The Determining Role of Nb Interlayer on Interfacial Microstructure and Mechanical Properties of Ti/Steel Clad Plate by Vacuum Rolling Cladding

Abstract

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.

Microstructure and mechanical property of titanium steel by vacuum roll-cladding with interlayer

“…The size of the TA2 test plate was 130 mm×90 mm×5.3 mm and the size of the Q345R plate was 160 mm×120 mm×20 mm. Based on the previous research [17,18,[20][21][22], the thickness of industrial pure Fe foil and industrial pure Ni foil were both chosen as 0.1 mm. The chemical composition (mass fraction) of TA2 and Q345R steel are given in Table 1.…”

“…Two intermetallic compounds, TiFe and TiFe 2 , can be formed between Fe and Ti according to the Fe-Ti phase diagram. And the temperature range for the formation of the two intermetallic compounds runs through the solid phase zone; therefore, its formation process is irreversible and cannot be eliminated by changing the rolling temperature and post-rolling heat treatment [17].…”

“…In addition, vacuum rollcladding can produce wide and thick plates, which has broad application prospects [14][15][16]. Though oxides and nitrides at the interface can be effectively inhibited during vacuum roll-cladding, TiC and Ti-Fe metal brittle compounds are easily formed at the interface of Ti and steel during the process of heating, rolling and cooling, which reduce the interfacial bonding property of Ti steel clad plate [17][18][19].…”

“…Yu et al [18] used the pure Fe interlayer between titanium and carbon steel during hot-rolling bonding and found that the bonding strength was highest at 850°C, which could reach 237.6 MPA. Xie et al [17] used the Nb interlayer during vacuum roll-cladding and investigated microstructure and mechanical properties of titanium-steel plates. The interdiffusion of Fe, Ti and C was effectively inhibited by the Nb interlayer at a heating temperature of 800°C.…”

Analytical Investigation on the Evolution and Growth of β-Ti and Fe-Nb-Based Intermetallics in Diffusion Coupled Joints of Ti6Al4V|Nb|SS

“…Xie et al [26] conducted an exhaustive study on the effect of Nb interlayer (~80-μm thick) on the vacuum roll cladding of Ti and steel at three different temperatures: 800, 900, and 1000 °C. The study highlighted that the joints with Nb outperform in mechanical characterization when the processing temperature is in between 800 and 900 °C.…”