Enhanced interfacial bonding strength via multi-scale microstructure formation in 304SS/TA2 composite tubes fabricated by three-roll skew rolling

The widespread application of titanium/steel composite tubes in marine engineering and petrochemical industries has been severely restricted by the absence of efficient fabrication methods. In this study, high-strength 304 stainless steel (304SS)/TA2 composite tubes with metallurgical bonding were successfully fabricated using a three-roll skew rolling process, filling the gap in producing titanium/steel composite tubes with large length-to-diameter ratios. Based on the unique non-uniform deformation characteristics of three-roll skew rolling, this study systematically investigates the influence of temperature on interfacial microstructure and bonding strength. The results show that the bonding strength of 304SS/TA2 composite tubes first increases and then decreases within the temperature range of 600–800°C. Compared to traditional explosion welding (∼185 MPa) and diffusion bonding (∼150 MPa), the peak bonding strength of 247.73 MPa at 700°C represents a 34% improvement. The enhanced bonding strength can be attributed to two key mechanisms: (1) The formation of a solid solution strengthening layer and β-Ti phase, which effectively impedes strain transfer from the TA2 side to the interface, thereby delaying interfacial failure; (2) The synergistic interaction between discontinuous micron-scale β-Ti phases and nano-scale TiC particles near the interface, which collectively contribute to a multi-scale particle pinning effect, further reinforcing interfacial bonding. These findings indicate that precise temperature control during three-roll skew rolling can effectively tailor interfacial structures, providing a viable technical pathway for achieving high-strength bonding in dissimilar metal composite tubes.