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   Home - Steel Making - Categories - Manufacturing and the Economy of Machinery

Steel Making

Forging High-speed Steel
Heat very slowly and carefully to from 1,800 to 2,000 deg.F....

Heat-treating Equipment And Methods For Mass Production
The heat-treating department of the Brown-Lipe-Chapin Company...

For Milling Cutters And Formed Tools
FORGING.--Forge as before.--ANNEALING.--Place the steel in a ...

Flange Shields For Furnaces
Such portable flame shields as the one illustrated in Fig. 1...

Quenching
It is considered good practice to quench alloy steels from th...

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

Temperatures To Use
As soon as the temperature of the steel reaches 100 deg.C. (...

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

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

Tensile Properties
Strength of a metal is usually expressed in the number of pou...

An Automatic Temperature Control Pyrometer
Automatic temperature control instruments are similar to the ...

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

Rate Of Cooling
At the option of the manufacturer, the above treatment of gea...

Heat Treatment Of Milling Cutters Drills Reamers Etc
THE FIRE.--Gas and electric furnaces designed for high heats ...

Introduction Of Carbon
The matter to which these notes are primarily directed is the...

The Effect Of Tempering On Water-quenched Gages
The following information has been supplied by Automatic and ...

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

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

Judging The Heat Of Steel
While the use of a pyrometer is of course the only way to hav...

Ebbw Vale And The Bessemer Process
After his British Association address in August 1856, Besseme...



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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