Wear behaviour of DMD-generated high-strength steels using multi-factor experiment design on a pin-on-disc apparatus

Direct metal deposition (DMD) is a laser-based powder-fed-type additive manufacturing technology 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. This investigation evaluates the quality and capability of DMD-generated high strength steel alloy parts to withstand severe sliding wear against mild steel counter face involving multi-factor experimental design. The specimens are produced by DMD as cylindrical pins and annular paddings coated on mild steel substrate. Experiments were conducted on a pin-on-disc wear tester under six different experimental regimes designed to take into account different material conditions of H13 tool steel and 316-L stainless steel. The wear characteristics were evaluated following ASTM standard G99 under dry and severe conditions involving direct metal to metal contact. The wear scars and tracks reveal oxidative flaking, plastic deformation and micro-ploughing of the surfaces depending on specific test condition. This study focuses on the evolution of co-efficient of friction and its variation while changing the material and operating conditions. The study also investigates the relationship of primary and secondary wear factors in terms of wear loss from the DMD specimen and the energy dissipation during sliding wear