Metallurgy Of Cast Iron

CONTRACTION VS. STRENGTH OF CAST IRON. 455 !,
I1
often be found between the " temper " of sands in one r|
shop. All three bars were plaeed equidistant in the j
mould and ^"ated by means of two upright lt sprues'1
which led down to a runner in the eope extending over
the three bars in the center, insuring the filling of the
three moulds at the same time with the same hand ladle
of iron. The test bars formed in the chill and dampest
sand showed a greater contraction than the ones
enclosed in the driest sand. I have conducted quite a
11 umber of these tests and always found in. them the
same results, those cast in the chill showing the greater
contraction. In several cases, the extremes of one
flask i^'ave a full one-sixteenth inch difference in
the contraction of the three bars. In the extremes be-
!
tween the "temper*1 of the wetter and drier sand, I
have found a difference of fully one thirty-second part <
of an inch to exist in the contraction of two one-half i inch bars poured from the same hand ladle at the same
moment, thereby proving" that a test bar as small as tj.
one-half inch square or round is altogether too sensi- V
live to variation in the " temper" of moulding sand to l
be relied upon to afford any true knowledge of the (|i
natural contraction of an iron. <j,
To discover what effect, if any, degrees in dampness (j or "temper" of sand have on a round bar cast on
end, I took a pattern one and one-eighth inch in M,
diameter and made a dry sand mould, using" a piece \
of six-inch ^»*as pipe to mould it in, leaving both ends Ij
open. After this little mould was dried in an oven, }
it was set on end upon a planed plate and the distance >;
equally divided between two empty #as pipes. Each 1 of these two latter pipes was then rammed, up with
" green sand " of a different temper. Each test bar ,es ,u •„ ,i j and ;i,nds pe!' (on of iron, or a ratio of 7.7 iron to i coke, in onler to deliver the melted iron in the same condition as on an ordinary day. In other words, an additional fuel consumption <>!' a little over 3,h per cent, is needed under the above conditions...................... 3,658 units £