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

Calibration Of Pyrometer With Common Salt
An easy and convenient method for standardization and one whi...

Highly Stressed Parts
The highly stressed parts on the Liberty engine consisted of ...

Knowing What Takes Place
How are we to know if we have given a piece of steel the ver...

Forging High-speed Steel
Heat very slowly and carefully to from 1,800 to 2,000 deg.F....

Impact Tests
Impact tests are of considerable importance as an indication ...

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

Affinity Of Nickel Steel For Carbon
The carbon- and nickel-steel gears are carburized separately...

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

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

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

Chrome-nickel Steel
Forging heat of chrome-nickel steel depends very largely on ...

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

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

Placing The Thermo-couples
The following illustrations from the Taylor Instrument Compan...

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

Annealing To Relieve Internal Stresses
Work quenched from a high temperature and not afterward tempe...

Uses Of The Various Tempers Of Carbon Tool Steel
DIE TEMPER.--No. 3: All kinds of dies for deep stamping, pres...

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

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



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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