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Suggestions For Handling High-speed Steels
The following suggestions for handling high-speed steels are ...

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

Machineability
Reheating for machine ability was done at 100 deg. less than ...

Judging The Heat Of Steel
While the use of a pyrometer is of course the only way to hav...

Drop Forging Dies
The kind of steel used in the die of course influences the he...

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

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

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

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

Nickel
Nickel may be considered as the toughest among the non-rare a...

Composition And Properties Of Steel
It is a remarkable fact that one can look through a dozen tex...

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

Carbon Tool Steel
Heat to a bright red, about 1,500 to 1,550 deg.F. Do not ham...

Sulphur
SULPHUR is another element (symbol S) which is always found i...

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

Protectors For Thermo-couples
Thermo-couples must be protected from the danger of mechanica...

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

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

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

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



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.





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Previous: Preventing Decarbonization Of Tool Steel



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