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Placing Of Pyrometers
When installing a pyrometer, care should be taken that it re...

Instructions For Working High-speed Steel
Owing to the wide variations in the composition of high-speed...

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

Application Of Liberty Engine Materials To The Automotive Industry
The success of the Liberty engine program was an engineer...

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

Steel For Chisels And Punches
The highest grades of carbon or tempering steels are to be re...

Preventing Decarbonization Of Tool Steel
It is especially important to prevent decarbonization in such...

Annealing Of Rifle Components At Springfield Armory
In general, all forgings of the components of the arms manufa...

Cyanide Bath For Tool Steels
All high-carbon tool steels are heated in a cyanide bath. Wi...

High Speed Steel
For centuries the secret art of making tool steel was handed ...

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

Placing The Thermo-couples
The following illustrations from the Taylor Instrument Compan...

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

Conclusions
Martien was probably never a serious contender for the honor ...

Temperature For Annealing
Theoretically, annealing should be accomplished at a tempera...

Open Hearth Process
The open hearth furnace consists of a big brick room with a l...

Application To The Automotive Industry
The information given on the various parts of the Liberty eng...

Protective Screens For Furnaces
Workmen needlessly exposed to the flames, heat and glare from...

Leeds And Northrup Optical Pyrometer
The principles of this very popular method of measuring tempe...

Highly Stressed Parts
The highly stressed parts on the Liberty engine consisted of ...



Quenching Tool Steel






Category: HARDENING CARBON STEEL FOR TOOLS

To secure proper hardness, the cooling of quenching of steel is
as important as its heating. Quenching baths vary in nature, there
being a large number of ways to cool a piece of steel in contrast
to the comparatively few ways of heating it.

Plain water, brine and oil are the three most common quenching
materials. Of these three the brine will give the most hardness,
and plain water and oil come next. The colder that any of these
baths is when the piece is put into it the harder will be the steel;
but this does not mean that it is a good plan to dip the heated
steel into a tank of ice water, for the shock would be so great
that the bar would probably fly to pieces. In fact, the quenching
bath must be sometimes heated a bit to take off the edge of the
shock.

Brine solutions will work uniformly, or give the same degree of
hardness, until they reach a temperature of 150 deg.F. above which
their grip relaxes and the metals quenched in them become softer.
Plain water holds its grip up to a temperature of approximately
100 deg.F.; but oil baths, which are used to secure a slower rate of
cooling, may be used up to 500 deg. or more. A compromise is sometimes
effected by using a bath consisting of an inch or two of oil floating
on the surface of water. As the hot steel passes through the oil,
the shock is not as severe as if it were to be thrust directly
into the water; and in addition, oil adheres to the tool and keeps
the water from direct contact with the metal.

The old idea that mercury will harden steel more than any other
quenching material has been exploded. A bath consisting of melted
cyanide of potassium is useful for heating fine engraved dies and
other articles that are required to come out free from scale. One
must always be careful to provide a hood or exhaust system to get
rid of the deadly fumes coming from the cyanide pot.

The one main thing to remember in hardening tool steel is to quench
on a rising heat. This does not mean a rapid heating as a slow
increase in temperature is much better in every way.





Next: The Theory Of Tempering

Previous: Double Annealing



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