Effect of rolling temperature on microstructure and mechanical properties of Ti/steel clad plates fabricated by cold spraying and hot-rolling

The effect of rolling temperature on the interfacial microstructure and mechanical properties of Ti/steel clad plates, fabricated by a newly designed method (cold spraying and hot-rolling), was studied. For this purpose, three rolling temperatures (i.e. 850, 950, 1050 degrees C) were selected to completely understand the bonding mechanism at Ti/steel interface. The type of interfacial compounds and thickness of the diffusion layers were found to be the main factors controlling the mechanical properties of the Ti/steel clad plates. Results showed that the Ti/steel clad plate rolled at 850 degrees C exhibited metallurgical bonding due to the formation of a 250 nm thick TiC diffusion layer at the interface, and resulted in the best elongation. In contrast, the sample rolled at 950 degrees C developed a 400 nm thick diffusion layer which was composed of TiC and FeTi compounds, leading to the best tensile strength. When the rolling temperature was increased to 1050 degrees C, the thickness of the diffusion layer (composed of coarse TiC and FeTi phases) was sharply increased to 4 mu m, and the sample displayed poor tensile strength and elongation.