Investigation of Microstructure and Wear Behaviors of AZ91 Alloy Under Different Heat Treatments

Abstract

This article aims to experimentally investigate the effect of heat treatment applied to AZ91 magnesium alloys on wear behavior under different applied load conditions. Apart from as-cast AZ91 alloy, AZ91 alloy samples were subjected to both solid-solution treatment (400°C for 16 hours) and three different aging processes (216°C for 4, 8 and, 12 hours) under three different applied loads (10 N, 25 N and, 50 N). Microstructural, characteristic, hardness, friction coefficient, and wear rate behavior under various applied loads were investigated against each other. The results showed that the wear rate increased in all samples with the applied load, while the friction coefficient decreased. While the highest wear rate was observed only in the solid-solution treated sample, it was observed that the wear rate changed inversely with the aging time. Furthermore, the micro-hardness increased in direct proportion with the aging time. While it was observed that the sample, which was aged for 12 hours, wore 13.6% less under 10 N load than the sample that was only treated with solid-solution, the results showed that the same sample wore about 25% less under 50 N load. The increase in β-precipitates in the structure with the aging period increased the micro-hardness, while the increase in hardness decreased the wear.