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Steel Making

A Chromium-cobalt Steel
The Latrobe Steel Company make a high-speed steel without tun...

Heavy Forging Practice
In heavy forging practice where the metal is being worked at...

Gears
The material used for all gears on the Liberty engine was sel...

Annealing In Bone
Steel and cast iron may both be annealed in granulated bone. ...

The Care Of Carburizing Compounds
Of all the opportunities for practicing economy in the heat-t...

Affinity Of Nickel Steel For Carbon
The carbon- and nickel-steel gears are carburized separately...

Alloying Elements
Commercial steels of even the simplest types are therefore p...

The Forging Of Steel
So much depends upon the forging of steel that this operation...

Tempering Colors On Carbon Steels
Opinions differ as to the temperature which is indicated by t...

Preventing Carburizing By Copper-plating
Copper-plating has been found effective and must have a thick...

Impact Tests
Impact tests are of considerable importance as an indication ...

Annealing Method
Forgings which are too hard to machine are put in pots with ...

Sulphur
SULPHUR is another element (symbol S) which is always found i...

Hardening High-speed Steels
We will now take up the matter of hardening high-speed steels...

Annealing Work
With the exception of several of the higher types of alloy s...

Care In Annealing
Not only will benefits in machining be found by careful anne...

Tungsten
Tungsten, as an alloy in steel, has been known and used for a...

Robert Mushet
Robert (Forester) Mushet (1811-1891), born in the Forest of D...

Effect Of A Small Amount Of Copper In Medium-carbon Steel
This shows the result of tests by C. R. Hayward and A. B. Joh...

Annealing
There is no mystery or secret about the proper annealing of d...



The Modern Hardening Room






Category: HARDENING CARBON STEEL FOR TOOLS

A hardening room of today means a very
different place from the dirty, dark smithshop in the corner with
the open coal forge. There, when we wanted to be somewhat particular,
we sometimes shoveled the coal cinders to one side and piled a great
pile of charcoal on the forge. We now have a complete equipment;
a gas- or oil-heating furnace, good running water, several sizes
of lead pots, and an oil tank large enough to hold a barrel of
oil. By running water, we mean a large tank with overflow pipes
giving a constant supply. The ordinary hardening room equipment
should consist of:

Gas or oil muffle furnace for hardening.
Gas or oil forge furnace.
A good size gas or oil furnace for annealing and case-hardening.
A gas or oil furnace to hold lead pots.
Oil tempering tank, gas- or oil-heated.
Pressure blower.
Large oil tank to hold at least a barrel of oil.
Big water tank with screen trays connected with large pipe from bottom
with overflow.
Straightening press.
The furnace should be connected with pyrometers and tempering tank with
a thermometer.

Beside all this you need a good man. It does not make much difference
how completely the hardening department is fitted up, if you expect
good work, a small percentage of loss and to be able to tackle anything
that comes along, you must have a good man, one who understands
the difference between low- and high-carbon steel, who knows when
particular care must be exercised on particular work. In other
words, a man who knows how his work should be done, and has the
intelligence to follow directions on treatments of steel on which
he has had no experience.

Jewelers' tools, especially for silversmith's work, probably have
to stand the greatest punishment of any all-steel tools and to
make a spoon die so hard that it will not sink under a blow from
an 1,800-lb. hammer with a 4-ft. drop, and still not crack, demands
careful treatment.

To harden such dies, first cover the impression on the die with
paste made from bone dust or lampblack and oil. Place face down
in an iron box partly filled with crushed charcoal, leaving back
of die uncovered so that the heat can be seen at all times. Heat
slowly in furnace to a good cherry red. The heat depends on the
quality and the analysis of steel and the recommended actions of
the steel maker should be carefully followed. When withdrawn from
the fire the die should be quenched as shown in Fig. 80 with the
face of die down and the back a short distance out of the water.
When the back is black, immerse all over.



If such a tank is not at hand, it would pay to rig one up at once,
although a barrel of brine may be used, or the back of the die
may be first immersed to a depth of about 1/2 in. When the piece
is immersed, hold die on an angle as in Fig. 81.



This is for the purpose of expelling all steam bubbles as they
form in contact with hot steel. We are aware of the fact that a
great many toolmakers in jewelry shops still cling to the overhead
bath, as in Fig. 82, but more broken pieces and more dies with
soft spots are due to this method than to all the others combined,
as the water strikes one spot in force, contracting the surface
so much faster than the rest of the die that the results are the
same as if an uneven heating had been given the steel.





Next: Take Time For Hardening

Previous: Hardening Carbon Steel For Tools



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