| 摘要 |
PURPOSE:To manufacture a machine structural steel providing machine parts having high toughness, by refining a carbon steel containing specific percentages of C, Si, Mn, etc., by casting and cooling a billet under specific conditions by continuous casting, and by rolling the above into steel bars and wire rods without delay. CONSTITUTION:A carbon steel or alloy steel for machine structural use which has a composition containing, by weight, 0.25-0.61% C, 0.15-0.35% Si, and 0.60-1.65% Mn, also containing, if necessary, <=1.20% Cr, <=0.30% Mo, and <=2.00% Ni, further containing 0.020-0.100% Al, 0.0030-0.0200% N, and 0.01-0.07% Ti, and satisfying Ti/N=1.0-3.4 is refined by the ordinary method. The resulting molten metal is cast into a billet by continuous casting at >=20 deg.C/min cooling rate through the temp. range from the solidifying point to 1,000 deg.C. Subsequently, the billet is immediately rolled into steel bars and wire rods, obviating the necessity of cogging. In this way, the machine structural steel providing machine parts having high toughness can be obtained.
|
