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Steel Making

Take Time For Hardening
Uneven heating and poor quenching has caused loss of many ve...

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

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

High-carbon Machinery Steel
The carbon content of this steel is above 30 points and is ha...

Machineability
Reheating for machine ability was done at 100 deg. less than ...

Placing Of Pyrometers
When installing a pyrometer, care should be taken that it re...

Gears
The material used for all gears on the Liberty engine was sel...

Rate Of Cooling
At the option of the manufacturer, the above treatment of gea...

Annealing Alloy Steel
The term alloy steel, from the steel maker's point of view, r...

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

The Packing Department
In Fig. 56 is shown the packing pots where the work is packe...

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

Heating Of Manganese Steel
Another form of heat-treating furnace is that which is used ...

For Milling Cutters And Formed Tools
FORGING.--Forge as before.--ANNEALING.--Place the steel in a ...

Oil-hardening Steel
Heat slowly and uniformly to 1,450 deg.F. and forge thorough...

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

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

Blending The Compound
Essentially, this consists of the sturdy, power-driven separa...

Hardening Operation
Hardening a gear is accomplished as follows: The gear is tak...

The Thermo-couple
With the application of the thermo-couple, the measurement of...



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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