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Steel Making

Testing And Inspection Of Heat Treatment
The hard parts of the gear must be so hard that a new mill f...

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

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

Effect Of A Small Amount Of Copper In Medium-carbon Steel
This shows the result of tests by C. R. Hayward and A. B. Joh...

Chromium when alloyed with steel, has the characteristic func...

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

PHOSPHORUS is an element (symbol P) which enters the metal fr...

Rate Of Cooling
At the option of the manufacturer, the above treatment of gea...

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

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

Heat-treating Equipment And Methods For Mass Production
The heat-treating department of the Brown-Lipe-Chapin Company...

Oil-hardening Steel
Heat slowly and uniformly to 1,450 deg.F. and forge thorough...

The Pyrometer And Its Use
In the heat treatment of steel, it has become absolutely nece...

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

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

Care In Annealing
Not only will benefits in machining be found by careful anne...

The Effect Of Tempering On Water-quenched Gages
The following information has been supplied by Automatic and ...

Cutting-off Steel From Bar
To cut a piece from an annealed bar, cut off with a hack saw,...

Air-hardening Steels
These steels are recommended for boring, turning and planing...

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

Annealing To Relieve Internal Stresses


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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