Sigma Phase Precipitation of Duplex Stainless Steel and Its Effect on Corrosion Resistance

摘要

The present study concerns the influence of aging parameters on the microstructure and corrosion behavior of duplex stainless steel S31803 and S32750. It has been found that the microstructural evolutions were extremely sensitive to sigma phase precipitation during aging treatment, and sigma phase was enhanced with the increase of aging time from 2 min to 120min at its precipitation peak temperature 850℃ for S31803 and 920℃ for S32750 steels respectively. The precipitation of sigma phase in S32750 is ahead of that in S31803 steel, within 10min, the sigma phase precipitation rate of S32750 is much faster than that of S31803 steel. The precipitation amount of sigma phases in S32750 steel is noticeable higher than that in S31803 steel during any aging treatment. The corrosion resistance is directly influenced by the abundant sigma phases, especially for the S32750. This result is helpful for practical aging treatment establishment of the S31803 and S32750 duplex stainless steels.