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

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

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

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

Heavy Forging Practice
In heavy forging practice where the metal is being worked at...

S A E Heat Treatments
The Society of Automotive Engineers have adopted certain heat...

Short Method Of Treatment
In the new method, the packed pots are run into the case-har...

Hardening High-speed Steels
We will now take up the matter of hardening high-speed steels...

Detrimental Elements
Sulphur and phosphorus are two elements known to be detrimen...

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

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

Corrosion
This steel like any other steel when distorted by cold worki...

Cyanide Bath For Tool Steels
All high-carbon tool steels are heated in a cyanide bath. Wi...

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

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

Fatigue Tests
It has been known for fifty years that a beam or rod would fa...

Temperature Recording And Regulation
Each furnace is equipped with pyrometers, but the reading an...

Impact Tests
Impact tests are of considerable importance as an indication ...

Quenching The Work
In some operations case-hardened work is quenched from the bo...

Annealing
ANNEALING can be done by heating to temperatures ranging from...



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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