μm away from the joint interface. The simulation results found that temperature increase near the joint interface was mainly due to the thermodynamics work occurred by compression at the collision point. The melting temperature near the collision point increased by high pressure in compression, but its duration was very short (a few μs). It is indicated that local melting occurred at the vortex zone and near the joint interface, in which Cu and Al were mixed and the temperature exceeded the melting temperature of both Cu and Al. The shape and location of local melting zone predicted by simulation was in good agreement with the experimentally observed IML.
