High strength carburizing steel having improved durability

Abstract

A carburizing steel includes, based on a total wt % of the carburizing steel: 0.1 wt % or more and 0.3 wt % or less of C (carbon); 2.0 wt % or more and 2.7 wt % or less of Cr (chrome); 0.4 wt % or more of Si (silicon); 0.3 wt % or more and 0.7 wt % or less of Mo (molybdenum); less than 0.7 wt % of Mn (manganese); and 0.6 wt % or more and 1.5 wt % or less of Ni (nickel).

What is claimed is: 
     
         1 . A carburizing steel comprising, based on a total wt % of the carburizing steel:
 0.1 wt % or more and 0.3 wt % or less of C (carbon):   2.0 wt % or more and 2.7 wt % or less of Cr (chrome);   0.4 wt % or more and 0.7 wt % or less of Si (silicon);   0.3 wt % or more and 0.7 wt % or less of Mo (molybdenum);   less than 0.7 wt % of Mn (manganese); and   0.6 wt % or more and 1.5 wt % or less of Ni (nickel).   
     
     
         2 . The carburizing steel of  claim 1 , further comprising one or more of Ti (titanium), V (vanadium), and Nb (niobium). 
     
     
         3 . The carburizing steel of  claim 2 , wherein the sum of the Ti (titanium), the V (vanadium), and the Nb (niobium) is 1.0 wt % or less with respect to the total wt % of the carburizing steel. 
     
     
         4 . The carburizing steel of  claim 1 , further comprising 1 to 30 ppm of B (boron). 
     
     
         5 . The carburizing steel of  claim 1 , wherein a value of the following formula is 0.2 or more,
   [Ni]+0.3[Mn])/([Cr]+3[Si],   where [Ni], [Mn], [Cr], [Si] mean the wt % of Ni, Mn, Cr, Si, respectively.   
     
     
         6 . The carburizing steel of  claim 1 , wherein the content of the Si (silicon) is 0.6 wt % or more and 0.7 wt % or less. 
     
     
         7 . The carburizing steel of  claim 1 , wherein the content of the Ni (nickel) is 0.6 wt % or more and 1.0 wt % or less. 
     
     
         8 . The carburizing steel of  claim 1 , wherein the content of the Mn (manganese) is 0.1 wt % or more and 0.5 wt % or less. 
     
     
         9 . The carburizing steel of  claim 1 , wherein the carburizing steel has a carburizing hardness of 780 Hv or more. 
     
     
         10 . The carburizing steel of  claim 1 , wherein the carburizing steel has a bending strength of 3,000 MPa or more. 
     
     
         11 . A carburizing steel comprising, based on a total wt % of the carburizing steel:
 0.1 wt % or more and 0.3 wt % or less of C (carbon);   2.0 wt % or more and 2.7 wt % or less of Cr (chrome), 0.4 wt % or more and 0.7 wt % or less of Si (silicon);   0.3 wt % or more and 0.7 wt % or less of Mo (molybdenum);   less than 0.7 wt % of Mn (manganese); 0.6 wt % or more and 1.5 wt % or less of Ni (nickel);   1.0 wt % or less of the sum of Ti (titanium), V (vanadium), and Nb (niobium); and   1 to 30 ppm of B (boron),   wherein a value of the following formula satisfies 0.2 or more,
   [Ni]+0.3[Mn])/([Cr]+3[Si], 
   where [Ni], [Mn], [Cr], [Si] mean the wt % of Ni, Mn, Cr, Si, respectively.   
     
     
         12 . The carburizing steel of  claim 11 , wherein the content of the Si (silicon) is 0.6 wt % or more and 0.7 wt % or less. 
     
     
         13 . The carburizing steel of  claim 11 , wherein the content of the Ni (nickel) is 0.6 wt % or more and 1.0 wt % or less. 
     
     
         14 . The carburizing steel of  claim 11 , wherein the content of the Mn (manganese) is 0.1 wt % or more and 0.5 wt % or less. 
     
     
         15 . The carburizing steel of  claim 11 , wherein the carburizing steel has a carburizing hardness of 780 Hv or more. 
     
     
         16 . The carburizing steel of  claim 11 , wherein the carburizing steel has a bending strength of 3,000 MPa or more.