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

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

Silicon
Silicon prevents, to a large extent, defects such as gas bubb...

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

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

Effects Of Proper Annealing
Proper annealing of low-carbon steels causes a complete solu...

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

Annealing Of High-speed Steel
For annealing high-speed steel, some makers recommend using g...

The Thermo-couple
With the application of the thermo-couple, the measurement of...

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

Using Illuminating Gas
The choice of a carburizing furnace depends greatly on the fa...

Non-shrinking Oil-hardening Steels
Certain steels have a very low rate of expansion and contract...

Sulphur
Sulphur is another impurity and high sulphur is even a greate...

Mushet And Bessemer
That Mushet was "used" by Ebbw Vale against Bessemer is, perh...

Liberty Motor Connecting Rods
The requirements for materials for the Liberty motor connecti...

Fatigue Tests
It has been known for fifty years that a beam or rod would fa...

Optical System And Electrical Circuit Of The Leeds & Northrup Optical Pyrometer
For extremely high temperature, the optical pyrometer is lar...

Short Method Of Treatment
In the new method, the packed pots are run into the case-har...

Plant For Forging Rifle Barrels
The forging of rifle barrels in large quantities and heat-tre...

Annealing In Bone
Steel and cast iron may both be annealed in granulated bone. ...



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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