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Steel Making

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

Judging The Heat Of Steel
While the use of a pyrometer is of course the only way to hav...

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

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

The Pyrometer And Its Use
In the heat treatment of steel, it has become absolutely nece...

Using Illuminating Gas
The choice of a carburizing furnace depends greatly on the fa...

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

An Automatic Temperature Control Pyrometer
Automatic temperature control instruments are similar to the ...

Uses Of The Various Tempers Of Carbon Tool Steel
DIE TEMPER.--No. 3: All kinds of dies for deep stamping, pres...

The Leeds And Northrup Potentiometer System
The potentiometer pyrometer system is both flexible and subst...

Quenching
It is considered good practice to quench alloy steels from th...

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

Ebbw Vale And The Bessemer Process
After his British Association address in August 1856, Besseme...

Refining The Grain
This is remedied by reheating the piece to a temperature slig...

Annealing Method
Forgings which are too hard to machine are put in pots with ...

A Satisfactory Luting Mixture
A mixture of fireclay and sand will be found very satisfactor...

Tool Or Crucible Steel
Crucible steel can be annealed either in muffled furnace or b...

Pickling The Forgings
The forgings were then pickled in a hot solution of either ni...

Forging High-speed Steel
Heat very slowly and carefully to from 1,800 to 2,000 deg.F....

The Care Of Carburizing Compounds
Of all the opportunities for practicing economy in the heat-t...



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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