Dry sliding wear in high density Fe–2%Ni based P/M alloys

Dry sliding wear behaviour of Fe–2Ni–0.47C (material A) and Fe–2Ni–0.2C (material B) powder metallurgy (P/M) alloys has been studied on a pin-on-disc wear tester using an alloy steel pin and disc of hardness HRC 62. The P/M alloys in the as sintered (∼90 HRB) as well as in the hardened and tempered (∼30 and ∼40 HRC) conditions were investigated for their wear behaviour. Wear rate was found to initially decrease and then remain constant with sliding distance in all the materials, it being least for the specimen hardened and tempered to ∼40 HRC. Optical microscopy was performed to characterise the basic microstructures associated with different heat treatments. SEM observations of the worn surface revealed plastic deformation with delamination of surface layers by subsurface cracks as the mechanism in the as-sintered condition. Microploughing and formation of surface platelets and traces of their detachment was found to be the dominant wear mechanism for the hardened and tempered specimens.