AFS Library


Journal: Transactions of the American Foundrymen's Society V 71 P 783-790, 1963 (8 p)
Author: Brokloff, J, Chao, H C, Van Vlack, L H and Flinn, R A

This progress report summarizes the significant data which have been obtained concerning the (1) nature, (2) causes and (3) means of prevention of macroinclusions in steel castings. Based on this summary, new techniques for research are proposed and illustrated. 1. In aluminum killed green sand castings it has been shown that typical macroinclusions are composed of corundum (A1203) and a silicate glass. In some cases of high F e d content the corundum is altered to hercynite (FeOAl203). 2. Inclusions of this type can originate from four sources: a) During deoxidation with aluminum in the ladle. b) Reaction of Al with the ladle refractories. c) Reaction of Al and other elements in the steel with air and mold gases during pouring. d) Reaction of the steel with mold materials. The volume of the inclusions can be increased by agglomeration with loose sand of the mold. 3. Several means of prevention have been tried. The addition of fluxes such as calcium fluoride with the hope of causing the inclusions to seep into the mold wall resulted in unsatisfactory casting surfaces. The control of metal flow, using a whirl gate as an inclusion trap has been successful in some cases. New techniques are proposed to evaluate more definitely the causes of macroinclusions. These include a melting furnace with vacuum or controlled atmosphere in which inclusions can be generated under controlled conditions and collected for examination. With a satisfactory basic investigation of the kinetics of inclusion formation, better remedial measures should develop.

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