WC-Co/316L stainless steel joining by laser powder bed fusion for multi-material cutting tools manufacturing

Joining cemented carbides and steels is particularly challenging due to the very dissimilar thermal properties that lead to high residual stresses at the interface, where in addition, brittle phases can be formed. An effective carbide-steel joint can unleash the creation of multi-material parts for several applications, and in this sense, it is of utmost importance to develop efficient methods for their fabrication. This work proposes a novel approach, using the high fabrication freedom of laser powder bed fusion technology to additively manufacture 316L stainless steel on a WC-Co substrate, to obtain complex multi-material cutting tools, with dissimilar materials in different locations. Results showed a good bonding between materials, since a dense, well-defined, and capable of withstanding cutting forces interface was obtained. The 316L stainless steel hardness ranges from 238 HV to 302 HV, with a direct correlation being found between the energy density used during laser powder bed fusion and the obtained hardness. This approach was found effective to produce multi-material WC-Co/316L stainless steel cutting tools with good metallurgical bonding and mechanical strength, without the need of adding an interfacial material.