連続鋳造における一次冷却について

Abstract

A series of experiments on the primary cooling of continuous casting of steel was carried out.In this report it is defined that the solidification in mold is "the primary solidification" and the cooling of this stage is "the primary cooling" and that the solidification in spray zone is "the secondary solidification" and the cooling of this stage is "the secondary cooling".Based on the principle of normal ingot casting, it was presumed that main factors affecting the primary solidification of continuous casting should be as follows:Shape of moldEvenness of cooling in moldCasting temperatureCasting speedExperiments on the effects of these factors on continuous cast billets mainly of square type reveal the following facts.(1) Corner radius of mold affects longitudinal surface cracks of square billets. There is a suitable corner radius for each size of billets to get rid of surface cracks. (Fig. 1)(2) Unevenness of the primary cooling induces longitudinal cracks on the surface of billets. (Table 2)(3) Too high casting temperature induces longitudinal cracks on the surface of billets. (Fig. 2)These relationships in continuous casting are just same as those in normal ingot casting.(4) Commonly, casting speed does not affect continuously cast billets. But exceptionally in round billet, too high casting speed induces longitudinal cracks on the surface of billets. (Table 5)