Effects of the Volume Fraction of the Secondary Phase after Solution Annealing on Electrochemical Properties of Super Duplex Stainless Steel UNS S32750

Super duplex stainless steel (SDSS) is used for manufacturing large valves and pipes in offshore plants because of its excellent strength corrosion resistance. Large are manufactured by forging after casting, the outside inside microstructures different owing to difference cooling rate caused thermal conductivity. This microstructural variation causes cracks during solution annealing, which breaks materials. To study resistance SDSS forged material, influence microstructure according between rates cast was evaluated. analyze effects secondary phase fraction before annealing on resistance, with without measured using potentiodynamic polarization test critical temperature precipitation phase. In test, decreased activation increased rate. The pitting exhibited effect