Microstructure, Mechanical Properties and Fretting Wear Behavior of Gravity Die Cast and Squeeze Cast AZ91 Mg Alloy

Abstract

In the present work, the change in microstructure and mechanical properties of squeeze cast (SC) AZ91 Mg alloy has been studied by comparing it with conventional gravity die-cast (GC) AZ91 alloy. The present study also focuses on the effect of microstructure change in GC and SC AZ91 samples on the fretting wear behavior. The fretting wear studies are conducted on GC and SC AZ91 samples against the EN31 steel pin by variation in applied loads (5, 10, 15 N) and oscillating frequencies (5, 10, 15 Hz). SC AZ91 alloy exhibits improved tensile properties than that of GC AZ91 due to refined microstructure. The study demonstrates that the average coefficient of friction decreases with an increase in normal load and increases with an increase in frequency for both GC and SC AZ91. The wear volume loss is found to increase with an increase in applied load and frequency. It is proposed that the wear in GC and SC AZ91 alloy is caused by a combination of adhesion, oxidation, delamination, and abrasion under different fretting conditions. For every condition studied in the present work, the SC AZ91 exhibits better fretting wear resistance compared to GC AZ91. © 2023, ASM International.