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Steel Making

Heating Of Manganese Steel
Another form of heat-treating furnace is that which is used ...

Correction For Cold-junction Errors
The voltage generated by a thermo-couple of an electric pyrom...

Carburizing By Gas
The process of carburizing by gas, briefly mentioned on page ...

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

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

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

Nickel may be considered as the toughest among the non-rare a...

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

The Effect
The heating at 1,600 deg.F. gives the first heat treatment w...

Pyrometry And Pyrometers
A knowledge of the fundamental principles of pyrometry, or th...

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

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

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

PHOSPHORUS is an element (symbol P) which enters the metal fr...

Effect Of Different Carburizing Material
[Illustrations: FIGS. 33 to 37.] Each of these different p...

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

Preparing Parts For Local Case-hardening
At the works of the Dayton Engineering Laboratories Company, ...

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

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

Rate Of Absorption
According to Guillet, the absorption of carbon is favored by ...

The Pyrometer And Its Use


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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