Microstructure and mechanical properties of CP-Ti/X65 bimetallic sheets fabricated by explosive welding and hot rolling

CP-Ti/X65-pipe-steel bimetallic sheet was fabricated by explosive welding and hot rolling (W&R). Trace of the wavy CP-Ti/X65 interface formed from explosive welding was observed along the straight CP-Ti/X65 interface of bimetallic sheet fabricated by W&R. The microstructure and component analysis showed the following. (i) The cross-section of the X65 zone consisted of a 2–5μm-wide Ti diffusion layer next to the interface, a 150–200μm-wide decarbonization layer, and the rest area with a banded structure morphology. (ii) There were numerous voids and a slight C element enrichment at the interface. (iii) The section of the CP-Ti zone consisted of a 10–50μm-wide Fe diffusion zone next to the interface, a residual adiabatic shear band zone next to Fe diffusion zone, and the rest region composed of the α-Ti microstructure. The micro-hardness profile across CP-Ti/X65 interface was measured. The variation patterns of the mechanical properties of the bimetallic sheet in the thickness direction were obtained from stratified tensile tests. The shear test proved that the CP-Ti/X65 bimetallic sheet produced by W&R had acceptable shear bond strength. The microstructure and alloy element distribution across the TA1/X65 interfaces of as-welded, heat treated and extruded TA1/X65 bimetallic sheets were studied and compared. [Display omitted] •Big-size TA1/X65 sheet is achieved by explosive welding & hot rolling.•Periodic characteristic of microstructure across TA1/X65 interface is studied.•Mechanical inhomogeneity of TA1/X65 bimetallic sheet is studied.•Variation of chemical composition across TA1/X65 interface is studied.•Proposal abound for improving performance of TA1/X65 bimetallic sheet is given.