Study on enhanced bonding performances and fracture mechanisms of vacuum hot-forged Ti/steel clad plates with Nb+Ni dual-interlayers

Ti/steel clad plate holds promising prospects in a wide range of corrosive environments, particularly in marine engineering and petrochemical industry. However, directly bonded Ti/steel clad plates typically suffer from inadequate interfacial strength due to the formation of detrimental Fe-Ti intermetallic compounds (IMCs). This study proposes the implementation of Nb+Ni dual-interlayers of varying thicknesses to suppress IMCs and enhance the bonding performances, with the bonding mechanisms and fracture mechanisms systematically unveiled. The analysis of the interfacial microstructure indicated that the initial thickness of the dual-interlayers influenced the bonding mechanism and phase distribution, thereby affecting the mechanical properties of the clad plates. The clad plate with 30 μm Nb + 50 μm Ni interlayers exhibited the highest average shear strength of 302 MPa, confirming the effectiveness of Nb+Ni dual-interlayers in overcoming the inability of directly bonded Ti/steel clad plates through hot-forging. The fracture mechanism, elucidated by the fracture observation and the interrupted tensile tests, indicated that the interfacial Ni₃Nb layer is closely related to the mechanical properties. Appropriate dual-interlayer thickness ensures the attenuation of Ni₃Nb layer and its superior deformation resistance ability is the key factor in enhanced bonding performances. These findings emphasise the critical role of Nb+Ni dual-interlayers with appropriate thickness in enhancing the mechanical properties of clad plates, offering novel insights for enhancing dissimilar metal bonding in industrial applications.