Effect of Annealing on Electrochemical Corrosion Behavior for Cold Spinned U-6.5Nb Alloy

Tubular U-6.5Nb alloy part was fabricated by cold spinning. The as-spinned alloys were then annealed at 400, 600 and 700 ℃ for 1 h, respectively. The electrochemical corrosion behaviors in aqueous solution containing 50 μg/g Cl－ were examined. Scanning electron microscope was used to characterize the surface morphology and microstructures of U-6.5Nb alloy. The single phase alloys, including as-spinned alloy and as-annealed alloy at 700 ℃ have higher corrosion potentials and smaller corrosion currents, and that the dual-phase alloy annealed at 400 and 600 ℃ has lower corrosion potentials and greater corrosion currents. Single phase alloys are more resistant to corrosion than dual-phase alloys. Pits corrosion occurs on the surface of single-phase alloys, while homogeneous corrosion occurs on the surface of dual-phase alloys. The inhomogeneous distribution of Nb in the dual-phase alloy is responsible for its poor corrosion resistance.