Laser surface melting of electro-metallurgic WC/steel composites

Laser surface melting was used to treat electro-metallurgic WC/steel composites. The microstructure and properties of the melted zone were investigated. It was found that a homogenous and fine microstructure was formed in the melted zone. A significant phase precipitated was the herringbone eutectic carbide of Fe₃W₃C. The volume fraction of the eutectics was related to the thermal absorption increasing with the decrease of scanning rate. Preheating was beneficial to form the orientation dendrite structure and to increase the volume fraction of the eutectics. The laser melted surface possessed better microhardness and wear resistance compared to the substrate. The volume fraction of the eutectics played an important role on the wear resistance which increased with the increase of the volume fraction of the eutectics. The wear resistance was mainly depended on the content of the primary WC, as increased with the increase of the content of WC. The improvement of interface bonding, fine eutectic precipitation and structure refinement etc. were regarded as the micro-mechanism of enhancing the surface properties.