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

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

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

Vanadium
Vanadium has a very marked effect upon alloy steels rich in c...

Composition Of Transmission-gear Steel
If the nickel content of this steel is eliminated, and the pe...

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

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

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

Quenching
It is considered good practice to quench alloy steels from th...

Using Illuminating Gas
The choice of a carburizing furnace depends greatly on the fa...

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

Flange Shields For Furnaces
Such portable flame shields as the one illustrated in Fig. 1...

Cyanide Bath For Tool Steels
All high-carbon tool steels are heated in a cyanide bath. Wi...

Standard Analysis
The selection of a standard analysis by the manufacturer is t...

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

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

Separating The Work From The Compound
During the pulling of the heat, the pots are dumped upon a ca...

For Milling Cutters And Formed Tools
FORGING.--Forge as before.--ANNEALING.--Place the steel in a ...

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

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



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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