A Study on Wear Behaviour of Laser Direct Metal Deposited High Strength H13 Tool Steel

Laser assisted direct metal deposition (DMD) additive manufacturing process provides a realistic opportunity to create solid and porous structures from high strength metallic alloys that can be used as coatings, foams and sandwiched structures and as highly stressed components in contact with other metallic components. Very little studies seem to have been reported on the wear behaviour of parts fabricated by the laser DMD process in relation to various design parameters for various metals. This paper presents an investigation on the sliding wear behaviour of the DMD generated structures of high strength H13 tool steel using the pin-on-disc machine. The structures were machined and finished as pins for subsequent wear testing against a solid disc made of high carbon steel surface. The study includes effect on abrasive wear by variation of several design variables which include contact load, sliding speed and sliding distance. The mode of wear is chosen to be severe which consists of dry wear and speeds near or above 1 m/s. Wear volume and co-efficient of frictions are the two main wear parameters analysed in combination with the primary or design variables. The relationship between the design factors and the ensuing wear loss is discussed which proves the highly non-linear frictional behaviour. The results highlight a wear performance for laser generated H13 specimen that is strong and consistent although inferior to the wear behaviour of wrought tool steels. Despite lack of hot and cold working and any heat treatment, H13 specimens show little signs of micro-chipping and flaking under high loads.