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Application To The Automotive Industry
The information given on the various parts of the Liberty eng...

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

Optical System And Electrical Circuit Of The Leeds & Northrup Optical Pyrometer
For extremely high temperature, the optical pyrometer is lar...

Protectors For Thermo-couples
Thermo-couples must be protected from the danger of mechanica...

Furnace Data
In order to give definite information concerning furnaces, fu...

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

Lathe And Planer Tools
FORGING.--Gently warm the steel to remove any chill, is parti...

Non-shrinking Oil-hardening Steels
Certain steels have a very low rate of expansion and contract...

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

Pyrometers
Armor plate makers sometimes use the copper ball or Siemens' ...

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

Calibration Of Pyrometer With Common Salt
An easy and convenient method for standardization and one whi...

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

Tensile Properties
Strength of a metal is usually expressed in the number of pou...

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

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

Sulphur
Sulphur is another impurity and high sulphur is even a greate...

The Penetration Of Carbon
Carburized mild steel is used to a great extent in the manufa...

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

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



Pyrometry And Pyrometers






Category: PYROMETRY AND PYROMETERS

A knowledge of the fundamental principles of pyrometry, or the
measurement of temperatures, is quite necessary for one engaged
in the heat treatment of steel. It is only by careful measurement
and control of the heating of steel that the full benefit of a
heat-treating operation is secured.

Before the advent of the thermo-couple, methods of temperature
measurement were very crude. The blacksmith depended on his eyes
to tell him when the proper temperature was reached, and of course
the color appeared different on light or dark days. Cherry
to one man was orange to another, and it was therefore almost
impossible to formulate any treatment which could be applied by
several men to secure the same results.

One of the early methods of measuring temperatures was the iron
ball method. In this method, an iron ball, to which a wire was
attached, was placed in the furnace and when it had reached the
temperature of the furnace, it was quickly removed by means of
the wire, and suspended in a can containing a known quantity of
water; the volume of water being such that the heat would not cause
it to boil. The rise in temperature of the water was measured by a
thermometer, and, knowing the heat capacity of the iron ball and
that of the water, the temperature of the ball, and therefore the
furnace, could be calculated. Usually a set of tables was prepared
to simplify the calculations. The iron ball, however, scaled, and
changed in weight with repeated use, making the determinations
less and less accurate. A copper ball was often used to decrease
this change, but even that was subject to error. This method is
still sometimes used, but for uniform results, a platinum ball,
which will not scale or change in weight, is necessary, and the
cost of this ball, together with the slowness of the method, have
rendered the practice obsolete, especially in view of modern
developments in accurate pyrometry.





Next: Pyrometers

Previous: Furnace Data



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