| 摘要 |
PURPOSE: A method for inline spheroidizing annealing of alloy steel for cold forging and a method for manufacturing alloy steel for cold forging using the same are provided to improve the productivity and production costs of alloy steel for cold forging by inserting a spherodizing annealing process into a hot-rolled material cooling process. CONSTITUTION: A method for inline spheroidizing annealing of alloy steel for cold forging comprises the steps of: hot rolling steel(S-11), heating the hot rolled steel by A1+50°C to A1+60°C when the temperature of the hot rolled steel reaches A1(A1 transformation point temperature)-55°C to A1-45°C(S-21), maintaining the heated steel at A1+45°C to A1+55°C for 30 to 40 minutes(S-22), and cooling the steel by A1-55°C to A1-45°C at a cooling rate of 0.5-1°C/min(S-23), wherein the steel comprises 0.3-0.5 weight% of carbon and Fe and inevitable impurities. [Reference numerals] (S-11) Hot rolling step; (S-21) Heating step; (S-22) Maintaining step; (S-23) Cooling step; (S-31) Air-cooling step |
