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Hacker, Robert W. (ed.) / The Wisconsin engineer
Volume 53, Number 4 (January 1949)

W. M. H.; R. R. J.
The way we see it,   pp. 17-32 ff.


Page 20


CASTING .1. .
                   (continulced IIo0112 Page 8),
tion by allowing a slower rate of travel. The tundish re-
duces the velocity of the metal by reducing the distance
which the metal must fall into the mold. It also minimizes
turbulence.
  Refractories were also an important consideration. Ac-
curate flows of metal are required with little slag, so a
refractory was required which would not erode under con-
stant operation. The refractory problem has been met but
some improvements are expected.
  Optimum casting conditions are affected by several con-
ditions. The more rapid the casting rate the better the
surface of the billet. The more rapid the rate the less
time the metal is in contact with the mold when rapid heat
extraction can occur. To obtain best results the metal
should enter the mold at optimum viscosity. To accom-
plish proper cooling for a more rapid casting rate the
heat conductivity of the mold could be increased and the
effectiveness of the coolant increased.
           Advantages of Continuous Casting
  Continuous casting meets the established requirements
of sound steel making practice, in many cases better than
conventional practices. The following have been sum-
marized from Iron Age:
  (1) A truly sound ingot solidifies progressively from
bottom to top. This is accomplished in continuous cast-
ings more ideally because of the flexibility of the heat
withdrawal pattern.
  (2) Fast cooling minimizes ingotism and segregation of
minor constituents. Continuous cast steel results in fine
and uniform crystalline structure and surprisingly little
segregation.
  (3) The best steels are cast in big-end-up ingots to
minimize pipe and segregation. Continuous casting almost
ideally meets these conditions.
  (4) The surface of the ingot should be relatively free
from cracks and checking and the interior should be free
of entrapped slag. These conditions also cause difficulty
in continuous casting but it violates these requirements
far less than conventional casting.
  (5) Steels of the best quality should not have planes
of weakness due to columnar growth. Continuous cast
steel solidifies to a finer grain because of rapid cooling.
Satisfactory control, however, was obtained by using the
best cross section combined with regulated cooling in
the mold and below it.
  (6) The best ingot is relatively long with little taper.
Continuously cast billets may be as long as desired and
there is no taper.
  (7) A small ingot generally gives a better quality
product. Continuous cast billets are of small cross sec-
tion-an oval section of proportions satisfying the require-
ments of good casting and rolling practice.
                      Future Plans
  Plans have been worked out for a plant of such a size
as would provide 7,500 to 15,000 tons of steel a month. It
would employ two 15-ton arc furnaces for primary heat-
ing. Five ton ladles would transfer the metal to holding
and pouring stations on the pouring floor. The actual
pouring arrangement would be the same as that now in
operation-with refinements.
  The Babcock Wilcox Company has established various
improvements and changes to be made in the future:
  (a) Experiment with more varieties of steel now that
the physics of good casting is understood for .15-.20 car-
bon steel.
  (b) Install arc-type furnaces of about 7 ton capacity
with lip-pouring facilities to replace the present 5000
pound ladle.
  (c) Install a control, already being developed, to con-
trol the pouring now controlled by visual and manual
means.
  (d) Experiment with new shapes and sizes of cross
sections. A cross section of 45 square inches has already
been suggested.
  These improvements will undoubtedly mean standard-
ized commercial production of steel by continuous cast-
ing. In a year or two such facilities will undoubtedly be
not uncommon in decentralized production of steel at
lower production costs.
     Note: Much of the information contained in this article
   was obtained from an article by Mr. Lippert of Iron Age.
THE WISCONSIN ENGINEER
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