Effects Of Zn On Microstructures And Properties Of Aluminum Alloy5059

Aluminum alloy5059has been widely studied as new generation aluminum armor. With increase of Zn content, the mechanical properties of the alloy have been improved, while the corrosion resistance of the alloy has been deteriorated rapidly. How to obtain aluminum alloy with high mechanical properties and excellent corrosion resistance is of great importance to develop the new generation armor. Research shows that the alloying element Zn can effectively ameliorate the corrosion behavior of the high magnesium aluminum alloy. In this thesis, the influences of Zn on microstructures and properties of aluminum alloy5059with high magnesium were investigated by phase diagram calculation, experiment and testing analysis systemically. Main conclusions are the following:(1)The optimal homogenization processing is established. With increasing of homogenization temperature for a certain holding time, the segregation of ingot structure is gradually eliminated. When the temperature increases to460℃, the alloy appears slight burnt. At a certain homogenization temperature, with prolonging of the hold time, the composition of the alloy becomes more and more uniform. After24h, the composition does not change significantly. Therefore, the best homogenization processing is450℃×24h.(2)The effect of Zn content on microstructures and mechanical properties of the alloy is revealed. When Zn content is lower than1.8wt.%, there are few differences in microstructures and the ingot structure mainly consists of the a(Al) matrix and β(Al3Mg2) phase. With increasing of Zn content, the strength of the alloy is increased while the elongation is decreased. When Zn content reaches1.8wt.%, the5059-H131aluminum alloy has the highest tensile strength(447.9MPa) and yield strength(373.2MPa), at the same time maintains a higher elongation(9.9%).(3)The influence of Zn on corrosion behavior of the alloy is obtained. Zn contributes to the improvement of corrosion resistance as the Zn addition can make the electrode potential of the alloy down and inhibit the precipitation of (3(Al3Mg2) phase along grain boundary, which in turn enhances the alloy’s corrosion resistance. When Zn content is lower than1.8wt.%, the corrosion resistance is improved with increasing of Zn content.(4) The effect of Zn content on the dynamic mechanical properties of the alloy is revealed. Zn can improve the dynamic mechanical properties of the alloy to a certain extent. When Zn content is lower than1.8wt.%, with increasing of the Zn content, the dynamic mechanical properties of the alloy is enhanced. What is more, the alloy is sensitive to strain rate.