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

Steel Making

The Quenching Tank
The quenching tank is an important feature of apparatus in c...

Preventing Decarbonization Of Tool Steel
It is especially important to prevent decarbonization in such...

Non-shrinking Oil-hardening Steels
Certain steels have a very low rate of expansion and contract...

Typical Oil-fired Furnaces
Several types of standard oil-fired furnaces are shown herew...

Correction By Zero Adjustment
Many pyrometers are supplied with a zero adjuster, by means ...

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

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

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

Air-hardening Steels
These steels are recommended for boring, turning and planing...

Protective Screens For Furnaces
Workmen needlessly exposed to the flames, heat and glare from...

Drop Forging Dies
The kind of steel used in the die of course influences the he...

The Electric Process
The fourth method of manufacturing steel is by the electric f...

The Effect Of Tempering On Water-quenched Gages
The following information has been supplied by Automatic and ...

Hardening High-speed Steel
In forging use coke for fuel in the forge. Heat steel slowly ...

Testing And Inspection Of Heat Treatment
The hard parts of the gear must be so hard that a new mill f...

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

Carbon Steels For Different Tools
All users of tool steels should carefully study the different...

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

Steel Worked In Austenitic State
As a general rule steel should be worked when it is in the a...

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



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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