Experimental investigation of explosion-welded CP-Ti/Q345 bimetallic sheet filled with Cu/V based flux-cored wire

Highlights: • CP-Ti/Q345 bimetallic sheets were produced by explosive welding. • Cu/V based filler materials were designed to join the bimetallic sheets. • Severe cracks and lack of penetration emerged in TIG welded joint with Cu/V solid wires. • Continuously distributed microstructures were revealed in flux-cored wire welded joint. • Large stress in CP-Ti/Q345 interface was detrimental to the joint integrity. - Abstract: Explosive welding is widely applied to joining Ti with steel in recent years. However, joining the explosion-bonded CP-Ti/Q345 bimetallic sheets has not been thoroughly investigated. In this paper, explosion-bonded CP-Ti/Q345 bimetallic sheets were applied as base metal and intermediate materials were employed to join the bimetallic sheets. Based on the element metallurgical compatibility, Cu/V based filler metals (solid wire and flux-cored wire) were designed as intermediate layers for TIG welding method. To determine the feasibility of these filler metals, microstructures were analyzed by optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Microhardness tests were used to compare the brittleness of the intermetallics in the weld joints. Tensile strength test was performed to evaluate the strength of the joint. The results showed that the feasibility of the Cu/V based solid wires was poor due to metallurgical incompatibilities. The joint filled with Cu/V solid wires suffered severe cracks. Such defects reduced if a Cu–V flux-cored wire was used. It was attributed to continuously distributed microstructures in weld joint and low heat input with the Cu–V flux-cored wire