Los Angeles herald., 1908-06-07
CAST IRON Is MADE
MALLEABLE BY PROCESS
FURTHER PROGRESS is STILL
EXPECTED
Prominent Scotch Engineer Delivers
Address Explaining Efforts Which
Have Been Made in the
Past

The art of rendering iron castings
malleable, that is to say, capable sof
being bent without fracturing. is one
which has made remarkable progress
In the immediate past and in Whlcn
still further advance may be looked
for in the near future. 1t is section
of metallurgy which naturally requires
special study of detail for its full
understanding. but as with most sub
jecIs of a technical character, 1t is
readily susceptible of general compre-
hension by the lay mind which nor
nally takes an interest In these mat
ters.
Rarely has the history and funda-
mental principles of the subject been
more lucidly or briefly eXpounded than
in a paper recently read before the In
stitution of Engineers and Shipbuilders
in Scotland by w. H. Hatfield His
thesis first treats of the primitive ef-
forts at iron smelling practiced by the
early inhabitants of our own and other
countries; it then goes on to explain
the forced development of the art or
forging owing to the malleable nature
of the pure iron which was then the
sole product of those simple hearths;
and it thus leads up to the almost ac-
cidental production of cast iron as the
ultimate outcome of larger furnaces
and the increased temperature obtained
from the use of forced draught. Evil
dence of cast iron bein~ used in this
country dates back to the fourteenth
century.
Is Extremely Brittle
Cast iron, as everyone known, facili-
tates the construction of complicated
forms which would be difficult and eX-
pensive to forge, but it possesses the
drawback of being extremely brittle,
and therefore it's utility in the engineer
ing industry has strict limitations. 1t is
with the object of ductility of wrought
iron that the subsequent heat treatment
or annealing of the finished casting Is
attributable to the presence of COM
paratively large proportion of carbon
chemically combined with the iron, and
IL is the object of the subsequent treat
ment above mentioned to change this
state, thereby purifying the iron itself,
and thus rendering it's condition more
closely allied to that which 1t would
naturally assume in forged facsimile.
Referring to the typical structure or
cast iron, the author states that all the
carbon in the combined state, the car
bon of representation being present
as carbide, Fec, while the carbon OF
| 'saturation' is present as compound
roughly equivalent to Fe2,4C," the re-
suit of annealing is "a casting in which
| the carbideS are completely proken
down into pure carbon and iron."
Two methods of treatment are in
vogue, one, known as the Reaumur, dis
covered in 1922. having been generally
adopted throughout Europe, while the
! other. known as the "black heart" pro-
cess, is of later date, and has been
mainly developed in America. The NAL
Liability of castings treated by the
Reaumur process is due to the ABSORB
| tion of IL. carbon by red oxide or iron,
in which the casting is embedded prior
to it's heat treatment. In America, on
the other. hand, where the natural re-
sources produce comparatively pure
iron with very little sulphur, the black
heart, process of annealing has quite
different result, for instead of eliminatt-
ing the carbon from the casting 1t
merely precipitates it in patches. In
this condition it's presence is structur-
err,, anaIopous to that of the Stag in
voiyed with pure wrought iron, and, ac-
cording to Mr.. Hatfield, Is but little
more detrimental