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Steel Making

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

Crankshaft
The crankshaft was the most highly stressed part of the entir...

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

Gas Consumption For Carburizing
Although the advantages offered by the gas-fired furnace for ...

The Penetration Of Carbon
Carburized mild steel is used to a great extent in the manufa...

Annealing Of Rifle Components At Springfield Armory
In general, all forgings of the components of the arms manufa...

Heat Treatment Of Axles
Parts of this general type should be heat-treated to show the...

Heating
Although it is possible to work steels cold, to an extent de...

Annealing Work
With the exception of several of the higher types of alloy s...

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

Application To The Automotive Industry
The information given on the various parts of the Liberty eng...

Molybdenum
Molybdenum steels have been made commercially for twenty-five...

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

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

Open Hearth Process
The open hearth furnace consists of a big brick room with a l...

Heat-treating Department
The heat-treating department occupies an L-shaped building. ...

Steel Can Be Worked Cold
As noted above, steel can be worked cold, as in the case of ...

Instructions For Working High-speed Steel
Owing to the wide variations in the composition of high-speed...

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

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



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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