Interfacial modification of titanium/steel composites and its effect on the growth pattern of Fe-Ti compounds

Abstract

The formation of brittle compounds at the titanium/steel interface, which weakens bonding strength, is a significant challenge that must be addressed to broaden its use in sectors like petrochemical engineering and pressure vessels. Previous research has improved bonding strength by adjusting the diffusion coefficient on the titanium side. However, it also revealed problems with the rapid increase in TiC layer thickness and the precipitation of Fe-Ti compounds at temperatures above 950°C. This study introduces a new method based on the coordinated control of titanium/steel diffusion coefficients to create a TiC barrier effect at the interface, thus preventing the formation of brittle Fe-Ti compounds. The research methodically examines the effects of coordinated diffusion coefficient control between 850°C and 1000°C on the composite interface structure and further enhances bonding strength. The findings show that the coordinated control of titanium/steel diffusion coefficients effectively stabilizes the interface structure as α-Ti, TiC, and γ-Fe, inhibiting the formation of Fe-Ti compounds. As the rolling temperature rises from 850°C to 1000°C, the bonding strength increases from 190 MPa to 340 MPa. Near the composite interface on the steel side, a (101) oriented layer forms, and the diffusion distance of carbon significantly decreases to 10μm. The composite interface layer transitions from a mixed layer of TiC and Fe-Ti with a thickness of approximately 470 nm to a uniform and continuous TiC layer about 200 nm thick. This breakthrough overcomes the limitations of rolling temperature and excessive thickening of interface brittle compounds, expanding the process window for titanium/steel composite material preparation and establishing a link between diffusion coefficients, interface structure, and mechanical properties.