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

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

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

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

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

Pyrometers
Armor plate makers sometimes use the copper ball or Siemens' ...

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

Phosphorus
PHOSPHORUS is an element (symbol P) which enters the metal fr...

S A E Heat Treatments
The Society of Automotive Engineers have adopted certain heat...

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

Cutting-off Steel From Bar
To cut a piece from an annealed bar, cut off with a hack saw,...

Hardening Carbon Steel For Tools
For years the toolmaker had full sway in regard to make of st...

Carburizing Material
The simplest carburizing substance is charcoal. It is also th...

The Forging Of Steel
So much depends upon the forging of steel that this operation...

A Satisfactory Luting Mixture
A mixture of fireclay and sand will be found very satisfactor...

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

Brown Automatic Signaling Pyrometer
In large heat-treating plants it has been customary to mainta...

Composition And Properties Of Steel
It is a remarkable fact that one can look through a dozen tex...

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

Annealing Alloy Steel
The term alloy steel, from the steel maker's point of view, r...



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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