Wessington Springs herald. (Wessington Springs, Aurora County, Dakota [S.D.]) 1883-1891, 1884-10-10
Smelling and Casting Of Iron.

Tho mettalurgical processes am.
,'.ed in the extraction or iron nro.
pcs metal which contains carrie
l u; 'on. manganese, and other snh'
slances. Pure iron, having a very high
i1.jnr point, is not well applicable to
iannjry purposes; the material wa
Sare TO examine is iron combined with
l"rbon. The presence of carbsn, II be-
:.r combined and disseminated rs
nr*oohfte through the iron. causes a
,wer1ng of the fusing point. When
ra ron is molten in a cupola furnace.
he air comes in contact with particles
u the liquid metal and the carbon
thereof: the metal is partly d%ecarbon-
;,ed. The impurities, silicon, man
ranc4c, and small quantity of iron are
sonycrted into oxides, producing the
s,ag.
other products of oxidation, carbonic
wide and iron oxide, are dissolved in
tbe molten iron. The air blown into
tn furnace generally contains aqueous
yapor, and by its action upon burning
coke hydrogen is generated. Moltenn
iron, possessing the property of dissoly-
inr three times its volume Of hydrogen.
4, has been shown by the latest hives.
tieations, IS thus charged with carbonic
oxide, hydrogen and iron oxide. On
cooling of the metal the gases are
emitted; they are the cause of the
spongv, pumlcestone-like surface
Structure observed on solicited metal
HI. masses.
Iron being molten al q low tempera-
ture. and then tapped off and poured
into moulds, liberates the dissolved
gases within the mould. The structure
et such q casting exhibits the presence
ct cavities and a high degree OF poros-
ity. Such cavities have pease-like shape
near the surface, and assume that of a
sphere toward the center of the metal:
the, are sometimes connected with each
other by small channels. When heated
more rapidly and far above it's fusinr
point. iron becomes more applicable to
foundry purposes. The molten metal
remaining for some time in the ladle
and being agitated by the aid of a bar
before it is poured into the moulds.
permits a free CELEBRATION oil dissolved
gases,
The property Of iron Of absorbing
gases and iron oxide is increased by re-
melting of iron; for homogeneous cast
ings iron must be used which has not
previously served the same purpose.
The spongy structure OF y casting is al.
50 caused by the moulding material.
When the oriices of a mould become
gradually filled with molten metal, the
escape OF gases depends on the physical
nature OF the moulding material. The
latter containing moisture and organic
Substances generates aqueous vapor
and other gases, which cause the lorna.
ion of surface cavities. These cavities
aye covered with a film of ox:dized
metal, while those produced by dis
solved gases have a bright metallic sur
lace.
The difficulties involved in the cast.
ing Of homogeneous ARTICLES are partly
overcome by the use of a suitable por-
Gus sand. Another class of cavities is
that called druse. The cavities of Il
druse are studded with iron crystals of
dendritic form. The formation of
these cavities is caused by abnor-
mai shrinkage during solidifi-
|%eation. Another phenomenon gener-
ally called sucking must be assigned to
the same cause; it is generally observed
on parts of castings where a large
1uantitY Of metal has been collected.
Il is therefore advisable in the manu-
%iacrure OF castings to give them an G quail
wall thickness, which has the advan-
tage that the tension is most equally
/ distributed throughout the mass. On
cooling of the liquid metal within the
mod, the particles which are in con-
III t with the mold are sooner solicited
than those more distant, and promote
a motion OF the liquid material from
places OF greatest to such OF less accu.
mutation, thus forming druses.