Method of manufacturing non-quenched and tempered steel product

Abstract

This invention relates to a method of manufacturing a non-quenched and tempered steel product, including hot forging a steel material at about 1150˜1250° C. so that the volume thereof is 120% or less, rapidly cooling the hot forged material to about 650˜700° C. at a cooling rate of about 10° C./s or more, and performing warm coining at a temperature of about 600° C. or higher.

1 . A method of manufacturing a non-quenched and tempered steel product, comprising:
 hot forging a steel material at about 1150˜1250° C. so that a volume thereof is about 120% or less;   rapidly cooling, by high pressure liquid nitrogen, the hot forged material to about 650˜700° C. at a cooling rate of about 10° C./s or more; and   performing warm coining at a temperature of about 600° C. or higher on the rapidly cooled material,   wherein the non-quenched and tempered steel product is produced without spot blasting the material.   
     
     
         2 . A method of manufacturing a non-quenched and tempered steel product, comprising:
 hot forging a steel material at about 1150˜1250° C. so that a volume thereof is about 120% or less;   rapidly cooling the hot forged material, by high pressure liquid nitrogen to a temperature of 680° C. or less; and   once the hot forged material has been rapidly cooled to 680° C. or less, warm coining four faces of top/bottom/left/right of the material at about 600˜680° C. so that the volume thereof is about 100˜120% on the rapidly cooled material   wherein the non-quenched and tempered steel product is produced without spot blasting the material.   
     
     
         3 . A method of manufacturing a non-quenched and tempered steel product, comprising:
 hot forging a steel material at about 1150˜1250° C. so that a volume thereof is about 120% or less;   rapidly cooling, by high pressure liquid nitrogen, the hot forged material to about 650˜700° C. at a cooling rate of about 10° C./s or more; and   once the hot forged material has been rapidly cooled to about 650˜700° C., warm coining four faces of top/bottom/left/right of the material at about 600˜680° C. so that the volume thereof is about 100˜120% on the rapidly cooled material,   wherein the non-quenched and tempered steel product is produced without spot blasting the material.   
     
     
         4 . The method of  claim 1 , wherein the hot forging is performed by processing the steel material so that the volume thereof is about 140% or less upon buster, about 130% or less upon blocker, and about 120% or less upon finisher. 
     
     
         5 . The method of  claim 2 , wherein the hot forging is performed by processing the steel material so that the volume thereof is about 140% or less upon buster, about 130% or less upon blocker, and about 120% or less upon finisher. 
     
     
         6 . The method of  claim 3 , wherein the hot forging is performed by processing the steel material so that the volume thereof is about 140% or less upon buster, about 130% or less upon blocker, and about 120% or less upon finisher. 
     
     
         7 . The method of  claim 1 , wherein the warm coining further comprises transporting the coined material into a warm holding furnace at about 550˜650° C. so that residual stress is relieved. 
     
     
         8 . The method of  claim 2 , wherein the warm coining further comprises transporting the coined material into a warm holding furnace at about 550˜650° C. so that residual stress is relieved. 
     
     
         9 . The method of  claim 3 , wherein the warm coining further comprises transporting the coined material into a warm holding furnace at about 550˜650° C. so that residual stress is relieved. 
     
     
         10 . The method of  claim 7 , wherein the transporting further comprises performing shot blasting for removing scales from the transported material. 
     
     
         11 . The method of  claim 8 , wherein the transporting further comprises performing shot blasting for removing scales from the transported material. 
     
     
         12 . The method of  claim 9 , wherein the transporting further comprises performing shot blasting for removing scales from the transported material. 
     
     
         13 . The method  claim 1 , wherein the non-quenched and tempered steel product is a connecting rod for automobiles. 
     
     
         14 . The method  claim 2 , wherein the non-quenched and tempered steel product is a connecting rod for automobiles. 
     
     
         15 . The method  claim 3 , wherein the non-quenched and tempered steel product is a connecting rod for automobiles.