Effect of Chemistry and Heat Treatment on the Pitting Corrosion Resistance of Three Duplex Stainless Steels

摘要

The effect of chemistry and heat treatment on pitting corrosion resistance of three cast duplex stainless steels was examined through mass loss, pitting density, and critical pitting temperature (CPT). Three chemistries were selected for testing: UNS J92205 (baseline) and a lower and higher cost alloy compared to UNS J92205. The lower and higher cost chemistries were determined based on cost and the corrosion resistance effects of nitrogen, chromium, nickel, and molybdenum. Ferric chloride corrosion tests (modified ASTM G48 standard) were used to determine the CPT of the three chemistries in the as-cast and heat treated conditions. When heat treated at 1200°C for 1 hour and quenched in water, the lower and higher cost chemistries had a CPT of 85°C while the UNS J92205 had a CPT of 60°C. In the as-cast condition, the CPT's were lower for all chemistries. Overall, the lower cost chemistry had comparable pitting corrosion resistance compared to the higher cost chemistry and both the lower and higher cost chemistries had better pitting corrosion resistance compared to the UNS J92205 chemistry.