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

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...

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

Hardening
Steel is hardened by quenching from above the upper critical....

Heat-treating Department
The heat-treating department occupies an L-shaped building. ...

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

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

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

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

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

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

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

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

Case-hardening Treatments For Various Steels
Plain water, salt water and linseed oil are the three most co...

Hardness Testing
The word hardness is used to express various properties of me...

Temperatures To Use
As soon as the temperature of the steel reaches 100 deg.C. (...

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

Introduction Of Carbon
The matter to which these notes are primarily directed is the...

Steel Can Be Worked Cold
As noted above, steel can be worked cold, as in the case of ...



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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