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
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
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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