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

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

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

Connecting Rods
The material used for all connecting rods on the Liberty engi...

Annealing
ANNEALING can be done by heating to temperatures ranging from...

Leeds And Northrup Optical Pyrometer
The principles of this very popular method of measuring tempe...

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

Bessemer Process
The bessemer process consists of charging molten pig iron int...

A Chromium-cobalt Steel
The Latrobe Steel Company make a high-speed steel without tun...

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

The Leeds And Northrup Potentiometer System
The potentiometer pyrometer system is both flexible and subst...

Crucible Steel
Crucible steel is still made by melting material in a clay or...

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

Testing And Inspection Of Heat Treatment
The hard parts of the gear must be so hard that a new mill f...

Ebbw Vale And The Bessemer Process
After his British Association address in August 1856, Besseme...

Annealing Method
Forgings which are too hard to machine are put in pots with ...

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

Heat Treatment Of Axles
Parts of this general type should be heat-treated to show the...

Manganese
MANGANESE is a metal much like iron. Its chemical symbol is M...

Correction By Zero Adjustment
Many pyrometers are supplied with a zero adjuster, by means ...



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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