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

Refining The Grain
This is remedied by reheating the piece to a temperature slig...

Heat Treatment Of Gear Blanks
This section is based on a paper read before the American Gea...

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

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

Steel For Chisels And Punches
The highest grades of carbon or tempering steels are to be re...

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

Hardening Carbon Steel For Tools
For years the toolmaker had full sway in regard to make of st...

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

The Thermo-couple
With the application of the thermo-couple, the measurement of...

High-chromium Or Rust-proof Steel
High-chromium, or what is called stainless steel containing f...

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

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

Crankshaft
The crankshaft was the most highly stressed part of the entir...

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

Annealing
There is no mystery or secret about the proper annealing of d...

The Theory Of Tempering
Steel that has been hardened is generally harder and more br...

Making Steel Balls
Steel balls are made from rods or coils according to size, st...

Steel Before The 1850's
In spite of a rapid increase in the use of machines and the ...

The Electric Process
The fourth method of manufacturing steel is by the electric f...



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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