High strength corrosion-resistant stainless steel

Abstract

Chromium-nickel-manganese steel characterized by good welding properties, which steel in the as-welded condition enjoys a combination of strength, ductility and impact resistance, along with good resistance to intergranular corrosion and good resistance to general corrosive attack. The steel contains about 20% to 25% chromium, about 6% to 17% nickel, about 3.5% to 7% manganese, about .15% to .50% nitrogen, with carbon not exceeding about .08, and with at least one of the three ingredients molybdenum, columbium and vanadium. For a best combination of properties at least two of the three ingredients are employed.

We claim as our invention: .[. 
     
       1.  Alloy steel of improved resistance to intergranular corrosion having a tensile strength exceeding some 100,000 p.s.i. at room temperature together with an elongation in 2" of at least about 30% and essentially consisting of about 20.5% to about 25% chromium, about 6% to about 17% nickel, about 3.5% to about 7% manganese, about .15% to about .50% nitrogen, at least two ingredients selected from the group consisting of molybdenum, columbium and vanadium wherein molybdenum is about .5% to about 4%, columbium about .1% to about .7% and vanadium about .05% to about .5%, with carbon less than .08%, silicon not exceeding about .7% and remainder substantially all iron..]. .[. 
     
     
       2.  Alloy steel of improved resistance to intergranular corrosion having a tensile strength exceeding some 100,000 p.s.i. at room temperatures together with an elongation in 2" of at least about 30% and essentially consisting of chromium about 21% to about 25%, nickel about 7.5% to about 16%, manganese about 4% to less than 6%, nitrogen about .20% to about .40%, at least two ingredients selected from the group consisting of molybdenum, columbium and vanadium wherein molybdenum is about 1% to about 3%, columbium about .2% to about .4% and vanadium about .1% to about .5%, with carbon not exceeding .03%, silicon up to about .4%, and remainder substantially all iron..]. .[.3. Alloy steel of improved resistance to intergranular corrosion having a tensile strength of at least about 125,000 p.s.i. with an elongation in 2" of at least about 30% and essentially consisting of about 22.5% to about 24.5% chromium, about 7.5% to about 15.5% nickel, about 4.5% to about 5.5% manganese, about .3% to about .4% nitrogen, about .5% to less than 3% molybdenum, at least one of the ingredients selected from the group consisting of columbium and vanadium wherein columbium is about .1% to about .5% and vanadium about .1% to about .5%, carbon not exceeding about .06%, silicon less than .5%, 
     
     
        and remainder substantially all iron..]. 4. Alloy steel of improved corrosion-resistance together with strength and ductility and essentially consisting of about 23% to about 25% chromium, about 9.5% to about 15.5% nickel, about 4% to less than 6% manganese, about .20% to about .40% nitrogen, about 1.5% to about 2.5% molybdenum, about .2% to about .4% columbium, about .1% to about .5% vanadium, about .03% to about .06% carbon, about .25% to about .4% silicon, and remainder substantially all iron. .[.5. Alloy steel of improved resistance to intergranular corrosion having a tensile strength exceeding some 100,000 p.s.i. at room temperatures together with an elongation in 2" of at least about 30% and essentially consisting of about 20.5% to about 25% chromium, about 11% to about 13% nickel, about 4.5% to about 5.5% manganese, about .20% to about .40% nitrogen, about 1.5% to about 2.5% molybdenum, at least one of the ingredients selected from the group consisting of columbium and vanadium wherein columbium is about .20% to about .40% and vanadium about .05% to about .40%, carbon not exceeding about .05%, and remainder substantially all iron..]. .[.6. Alloy steel of improved resistance to intergranular corrosion having a tensile strength exceeding some 100,000 p.s.i. at room temperatures together with an elongation in 2" of at least about 30% and essentially consisting of about 23% to about 25% chromium, about 11.5% to about 15.5% nickel, about 4.5% to about 5.5% manganese, about .30% to about .40% nitrogen, about 1.5% to about 2.5% molybdenum, at least one of the ingredients selected from the group consisting of columbium and vanadium wherein columbium is about .15% to about .30% and vanadium about .10% to about .50%, with carbon not exceeding about .05%, and remainder substantially all iron..]. .[.7. Alloy steel of improved corrosion-resistance together with strength and ductility and essentially consisting of about 23.5% to about 24.5% chromium, about 13% to about 15.5% nickel, about 4.5% to about 5.5% manganese, about .30% to about .40% nitrogen, about 1.75% to about 2.25% molybdenum, about .15% to about .30% columbium, about .10% to about .30% vanadium, with carbon not exceeding about .06%, and remainder substantially all iron..]. .[.8. Alloy steel of improved corrosion-resistance together with strength and ductility and essentially consisting of about 23% to about 24% chromium, about 9.5% to about 10.5% nickel, about 4.5% to about 5.5% manganese, about .30% to about .40% nitrogen, about 1.75% to about 2.25% molybdenum, about .15% to about .25% columbium, about .15% to about .25% vanadium, carbon not exceeding about .06%, and remainder substantially all iron..]. .[.9. Alloy steel of improved corrosion-resistance together with strength and ductility and essentially consisting of about 21% to about 24% chromium, about 11% to about 13% nickel, about 4.5% to about 5.5% manganese, about .25% to about .4% nitrogen, about 2% to about 3% molybdenum, columbium about .1% to about .4%, carbon not exceeding about .05%, silicon not exceeding about .4%, and remainder substantially all iron..]. .[.10. Alloy steel of improved corrosion-resistance together with strength and ductility and essentially consisting of about 23% to about 24% chromium, about 15% to about 16% nickel, about 4.5% to about 5.5% manganese, about .3% to about .4% nitrogen, about 2.5% to about 3% molybdenum, columbium about .1% to about .5%, about .025% to about .035% carbon, and remainder substantially all iron..]. .[.11. Alloy steel of improved resistance to intergranular corrosion having a tensile strength exceeding some 100,000 p.s.i. at room temperatures together with an elongation in 2" of at least about 30% and essentially consisting of about 20.5% to about 22% chromium, about 6% to about 9% nickel, about 3.5% to less than 6% manganese, about .25% to about .4% nitrogen, with at least two of the ingredients selected from the group consisting of molybdenum, columbium and vanadium wherein molybdenum is about 1.5% to about 2.5%, columbium about .2% to about .4% and vanadium about .1% to about .5%, carbon not exceeding about .06%, and remainder substantially all iron..]. .[.12. Alloy steel of improved resistance to intergranular corrosion having a tensile strength of at least about 125,000 p.s.i. with an elongation in 2" of at least about 30% and essentially consisting of about 23.5% to about 24.5% chromium, about 9.5% to about 15.5% nickel, about 4.5% to about 5.5% manganese, about .3% to about .4% nitrogen, about 1.5% to about 2.5% molybdenum, at least one of the ingredients selected from the group consisting of columbium and vanadium wherein columbium is about .1% to about .3% and vanadium about .2% to about .4%, carbon not exceeding about .06%, and remainder substantially all iron..]. .[.13. Alloy steel of improved resistance to intergranular corrosion having a tensile strength of at least about 125,000 p.s.i. with an elongation in 2" of at least about 30% and essentially consisting of about 23.5% to about 24.5% chromium, about 10% to about 12% nickel, about 4.5% to about 5.5% manganese, about .3% to about .4% nitrogen, about 1.75% to about 2.25% molybdenum, at least one of the ingredients selected from the group consisting of columbium and vanadium wherein columbium is about .15% to about .25% and vanadium about .15% to about .30%, carbon not exceeding about .05%, and remainder substantially all iron..]. .[.14. Alloy steel of improved corrosion-resistance together with strength and ductility and essentially consisting of about 21.5% to about 24% chromium, about 7% to about 8% nickel, about 4.5% to about 5.5% manganese, about .2% to about .4% nitrogen, about .5% to about 1.5% molybdenum, about .2% to about .4% columbium, about .1% to about .4% vanadium, carbon not exceeding about 0.6%, and remainder substantially all iron..]. .[.15. Alloy steel of improved corrosion-resistance together with strength and ductility and essentially consisting of about 22% to about 24% chromium, about 9% to about 10% nickel, about 4.5% to about 5.5% manganese, about .2% to about .4% nitrogen, about 1% to about 2% molybdenum, about .2% to about .4% columbium, about .1% to about .4% vanadium, carbon not exceeding about .05%, and remainder substantially all iron..]. .[.16. Alloy steel of improved corrosion-resistance together with strength and ductility and essentially consisting of about 23% to about 24% chromium, about 12% to about 14% nickel, about 4.5% to about 5.5% manganese, about .2% to about .4% nitrogen, about 1.7% to about 2.9% molybdenum, about .1% to about .4% columbium, with or without about .1% to about .4% vanadium, carbon not exceeding about .06%, and remainder substantially all iron..]. .[.17. Alloy steel of improved corrosion-resistance together with strength and ductility and essentially consisting of about 23% to about 24% chromium, about 13% to about 14% nickel, about 4.5% to about 5.5% manganese, about .2% to about .4% nitrogen, about 1.75% to about 2.75% molybdenum, about .2% to about .3% columbium, about .1% to about .3% vanadium, with carbon not exceeding about .06%, and remainder substantially all iron..]. .Iadd. 18. Substantially austenitic alloy steel of improved resistance to intercrystalline corrosion in the welded condition, said steel having a tensile strength exceeding some 100,000 p.s.i. at room temperature together with an elongation in 2" of at least about 30% and essentially consisting of about 20.5% to 25% chromium, about 6% to about 17% nickel, about 3.5% to about 7% manganese, about 0.15% to about 0.50% nitrogen, about 0.5% to about 4% molybdenum, about 0.05% to about 0.5% vanadium, with carbon about 0.03% to 0.06%, silicon not exceeding about 0.7% and remainder substantially all iron. .Iaddend..Iadd. 19. Alloy steel according to claim 18, essentially consisting of about 20.5% to 25% chromium, about 6% to about 17% nickel, about 3.5% to about 7% manganese, about 0.15% to about 0.50% nitrogen, about 0.5% to about 4% molybdenum, about 0.1% to about 0.7% columbium, about 0.05% to about 0.5% vanadium, with carbon about 0.03% to 0.06%, silicon not exceeding about 0.7% and remainder substantially all iron..Iaddend.