Influence of Microstructural morphology on Pitting Corrosion Resistance of Duplex Stainless Steel Weld Metals

Abstract

The formation mechanism of microstructure of duplex stainless steel weld metals with different N content and heat input and the effects of microstructural factors on pitting corrosion resistance of them were investigated. As N content of weld metal increased, ferrite content decreased and Cr nitride content increased. However, once N content exceeded a certain value, Cr nitride content decreased. As the ferrite content of the weld metal decreased, the critical pitting temperature (CPT) increased, and as N content increased, CPT increased. Thud, the pitting corrosion resistance of duplex stainless steel weld metals must be affected by both of N content and Cr nitride, and the precipitation of Cr nitride must be also affected by N content and the ferrite content due to N content and the weld heat input. The results indicated that these microstructural factors was important index to evaluate the pitting corrosion resistance of duplex stainless steel weld metals..