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Steel Making

Protectors For Thermo-couples
Thermo-couples must be protected from the danger of mechanica...

Take Time For Hardening
Uneven heating and poor quenching has caused loss of many ve...

Instructions For Working High-speed Steel
Owing to the wide variations in the composition of high-speed...

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

Carbon In Tool Steel
Carbon tool steel, or tool steel as it is commonly called, us...

Process Of Carburizing
Carburizing imparts a shell of high-carbon content to a low-...

SILICON is a very widespread element (symbol Si), being an es...

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

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

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

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

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

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

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

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

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

Detrimental Elements
Sulphur and phosphorus are two elements known to be detrimen...

Annealing Alloy Steel
The term alloy steel, from the steel maker's point of view, r...

Carbon Steels For Different Tools
All users of tool steels should carefully study the different...

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

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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