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Steel Making

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

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

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

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

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

Standard Analysis
The selection of a standard analysis by the manufacturer is t...

Correction For Cold-junction Errors
The voltage generated by a thermo-couple of an electric pyrom...

Quenching
It is considered good practice to quench alloy steels from th...

Properties Of Alloy Steels
The following table shows the percentages of carbon, manganes...

Carburizing Material
The simplest carburizing substance is charcoal. It is also th...

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

Carbon-steel Forgings
Low-stressed, carbon-steel forgings include such parts as car...

Effect Of Different Carburizing Material
[Illustrations: FIGS. 33 to 37.] Each of these different p...

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...

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

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

Brown Automatic Signaling Pyrometer
In large heat-treating plants it has been customary to mainta...

Leeds And Northrup Optical Pyrometer
The principles of this very popular method of measuring tempe...

Pickling The Forgings
The forgings were then pickled in a hot solution of either ni...



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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