| 摘要 |
PROBLEM TO BE SOLVED: To improve the pitting corrosion resistance of a duplex stainless steel by using a pitting corrosion resisting parameter and optimizing the contents of Cr, Mo and N in the duplex stainless steel. SOLUTION: This steel is the one having a compsn. contg. <=0.05% C, <=2.0% Si <=2.0% Mn, <=0.01% S, 20 to 28% Cr, 1 to 5% Mo, <=0.4% N, and the balance Fe with inevitable impurities and satisfying the relational inequality of [Cr]+3 [Mo]+16 [N]>=34.5. Furthermore, [ ] denotes the compositional components in the austenitic phases. Preferably, this compsn. is mixed with <=0.20% Cu. More preferably, the compsn. is mixed with one or two kinds among <=2.0% Ti, <=2.0% V and 2.0% W. The steel is subjected to solution treatment at 1000 to 1100 deg.C after hot rolling and is used, and the corrosion rate in a 24 hr immersing test in an aq. soln. of 6% FeC3 +0.05N-HCI at 50 deg.C is approximately zero. |
