Carburized alloy steel having superior durability and method of manufacturing the same

Abstract

A carburized alloy steel including, based on the total weight of the alloy steel, 0.1 to 0.35 wt % of carbon (C), 0.1 to 2 wt % of silicon (Si), 0.1 to 1.5 wt % of manganese (Mn), 3 to 5.5 wt % of chromium (Cr), 0.2 to 0.5 wt % of molybdenum (Mo), more than 0 wt % and 0.07 wt % or less of niobium (Nb), more than 0 wt % and 0.3 wt % or less of vanadium (V), more than 0 wt % and 0.2 wt % or less of titanium (Ti), more than 0 wt % and 0.015 wt % or less of nitrogen (N), 0.002 to 0.005 wt % of boron (B), and a balance of iron (Fe). A method of manufacturing the same is also provided.

What is claimed is: 
     
         1 . A carburized alloy steel comprising:
 based on a total weight of the alloy steel, 0.1 to 0.35 wt % of carbon (C), 0.1 to 2 wt % of silicon (Si), 0.1 to 1.5 wt % of manganese (Mn), 3 to 5.5 wt % of chromium (Cr), 0.2 to 0.5 wt % of molybdenum (Mo), more than 0 wt % and 0.07 wt % or less of niobium (Nb), more than 0 wt % and 0.3 wt % or less of vanadium (V), more than 0 wt % and 0.2 wt % or less of titanium (Ti), more than 0 wt % and 0.015 wt % or less of nitrogen (N), 0.002 to 0.005 wt % of boron (B), and a balance of iron (Fe).   
     
     
         2 . The carburized alloy steel of  claim 1 , wherein a content of carbon (C) is 0.18 to 0.33 wt %, a content of silicon (Si) is 0.69 to 1.06 wt %, a content of manganese (Mn) is 0.74 to 0.98 wt %, a content of chromium (Cr) is 3.2 to 5.3 wt %, a content of molybdenum (Mo) is 0.29 to 0.38 wt %, a content of niobium (Nb) is 0.062 to 0.064 wt %, a content of vanadium (V) is 0.19 to 0.27 wt %, a content of titanium (Ti) is 0.14 to 0.18 wt %, a content of nitrogen (N) is 0.0051 to 0.0056 wt %, and a content of boron (B) is 0.0026 to 0.0043 wt %. 
     
     
         3 . The carburized alloy steel of  claim 1 , wherein a content of carbon (C) is 0.18 wt %, a content of silicon (Si) is 1.06 wt %, a content of manganese (Mn) is 0.98 wt %, a content of chromium (Cr) is 5.3 wt %, a content of molybdenum (Mo) is 0.38 wt %, a content of niobium (Nb) is 0.064 wt %, a content of vanadium (V) is 0.27 wt %, a content of titanium (Ti) is 0.14 wt %, a content of nitrogen (N) is 0.0051 wt %, and a content of boron (B) is 0.0026 wt %. 
     
     
         4 . A transmission component of a vehicle comprising the alloy steel of  claim 1 . 
     
     
         5 . A transmission component of a vehicle comprising the alloy steel of  claim 2 . 
     
     
         6 . A transmission component of a vehicle comprising the alloy steel of  claim 3 . 
     
     
         7 . A method of manufacturing a carburized alloy steel, comprising:
 a first step of manufacturing the alloy steel, the alloy steel comprising, based on a total weight of the alloy steel, 0.1 to 0.35 wt % of carbon (C), 0.1 to 2 wt % of silicon (Si), 0.1 to 1.5 wt % of manganese (Mn), 3 to 5.5 wt % of chromium (Cr), 0.2 to 0.5 wt % of molybdenum (Mo), more than 0 wt % and 0.07 wt % or less of niobium (Nb), more than 0 wt % and 0.3 wt % or less of vanadium (V), more than 0 wt % and 0.2 wt % or less of titanium (Ti), more than 0 wt % and 0.015 wt % or less of nitrogen (N), 0.002 to 0.005 wt % of boron (B), and a balance of iron (Fe);   a second step of carburizing heat-treating the alloy steel at 880 to 940° C. for 1.5 to 2 hours;   a third step of oil-quenching the carburized alloy steel to 80 to 120° C.; and   a fourth step of tempering the oil-quenched alloy steel at 170 to 200° C. for 1 to 3 hours.   
     
     
         8 . The method of  claim 7 , wherein a content of carbon (C) is 0.18 to 0.33 wt %, a content of silicon (Si) is 0.69 to 1.06 wt %, a content of manganese (Mn) is 0.74 to 0.98 wt %, a content of chromium (Cr) is 3.2 to 5.3 wt %, a content of molybdenum (Mo) is 0.29 to 0.38 wt %, a content of niobium (Nb) is 0.062 to 0.064 wt %, a content of vanadium (V) is 0.19 to 0.27 wt %, a content of titanium (Ti) is 0.14 to 0.18 wt %, a content of nitrogen (N) is 0.0051 to 0.0056 wt %, and a content of boron (B) is 0.0026 to 0.0043 wt %. 
     
     
         9 . The method of  claim 7 , wherein a content of carbon (C) is 0.18 wt %, a content of silicon (Si) is 1.06 wt %, a content of manganese (Mn) is 0.98 wt %, a content of chromium (Cr) is 5.3 wt %, a content of molybdenum (Mo) is 0.38 wt %, a content of niobium (Nb) is 0.064 wt %, a content of vanadium (V) is 0.27 wt %, a content of titanium (Ti) is 0.14 wt %, a content of nitrogen (N) is 0.0051 wt %, and a content of boron (B) is 0.0026 wt %.