Analysing the Cause of Brittle Fracture of Oxygen-free Copper Pipe Brazed at High Temperature

Brittle fractures appearing at the brazing joint of the compressor shell of a refrigerator and the oxygen-free copper gas drainage pipe have been studied. The main causes of the brittle fractures are investigated by: analysing the elements of the raw materials and the brittleness caused by high temperature oxidization, visually observing the fractured surfaces of the copper pipe; and, examining the microscopic appearance and the microscopic elemental composition of fractured surfaces using SEM and EDXA respectively. The experiments indicate that the main causes of brittle fractures are the oxidization of oxygen-free copper pipe, the absorption of hydrogen during the brazing process, which results in hydrogen brittleness. The factors which might affect the brittleness and other performance criteria of the copper brazing joint are also discussed in this paper. In addition, suggestions about parameter control are put forth.