Process chain development for additive manufacturing of cemented carbide

Abstract

Cemented carbide is a difficult material to be processed by Additive Manufacturing (AM) necessitating the need for process chain development to overcome the limitations of AM. Selective Laser Sintering (SLS) is proven to be the best AM process for making a complex product, and has potential to help produce a defect-free cemented carbide product. Consequently, in the present work, SLS is selected for process chain development study. Optimized SLS parameters are obtained to process WC-17Co (cemented carbide), which are able to furnish products of appreciable dimensional accuracy containing various fine features. In order to further improve product properties and remove any deficiencies, heat treatment is selected as a post-processing, which is accomplished in a furnace by heating samples at various temperatures (400, 600, 800 and 1000 °C) for a fixed duration of 3 h and by letting them cool inside the furnace. Samples are subsequently characterized to determine their hardness, fracture toughness, microstructure, wear resistance, composition of various phases and types of compounds formed. It is found that a moderate heat treatment has beneficial effects as the treatment at 600 °C furnished better hardness and fracture toughness while at 400 °C gave the best wear resistance. It is concluded that the heat treatment can be included as a complementary processing technique for producing cemented carbides as it has helped achieve products having better mechanical and wear properties.