What elements do alloy die casting ingots require?
Copper and aluminum composition of solid solution, when the temperature is at 548 DEG C, the solubility of copper in aluminum should be 5.65%, room temperature dropped to about 0.1%, the increase of copper content, fluidity of the alloy can be increased, the tensile strength and hardness, corrosion resistance and reduce the plasticity, the cracking tendency increases.
Zinc can improve fluidity, increase brittleness and reduce corrosion resistance in aluminum alloy. Therefore, zinc content should be controlled in the specified range. As for the ZL401 alloy with high zinc content, it has better casting performance and mechanical properties, and the cutting process is better.
Adding a small amount of magnesium (about 0.2 - 0.3%) to high silicon aluminum alloy can increase the strength and yield limit and improve the machinability of the alloy. Aluminum alloy containing 8% mg has good corrosion resistance, but its casting properties are poor, the strength and plasticity at high temperature are low, and the cooling shrinkage is large, so it is easy to produce hot cracking and loose.
Silicon is the major element in most die cast aluminum alloys. It can improve the casting properties of alloys. Silicon and aluminum can form solid solutions. At 577 DEG C, the solubility of silicon in aluminium is 1.65%, at room temperature is 0.2%, and when silicon content is up to 11.7%, silicon and aluminum form eutectic. Improve the high temperature molding properties of the alloy, reduce shrinkage, no hot cracking tendency. Two element aluminum base alloy has high corrosion resistance. When the content of silicon in the alloy exceeds the eutectic component, and the impurities such as copper and iron are long, the hard point of free silicon appears, which makes the machining difficult. The corrosion of the cast silicon crucible by high silicon aluminum alloy is serious.
