Study on the Microstructure and Corresponding Stress Corrosion Cracking Behavior of Joints of Copper Tubes.

The effects of joining methods on the microstructure and corresponding stress corrosion cracking (SCC) behavior of copper tubes used in heat exchangers are evaluated by microstructure characterization and the slow strain rate testing (SSRT). The results show that the brazed joint (BJ) had worse SCC behavior and poorer fracture toughness than the mechanical joint (MJ). The fracture surfaces of the BJ and MJ samples after SSRT demonstrated the different fracture behaviors of the samples, especially intergranular brittle fracture in the BJ. Copper oxide layer on BJ is found to be extremely detrimental to the SCC behavior. Furthermore, a numerical model is established to predict and analyze the onset of the SCC along the surface of BJ. [ABSTRACT FROM AUTHOR]