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In this paper, the copper-based welding wire was used to complete the double-layer billet assembling, and bimetal Ti/steel clad plates were successfully prepared by hot rolling. The transverse bonding strength distribution was studied through microstructure characterization and the finite element method (FEM). The influence factors of oxidation, temperature, and stress were discussed. The results showed that the bond strength exhibited a transverse heterogeneity, which was 294 MPa at the width center and gradually decreased to 101 MPa at the width edge. Correspondingly, the interface at the center was well bonded while it contained cracks and voids at the edge. The oxidation occurred only at the edge for cracking in the weld during rolling, which deteriorated the bonding strength. The temperature along the width direction had little effect on the bonding strength for its small drop. Compared with these, the decreased normal stress from center to edge caused by the width resistance and metal flow characteristics was the main reason for the transverse heterogeneity of bonding strength. Based on this, a transverse bonding strength prediction equation considering the distribution of stress and bonding strength was proposed, and the relative error of it was 8 ~ 15%. [ABSTRACT FROM AUTHOR]

• TA2/Q235 clad plates was prepared by cold spraying and hot rolling. • A flat and uniform TiC layer of 200 nm-thick was formed at the interface. • The TiC layer inhibited the formation of the FeTi and FeTi 2 compound layers. • The TA2/Q235 clad plate with 560 MPa UTS and 32 % elongation is obtained. TA2/Q235 clad plates were fabricated using a combination of cold spraying and hot rolling techniques. The cold spraying process involved the high-speed impact that compressed the oxide film present on the surface of both the Ti particle and the steel plate. This compression led to a strong prebonding at the TA2/Q235 interface. Subsequently, a 200 nm-thick interface layer of TiC was formed during the hot rolling process. This TiC layer effectively inhibited the formation of FeTi and Fe 2 Ti compound layers. As a result, the clad plates exhibited excellent mechanical properties, including an ultimate tensile strength of 560 MPa and an elongation of 32 %. [ABSTRACT FROM AUTHOR]

We elucidate here the determining role of Nb interlayer on mechanical properties of Ti/steel clad plate fabricated by vacuum rolling cladding (VRC) as a function of different heating temperatures. A critical analysis on the clad interface via electron probe micro-analyzer, X-ray diffractometer and shear testing were conducted to investigate the influence of TiC, Fe-Nb and TiFe compounds and Nb-Ti solid solution on microstructural evolution and shear properties of Ti/steel clad plate. The inter-diffusion between Ti, C and Fe was effectively restrained by adding the Nb interlayer at heating temperature of 800 °C, and average shear strength of 279 MPa was achieved. With increase of heating temperature, Nb-Ti solid solution was formed at the Ti/Nb interface, which reduced mechanical properties of clad plate at 900 °C. At 1000 °C, TiC and Nb-Fe compounds and Nb-Ti solid solution were formed at the interface, and minimum average shear strength of 152 MPa was achieved. The detailed analysis on the clad interface suggested that ideal shear strength can be obtained through the addition of Nb interlayer and selecting appropriate heating temperature.

Ti/steel clad plates have good corrosion resistance and lower titanium cost. However, the low interfacial bond strength severely restricts their wide application. In this study, a new process is proposed for preparing Ti/steel clad plates with high bond strength by employing double-layered slab assembly and hot rolling. The effect of temperature on bond strength is systematically studied. The results show that the shear strength initially increases and then decreases with increasing temperature from 700 °C to 950 °C. The maximum strength value of 311 MPa is obtained at 850 °C with a reduction rate of 30 % in a single pass. The mechanism analysis shows that the bond strength is affected by temperature in terms of metal deformation, elemental diffusion and intermetallic compound (IMC) formation. In addition, the shear strength depends on different degrees of dislocation strengthening and recrystallization in the titanium matrix when the fracture is located at titanium matrix near the interface. Finally, a phenomenological prediction mechanism-based model is developed to describe the relationship between the temperature and the bond strength. This research can provide guidance for the hot rolling preparation of Ti/steel clad plates with high bond strength. [Display omitted] • Ti/steel plates were fabricated by double-layered slab assembly and hot rolling. • A superior bond strength of 311 MPa was obtained at 850 °C. • Microstructure evolution was characterized. • Bonding mechanism at different temperatures was analyzed. • A phenomenological prediction mechanism-based model was proposed. [ABSTRACT FROM AUTHOR]

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 °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 °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 °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 °C, the thickness of the diffusion layer (composed of coarse TiC and FeTi phases) was sharply increased to 4 μm, and the sample displayed poor tensile strength and elongation. [ABSTRACT FROM AUTHOR]

A novel method was designed to fabricated Ti/steel clad plates via cold spray additive manufacturing (CSAM) and hot-rolling. In order to study the influence of annealing on the microstructure and mechanical properties of the Ti/steel clad plates, the as-rolled clad plates were subjected to different annealing temperatures in the order: 450, 550 and 650 °C. It was revealed that CSAM and hot-rolling promote metallurgical bonding between Ti/Ti as well as Ti/steel interfaces, thus resulting in Ti/steel clad plates with excellent mechanical properties. The annealing treatment promotes inter-diffusion of Ti and Fe across the Ti/steel interface and improves the microstructures of the as-rolled Ti/steel clad plates. The results show that when the annealing temperature is low (i.e. 450 °C), the elongation of the specimen increases while the ultimate tensile strength and shear strength both decrease through recovery and recrystallization mechanisms. However, when the annealing temperature is too high (i.e. 650 °C), the elongation and strength of the specimen decrease sharply due to the nucleation and growth of brittle TiC and FeTi compounds. The annealing, at 550 °C for 3 h, was pin-pointed as the optimum post-rolling treatment to achieve superior ultimate tensile strength (564 MPa), shear strength (280 MPa) and elongation (18%) in the clad plate. • Ti/steel clad plates were fabricated by cold spraying and hot-rolling. • Effect of annealing on the structure and performance of the samples was studied. • Annealing improves mechanical properties through recovery and recrystallization. • Annealing reduces the dislocation density, promoting elongation of the sample. • High temperature promotes the growth of TiC, harming the sample's performance. [ABSTRACT FROM AUTHOR]

An innovative approach is designed to fabricate Ti/steel clad plates. Instead of using Ti sheets, pure Ti powder was initially deposited on steel plates using cold spray additive manufacturing (CSAM). Then well bonded Ti/steel clad plates were obtained through hot-rolling and annealing operations. The mechanical properties of the clad plates at different processing stages were evaluated by performing a series of tensile tests and shear tests. It was revealed that the Ti/steel clad plates had excellent shear strength (280 Mpa), ultimate tensile strength (UTS, 564 Mpa) and decent elongation (EL, 18%). Microstructural investigation of the specimens was performed by scanning electron microscopy (SEM), electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM). It was revealed that cold spraying offers good pre-bonding of Ti with the steel plate thereby suppressing cracking and oxidation at the interface. Hot-rolling treatment repaired the pores/defects in the as-sprayed Ti coating and resulted in metallurgical bonding between Ti particles as well as Ti/steel interface, which remarkably improved the strength of the material. High dislocation density in the clad plates were further eliminated by the annealing treatment through recovery, recrystallization and grain growth mechanisms, which greatly improved the toughness of the samples. Image 1 • Ti/steel clad plates were fabricated via cold spray additive manufacturing followed by hot rolling and annealing co-treatments. • The Ti/steel clad plates show excellent tensile strength, elongation and shear strength. • Cold spray resulted in pre-bonding of the Ti/steel interface and inhibition of oxidation at the interface. • Hot rolling repaired the defects and resulted in metallurgical bonding of Ti/steel （Ti/Ti） interface. • Annealing led to recovery and recrystallization, which resulted in increased toughness. [ABSTRACT FROM AUTHOR]

We elucidate here the determining role of Nb interlayer on mechanical properties of Ti/steel clad plate fabricated by vacuum rolling cladding (VRC) as a function of different heating temperatures. A critical analysis on the clad interface via electron probe micro-analyzer, X-ray diffractometer and shear testing were conducted to investigate the influence of TiC, Fe-Nb and TiFe compounds and Nb-Ti solid solution on microstructural evolution and shear properties of Ti/steel clad plate. The inter-diffusion between Ti, C and Fe was effectively restrained by adding the Nb interlayer at heating temperature of 800 °C, and average shear strength of 279 MPa was achieved. With increase of heating temperature, Nb-Ti solid solution was formed at the Ti/Nb interface, which reduced mechanical properties of clad plate at 900 °C. At 1000 °C, TiC and Nb-Fe compounds and Nb-Ti solid solution were formed at the interface, and minimum average shear strength of 152 MPa was achieved. The detailed analysis on the clad interface suggested that ideal shear strength can be obtained through the addition of Nb interlayer and selecting appropriate heating temperature. [ABSTRACT FROM AUTHOR]