Crack mitigation in laser engineered net shaping of WC-10wt%FeCr cemented carbides
Emma Molobi, Natasha Sacks, Maritha Theron
Abstract
Laser engineered net shaping of a WC-10wt%FeCr cemented carbide showed cracking during deposition despite using a full factorial design of experiments matrix along with single and multiple objective optimization models to establish an optimal parameter set. In this study four techniques namely, laser re-melting, use of FeCr and Ni-alloy butter layers, and substrate preheating, were used in an effort to reduce the crack susceptibility of deposited samples and the resultant effects on microstructure and hardness were studied. Laser re-melting improved the surface morphology of the deposited samples and reduced the number of primary and secondary cracks, however the hardness decreased. The Ni-alloy butter layer reduced the formation of secondary cracking and led to an increase in hardness, while the FeCr butter layer resulted in increased primary cracks and a reduced hardness. Substrate preheating reduced crack formation and led to an increase in the hardness with the reduction in cracking being attributed to a reduction of the initial thermal gradient.