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Suggestions For Handling High-speed Steels
The following suggestions for handling high-speed steels are ...

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

Temperature For Annealing
Theoretically, annealing should be accomplished at a tempera...

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

Care In Annealing
Not only will benefits in machining be found by careful anne...

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

Flange Shields For Furnaces
Such portable flame shields as the one illustrated in Fig. 1...

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

Effect Of A Small Amount Of Copper In Medium-carbon Steel
This shows the result of tests by C. R. Hayward and A. B. Joh...

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

Annealing Of High-speed Steel
For annealing high-speed steel, some makers recommend using g...

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

Introduction Of Carbon
The matter to which these notes are primarily directed is the...

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

Classifications Of Steel
Among makers and sellers, carbon tool-steels are classed by g...

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

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

Critical Points
One of the most important means of investigating the properti...

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

Surface Carburizing
Carburizing, commonly called case-hardening, is the art of pr...



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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