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Steel Making

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

Open Hearth Process
The open hearth furnace consists of a big brick room with a l...

Compensating Leads
By the use of compensating leads, formed of the same materia...

Judging The Heat Of Steel
While the use of a pyrometer is of course the only way to hav...

Tempering Round Dies
A number of circular dies of carbon tool steel for use in too...

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

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

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

Annealing In Bone
Steel and cast iron may both be annealed in granulated bone. ...

Hardening
The forgings can be hardened by cooling in still air or quen...

Lathe And Planer Tools
TO FORGE.--Gently warm the steel to remove any chill is parti...

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

Surface Carburizing
Carburizing, commonly called case-hardening, is the art of pr...

Bessemer Process
The bessemer process consists of charging molten pig iron int...

The Forging Of Steel
So much depends upon the forging of steel that this operation...

Alloying Elements
Commercial steels of even the simplest types are therefore p...

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

Application Of Liberty Engine Materials To The Automotive Industry
The success of the Liberty engine program was an engineer...

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

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



The Pyrometer And Its Use






Category: PYROMETRY AND PYROMETERS

In the heat treatment of steel, it has become absolutely necessary
that a measuring instrument be used which will give the operator an
exact reading of heat in furnace. There are a number of instruments
and devices manufactured for this purpose but any instrument that
will not give a direct reading without any guess work should have
no place in the heat-treating department.

A pyrometer installation is very simple and any of the leading
makers will furnish diagrams for the correct wiring and give detailed
information as to the proper care of, and how best to use their
particular instrument. There are certain general principles, however,
that must be observed by the operators and it cannot be too strongly
impressed upon them that the human factor involved is always the
deciding factor in the heat treatment of steel.

A pyrometer is merely an aid in the performance of doing good work,
and when carefully observed will help in giving a uniformity of
product and act as a check on careless operators. The operator
must bear in mind that although the reading on the pyrometer scale
gives a measure of the temperature where the junction of the two
metals is located, it will not give the temperature at the center
of work in the furnace, unless by previous tests, the heat for
penetrating a certain bulk of material has been decided on, and
the time necessary for such penetration is known.

Each analysis of plain carbon or alloy steel is a problem in itself.
Its critical temperatures will be located at slightly different
heats than for a steel which has a different proportion of alloying
elements. Furthermore, it takes time for metal to acquire the heat
of the furnace. Even the outer surface lags behind the temperature
of the furnace somewhat, and the center of the piece of steel lags
still further. It is apparent, therefore, that temperature, although
important, does not tell the whole story in heat treatment. Time
is also a factor.

Time at temperature is also of great importance because it takes
time, after the temperature has been reached, for the various internal
changes to take place. Hence the necessity for soaking, when
annealing or normalizing. Therefore, a clock is as necessary to
the proper pyrometer equipment as the pyrometer itself.

For the purpose of general work where a wide range of steels or
a variable treatment is called for, it becomes necessary to have
the pyrometer calibrated constantly, and when no master instrument
is kept for this purpose the following method can be used to give
the desired results:





Next: Calibration Of Pyrometer With Common Salt

Previous: The Thermo-couple



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