Effect of Cr on Grain Refinement and Mechanical Properties of Al-Si-Mg Alloys

Abstract:

Grain growth of Aluminium alloys at high temperature reduces their strength significantly. Therefore it is essential to control the grain growth by suitable techniques. The effect of Cr on refining the grain structure of Al alloys is investigated in the present work. Cr is added into Al-Si-Mg alloy by stir casting techniques. Subsequently the alloys were subjected to annealing at 500oC for 1 hour to study the grain growth behavior of these alloys. An optical microscope is used to analyze the grain size and microstructure. The mechanical properties of these alloys were studied using a universal testing machine. The Cr additions were varied between 0.5 to 4 weight percent. The Cr addition had shown a significant effect in refining the grain size of Al-Si-Mg alloys. The average grain diameter after annealing was found to be about 151 μm in unalloyed samples while, the 2 wt % Cr added samples showed about 92 μm. The second phase particles, Al₇Cr found precipitated along the grain boundaries apart from Al₂Si and Mg₂Si. However Cr additions more than 2% does not show significant role in refining the grain size. Cr also improved the mechanical properties such as yield strength, ultimate tensile strength and fracture toughness moderately.

• Periodical: Applied Mechanics and Materials (Volumes 789-790)
• Pages: 95-99
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.789-790.95
• Online since: September 2015
• Authors: Aakash Kumar*, Gaurav Sharma, Chandrabalan Sasikumar, Shahrukh Shamim, Himkar Singh
• Keywords: Al-Si-Mg Alloys, Chromium, Grain Refinement, Intermetallic Particles, Mechanical Properties, Recrystallization

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