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

Hardening
The forgings can be hardened by cooling in still air or quen...

Heat Treatment Of Axles
Parts of this general type should be heat-treated to show the...

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

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

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

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

Properties Of Alloy Steels
The following table shows the percentages of carbon, manganes...

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

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

Take Time For Hardening
Uneven heating and poor quenching has caused loss of many ve...

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

Heat-treating Department
The heat-treating department occupies an L-shaped building. ...

Hints For Tool Steel Users
Do not hesitate to ask for information from the maker as to t...

Carbon-steel Forgings
Low-stressed, carbon-steel forgings include such parts as car...

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

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

Rate Of Absorption
According to Guillet, the absorption of carbon is favored by ...

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

Annealing
ANNEALING can be done by heating to temperatures ranging from...



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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