A Review on the Effects of Casting Quality, Microstructure and Mechanical Properties of Cast Al-Si-0.3Mg Alloy
Volume 12, Number 2, March 2016 - Paper 5 - pp. 143-154
S. NALLUSAMYDean, Department of Mechanical Engineering, Dr. M. G .R. Educational and Research Institute University, Chennai, 600095, Tamilnadu, INDIA.
(Received on September 26, 2015, Revised on December 08, 2015)
This paper investigates a study on the effects of heat treatment on the microstructure, quality of casting and mechanical properties of Al-7Si-0.3Mg (LM25) alloy. The large reputation of Al-7Si-0.3Mg (LM25) alloy in automobile industry stems from its light weight (density of about 2.68 g/cc), high strength to weight ratio, excellent casting characteristics, high corrosion resistance, low coefficient of thermal expansion, good thermal & electrical conductivity and good mechanical properties including high machinability and workability. The microstructure of this alloy depends strongly on its composition and solidification rate. The slow-cooling rates encountered in sand castings lead to acicular silicon phase. The silicon phase in the form of large plates with sharp sides and edges act as internal stress risers in the microstructure and provide easy paths for fracture leading to inferior mechanical properties. The applications of this alloy demand several techniques and research methodologies to modify the microstructure and there by improve mechanical properties. Alloying, chemical modification, mould vibration during solidification and heat treatment were found to be effective in modifying the microstructure. In this view, this article presents the information?s about the influences of all such techniques which modify the microstructure and increase the quality of casting and mechanical properties.
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