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

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

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

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

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

Hardening High-speed Steel
In forging use coke for fuel in the forge. Heat steel slowly ...

Heat Treatment Of Steel
Heat treatment consists in heating and cooling metal at defin...

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

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

Tempering Round Dies
A number of circular dies of carbon tool steel for use in too...

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

Effect Of A Small Amount Of Copper In Medium-carbon Steel
This shows the result of tests by C. R. Hayward and A. B. Joh...

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

The Care Of Carburizing Compounds
Of all the opportunities for practicing economy in the heat-t...

Properties Of Steel
Steels are known by certain tests. Early tests were more or l...

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

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

The Quenching Tank
The quenching tank is an important feature of apparatus in c...

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

Hardness Testing
The word hardness is used to express various properties of me...



Refining The Grain






Category: CASE-HARDENING OR SURFACE-CARBURIZING

This is remedied by reheating the piece to a temperature slightly
above the critical temperature of the case, this temperature
corresponding ordinarily to that of steel having a carbon content
of 85 points, When this is again quenched, the temperature, which
has not been high enough to disturb the refined core, will have
closed the grain of the case and toughened it. So, instead of but
one heat and one quenching for this class of work, we have three
of each, although it is quite possible and often profitable to
omit the quenching after carburizing and allow the piece or pieces
and the case-carburizing box to cool together, as in annealing.
Sometimes another heat treatment is added to the foregoing, for
the purpose of letting down the hardness of the case and giving
it additional toughness by heating to a temperature between 300 deg.
and 500 deg.. Usually this is done in an oil bath. After this the piece
is allowed to cool.

It is possible to harden the surface of tool steel extremely hard
and yet leave its inner core soft and tough for strength, by a
process similar to case-hardening and known as pack-hardening.
It consists in using tool steel of carbon contents ranging from
60 to 80 points, packing this in a box with charred leather mixed
with wood charcoal and heating at a low-red heat for 2 or 3 hr.,
thus raising the carbon content of the exterior of the piece. The
article when quenched in an oil bath will have an extremely hard
exterior and tough core. It is a good scheme for tools that must
be hard and yet strong enough to stand abuse. Raw bone is never
used as a packing for this class of work, as it makes the cutting
edges brittle.





Next: Case-hardening Treatments For Various Steels

Previous: The Quenching Tank



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