Influence of heat treatments at 475 and 400?°C on the pitting corrosion resistance and sensitization of UNS S32750 and UNS S32760 superduplex stainless steels

Some precipitation reactions of superduplex stainless steels (SDSS) can improve hardness, yield, and ultimate strength, but with substantial decrease of corrosion resistance. One of these reactions is the spinodal decomposition of ferrite into Cr-rich fine precipitates (a') and Cr-depleted matrix during low temperature aging. In this work, the effect of the a' precipitation on the pitting corrosion resistance was investigated. The results showed that short duration heat treatments at 475 degrees C do not decrease the pitting corrosion resistance, but increase the hardness of UNS S32750 and S32760 SDSS. The limits of heat treatment duration for both steels were determined.