Experimental and numerical investigation of microstructure and evolution of TiNi Alloy/Q235 Steel interfaces prepared by explosive welding

Abstract This work presents a systematic study of microstructure and mechanical property of TiNi Alloy/Q235 steel explosive-welded interface. The structure evolution as well as the thermodynamic state during the welding process was simulated using Smoothed Particle Hydrodynamic (SPH) numerical method. The interface is featured by regular wave structure with a period of ∼400 μm and an amplitude of ∼120 μm, resulting from the periodic interaction process of jets and colliding plates. Furthermore, it was found that the waves do not form in the initial collision zone, but undergo an evolutionary process of straight-irregular small wave-steady wave transformation. Intermetallic compounds like Fe2Ti and Ni3Ti were found in melting zones, which are the source of the microscopic cracks. Even so, the interface exhibits good bonding strength of 291 MPa that is higher than the Q235 steel of 180 MPa. The nanoindentation results show the hardness values decrease at first and then increase to the initial value with increasing distance from the bonding interface. The melting zone exhibits an ultrahigh hardness of 11.06 GPa, which confirms the formation of brittle intermetallic in the melting zone.