Effect of As-Cast Cooling on the Microstructure and Mechanical Properties of Age-Hardened 7000 Series Aluminium Alloy (original) (raw)
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An investigation was carried out to understand the effect of Mg addition on the hardness, the wear rate and the cooling rate of cast Al-Cu-Mg alloy. The effect of Mg content was assessed by melting the Al-Cu-Mg alloy in a muffle furnace with the addition of varying wt% Mg (1-3% wt). The cooling curves were plotted for both sand and die castings. The chemical composition of the cast alloy was computed by using arc spectrometry. The microstructural evaluation was carried out using optical and electron microscope. It was observed that the secondary dendritic arm spacing reduced with Mg content concluding that Mg addition improves the formation of nucleation sites and thereby results in grain refinement. The Brinell hardness tester was used to measure the hardness of the alloy. It was found that the hardness increased with Mg content and comparatively, die cast samples showed improved hardness when compared with that of sand cast samples. The hardness of the developed alloy was compared with that of the base alloy and the effectiveness of the alloying element was evaluated. Wear test was carried out using the Pin-on-disc wear testing apparatus under dry sliding conditions in air. Reduction in mass loss was observed with Mg addition. The effect of Mg on UTS, Young's modulus and elongation were also evaluated. Salt water immersion test with 5% NaCl solution was carried out for 120 hrs and no weight loss was observed. The alloy was developed and the effect of cooling rate and on Mg addition on the mechanical and wear properties of cast Al-Cu-Mg alloy was assessed. The effect of heat treatment on the properties will be carried out as a future work.