Copper knowledge: pure copper annealing

Date:2020-05-27

Ordinary pure copper is a copper with a mass fraction of not less than 99.7%, and oxygen-containing copper with very few impurities. The appearance is purple-red, so it is also known as red copper. Pure copper annealing refers to the pure copper heat treatment process, which refers to slowly heating pure copper to a certain temperature, maintaining it for a sufficient time, and then cooling at an appropriate rate. The purpose is to reduce the hardness and improve the machinability; eliminate residual stress, stabilize the size, reduce the tendency of deformation and cracks; refine the grain, adjust the structure, and eliminate the defects of the structure. To be precise, annealing is a heat treatment process for materials, including metallic materials and non-metallic materials.

　　 Pure copper annealing refers to the pure copper heat treatment process, which refers to slowly heating pure copper to a certain temperature for a sufficient time, and then cooling at an appropriate rate. The purpose is to reduce the hardness and improve the machinability; eliminate residual stress, stabilize the size, reduce the tendency of deformation and cracks; refine the grain, adjust the structure, and eliminate the defects of the structure. To be precise, annealing is a heat treatment process for materials, including metallic materials and non-metallic materials.

　　 Ordinary pure copper is copper with a mass fraction of not less than 99.7%, oxygen-containing copper with very little impurities, and a purple-red appearance.

　　Chinese copper processing materials can be divided into ordinary copper (T1, T2, T3), oxygen-free copper (oxygen-free copper, silver oxygen-free copper, zirconium oxygen-free copper and dispersed oxygen-free copper), phosphorous deoxidized copper, with a small amount added There are four types of alloying special copper (arsenic copper, tellurium copper, silver copper, sulfur copper and zirconium copper). The electrical conductivity and thermal conductivity of copper is second only to silver, and it is widely used to make electrical and thermal equipment. Red copper has good corrosion resistance in the atmosphere, sea water and certain non-oxidizing acids (hydrochloric acid, dilute sulfuric acid), alkalis, salt solutions and various organic acids (acetic acid, citric acid), and is used in the chemical industry. In addition, red copper has good weldability, and can be made into various semi-finished products and finished products by cold and thermoplastic processing. In the 1970s, the output of red copper exceeded the total output of other types of copper alloys.

Pure copper annealing purpose：

　　(1)Reduce hardness and improve machinability.

　　(2)Eliminate residual stress, stabilize dimensions, reduce deformation and crack tendency；

　　(3)Refine the crystal grains, adjust the structure, and eliminate the structure defects.

　　(4)Uniform material structure and composition, improve material performance or make preparation for subsequent heat treatment.

　　In production, the annealing process is widely used. According to the different purposes of annealing required by the workpiece, there are a variety of annealing process specifications, commonly used are complete annealing, spheroidizing annealing, and stress relief annealing.