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Steel Making

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

Hardening Operation
Hardening a gear is accomplished as follows: The gear is tak...

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

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

Fatigue Tests
It has been known for fifty years that a beam or rod would fa...

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

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

The Influence Of Size
The size of the piece influences the physical properties obta...

Preventing Carburizing By Copper-plating
Copper-plating has been found effective and must have a thick...

High Speed Steel
For centuries the secret art of making tool steel was handed ...

Chrome-nickel Steel
Forging heat of chrome-nickel steel depends very largely on ...

Crankshaft
The crankshaft was the most highly stressed part of the entir...

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

Carburizing By Gas
The process of carburizing by gas, briefly mentioned on page ...

Silicon
Silicon prevents, to a large extent, defects such as gas bubb...

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

Flange Shields For Furnaces
Such portable flame shields as the one illustrated in Fig. 1...

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

Hardening
The forgings can be hardened by cooling in still air or quen...

Separating The Work From The Compound
During the pulling of the heat, the pots are dumped upon a ca...



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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