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Steel Making

Detrimental Elements
Sulphur and phosphorus are two elements known to be detrimen...

Carbon In Tool Steel
Carbon tool steel, or tool steel as it is commonly called, us...

The crankshaft was the most highly stressed part of the entir...

Quenching The Work
In some operations case-hardened work is quenched from the bo...

Phosphorus is one of the impurities in steel, and it has been...

Correction For Cold-junction Errors
The voltage generated by a thermo-couple of an electric pyrom...

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

High-chromium Or Rust-proof Steel
High-chromium, or what is called stainless steel containing f...

Surface Carburizing
Carburizing, commonly called case-hardening, is the art of pr...

Furnace Data
In order to give definite information concerning furnaces, fu...

Quality And Structure
The quality of high-speed steel is dependent to a very great ...

The Theory Of Tempering
Steel that has been hardened is generally harder and more br...

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

Non-shrinking Oil-hardening Steels
Certain steels have a very low rate of expansion and contract...

Compensating Leads
By the use of compensating leads, formed of the same materia...

Hardness Testing
The word hardness is used to express various properties of me...

Process Of Carburizing
Carburizing imparts a shell of high-carbon content to a low-...

Annealing To Relieve Internal Stresses
Work quenched from a high temperature and not afterward tempe...

Knowing What Takes Place
How are we to know if we have given a piece of steel the ver...

Reheating for machine ability was done at 100 deg. less than ...

For Milling Cutters And Formed Tools


FORGING.--Forge as before.--ANNEALING.--Place the steel in a pipe,
box or muffle. Arrange the steel so as to allow at least 1 in.
of packing, consisting of dry powder ashes, powdered charcoal,
mica, etc., between the pieces and the walls of the box or pipe.
If using a pipe close the ends. Heat slowly and uniformly to a
cherry red, 1,375 to 1,450 deg.F. according to size. Hold the steel at
this temperature until the heat has thoroughly saturated through
the metal, then allow the muffle box and tools to cool very slowly
in a dying furnace or remove the muffle with its charge and bury
in hot ashes or lime. The slower the cooling the softer the steel.

The heating requires from 2 to 10 hr. depending upon the size of
the piece.

HARDENING AND TEMPERING.--It is preferable to use two furnaces
when hardening milling cutters and special shape tools. One furnace
should be maintained at a uniform temperature from 1,375 to 1,450 deg.F.
while the other should be maintained at about 2,250 deg.F. Keep the
tool to be hardened in the low temperature furnace until the tool
has attained the full heat of this furnace. A short time should be
allowed so as to be assured that the center of the tool is as hot
as the outside. Then quickly remove the tool from this preheating
furnace to the full heat furnace. Keep the tool in this furnace only
as long as is necessary for the tool to attain the full temperature
of this furnace. Then quickly remove and quench in oil or in a
dry air blast. Remove before the tool is entirely cold and draw
the temper in an oil bath by raising the temperature of the oil
to from 500 to 750 deg.F. and allow this tool to remain, at this
temperature, in the bath for at least 30 min., insuring uniformity
of temper; then cool in the bath, atmosphere or oil.

If higher drawing temperatures are desired than those possible
with oil, a salt bath can be used. A very excellent bath is made
by mixing two parts by weight of crude potassium nitrate and three
parts crude sodium nitrate. These will melt at about 450 deg.F. and
can be used up to 1,000 deg.F. Before heating the steel in the salt
bath, slowly preheat, preferably in oil. Reheating the hardened
high-speed steel to 1,000 deg.F. will materially increase the life
of lathe tools, but milling and form cutters, taps, dies, etc.,
should not be reheated higher than 500 to 650 deg.F., unless extreme
hardness is required, when 1,100 to 1,000 deg.F., will give the hardest

Next: Instructions For Working High-speed Steel

Previous: Lathe And Planer Tools

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