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Steel Making

Preventing Carburizing By Copper-plating
Copper-plating has been found effective and must have a thick...

Protective Screens For Furnaces
Workmen needlessly exposed to the flames, heat and glare from...

Manganese
MANGANESE is a metal much like iron. Its chemical symbol is M...

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

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

The Penetration Of Carbon
Carburized mild steel is used to a great extent in the manufa...

Heat Treatment Of Steel
Heat treatment consists in heating and cooling metal at defin...

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

Heat Treatment Of Milling Cutters Drills Reamers Etc
THE FIRE.--Gas and electric furnaces designed for high heats ...

Pyrometers For Molten Metal
Pyrometers for molten metal are connected to portable thermoc...

Carburizing Low-carbon Sleeves
Low-carbon sleeves are carburized and pushed on malleable-ir...

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

Correction By Zero Adjustment
Many pyrometers are supplied with a zero adjuster, by means ...

Critical Points
One of the most important means of investigating the properti...

Plant For Forging Rifle Barrels
The forging of rifle barrels in large quantities and heat-tre...

Effects Of Proper Annealing
Proper annealing of low-carbon steels causes a complete solu...

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

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

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

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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