Analysis of magnesium addition, hydrogen porosity and T6 heat treatment effects on mechanical and microstructural properties of pressure die cast 7075 aluminum alloy

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2012

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Alat, Ece

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Aluminum alloys are having more attention due to their high specific stiffness and processing advantages. 7075 aluminum alloy is a wrought composition aluminum alloy in the Al-Zn-Mg-Cu series. Due to the significant addition of these alloying elements, 7075 has higher strength compared to all other aluminum alloys and effective precipitation hardenability characteristic. On the other hand, aluminum alloys have some drawbacks, which hinder the widespread application of them. One of the most commonly encountered defects in aluminum alloys is the hydrogen porosity. Additionally, in case of 7075, another problem is the lack of fluidity. Magnesium addition is thought to be effective in compensating this deficiency. Accordingly, in this study, die cast 7075 aluminum alloy samples with hydrogen porosity and additional magnesium content were investigated. The aim was to determine the relationship between hydrogen content and hydrogen porosity, and the effects of hydrogen porosity, additional magnesium and T6 heat treatment on ultimate tensile and flexural strength properties of pressure die cast 7075 aluminum alloy. 7075 aluminum alloy returns were supplied from a local pressure die casting company. After spectral analysis, pressure die casting was conducted at two stages. In the first stage, 7075 aluminum alloy with an increase in magnesium concentration was melted and secondly 7075 aluminum alloy was cast directly without any alloying addition. While making those castings, hydrogen content was measured continuously before each casting operation. As a final operation T6 heat treatment is carried out for certain samples. Finally, in order to accomplish our aim, mechanical and microstructural examination tests were conducted.

Subject Keywords

Aluminum, Magnesium, Aluminum alloys, Hydrogen., Porosity., Die-casting.

URI

http://etd.lib.metu.edu.tr/upload/12615018/index.pdf
https://hdl.handle.net/11511/21791

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

E. Alat, “Analysis of magnesium addition, hydrogen porosity and T6 heat treatment effects on mechanical and microstructural properties of pressure die cast 7075 aluminum alloy,” M.S. - Master of Science, Middle East Technical University, 2012.