Alloy steel for hot forging and heat treatment method thereof

Abstract

Disclosed is an alloy steel for hot forging and a heat treatment method thereof, more particularly, an alloy steel for hot forging and a heat treatment method thereof, which includes iron as a base material, and about 0.08 to 0.13% by weight of carbon (C), about 1.3 to 1.5% by weight of manganese (Mn), and about 0.1 to 0.3% by weight of molybdenum (Mo), based on a total weight of the alloy steel. As such, a tempering process can be omitted to reduce process costs, while still providing excellent strength and toughness as compared to the alloy steel in the related art.

What is claimed is: 
     
         1 . An alloy steel for hot forging comprising:
 iron as a base material, and   about 0.08 to 0.13% by weight of carbon (C), about 1.3 to 1.5% by weight of manganese (Mn), and about 0.1 to 0.3% by weight of molybdenum (Mo), based on a total weight of the alloy steel.   
     
     
         2 . The alloy steel for hot forging of  claim 1 , further comprising:
 about 0.01 to 0.05% by weight of niobium (Nb).   
     
     
         3 . The alloy steel for hot forging of  claim 1 , further comprising:
 about 0.4 to 1% by weight of silicon (Si), about 0.8 to 1.2% by weight of chromium (Cr), and about 0.003% by weight or less of boron (B).   
     
     
         4 . The alloy steel for hot forging of  claim 1 , further comprising:
 about 0.01 to 0.04% by weight of titanium (Ti) and about 0.01 to 0.04% by weight of aluminum (Al).   
     
     
         5 . A heat treatment method of an alloy steel for hot forging, the method comprising:
 hot forging the alloy steel of  claim 1 ;   allowing the hot-forged alloy steel to air cool in a temperature range from about 970° C. to 1,010° C.; and   quenching the alloy steel air-cooled in the temperature range.   
     
     
         6 . The method of  claim 5 , wherein the hot forging is performed in a temperature range from about 1,150° C. to 1,250° C. 
     
     
         7 . The method of  claim 5 , wherein the quenching is performed by oil quenching using a quenching oil. 
     
     
         8 . The method of  claim 7 , wherein a temperature of the quenching oil is about 55° C. or less. 
     
     
         9 . The method of  claim 5 , wherein allowing the hot-forged alloy steel to air cool and quenching are carried out directly after the hot forging.