| 摘要 |
<p>PURPOSE: V-Free microalloyed steel with the same quality as high-strength alloy steel and a manufacturing method thereof are provided to secure a high yield ratio without additional alloying element V. CONSTITUTION: A manufacturing method of V-Free microalloyed steel with the same quality as high-strength alloy steel is as follows. A steel material is heated with 1200~1300°C for minutely extracting carbide and nitride. The steel material is hot-rolled with 900~1000°C. The steel material is composed of C 0.35~ 0.5 weight%, Si 0.30~0.60 weight%, Mn 1.30~1.70 weight%, S 0.020~0.050 weight%, Cr 0.20~0.40 weight%, Nb 0.020~0.050 weight%, N 80~180 ppm, and Fe and inevitable impurities.</p> |
