Fabrication of Inconel 625 superalloy welding wire by electrochemical cold drawing

The fabrication process of Inconel 625 superalloy welding wire by electrochemical cold drawing (ECD) was studied, as well as that by traditional cold drawing (TCD) for comparison. Three main processing parameters such as electrolyte kind, electrolyte concentration and current density were first optimized, and the welding wire was then fabricated at the optimal parameters. The results indicated that higher-rate and more uniform corrosion resulted in larger electrochemical plasticization (EP) effect and led the deformation to more concentrated to the surface layer during ECD, but contributing to a smaller work hardening. The welding wire with diameter of 2.4 mm was successfully prepared by ECD from the bar with diameter of 4 mm through 16 passes, while a wire with diameter of 2.6 mm was processed by TCD through 14 passes. The average cumulative reduction rate in cross section required for annealing during ECD was up to 18.42%, higher than 11.57% during TCD, due to the decreased work hardening from the EP effect in ECD. The annealing number during ECD was thereby significantly decreased from 7 times of TCD to 4 times for producing wires with same diameter of 2.6 mm. Furthermore, the ECD wire had smoother and brighter surface, and more uniform diameter than the TCD wire, meeting the requirements of the existing standards for superalloy welding wires. These findings confirm the great potential of the ECD technology in processing difficult-to-deform alloys.