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High-carbon Machinery Steel
The carbon content of this steel is above 30 points and is ha...

Corrosion
This steel like any other steel when distorted by cold worki...

Carburizing Low-carbon Sleeves
Low-carbon sleeves are carburized and pushed on malleable-ir...

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

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

Standard Analysis
The selection of a standard analysis by the manufacturer is t...

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

Manganese
MANGANESE is a metal much like iron. Its chemical symbol is M...

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

The Pyrometer And Its Use
In the heat treatment of steel, it has become absolutely nece...

Refining The Grain
This is remedied by reheating the piece to a temperature slig...

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

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

Heat Treatment Of Lathe Planer And Similar Tools
FIRE.--For these tools a good fire is one made of hard foundr...

Separating The Work From The Compound
During the pulling of the heat, the pots are dumped upon a ca...

Composition Of Transmission-gear Steel
If the nickel content of this steel is eliminated, and the pe...

Steel Can Be Worked Cold
As noted above, steel can be worked cold, as in the case of ...

Correction By Zero Adjustment
Many pyrometers are supplied with a zero adjuster, by means ...

Shrinking And Enlarging Work
Steel can be shrunk or enlarged by proper heating and cooling...

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



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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