A Non-Destructive Testing Method to Measure the Electrical Conductivity of Welded Electrolytic Tough Pitch Copper joints

A non-destructive eddy current testing was adapted in this investigation to investigate the electrical conductivity of electrolytic tough pitch copper. Various joining methods were used to join the copper, which were gas tungsten arc welding with two modes (constant current and pulsed current), solder braze, phosphor bronze braze, and friction stir welding. The test result indicated that copper joints that were made using solid-state welding process, especially the friction stir welding, had a greater electrical conductivity (5.7 × 107 Sm/m), as compared to their counterparts. The given improvement of the properties can be explained by the existence of fine, recrystallized grains in the joint interface with no intermetallic layer observed in the area of the weld itself. Phosphor bronze brazed and solder brazed joints, in contrast, had low electrical conductivity because of the abundance of large number of discontinuities and creation of intermetallic layers.