Purple copper bar, also known as red copper or pure copper, is named for its purplish-red color. Its various properties can be referred to under copper. Purple copper is industrial pure copper with a melting point of 1083°C, no allotropic transformation, and a relative density of 8.9. Its mass per unit volume is about 15% heavier than ordinary steel. Due to its rose-red hue and the purple appearance after surface oxidation, it is commonly referred to as purple copper. It is a type of copper containing a certain amount of oxygen, hence also known as oxygen-containing copper. Purple copper bars are not necessarily pure copper; sometimes, a small amount of deoxidizing elements or other elements are added to improve material quality and performance, thus also classified as copper alloys. In China, processed purple copper materials can be divided into four categories based on composition: ordinary purple copper (T1, T2, T3, T4), oxygen-free copper (TU1, TU2, and high-purity vacuum oxygen-free copper), deoxidized copper (TUP, TUMn), and special copper with small amounts of alloying elements (arsenic copper, tellurium copper, silver copper). The electrical and thermal conductivity of purple copper is second only to silver, making it widely used in the production of conductive and thermal conductive equipment. Purple copper exhibits good corrosion resistance in atmospheres, seawater, certain non-oxidizing acids (hydrochloric acid, dilute sulfuric acid), alkalis, salt solutions, and various organic acids (acetic acid, citric acid), making it suitable for the chemical industry. Additionally, purple copper has good weldability and can be processed through cold and hot plastic deformation into various semi-finished and finished products. In the 1970s, the production of purple copper exceeded the total output of all other types of copper alloys.