High strength cryogenic high manganese steels and methods of making the same

Abstract

Improved steel compositions and methods of making the same are provided. More particularly, the present disclosure provides high manganese (Mn) steel having enhanced strength and/or performance at cryogenic temperatures, and methods for fabricating high manganese steel compositions having enhanced strength and/or performance at cryogenic temperatures. The advantageous steel compositions/components of the present disclosure improve one or more of the following properties: strength, toughness, elastic modulus, thermal expansion coefficient and/or thermal conductivity. In general, the present disclosure provides high manganese steels tailored to resist wear and/or deformation at cryogenic temperatures.

1 . A method for fabricating a ferrous based component comprising:
 a) providing a composition having from 5 to 40 weight % manganese, from 0.01 to 1.2 weight % carbon, and the balance iron;   b) heating the composition to a temperature above the austenite recrystallization stop temperature of the composition or to a temperature to homogenize the composition;   c) cooling the composition to a rolling start temperature;   d) deforming the composition while the composition is at a temperature below the austenite recrystallization stop temperature of the composition; and   e) quenching the composition.   
     
     
         2 . The method of  claim 1 , wherein step c) includes cooling to a temperature below the T nr  temperature. 
     
     
         3 . The method of  claim 1 , wherein after step e), the carbide precipitate fraction volume of the composition is 5 volume % or less of the composition. 
     
     
         4 . The method of  claim 1 , further comprising after step e) a surface deformation step selected from the group consisting of shot peening, laser shock peening, surface burnishing and combinations thereof. 
     
     
         5 . The method of  claim 1 , wherein step e) includes rapidly quenching the composition. 
     
     
         6 . The method of  claim 1 , further comprising, after step e), heating the composition to a temperature above the austenite recrystallization stop temperature, and then quenching the composition. 
     
     
         7 . The method of  claim 1 , further comprising, prior to step c), deforming the composition while the composition is at a temperature above the austenite recrystallization stop temperature. 
     
     
         8 . The method of  claim 7 , wherein the composition is deformed at a temperature of from 700° C. to 1000° C. 
     
     
         9 . The method of  claim 1 , wherein step b) includes heating the composition to at least 1000° C. 
     
     
         10 . The method of  claim 1 , wherein step c) includes cooling the composition at a rate of from 2° C. per second to 60° C. per second. 
     
     
         11 . The method of  claim 1 , wherein the composition further includes one or more alloying elements selected from the group consisting of chromium, aluminum, silicon, nickel, cobalt, molybdenum, niobium, copper, titanium, vanadium, nitrogen, boron, zirconium, hafnium and combinations thereof. 
     
     
         12 . The method of  claim 11 , wherein the chromium ranges from 0.5 to 30 weight % of the total composition;
 wherein each of the nickel or cobalt ranges from 0.5 to 20 weight % of the total composition;   wherein the aluminum ranges from 0.2 to 15 weight % of the total composition;   wherein each of the molybdenum, niobium, copper, titanium or vanadium ranges from 0.02 to 10 weight % of the total composition;   wherein the silicon ranges from 0.01 to 10 weight % of the total composition;   wherein the nitrogen ranges from 0.01 to 3.0 weight % of the total composition;   wherein the boron ranges from 0.001 to 0.1 weight % of the total composition; and   wherein each of the zirconium or hafnium ranges from 0.2 to 6 weight % of the total composition.   
     
     
         13 . The method of  claim 1 , wherein the composition includes from 8 to 20 weight % manganese, from 0.3 to 0.7 weight % carbon, from 0.5 to 3 weight % chromium, from 0.5 to 2.0 weight % copper, from 0.1 to 1 weight % silicon, and the balance iron. 
     
     
         14 . A ferrous based component fabricated according to the steps comprising:
 a) providing a composition having from 5 to 40 weight % manganese, from 0.01 to 1.2 weight % carbon, and the balance iron;   b) heating the composition to a temperature above the austenite recrystallization stop temperature of the composition;   c) cooling the composition to a temperature below the austenite recrystallization stop temperature of the composition;   d) deforming the composition while the composition is at a temperature below the austenite recrystallization stop temperature of the composition; and   e) quenching the composition.   
     
     
         15 . The ferrous based component of  claim 14 , wherein after step e), the carbide precipitate fraction volume of the composition is 5 volume % or less of the composition. 
     
     
         16 . The ferrous based component of  claim 15 , further comprising after step e) a surface deformation step selected from the group consisting of shot peening, laser shock peening, surface burnishing and combinations thereof. 
     
     
         17 . The ferrous based component of  claim 14 , wherein step e) includes rapidly quenching the composition. 
     
     
         18 . The ferrous based component of  claim 14 , further comprising, after step e), heating the composition to a temperature above the austenite recrystallization stop temperature, and then quenching the composition. 
     
     
         19 . The ferrous based component of  claim 14 , further comprising, prior to step c), deforming the composition while the composition is at a temperature above the austenite recrystallization stop temperature. 
     
     
         20 . The ferrous based component of  claim 19 , wherein the composition is deformed at a temperature of from 700° C. to 1000° C. 
     
     
         21 . The ferrous based component of  claim 14 , wherein step b) includes heating the composition to at least 1000° C. 
     
     
         22 . The ferrous based component of  claim 14 , wherein step c) includes cooling the composition at a rate of from 2° C. per second to 60° C. per second. 
     
     
         23 . The ferrous based component of  claim 14 , wherein the composition further includes one or more alloying elements selected from the group consisting of chromium, aluminum, silicon, nickel, cobalt, molybdenum, niobium, copper, titanium, vanadium, nitrogen, boron, zirconium, hafnium and combinations thereof. 
     
     
         24 . The ferrous based component of  claim 23 , wherein the chromium ranges from 0.5 to 30 weight % of the total composition;
 wherein each of the nickel or cobalt ranges from 0.5 to 20 weight % of the total composition;   wherein the aluminum ranges from 0.2 to 15 weight % of the total composition;   wherein each of the molybdenum, niobium, copper, titanium or vanadium ranges from 0.02 to 10 weight % of the total composition;   wherein the silicon ranges from 0.01 to 10 weight % of the total composition;   wherein the nitrogen ranges from 0.01 to 3.0 weight % of the total composition;   wherein the boron ranges from 0.001 to 0.1 weight % of the total composition; and   wherein each of the zirconium or hafnium ranges from 0.2 to 6 weight % of the total composition.   
     
     
         25 . The ferrous based component of  claim 14 , wherein the composition includes from 8 to 20 weight % manganese, from 0.30 to 0.7 weight % carbon, from 0.5 to 3 weight % chromium, from 0.5 to 2.0 weight % copper, from 0.1 to 1 weight % silicon, and the balance iron.