Abstract
In order to reduce the solute segregation in steel ingots casted into iron molds, casting methods have been investigated specially from a viewpoint of solidification rate of molten steel.
Solidification rate of molten steel has been calculated by SARJANT'S in the case of big end down rectangular molds. The calculated times for complete solidification have been in relatively good agreements with the observed ones obtained by bar-test method. Accordingly this method has been applied to calculate the influence of mold thickness or mold radiator on the time for complete solidification of steel ingots. The obtained results have shown that these effects have been practically negligibly small. Electrical method has been used to measure the time for air-gap formation between mold and ingot initiated immediately the teem-end, and a calculative method for estimating the time for gap formation has been established.
Some experiments in practical scale have been done in order to investigate the scraping method which were reported to be beneficial in reducing the segregation in steel ingots. It has been concluded, however, that this method can not be effective for segregation without eliminating the horizontal solidification from the mold wall.
Finally a new method has been devised, in which some coolant such as air or water is introduced directly into the air gap and accelerates the enhanced cooling of steel ingots effectively. The experimental results have shown that the solute segregation is remarkably reduced by this method.
