| 摘要 |
PURPOSE:To cast continuously a B-contg. steel having no crazing flaw in the stage of casting continuously a billet from the molten B-contg. steel by cooling the molten steel in a prescribed temp. range at respectively the regulated contents of sol.Al and free N. CONSTITUTION:Cooling in range of 1,000-7,000 deg.C in continuous casting of a B- contg. steel is accomplished under the condition of <=0.04% sol.Al and <=10% free N. Such cooling is made possible by decreasing the amt. of the Al to be added for the sol.Al and replenishing necessary deoxidation by adding other deoxidative component. The decrease in the free N can be accomplished by various methods as well, for example, by addition of Ti. More specifically, Ti and N reacts approximately 100% with each other, the remaining free N is determined stoichiometrically by the formula. The generation of the crazing flaw near the long side of a billet that largely affects the yield in particular is prevented by the continuous casting under the above-described condition.
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