. Transactions. eedom from sur-face blowholes, snakes, etc., in evolution steelsare obtained when the ingots are bottom is the practice in the steel plants of ourlarge plate mills. Bottom-casting methods,however, are more expensive than top casting,a loss of approximately 5 per cent, being dueto runners and feed head. Similar results as to deep-seating of blow-holes and freedom from snakes have been ob-tained in division B steel by means ofwhat may be termed top-bottom casting;that is, employing a special pouring nozzlewhereby the pressure and velocity of liquidsteel as it enters the
. Transactions. eedom from sur-face blowholes, snakes, etc., in evolution steelsare obtained when the ingots are bottom is the practice in the steel plants of ourlarge plate mills. Bottom-casting methods,however, are more expensive than top casting,a loss of approximately 5 per cent, being dueto runners and feed head. Similar results as to deep-seating of blow-holes and freedom from snakes have been ob-tained in division B steel by means ofwhat may be termed top-bottom casting;that is, employing a special pouring nozzlewhereby the pressure and velocity of liquidsteel as it enters the mold from the ladle are greatly reduced without, however, diminishing the volumeof steel teemed per minute. During the war, a variety of ap-paratus was quite successfully used by various steel producers to ac-complish this end. Extensive tests are being made to develop thismethod of top-bottom teeming further, by reducing the high velocityof the hot stream as it leaves the nozzle of the ladle. It is the general. Fig. 3. 520 CASTING AND MOLDING STEEL INGOTS opinion that division B steel should be teemed near the upper limit ofthe casting tern perature, so that a large volume of gas may be evolvedfrom the ingot, whic h is the reverse of the practice for killed steel. It was found nece ssary, during the war, to improve the quality of thesteel ingot and decrease scrap losses in order to meet the large demand forfinished product. To obtain a large economy as well as improve thequality of steel product, the highest possible percentage of the ingotshould be of such physical condition that it can be worked into homogene-ous finished shapes or sections, thus reducingscrap losses with consequent unnecessary fueland labor waste in continuous remelting opera-tions. Each per cent, increase in sound, us-able ingot will effect a net annual saving ofover 500,000 tons of coal, coke, or equivalentfuel to the steel industry of our country. Thetotal annual monetary saving for each percent, increa
Size: 896px × 2791px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
