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Steel Making

Temperature Recording And Regulation
Each furnace is equipped with pyrometers, but the reading an...

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

Rate Of Absorption
According to Guillet, the absorption of carbon is favored by ...

Liberty Motor Connecting Rods
The requirements for materials for the Liberty motor connecti...

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

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

Compensating Leads
By the use of compensating leads, formed of the same materia...

Gas Consumption For Carburizing
Although the advantages offered by the gas-fired furnace for ...

Phosphorus
Phosphorus is one of the impurities in steel, and it has been...

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

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

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

Typical Oil-fired Furnaces
Several types of standard oil-fired furnaces are shown herew...

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

Sulphur
Sulphur is another impurity and high sulphur is even a greate...

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

Annealing Of High-speed Steel
For annealing high-speed steel, some makers recommend using g...

Highly Stressed Parts
The highly stressed parts on the Liberty engine consisted of ...

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

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



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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