Folded tin-zinc bronze Zinc is largely dissolved in copper-tin alloy, and the amount of zinc added to deformed tin bronze is generally less than 4%. Zinc can improve the fluidity of the alloy, reduce the crystallization temperature range and reduce reverse segregation. Listed in the current Chinese national standards in the zinc tin bronze brand QSn4-3, has good elasticity, abrasion resistance and resistance to magnetic, can under cold and hot pressure processing, easy to welding and brazing, machinability is good, in the atmosphere and fresh water, sea water corrosion resistance is good, for a variety of elastic element and pipe accessories, chemical equipment, resistance, high magnetic components and parts, etc. Folding tin zinc lead bronze Lead is actually immiscible in copper-tin alloys, and it is distributed among dendrites with single-phase black inclusions. It is not easy to evenly distribute the lead in the ingot, and a small amount of nickel is usually added to improve the distribution and refine the structure. Lead reduces the friction coefficient of tin bronze, improves its wear resistance and machinability, but slightly reduces its mechanical properties. 3%~5% zinc is often added in copper-tin-lead alloys to improve mechanical properties. The addition of 0.02%~0.1% zirconium or 0.02%~0.1% boron, especially the addition of 0.02%~0.2% rare-earth elements, can refine the lead particles and make them evenly distributed, so as to improve the microstructure, casting and mechanical properties of lead-tin bronze. The tin, zinc and lead bronze listed in the current Chinese national standard has two grades of qsn4-4-2.5 and qsn4-4-4, with high wear resistance and free cutting. It is mainly used in the form of plate and strip for automobile, tractor, iation and mechanical industry to manufacture bushing and bearing liner, which is known as automobile bronze. Copper is a non-ferrous metal closely related to human beings. It is widely used in electric, light industrial, mechanical manufacturing, construction industry, national defense industry and other fields. It is second only to aluminum in the consumption of non-ferrous metal materials in China. Tin bronze is a nonferrous metal alloy with the smallest shrinkage rate, which is used to produce castings with complex shape, clear outline and low air tightness requirements. Tin bronze is very resistant to corrosion in atmosphere, sea water, fresh water and steam, and is widely used in steam boilers and Marine ship parts. Phosphorous tin bronze has good mechanical properties and can be used as wear-resisting and elastic parts of high precision working machine. Leaded tin bronze is often used for wear - resistant parts and plain bearings. Zinc tin bronze can be used for high air tightness castings. Tin bronze is the most widely used and used in the electrical and electronic industry, accounting for more than half of the total consumption. This type of switches and printed circuit boards for various cables and conductors, motors and transformers are used in the manufacture of industrial valves and fittings, meters, plain bearings, moulds, heat exchangers and pumps in the manufacture of mechanical and transport vehicles. In the chemical industry is widely used in the manufacture of vacuum, distillation pot, brewing pot and so on. In the national defense industry, it is necessary to produce 130-140 tons of copper for every 3 million rounds of bullets, artillery shells and gun parts.