Effects of α/γ Phase Ratio and N Addition on the Corrosion Resistance of Si-bearing Duplex Stainless Steel in Nitric Acid

摘要: Duplex stainless steel is widely used in various service conditions due to its high mechanical properties and corrosion resistance. However, there have been few studies on the resistance of duplex highly oxidizing nitric acid, such as hot acid containing Cr6+ ions. In this study, effect Si content (Si=0–4 %), austenitic phase (γ) ratio volume N addition (N=0.1 %) 23-25 Cr was investigated. Corrosion test carried out boiling 8N HNO3+0.2 g//Cr6+ using TIG welded joint specimens. The relationship between microstructures configuration attack analyzed.Results show that (Si>3 steels effective improving Si-bearing without N, however, attacked at HAZ when γ less than 10 % more 40 %, because α sensitization σ formation, respectively. Nitrogen affected ratio, nitride carbide precipitation. A 50 found be most beneficial for intergranular 25Cr-Ni-4Si-N steel.