Cr-Mo alloy steel for transmission gear

Abstract

Cr—Mo alloy steel suitable for motor vehicle transmission gears and shafts is provided and can avoid solve problems associated with. Preferred Cr—Mo alloy steel of the invention comprises steel as a major component, about 0.17 to about 0.21 weight % of carbon, about 0.15 weight % or less of silicon, about 0.60 to about 0.85 weight % of manganese, about 0.02 weight % or less of phosphorus, about 0.03 weight % or less of sulfur, about 1.25 to about 1.45 weight % of chrome, about 0.55 to about 0.65 weight % of molybdenum, and about 0.015 to about 0.035 weight % of niobium.

1 . A Cr—Mo alloy steel, comprising steel as a major component, about 0.17 to about 0.21 weight % of carbon, about 0.15 weight % or less of silicon, about 0.60 to about 0.85 weight % of manganese, about 0.02 weight % or less of phosphorus, about 0.03 weight % or less of sulfur, about 1.25 to about 1.45 weight % of chrome, about 0.55 to about 0.65 weight % of molybdenum, and about 0.015 to about 0.035 weight % of niobium.  
     
     
         2 . The alloy steel of  claim 1  wherein the alloy steel is formed by addition of 15 ppm or less dissolved oxygen to the alloy steel mixture.  
     
     
         3 . The alloy steel of  claim 1  wherein the alloy steel comprises one or more of silicon, phosphorus, sulfur and oxygen.  
     
     
         4 . The alloy steel of  claim 1  wherein the alloy steel comprises silicon, phosphorus, sulfur and oxygen.  
     
     
         5 . The alloy steel of  claim 1  wherein the Cr—Mo alloy steel comprises 0.17 to 0.21 weight % of carbon, 0.1 weight % or less of silicon, 0.65 to 0.85 weight % of manganese, 0.015 weight % or less of phosphorus, 0.025 weight % or less of sulfur, 1.3 to 1.45 weight % of chrome, 0.6 to 0.65 weight % of molybdenum, 0.02 to 0.035 weight % of niobium, and oxygen as provided by addition of 15 ppm or less dissolved oxygen.  
     
     
         6 . The alloy steel of  claim 1  wherein the Cr—Mo alloy is at least essentially free of nickel.  
     
     
         7 . The alloy steel of  claim 1  wherein the Cr—Mo alloy is completely free of nickel.  
     
     
         8 . An alloy steel comprising: 
 about 0.17 to about 0.21 weight % of carbon, about 0.15 weight % or less of silicon, about 0.60 to about 0.85 weight % of manganese, about 0.02 weight or less of phosphorus, about 0.03 weight or less of sulfur, about 1.25 to about 1.45 weight % of chrome, about 0.55 to about 0.65 weight % of molybdenum, about 0.015 to about 0.035 weight % of niobium, and oxygen as provided by addition of 15 ppm or less dissolved oxygen, with balance being steel.    
     
     
         9 . The alloy steel of  claim 8  wherein the alloy steel is at least essentially free of nickel.  
     
     
         10 . A method for producing an alloy steel comprising: 
 admixing steel, about 0.17 to about 0.21 weight % of carbon, about 0.15 weight % or less of silicon, about 0.60 to about 0.85 weight % of manganese, about 0.02 weight % or less of phosphorus, about 0.03 weight % or less of sulfur, about 1.25 to about 1.45 weight % of chrome, about 0.55 to about 0.65 weight % of molybdenum, and about 0.015 to about 0.035 weight % of niobium.    
     
     
         11 . The method of  claim 10  wherein the alloy steel is at least essentially free of nickel.  
     
     
         12 . A vehicle component comprising alloy steel of  claim 1 .  
     
     
         13 . The component of  claim 12  wherein the component comprising the alloy steel is a transmission gear of a motor vehicle.  
     
     
         14 . The component of  claim 12  wherein the component comprising the alloy steel is a transmission shaft of a motor vehicle.