| 摘要 |
<p>Bloom is mfd. by bottom casting a liq. material in a mould without a refractory lining and without a head or foot. The ratio of the height of the bloom to its mean dia. is at max. 1.3. During casting and solidification, the upper face of the bloom is covered with an exothermic or insulating medium which prevents rapid cooling of the face. When the bloom is intended for the prodn. of a hollow forging the max. ratio is 1.2 and when it is intended for the prodn. of a flat forging the max. ratio is 0.8. Used for casting blooms for the prodn. of flat or hollow forgings. The bloom does not exhibit centre line shrinkage so that the forging can be placed directly under a press after heating without complicated heating. Inclusions rise to the upper surface of the bloom and are easily removed. Through the absence of a head, the solidification time is shortened and this use causes a redn. in the degree of segregation. The bloom is easily converted to both flat and hollow forgings.</p> |
