Wear behaviour of a Mg alloy subjected to friction stir processing

Abstract

In the present investigation, wear behaviour of a Mg alloy AE42 was examined under as-cast as well as friction stir processed conditions. Friction stir processing (FSP) was carried out at an optimized set of FSP parameters. Wear tests were performed in a pin-on-disc configuration using Universal Tribometer. The load range was varied from 5 to 20N, whereas sliding velocity from 0.33 to 3m/s. Worn surfaces and wear debris were analyzed using SEM and EDS for the determination of different wear mechanisms. The friction stir processed (FSPed) AE42 alloy demonstrated significant decrease in the wear rate which may be attributed to the microstructural refinement resulting in enhanced hardness and ductility of the FSPed alloy along with higher work hardening capability. At low loads, wear mechanism transformed from oxidation and abrasive wear at low sliding velocity to delamination at high velocity. At intermediate loads, oxidation and abrasion characterized the worn surface at low velocity, whereas delamination and plastic deformation were found to be major wear mechanisms at high velocities. At high loads, the corresponding mechanisms were abrasion, delamination and plastic deformation at low velocity, whereas severe plastic deformation and delamination at high velocities.