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Steel Making

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

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...

Heat Treatment Of Punches And Dies Shears Taps Etc
HEATING.--The degree to which tools of the above classes shou...

Placing The Thermo-couples
The following illustrations from the Taylor Instrument Compan...

Heat Treatment Of Axles
Parts of this general type should be heat-treated to show the...

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

Gas Consumption For Carburizing
Although the advantages offered by the gas-fired furnace for ...

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

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

Air-hardening Steels
These steels are recommended for boring, turning and planing...

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

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

MANGANESE is a metal much like iron. Its chemical symbol is M...

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

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

Restoring Overheated Steel
The effect of heat treatment on overheated steel is shown gra...

Quenching Tool Steel
To secure proper hardness, the cooling of quenching of steel ...

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

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

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

Complete Calibration Of Pyrometers


For the complete calibration
of a thermo-couple of unknown electromotive force, the new couple
may be checked against a standard instrument, placing the two bare
couples side by side in a suitable tube and taking frequent readings
over the range of temperatures desired.

If only one instrument, such as a millivoltmeter, is available,
and there is no standard couple at hand, the new couple may be
calibrated over a wide range of temperatures by the use of the following

Water, boiling point 212 deg.F.
Tin, under charcoal, freezing point 450 deg.F.
Lead, under charcoal, freezing point 621 deg.F.
Zinc, under charcoal, freezing point 786 deg.F.
Sulphur, boiling point 832 deg.F.
Aluminum, under charcoal, freezing point 1,216 deg.F.
Sodium chloride (salt), freezing point 1,474 deg.F.
Potassium sulphate, freezing point 1,958 deg.F.

A good practice is to make one pyrometer a standard; calibrate it
frequently by the melting-point-of-salt method, and each morning
check up every pyrometer in the works with the standard, making the
necessary corrections to be used for the day's work. By pursuing
this course systematically, the improved quality of the product
will much more than compensate for the extra work.

The purity of the substance affects its freezing or melting point.
The melting point of common salt is given in one widely used handbook
at 1,421 deg.F., although chemically pure sodium chloride melts at
1,474 deg.F. as shown above. A sufficient quantity for an extended
period should be secured. Test the melting point with a pyrometer
of known accuracy. Knowing this temperature it will be easy to
calibrate other pyrometers.

Next: Placing Of Pyrometers

Previous: Calibration Of Pyrometer With Common Salt

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