| 摘要 |
<p>Cold forged steel and a method for manufacturing the same are provided to improve cold forging property by spheroidizing carbide at the same time as fine-graining a matrix structure. A method for manufacturing cold forged steel comprises a step of performing quenching by heating a material at 950°C for several seconds, a step of high-temperature tempering the material at 700°C for several seconds after water cooling, and a step of performing cold forging after water cooling. The material is composed mainly of iron(Fe), and contains carbon(C) 0.20~0.30 weight%, silicon(Si) 0.40~0.60 weight%, manganese(Mn) 1.00~1.60 weight%, phosphorus(P) 0.030 weight% or less, sulfur(S) 0.010~0.050 weight% or less, aluminum(Al) 0.005~0.050 weight%, chrome(Cr) 0.10~0.15 weight%, titanium(Ti) 0.005~0.050 weight%, copper(Cu) 0.20~0.30 weight%, boron(B) 0.0005~0.0050 weight%, and calcium(Ca) 0.0005~0.0020 weight%.</p> |
