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Temperature Recording And Regulation
Each furnace is equipped with pyrometers, but the reading an...

Annealing To Relieve Internal Stresses
Work quenched from a high temperature and not afterward tempe...

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

Uses Of The Various Tempers Of Carbon Tool Steel
DIE TEMPER.--No. 3: All kinds of dies for deep stamping, pres...

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

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

Application Of Liberty Engine Materials To The Automotive Industry
The success of the Liberty engine program was an engineer...

Application To The Automotive Industry
The information given on the various parts of the Liberty eng...

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

The Effect
The heating at 1,600 deg.F. gives the first heat treatment w...

Impact Tests
Impact tests are of considerable importance as an indication ...

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

Composition Of Transmission-gear Steel
If the nickel content of this steel is eliminated, and the pe...

Oil-hardening Steel
Heat slowly and uniformly to 1,450 deg.F. and forge thorough...

Annealing Work
With the exception of several of the higher types of alloy s...

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

Alloying Elements
Commercial steels of even the simplest types are therefore p...

Chromium
Chromium when alloyed with steel, has the characteristic func...

Silicon
SILICON is a very widespread element (symbol Si), being an es...

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



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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