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

Heat Treatment Of Punches And Dies Shears Taps Etc
HEATING.--The degree to which tools of the above classes shou...

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

Steel Before The 1850's
In spite of a rapid increase in the use of machines and the ...

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

Heating
Although it is possible to work steels cold, to an extent de...

Instructions For Working High-speed Steel
Owing to the wide variations in the composition of high-speed...

Carbon In Tool Steel
Carbon tool steel, or tool steel as it is commonly called, us...

Air-hardening Steels
These steels are recommended for boring, turning and planing...

Protective Screens For Furnaces
Workmen needlessly exposed to the flames, heat and glare from...

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

The Theory Of Tempering
Steel that has been hardened is generally harder and more br...

Case-hardening Treatments For Various Steels
Plain water, salt water and linseed oil are the three most co...

Forging High-speed Steel
Heat very slowly and carefully to from 1,800 to 2,000 deg.F....

The Penetration Of Carbon
Carburized mild steel is used to a great extent in the manufa...

Preparing Parts For Local Case-hardening
At the works of the Dayton Engineering Laboratories Company, ...

Blending The Compound
Essentially, this consists of the sturdy, power-driven separa...

Furnace Data
In order to give definite information concerning furnaces, fu...

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

Quenching The Work
In some operations case-hardened work is quenched from the bo...



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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