304 austenite stainless steel plate and HSLA steel plate were subjected to vacuum rolling cladding (VRC). The microstructure characteristic and properties of the clad interface were investigated in detail. During the VRC process, the clad interface was held at a high vacuum all the time, resulting in significantly decreased oxidation at the interface. A small amount of very fine oxide particles (diameter < 0:5 mm) can be found at the clad interface, and no obvious defects were observed. The remarkable diffusion of Ni and Cr elements led to the formation of a transition zone with high hardness. The shear strength of the clad interface was as high as 487 MPa, and the fracture occurred at the HSLA steel near the transition zone. No cracks were found at the clad interface after the 180 bending tests with both outside and inside manners.

Vacuum hot roll bonding (VHRB) was used to bond pure titanium (Ti) plate to a 304 stainless steel (SS) plate with a niobium (Nb) interlayer, with the aim of producing a high-quality Ti-SS clad plate. The roll-bonding process was performed at different temperatures in the range of 850-1000 • C, followed by characterization of microstructure and mechanical properties. The study demonstrates that the interfaces are free from cracks and discontinuities, and interdiffusion between the stainless steel and the titanium is effectively prevented by inserting a layer of pure Nb foil. No intermetallic reaction layer occurred at the Nb-Ti interface at any of the investigated temperatures. An intermetallic FeNb phase was formed at the Nb-SS interface when bonding was performed at 950 • C and above. The presence of the FeNb layer was confirmed by x-ray diffraction. The maximum shear strength of ∼396 MPa was obtained when bonding is carried out at 900 • C. However, the formation of the FeNb layer at roll bonding temperature greater than 900 • C led to decrease in shear strength. Ductile fracture occurred through the Ti-Nb interface for roll-bonded temperatures of up to 900 • C. On the other hand, at temperature of 950 • C and above, failure occurred through the Nb-SS interface, with brittle fracture characteristics.

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