The herald. (Big Stone City, Dak. [S.D.]) 1883-1890, 1889-03-01
TEMPERlNC STEEL.
How It Il Done And Theories Accounting
for the Process.

In the whole range of mechanical
arts, SAYS the Jewo'ry hatHeW, it would
be nearly impossible to 1ind another
process al once 50 simple and 50 COM
mon in principle and yet 50 litNe un-
derstood in theory, as the hardening
and tempcring of steel. II was proba-
bly this fact which some years ago he'd
the Institute Of Mechanical Engineers
Of England to place this subject among
those to be specially investigated hy
committee Of its own members, who
reported upon it in due time. Io
illustrate the facts that require selenti-
fic explanation. the process OF haden-
ing and tcmperin@ Il cold cElSel, which
is usually done at one operation, may
be briefly described.
After heating the point it is dipped
in cold water and thus the tool is
hardened After cooling the smith
lifts the steel from the water and
watches it closely, as the heat remain
ine in the body of the metal dtfuses
itself through the hardened portion.
As the heat spreads the color passes
from a white luster to pale yellow, -
straw color, to Il broWnish orange.
Then the point is dropped into the
water again, in the full confidence
that after cooling the temper will ~
that desired. If the smith delayed the
brown would become drappiea with
purple and would then pass success
lively into full purple, light blue, full
blue, dark blue, aud each color would
give its own temper upon cooling. aS
bright blue for swords and watch
springs, dark blue for SAWS, etc.
These are the well known facts, and
vet their ..hoW' and why" has always
been equally a mystery 10 the artist
and the scientist, although upon the
correct solution Of the problem de-
pends 50 important 4 matter as khoWl-
edup Of how best to reachthat llllcluus
compromise which should bend the
maximum of hardness and toH9hne>e
Now either can be procured at pleasure,
as the colder the bath the harder the
steel. and the slower (aS in oil the
tougher: but the extreme hardness is
produced at the strength OF tenaeItY,
and vice VERSA The committees eoA-
cllsion WAS suggested bv Edisoa,s eN-
perlments upon wire. which he made
bubble in 1919 These experiments
showed that lncandrseent pI.latinum
wire became covered with minute
assures, due to the expiration Of the
occluded gases under the action Of
heat and that when the wire WAS
cooled in 4 vacuum the assures closed
By il succession Of heatln@s and cool-
ings the gases We're entirely expelled
and the platinum became much harder
and densrr. As the committee SUE
rests il may be that the first and eN-
treme heat dries out the gases oeciadel
at ordinary temperature, thus pro-
ducing the denseness OF hard steel.
When the metal is slightly heated, AS
ia tempering. reabsorption begins. and
the characteristic colors are due 10 the
changes in tire surface, the gradual
opening Of minute assures, which are
produced by this rcabsorption.
In connection with this latest theory
NAV be mcntioncd one or two earlier
ones One is that when steel IS heated
the carbon becomes amorphous and
the steel i soft. while il cooled quickly
the carbon erNstailzes. taking tire
properties of diamond. and the steel
becomes. as it were. diamond Set ia
iron. This theory Of julien, = Is, per-
hapS. the most striking one. bui. whit,
accounting for hardness, il doc, lo'
explain tile temper Of steel, 10 say
nothing Of objections 10 tile postull.ce
llQuefactlon pI carbon.