Pitting Corrosion Resistance on Annealing Treated Super Duplex Stainless Steel S32750

The pitting corrosion resistance of S32750 super duplex stainless steel, annealing treated at temperatures of 950-1200 degrees C for 20-60 min, was investigated using potentiodynamic polarization tests. The results show that the volume fractions of ferrite in the S32750 duplex stainless steel increased from 48.9% to 68.4% as annealing temperatures increased from 950 to 1200 degrees C. The pitting potential of the sample increased first and then decreased from an annealing temperature of 950 to 1050 degrees C, and the highest pitting potential was observed after annealing at 1050 degrees C for 35 min. The pitting corrosion resistance of S32750 stainless steel is due to the combination of pitting resistance equivalent number (PREN) value, phase fraction and grain boundary area fraction, and the imbalance of corrosion potential.