WC / Stainless Steel Joints Produced by Direct Diffusion Bonding Using a Ni-Foil Interlayer

Cemented tungsten carbides are industrially one of the most used composite materials as cutting tools, wear parts and replacements of standard materials for tools, dies and machine components. This work focuses on various aspects of diffusion bonding of tungsten carbide to AISI 304 stainless steel using a Ni-foil interlayer. WC/Ni/AISI 304 combinations were diffusion bonded at 1000°C using different holding times under argon atmosphere. The microstructure characterization of the resulting interfaces was carried out by SEM and EPMA. The results show that successful joining between WC and AISI 304 steel is achieved by the formation of a diffusion zone at both ends of the Ni foil. All WC/Ni/AISI 304 samples have been joined with no severe interfacial cracking or porosity at the interface. The joint strength is determined by four-point bending testing, a maximum of 210 MPa for samples joined at 1000 ºC for 60 minutes has been achieved. These results indicate that there is a strong relationship between the thickness of the diffusion interface and the mechanical strength of the joints.