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Steel Making

Silicon
SILICON is a very widespread element (symbol Si), being an es...

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

Composition And Properties Of Steel
It is a remarkable fact that one can look through a dozen tex...

Quality And Structure
The quality of high-speed steel is dependent to a very great ...

Sulphur
Sulphur is another impurity and high sulphur is even a greate...

Protectors For Thermo-couples
Thermo-couples must be protected from the danger of mechanica...

William Kelly's Air-boiling Process
An account of Bessemer's address to the British Association w...

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

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

The Influence Of Size
The size of the piece influences the physical properties obta...

Chromium
Chromium when alloyed with steel, has the characteristic func...

Pyrometers For Molten Metal
Pyrometers for molten metal are connected to portable thermoc...

Annealing In Bone
Steel and cast iron may both be annealed in granulated bone. ...

Carbon-steel Forgings
Low-stressed, carbon-steel forgings include such parts as car...

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

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

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

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

Knowing What Takes Place
How are we to know if we have given a piece of steel the ver...

Piston Pin
The piston pin on an aviation engine must possess maximum res...



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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