Influences of Pickling and Solution Treatment on Pitting Corrosion Resistance of Stainless Steels

The effects of pickling and solution treatment on pitting corrosion resistance of stainless steel welded joints were studied.It was found that both pickling and solution treatment were considerably effective in improving and recovering the pitting corrosion resistance of all the investigated welds.For duplex steel welds the effect of solution treatment was more obvious than that of pickling without any grain growth.But for austenitic and super austenitic steel welds,solution treatment was less effective than pickling and caused grain growth in base metals.When both solution treatment and pickling were employed,the CPT of welds alloyed with higher amount of Mo and N was even higher than that of corresponding pickled base metals.The microstructures of base metal and welds before and after solution treatment were analyzed,and the reason,by which the pitting corrosion resistance of welds was improved,was discussed.In addition,the improving mechanism of pickling and the role of Mo and N in stainless steels were also described.