Effect of induction heating temperature on the interface of cold−hot-rolled titanium/steel composite plates

Abstract

Titanium/steel composite plates are widely used in petrochemical equipment, seawater desalination equipment, nuclear power equipment, ocean engineering, and other fields owing to the excellent corrosion resistance of titanium and low steel cost. Various methods have been adopted for manufacturing titanium/steel composite plates, which include explosive bonding, explosive-rolling bonding, diffusion bonding, and hot rolling bonding. Among these techniques, hot rolling bonding method enables the production of large-sized titanium/steel composite plates with high efficiency, low pollution, and low energy consumption. However, electron beam welding of billets is required to prevent interface oxidation and the formation of brittle compounds such as TiC, FeTi, and Fe2Ti on the interface, which may cause the degradation of mechanical properties of titanium/steel composite plates. In this study, the precomposite formation of billets was done through cold rolling and the titanium/steel composite plates were prepared via single pass hot rolling after induction heating to the hot rolling temperature. The effect of induction heating temperature on the interfacial structure and bonding properties of titanium/steel composite plates was studied. The results show that the interface of titanium/steel composite plates prepared by the cold–hot rolling composite method is tightly bonded without holes and gaps. The short induction heating and hot rolling time (<5 s) are insufficient for the formation of intermetallic compounds on the carbon steel side of the composite plates, yielding only a small number of blocky hardened layers at the titanium/steel interface. Higher induction heating temperature results in wider Ti and Fe element diffusion layer at the interface, with the maximum width of 8 μm obtained at 950 ℃. The titanium/steel composite plates in this study achieved good metallurgical bonding with induction heating temperatures of 750 ℃ to 950 ℃.

Keywords

• titanium/steel composite plate
• cold−hot roll bonding process
• induction heating
• interfacial microstructure
• interfacial properties