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Lathe And Planer Tools
TO FORGE.--Gently warm the steel to remove any chill is parti...

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

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

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

Gears
The material used for all gears on the Liberty engine was sel...

Double Annealing
Water annealing consists in heating the piece, allowing it to...

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

The Modern Hardening Room
A hardening room of today means a very different place from ...

Tempering Colors On Carbon Steels
Opinions differ as to the temperature which is indicated by t...

Carburizing Low-carbon Sleeves
Low-carbon sleeves are carburized and pushed on malleable-ir...

Mushet And Bessemer
That Mushet was "used" by Ebbw Vale against Bessemer is, perh...

Heavy Forging Practice
In heavy forging practice where the metal is being worked at...

Classifications Of Steel
Among makers and sellers, carbon tool-steels are classed by g...

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

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

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

Hints For Tool Steel Users
Do not hesitate to ask for information from the maker as to t...

Blending The Compound
Essentially, this consists of the sturdy, power-driven separa...

Placing The Thermo-couples
The following illustrations from the Taylor Instrument Compan...

Quenching Tool Steel
To secure proper hardness, the cooling of quenching of steel ...



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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