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   Home - Steel Making - Categories - Manufacturing and the Economy of Machinery

Steel Making

Liberty Motor Connecting Rods
The requirements for materials for the Liberty motor connecti...

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

Tungsten
Tungsten, as an alloy in steel, has been known and used for a...

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

Properties Of Steel
Steels are known by certain tests. Early tests were more or l...

Mushet And Bessemer
That Mushet was "used" by Ebbw Vale against Bessemer is, perh...

Carbon In Tool Steel
Carbon tool steel, or tool steel as it is commonly called, us...

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

Fatigue Tests
It has been known for fifty years that a beam or rod would fa...

Complete Calibration Of Pyrometers
For the complete calibration of a thermo-couple of unknown e...

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

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

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

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

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

Placing Of Pyrometers
When installing a pyrometer, care should be taken that it re...

Take Time For Hardening
Uneven heating and poor quenching has caused loss of many ve...

Tempering Colors On Carbon Steels
Opinions differ as to the temperature which is indicated by t...

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

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



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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