WEAR CHARACTERISATION OF FRICTION STIR PROCESSED AS21A MAGNESIUM ALLOY FOR DIFFERENT TEMPERATURE CONDITIONS

Abstract

The industry inclination towards the application of light-weight materials in automobile, aerospace and marine components can be attributed to their inbuilt characteristics like high specific strength and excellent machinability. Magnesium alloys are one of the promising light-weight materials which have shown recent widespread use in structural applications. The present study utilised Magnesium-Aluminium-Silicon (Mg-Al-Si) category based AS21A magnesium alloy. AS21A alloy is widely recognized for high thermal resistant characteristics since it contains the thermally stable Mg2Si second phase intermetallic compound. However, the coarse morphology of Mg2Si precipitates makes the AS21A alloy brittle in nature thus limiting their widespread application. Therefore Microstructural modification was carried out through several surface modification techniques to achieve fine precipitates thus enhancing the strength of magnesium alloy. Friction Stir Processing (FSP) is the fast growing technology which can refine the microstructure of AS21A alloy in solid state only unlike conventional techniques. FSP is gaining its position in fabrication and manufacturing industry as most used technique because it modifies the coarse grain structure of material to fine grain microstructure that leads to better machinability, improved wear resistance and also eliminates the various casting defects present in the materials like porosity by generating homogeneous dispersion of particles. The current study is confined to the Tribological characterization of Friction Stir Processed (FSPed) AS21A alloy consisting of fine Mg2Si precipitates. Tribological study was carried out at 10-30 N normal loads with respective temperature conditions ranging from 500C – 2000C. The wear behaviour was evaluated from Linear Reciprocating Tribometer (LRT) test rig and different conclusions were derived on the basis of results obtained, thus explaining the wear performance of FSPed AS21A alloy in elevated thermal ambient.