| 摘要 |
PURPOSE: A steel material and a manufacturing method thereof are provided to prevent the grain growth of austenite by adding Ti and Nb causing a pinning effect in order to form a modified carbonitride. CONSTITUTION: A manufacturing method for a steel material is as follows: a step of reheating a steel slab composed of 0.14-0.18wt% of C, 0.3-0.4wt% of Si, 1.0-1.3wt% of Mn, 0.02wt% or less of P, 0.005wt% or less of S, 0.01-0.05wt% of available Al, 0.01-0.02wt% of Nb, 0.2-0.3wt% of Cr, 0.001-0.005wt% of Ti, 0.005wt% or less of N, and the rest of Fe and other impurities(S110); a step of hot-rolling the reheated steel slab(S120); a step of cold-rolling the hot-rolled slab(S130); and a step of normalizing the cold steel(S140). [Reference numerals] (AA) Start; (BB) End; (S110) Slab reheating(SRT: 1100-1250°C); (S120) Hot rolling(FDT: 850-950°C); (S130) Cooling; (S140) Normalizing;
|
