Basic knowledge of copper and copper alloys

1. Pure copper and its basic characteristics
Pure copper is a rose-red metal, and the surface is purple after a copper oxide film is formed, so industrial pure copper is often called red copper or electrolytic copper. The density is 8-9g/cm3 and the melting point is 1083°C. Pure copper has good electrical conductivity and is widely used in the manufacture of wires, cables, brushes, etc.; it has good thermal conductivity and is often used to manufacture magnetic instruments and meters that must be protected from magnetic interference, such as compasses and aviation instruments; it has excellent plasticity and is easy to heat Pressure and cold pressure processing can be made into copper materials such as tubes, rods, wires, strips, strips, plates, and foils. Pure copper products include smelted products and processed products.
Second, the classification and characteristics of copper alloys
(1) Brass
Brass is an alloy of copper and zinc. The simplest type of brass is a copper-zinc binary alloy called simple brass or ordinary brass. Changing the zinc content in brass can obtain brass with different mechanical properties. The higher the zinc content in brass, the higher its strength and lower plasticity. The zinc content of brass used in industry does not exceed 45%. No matter how high the zinc content is, it will cause brittleness and deteriorate the properties of the alloy.
In order to improve certain properties of brass, brass with other alloying elements added to the unitary brass is called special brass. Commonly used alloying elements are silicon, aluminum, tin, lead, manganese, iron and nickel. Adding aluminum to brass can increase the yield strength and corrosion resistance of brass, and slightly reduce plasticity. Brass with less than 4% aluminum has good comprehensive properties such as processing and casting. Adding 1% tin to brass can significantly improve the brass’s ability to resist seawater and marine atmospheric corrosion, so it is called “navy brass”. Tin can also improve the cutting performance of brass. The main purpose of adding lead to brass is to improve machinability and wear resistance, and lead has little effect on the strength of brass. Manganese brass has good mechanical properties, thermal stability and corrosion resistance; adding aluminum to manganese brass can also improve its performance and obtain smooth surface castings. Brass can be divided into casting and pressure processing products. The chemical composition of commonly used processing brass.
(2) Bronze
Bronze is the earliest alloy used in history. It originally referred to copper-tin alloy. Because of its bluish-gray color, it was called bronze. In order to improve the process and mechanical properties of the alloy, other alloying elements, such as lead, zinc, and phosphorus, are added to most bronzes. Because tin is a rare element, many non-tin-free Wuxi bronzes are also used in the industry. They are not only cheap, but also have the required special properties. Wuxi bronzes mainly include aluminum bronze, beryllium bronze, manganese bronze and silicon bronze. There are also ternary or quaternary bronzes with more complex compositions. Copper alloys other than brass and cupronickel (copper-nickel alloy) are now called bronze.
Tin bronze has higher mechanical properties, better corrosion resistance, anti-friction properties and good casting properties; low sensitivity to overheating and gas, good welding performance, non-ferromagnetic, and small shrinkage coefficient. The corrosion resistance of tin bronze in the atmosphere, sea water, fresh water and steam is higher than that of brass. Aluminum bronze has higher mechanical properties than tin bronze, wear resistance, corrosion resistance, cold resistance, heat resistance, no ferromagnetism, good fluidity, no segregation tendency, and dense castings can be obtained. Adding elements such as iron, nickel and manganese to aluminum bronze can further improve the various properties of the alloy.
Bronze is also divided into two categories: pressure processing and casting products.
(3) Cupronickel
The copper-based alloy with nickel as the main additive element is silver-white and is called cupronickel. The copper-nickel binary alloy is called ordinary cupronickel, and the copper-nickel alloy with elements such as manganese, iron, zinc and aluminum is called complex cupronickel. Pure copper and nickel can significantly improve strength, corrosion resistance, electrical resistance and thermoelectricity. Industrial copper-nickel alloys can be divided into structural copper-nickel alloys and electrical copper-nickel alloys according to their performance characteristics and uses. They meet various corrosion resistance and special electrical and thermal properties.
3. Copper
Various shapes including rods, wires, plates, strips, strips, tubes, foils, etc., are made of pure copper or copper alloys and are collectively called copper. There are rolling, extruding and drawing methods for copper processing. In copper, plates and bars are hot-rolled and cold-rolled; strips and foils are cold-rolled; pipes and bars are divided into For extruded products and drawn products; wires are all drawn.