If a variety of alloys consist of more than two elements, they are called extra brass. For example, copper alloys consisting of lead, tin, manganese, nickel, iron and silicon. Brass has strong wear resistance. Extra brass is also called special brass. It has high strength, high hardness and strong resistance to chemical decay. In addition, the mechanical properties of cutting are also prominent. Seamless copper pipe drawn by brass has soft and strong wear resistance. Brass seamless pipes can be used for heat exchangers and condensers, cryogenic pipes and submarine transport pipes. Manufacturing sheet metal, bar, pipe, forging machine, etc. Copper content in 62%-68%, strong plasticity, manufacturing pressure equipment, etc. According to the different kinds of alloy elements contained in brass, brass can be divided into two types: popular brass and extraneous brass. Brass for pressure processing is called deformed brass. Brass is a copper alloy with zinc as an important additive element. It has an elegant yellow color and is collectively called brass. Copper-zinc binary alloy is called popular brass or abbreviated brass. More than three yuan brass is called extra brass or complex brass. Brass alloys containing less than 36% zinc are composed of solid solution and have good cold working properties. For example, brass containing 30% zinc is rarely used to make cartridge case, commonly known as cartridge case brass or 73 brass. Brass alloys with zinc content ranging from 36% to 42% consist of solid solutions, of which 64% brass with zinc content is the least commonly used. In order to improve the properties of popular brass, other elements such as aluminium, nickel, manganese, tin, silicon and lead are often added. Aluminum can improve the strength, hardness and corrosion resistance of brass, but make the plasticity low. It is suitable for mutual aid of condensate tubes and other corrosion-resistant machines. Tin can improve the strength of brass and the corrosion resistance to salt water, so it is called naval brass, which is used as ship thermal equipment and propeller. Lead improves the cutting properties of brass; this type of free-cutting brass is rarely used in clocks and watches. Brass castings are rarely used to make valves and pipe fittings.