US2013284319A1PendingUtilityA1

High Strength, High Toughness Steel Alloy

Individually held — no corporate assignee on recordPriority: Apr 27, 2012Filed: Apr 27, 2012Published: Oct 31, 2013
Est. expiryApr 27, 2032(~5.7 yrs left)· nominal 20-yr term from priority
Inventors:Paul M. Novotny
C22C 38/005C22C 38/02C22C 38/58C21D 6/001C21D 2211/008C22C 38/48C21D 1/18C22C 38/34C22C 38/002C21D 6/005C22C 38/46C21D 6/008C22C 38/04C22C 38/42C21D 6/004C22C 38/44
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Claims

Abstract

A high strength, high toughness steel alloy is disclosed. The alloy has the following weight percent composition. Element C 0.30-0.55 Mn  0.6-1.75 Si  0.9-2.8 Cr  0.6-2.5 Ni 2.70-7.0  Mo + ½ W 0.25-1.3  Cu 0.30-1.25 Co  0.01 max. V + (5/9) × Nb 0.10-1.0  Ti  0.01 max. Al 0.015 max. Ca 0.005 max. The alloy further includes a grain refining element selected from the group consisting of 0.0001-0.01% Mg, 0.001-0.025% Y, and a combination thereof. The balance of the alloy is iron and usual impurities. Also disclosed is a hardened and tempered steel article having very high strength and fracture toughness and formed from the alloy set forth above. The alloy article according to this aspect of the invention is further characterized by being tempered at a temperature of about 500° F. to 600° F.

Claims

exact text as granted — not AI-modified
1 . A high strength, high toughness steel alloy having good temper resistance, said alloy comprising, in weight percent, about: 
       
         
           
                 
                 
                 
               
                     
                 
                     
                   C 
                   0.30-0.55 
                 
                     
                   Mn 
                    0.6-1.75 
                 
                     
                   Si 
                    0.9-2.8 
                 
                     
                   Cr 
                    0.6-2.5 
                 
                     
                   Ni 
                   2.70-7.0 
                 
                     
                   Mo + ½ W 
                   0.25-1.3 
                 
                     
                   Cu 
                    0.3-1.25 
                 
                     
                   Co 
                    0.01 max. 
                 
                     
                   V + (5/9) × Nb 
                    0.1-1.0 
                 
                     
                   Ti 
                    0.01 max. 
                 
                     
                   Al 
                   0.015 max. 
                 
                     
                   Ca 
                   0.005 max. 
                 
                     
                 
             
                
               
               
                
                
                
                
                
                
                
                
                
                
                
                
                
               
            
           
         
         a grain-refining element selected from the group consisting of 0.0001-0.01% Mg, 0.001-0.025% Y, and a combination thereof; and 
         the balance being iron and usual impurities wherein phosphorus is restricted to about 0.01% max. and sulfur is restricted to not more than about 0.001% max., and wherein
   2≦(% Si+% Cu)/(% V+( 5/9)×% Nb)≦34.
 
 
       
     
     
         2 . The alloy as set forth in  claim 1  wherein the alloy contains at least about 0.002% yttrium. 
     
     
         3 . The alloy as set forth in  claim 2  wherein the alloy contains not more than about 0.020% yttrium. 
     
     
         4 . The alloy as set forth in  claim 1  wherein the alloy contains not more than about 0.006% magnesium. 
     
     
         5 . The alloy as set forth in  claim 1  wherein the alloy contains not more than about 0.002% calcium. 
     
     
         6 . The alloy as set forth in  claim 1  wherein the alloy contains at least about 0.35% carbon. 
     
     
         7 . The alloy as set forth in  claim 1  wherein the alloy contains at least about 0.7% manganese. 
     
     
         8 . The alloy as set forth in  claim 7  wherein the alloy contains not more than about 1.5% manganese. 
     
     
         9 . The alloy as set forth in  claim 1  wherein the alloy contains at least about 1.2% silicon. 
     
     
         10 . The alloy as set forth in  claim 9  wherein the alloy contains not more than about 2.7% silicon. 
     
     
         11 . The alloy as set forth in  claim 1  wherein the alloy contains at least about 0.7% chromium. 
     
     
         12 . The alloy as set forth in  claim 11  wherein the alloy contains not more than about 2.0% chromium. 
     
     
         13 . The alloy as set forth in  claim 1  wherein the alloy contains not more than about 5.0% nickel. 
     
     
         14 . The alloy as set forth in  claim 1  wherein Mo+½ W is at least about 0.4%. 
     
     
         15 . The alloy as set forth in  claim 14  wherein Mo+½ W is not more than about 1.1%. 
     
     
         16 . The alloy as set forth in  claim 1  wherein V+( 5/9)×Nb is at least about 0.25%. 
     
     
         17 . The alloy as set forth in  claim 1  wherein
   14.5≦(% Si+% Cu)/(% V+( 5/9) ×% Nb)≦34.
 
 
     
     
         18 . A high strength, high toughness steel alloy having good temper resistance, said alloy comprising, in weight percent, about: 
       
         
           
                 
                 
                 
               
                     
                 
                     
                   C 
                   0.35-0.50 
                 
                     
                   Mn 
                    0.7-1.5 
                 
                     
                   Si 
                    1.2-2.7 
                 
                     
                   Cr 
                    0.7-2.0 
                 
                     
                   Ni 
                   2.75-5.0 
                 
                     
                   Mo + ½ W 
                    0.4-1.1 
                 
                     
                   Cu 
                   0.35-1.2 
                 
                     
                   Co 
                    0.01 max. 
                 
                     
                   V + (5/9) × Nb 
                   0.25-1.0 
                 
                     
                   Ti 
                    0.01 max. 
                 
                     
                   Al 
                    0.01 max. 
                 
                     
                   Ca 
                   0.002 max. 
                 
                     
                 
             
                
               
               
                
                
                
                
                
                
                
                
                
                
                
                
                
               
            
           
         
         a grain-refining element selected from the group consisting of 0.0001-0.006% Mg, 0.002-0.020% Y, and a combination thereof; and 
         the balance being iron and usual impurities wherein phosphorus is restricted to about 0.01% max. and sulfur is restricted to not more than about 0.001% max., and wherein
   14.5≦(% Si+% Cu)/(% V+( 5/9)×% Nb)≦34.
 
 
       
     
     
         19 . A high strength, high toughness steel alloy having good temper resistance, said alloy comprising, in weight percent, about: 
       
         
           
                 
                 
                 
               
                     
                 
                     
                   C 
                   0.33-0.50 
                 
                     
                   Mn 
                    0.8-1.3 
                 
                     
                   Si 
                    1.0-2.70 
                 
                     
                   Cr 
                    1.5-1.8 
                 
                     
                   Ni 
                    3.0-5.0 
                 
                     
                   Mo + ½ W 
                   0.25-0.90 
                 
                     
                   Cu 
                    0.3-1.25 
                 
                     
                   Co 
                    0.01 max. 
                 
                     
                   V + (5/9) × Nb 
                    0.1-0.40 
                 
                     
                   Ti 
                    0.01 max. 
                 
                     
                   Al 
                   0.015 max. 
                 
                     
                   Ca 
                   0.001 max. 
                 
                     
                 
             
                
               
               
                
                
                
                
                
                
                
                
                
                
                
                
                
               
            
           
         
         a grain-refining element selected from the group consisting of 0.0001-0.008% Mg, 0.002-0.025% Y, and a combination thereof; and 
         the balance being iron and usual impurities wherein phosphorus is restricted to about 0.01% max. and sulfur is restricted to not more than about 0.001% max., and wherein
   14.5≦(% Si+% Cu)/(% V+( 5/9)×% Nb)≦34.
 
 
       
     
     
         20 . The alloy as set forth in  claim 19  wherein the alloy contains not more than about 0.45% carbon. 
     
     
         21 . The alloy as set forth in  claim 19  wherein the alloy contains at least about 0.40% carbon. 
     
     
         22 . The alloy as set forth in  claim 19  wherein the alloy contains not more than about 4.5% nickel. 
     
     
         23 . The alloy as set forth in  claim 19  wherein the alloy contains at least about 4.0% nickel. 
     
     
         24 . The alloy as set forth in  claim 19  wherein the alloy contains not more than about 1.2% copper. 
     
     
         25 . The alloy as set forth in  claim 19  wherein the alloy contains not more than about 0.006% magnesium. 
     
     
         26 . The alloy as set forth in  claim 19  wherein the alloy contains not more than about 0.020% yttrium. 
     
     
         27 . A high strength, high toughness steel alloy having good temper resistance, said alloy comprising, in weight percent, about: 
       
         
           
                 
                 
                 
               
                     
                 
                     
                   C 
                   0.33-0.45 
                 
                     
                   Mn 
                    0.8-1.3 
                 
                     
                   Si 
                    1.0-2.70 
                 
                     
                   Cr 
                    1.5-1.8 
                 
                     
                   Ni 
                    3.0-4.5 
                 
                     
                   Mo + ½ W 
                   0.25-0.90 
                 
                     
                   Cu 
                   0.35-1.25 
                 
                     
                   Co 
                    0.01 max. 
                 
                     
                   V + (5/9) × Nb 
                   0.10-0.40 
                 
                     
                   Ti 
                    0.01 max. 
                 
                     
                   Al 
                   0.015 max. 
                 
                     
                   Ca 
                   0.001 max. 
                 
                     
                 
             
                
               
               
                
                
                
                
                
                
                
                
                
                
                
                
                
               
            
           
         
         a grain-refining element selected from the group consisting of 0.0001-0.006% Mg, 0.002-0.025% Y, and a combination thereof; and 
         the balance being iron and usual impurities wherein phosphorus is restricted to about 0.01% max. and sulfur is restricted to not more than about 0.001% max., and wherein
   14.5≦(% Si+% Cu)/(% V+( 5/9)×% Nb)≦34.
 
 
       
     
     
         28 . A high strength, high toughness steel alloy having good temper resistance, said alloy comprising, in weight percent, about: 
       
         
           
                 
                 
                 
               
                     
                 
                     
                   C 
                   0.40-0.50 
                 
                     
                   Mn 
                    0.8-1.3 
                 
                     
                   Si 
                    1.5-2.70 
                 
                     
                   Cr 
                    1.5-1.8 
                 
                     
                   Ni 
                    4.0-5.0 
                 
                     
                   Mo + ½ W 
                   0.25-0.90 
                 
                     
                   Cu 
                    0.3-1.2 
                 
                     
                   Co 
                    0.01 max. 
                 
                     
                   V + (5/9) × Nb 
                   0.10-0.40 
                 
                     
                   Ti 
                    0.01 max. 
                 
                     
                   Al 
                   0.015 max. 
                 
                     
                   Ca 
                   0.001 max. 
                 
                     
                 
             
                
               
               
                
                
                
                
                
                
                
                
                
                
                
                
                
               
            
           
         
         a grain-refining element selected from the group consisting of 0.0001-0.008% Mg, 0.002-0.020% Y, and a combination thereof; and 
         the balance being iron and usual impurities wherein phosphorus is restricted to about 0.01% max. and sulfur is restricted to not more than about 0.001% max., and wherein
   14.5≦(% Si+% Cu)/(% V+( 5/9)×% Nb)≦34.
 
 
       
     
     
         29 . A hardened and tempered article made from a high strength, high toughness steel alloy as set forth in any of  claims 1 ,  18 ,  19 ,  27 , and  28  wherein the article is tempered at a temperature of about 500° F. to 600° F. 
     
     
         30 . The hardened and tempered article as set forth in  claim 29  which provides a room temperature tensile strength of at least about 295 ksi and a Charpy V-notch impact toughness of at least about 15 ft-lbs.

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