Joining of cemented carbides WC-Co and tool steel X153CrMoV12 with capacitor discharge welding process

Welding a combination of hard-to-weld materials such as cemented carbides WC-Co and tool steel X153CrMoV12 is a big challenge due to the diametrically different properties of the materials being joined. Such joint makes it possible to combine the high hardness of sintered carbide with the high fracture toughness of steel. Then, the unique property profile of joint allows to use the sintered carbides as a material for demanding applications that are subject to high levels of stress and wear. The connection of sintered carbides (WC-Co) with steel can be achieved in various ways. However, each of these techniques can lead to manufacturing defects. The solution can be the method of multi-capacitor discharge welding, which allows high temperatures to be reached for very short times. Standard single-capacitor systems do not allow control of the welding process. Therefore, in this study, a new multi-capacitor method was used for welding. The method allows influencing the process due to the variability of adjustable parameters, mainly targeted influencing of the welding current. After finding the optimized parameters, a set of test samples was welded from cemented carbides WC-Co and tool steel X153CrMoV12. The joined test specimens achieved a demonstrable fusion bond during the welding process. The connection occurred around the entire perimeter of the contact surface. During joining, a mixed layer (consisting of cemented carbide and tool steel components) and a melting zone (depleted of chromium) were created at the interface of the materials. The average quasi-static strength of the connection was 12.5 kN. The study provides insight into the use of the multi-capacitor discharge welding method to join a combination of difficult-to-weld materials suitable for demanding industrial applications.