Different zinc alloys have different physical and mechanical properties, which provides a choice for die casting design.
According to the manufacturing process, zinc alloy can be divided into two types: cast zinc alloy and deformed zinc alloy. The yield of cast alloys is much greater than that of deformed alloys. The composition, properties and uses of several important zinc alloys are listed in the table below.
Cast zinc alloys are divided into pressure-cast zinc alloys (solidified under external pressure) and gravity-cast zinc alloys (solidified only by gravity) depending on the casting method.
Die Casting Zinc Alloys Since the application of this alloy in the automotive industry in 1940, the output has increased dramatically. About 25% of the total zinc consumption is used to produce this alloy. Advanced and applicable technologies are being continuously adopted and developed rapidly. Corresponding related talents are also increasing, and there are a complete collection of steel talents. The most commonly used alloy is the Zn-Al-Cu-Mg system. Certain impurities significantly affect the properties of die-cast zinc alloys. Therefore, the content of impurities such as iron, lead, cadmium and tin is extremely strict, and the upper limit is 0.005%, 0.004%, 0.003%, and 0.02%, respectively. Therefore, the zinc alloy for die casting should use high purity zinc with a purity greater than 99.99% as a raw material.
Gravity cast zinc alloys can be cast in sand, plaster or hard molds. This zinc alloy not only has the characteristics of general die-cast zinc alloy, but also has high strength and good casting performance. The cooling rate has no obvious influence on mechanical properties. Residues and scraps can be recycled, the gate is simple, and it is not sensitive to overheating and remelting. The rate is small, the pores are small, and the plating can be performed by conventional methods.
In addition to the traditional varieties, Zn-Cu-0.1Ti and Zn-22Al alloys have appeared in the deformed zinc alloy industry. After the former alloy is rolled, the grain boundary moves can be hindered due to the arrangement of the dispersed particles of the TiZn15 intermetallic compound along the rolling direction.