Points To Note When Using Zinc-aluminum Alloy Parts

1. Poor corrosion resistance. When the impurity elements of lead, cadmium, and tin in the alloy composition meet the standards, the castings will be aging and deformed, which is manifested as volume expansion, mechanical properties, especially plasticity, significantly decreased, and even cracked after a long time.

Lead, tin, and cadmium have very little solubility in zinc-aluminum alloy parts, so they concentrate on the grain boundary and become the cathode, and the aluminum-rich solid solution becomes the anode, which promotes intergranular electrochemical corrosion in the presence of water vapor (electrolyte). Die castings are aged due to intergranular corrosion.

2, aging effect. The structure of zinc-aluminum alloy parts is mainly composed of a zinc-rich solid solution containing Al and Cu and an Al-rich solid solution containing Zn, and their solubility decreases with the decrease of temperature. However, due to the extremely fast solidification rate of die castings, the solubility of the solid solution is greatly saturated at room temperature. After a certain period of time, this kind of oversaturation will gradually be relieved, and the shape and size of the casting will slightly change.

3. Zinc-aluminum alloy parts should not be used in high and low temperature (below 0℃) working environment. Zinc-aluminum alloy parts have better mechanical properties at room temperature. However, the tensile strength at high temperature and the impact performance at low temperature are significantly reduced.

4. Zinc-aluminum alloy parts will have burrs on the surface due to insufficient clamping force, poor clamping, insufficient mold strength, and too high melting temperature. This phenomenon is called product flare, which is often the enterprise must face Post-processing process. At present, it is mainly solved by manual polishing, hydrogen-oxygen explosion and Zhaoling refrigerated shot blasting machine according to the nature of the product.