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Steel Making

Calibration Of Pyrometer With Common Salt
An easy and convenient method for standardization and one whi...

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

Temperature For Annealing
Theoretically, annealing should be accomplished at a tempera...

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

Vanadium
Vanadium has a very marked effect upon alloy steels rich in c...

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

Care In Annealing
Not only will benefits in machining be found by careful anne...

Gas Consumption For Carburizing
Although the advantages offered by the gas-fired furnace for ...

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

Nickel-chromium
A combination of the characteristics of nickel and the charac...

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

Pickling The Forgings
The forgings were then pickled in a hot solution of either ni...

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

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

Compensating Leads
By the use of compensating leads, formed of the same materia...

Pyrometers For Molten Metal
Pyrometers for molten metal are connected to portable thermoc...

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

Quality And Structure
The quality of high-speed steel is dependent to a very great ...

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

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



Annealing To Relieve Internal Stresses






Category: HARDENING CARBON STEEL FOR TOOLS

Work quenched from a high temperature and not afterward tempered
will, if complex in shape, contain many internal stresses which may
later cause it to break. They may be eased off by slight heating
without materially lessening the hardness of the piece. One way
to do this is to hold the piece over a fire and test it with a
moistened finger. Another way is to dip the piece in boiling water
after it has first been quenched in a cold bath. Such steps are
not necessary with articles which will afterward be tempered and
in which the strains are thus reduced.

In annealing steels the operation is similar to hardening, as far
as heating is concerned. The critical temperatures are the proper
ones for annealing as well as hardening. From this point on there
is a difference, for annealing consists in cooling as slowly as
possible. The slower the cooling the softer will be the steel.

Annealing may be done in the open air, in furnaces, in hot ashes
or lime, in powdered charcoal, in burnt bone, in charred leather
and in water. Open-air annealing will do as a crude measure in
cases where it is desired to take the internal stresses out of
a piece. Care must be taken in using this method that the piece
is not exposed to drafts or placed on some cold substance that
will chill it. Furnace annealing is much better and consists in
heating the piece in a furnace to the critical temperature and
then allowing the work and the furnace to cool together.

When lime or ashes are used as materials to keep air away from
the steel and retain the heat, they should be first heated to make
sure that they are dry. Powdered charcoal is used for high-grade
annealing, the piece being packed in this substance in an iron box
and both the work and the box raised to the critical temperature
and then allowed to cool slowly. Machinery steel may be annealed in
spent ground-bone that has been used in casehardening; but tool
steel must never be annealed in this way, as it will be injured
by the phosphorus contained in the bone. Charred leather is the
best annealing material for high-carbon steel, because it prevents
decarbonizing taking place.





Next: Double Annealing

Previous: Preventing Decarbonization Of Tool Steel



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