Dual-phase stainless steel

Abstract

A dual-phase ferritic-martensitic stainless steel includes, by weight, about 11.5% to about 12% Cr, about 0.8% to about 1.5% Mn, about 0.75% to about 1.5% Ni, 0% to about 0.5% Si, 0% to about 0.2% Mo, 0% to about 0.0025% B, Fe, and impurities. In various embodiments, the steel has a Brinell hardness (HB) and Charpy V-notch impact energy at −40° C. (CVN) such that CVN (ft-lb)+( 0.4 ×HB) is about 160 or greater. Articles of manufacture including the stainless steels also are disclosed.

We claim: 
     
         1 . A dual-phase ferritic-martensitic stainless steel comprising, by weight:
 about 11.5% to about 12% chromium;   about 0.8% to about 1.5% manganese;   about 0.75% to about 1.5% nickel;   0% to about 0.5% silicon;   0% to about 0.2% molybdenum;   0% to about 0.0025% boron;   iron; and   Impurities;   wherein the steel has a Brinell hardness (HB) and Charpy V-notch impact energy at −40° C. (CVN) such that CVN (ft-lb)+(0.4×HB) is about 160 or greater.   
     
     
         2 . The dual-phase ferritic-martensitic stainless steel of  claim 1 , wherein molybdenum content is 0% to about 0.1%. 
     
     
         3 . The dual-phase ferritic-martensitic stainless steel of  claim 1 , wherein nickel content is about 1.0% to about 1.5%. 
     
     
         4 . The dual-phase ferritic-martensitic stainless steel of  claim 1 , wherein manganese content is about 1.0% to about 1.5%. 
     
     
         5 . The dual-phase ferritic-martensitic stainless steel of  claim 1 , wherein boron content is about 0.002% to about 0.0025%. 
     
     
         6 . The dual-phase ferritic-martensitic stainless steel of  claim 1 , wherein hardness of the steel is about 300 HB or greater, and CVN of the steel is about 50 ft-lb or greater. 
     
     
         7 . The dual-phase ferritic-martensitic stainless steel of  claim 1 , wherein the steel has work hardenability up to a hardness of about 450 HB or greater. 
     
     
         8 . The dual-phase ferritic-martensitic stainless steel of  claim 1  comprising, by weight:
 about 11.5% to about 12% chromium; 
 about 1.0% to about 1.5% manganese; 
 about 1.0% to about 1.5% nickel; 
 0% to about 0.5% silicon; 
 0% to about 0.1% molybdenum; 
 0% to about 0.0025% boron; 
 0% to about 0.025% carbon; 
 0% to about 0.01% sulfur; 
 0% to about 0.03% nitrogen; 
 iron; and 
 impurities. 
 
     
     
         9 . The dual-phase ferritic-martensitic stainless steel of  claim 8 , further comprising at least one of copper and phosphorus. 
     
     
         10 . The dual-phase ferritic-martensitic stainless steel of  claim 8 , wherein the total concentration of carbon, nitrogen, phosphorus, and sulfur present is no greater than about 0.1%, by weight. 
     
     
         11 . The dual-phase ferritic-martensitic stainless steel of  claim 8 , wherein boron content is about 0.002% to about 0.0025%. 
     
     
         12 . The dual-phase ferritic-martensitic stainless steel of  claim 1 , consisting essentially of, by weight:
 about 11.5% to about 12% chromium;   about 0.8% to about 1.5% manganese;   about 0.75% to about 1.5% nickel;   0% to about 0.5% silicon;   0% to about 0.2% molybdenum;   0% to about 0.0025% boron;   0% to about 0.025% carbon;   0% to about 0.01% sulfur;   0% to about 0.03% nitrogen;   optionally at least one of copper and phosphorus;   iron; and   impurities.   
     
     
         13 . The dual-phase ferritic-martensitic stainless steel of  claim 1 , consisting essentially of, by weight:
 about 11.5% to about 12% chromium;   about 1.0% to about 1.5% manganese;   about 1.0% to about 1.5% nickel;   0% to about 0.5% silicon;   0% to about 0.1% molybdenum;   0% to about 0.0025% boron;   0% to about 0.025% carbon;   0% to about 0.01% sulfur;   0% to about 0.03% nitrogen;   optionally at least one of copper and phosphorus;   iron; and   impurities.   
     
     
         14 . The dual-phase ferritic-martensitic stainless steel of  claim 1 , consisting of, by weight:
 about 11.5% to about 12% chromium;   about 0.8% to about 1.5% manganese;   about 0.75% to about 1.5% nickel;   0% to about 0.5% silicon;   0% to about 0.2% molybdenum;   0% to about 0.0025% boron;   0% to about 0.025% carbon;   0% to about 0.01% sulfur;   0% to about 0.03% nitrogen;   optionally at least one of copper and phosphorus;   iron; and   impurities.   
     
     
         15 . The dual-phase ferritic-martensitic steel of  claim 1 , consisting of, by weight:
 about 11.5% to about 12% chromium;   about 1.0% to about 1.5% manganese;   about 1.0% to about 1.5% nickel;   0% to about 0.5% silicon;   0% to about 0.1% molybdenum;   0% to about 0.0025% boron;   0% to about 0.025% carbon;   0% to about 0.01% sulfur;   0% to about 0.03% nitrogen;   optionally at least one of copper and phosphorus;   iron; and   impurities.   
     
     
         16 . An article of manufacture including a dual-phase stainless steel as recited in  claim 1 . 
     
     
         17 . The article of manufacture of  claim 16 , wherein the article of manufacture is selected from parts and equipment used in oil sands extraction and parts and equipment used in sugar processing. 
     
     
         18 . An article of manufacture including a dual-phase stainless steel as recited in  claim 12 . 
     
     
         19 . The article of manufacture of  claim 18 , wherein the article of manufacture is selected from parts and equipment used in oil sands extraction and parts and parts and equipment used in sugar processing. 
     
     
         20 . An article of manufacture including a dual-phase stainless steel as recited in  claim 13 . 
     
     
         21 . The article of manufacture of  claim 20 , wherein the article of manufacture is selected from parts and equipment used in oil sands extraction and parts and parts and equipment used in sugar processing. 
     
     
         22 . An article of manufacture including a dual-phase stainless steel as recited in  claim 14 . 
     
     
         23 . The article of manufacture of  claim 22 , wherein the article of manufacture is selected from parts and equipment used in oil sands extraction and parts and parts and equipment used in sugar processing. 
     
     
         24 . An article of manufacture including a dual-phase stainless steel as recited in  claim 15 . 
     
     
         25 . The article of manufacture of  claim 24 , wherein the article of manufacture is selected from parts and equipment used in oil sands extraction and parts and equipment used in sugar processing.