Brass is an alloy of copper and zinc. The largest brass is a copper-zinc binary alloy, called roughly brass or ordinary brass. Copper with different mechanical effects can be obtained by tampering with the content of zinc in brass. The higher the content of zinc in brass, the higher the strength and the lower the plasticity. The zinc content of brass adopted in the industry is not more than 45%. The higher the zinc content, the brittleness will occur and the effect of the alloy will deteriorate. In order to improve a certain effect of brass, brass with other alloy elements added to the base of mono-brass is called extraordinary brass. Rare alloying elements include silicon, aluminium, tin, lead, manganese, iron and nickel. Adding aluminium to brass can improve the yield strength and corrosion resistance of brass, and decrease the plasticity slightly. Brass containing less than 4% aluminium has good processing and forging effects. Adding 1% tin to brass can significantly improve the brass's ability to resist salt water and terrestrial atmospheric corrosion, so it is called "hydraulics brass". Tin can also improve the cutting efficiency of brass. The important purpose of adding lead to brass is to improve the machinability and wear resistance. Lead has little effect on the strength of brass. Manganese brass has good mechanical effect, thermal invariance and corrosion resistance. Adding aluminium to manganese brass can improve its effect and obtain bright castings outside. Brass can be divided into forging and pressure processing products.