Method of producing forgings having excellent tensile strength and elongation from steel wire rods

Abstract

A method of producing forgings includes the steps of: forming forgings from a steel wire rod; heating the forgings to a temperature range of 830˜900° C.; subjecting the forgings to first tempering at a temperature range of 100˜300° C. after the heating at 830˜900° C.; and subjecting the forgings to second tempering at a temperature range of 300˜400° C, after the first tempering. In the first tempering, the forgings are quenched in a salt bath having a temperature in the range of 100˜300° C., and are tempered for 60˜130 minutes. In the second tempering, the forgings are quenched in a salt bath having a temperature in the range of 300—400° C., and are tempered for 30˜150 minutes.

1 . A method of producing forgings having a high tensile strength and an elongation, comprising:
 (a) forming forgings from a steel wire rod;   (b) heating the forgings to a temperature range of 830˜900° C.;   (c) subjecting the forgings to first tempering at a temperature range of 100˜300° C. after the heating at 830˜900° C.; and   (d) subjecting the forgings to second tempering at a temperature range of 300-400° C. after the first tempering.   
     
     
         2 . The method of  claim 1 , wherein the forgings are quenched in a salt bath having a temperature in the range of 100˜300° C. during the first tempering, and are tempered for 60˜130 minutes. 
     
     
         3 . The method of  claim 2 , wherein the forgings are quenched in a salt bath having a temperature in the range of 300˜400° C. during the second tempering, and are tempered for 30˜150 minutes. 
     
     
         4 . The method of  claim 3 , wherein the forgings are heated to 830˜900° C. for 30˜120 minutes. 
     
     
         5 . The method of  claim 1 , further comprising the step of preheating the forgings at a temperature range of 550˜650° C. for 30˜90 minutes before the forgings are heated to 830˜900° C. 
     
     
         6 . The method of  claim 1 , wherein the steel wire rod is made of a hardened wire material selected from the group consisting of nickel-chromium-molybdenum steel and chromium-molybdenum steel. 
     
     
         7 . The method of  claim 1 , wherein the forgings in step (a) are formed by employing the steps of:
 subjecting the steel wire rod to a first spheroidized annealing;   picking and coating the steel wire rod after the first spheroidized annealing;   subjecting the steel wire rod to intermediate drawing after the picking and coating of the steel wire rod;   subjecting the steel wire rod to a second spheroidized annealing after the intermediate drawing;   picking and coating the steel wire rod a second time;   subjecting the steel wire rod to skin-pass drawing after the picking and coating of the steel wire rod a second time;.and   stamp-forging and roll-threading the steel wire rod, thereby forming the forgings.