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Steel Making

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

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

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

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

Although it is possible to work steels cold, to an extent de...

Annealing To Relieve Internal Stresses
Work quenched from a high temperature and not afterward tempe...

Steel Before The 1850's
In spite of a rapid increase in the use of machines and the ...

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

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

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

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

Composition Of Transmission-gear Steel
If the nickel content of this steel is eliminated, and the pe...

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

Crucible Steel
Crucible steel is still made by melting material in a clay or...

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

Pyrometers For Molten Metal
Pyrometers for molten metal are connected to portable thermoc...

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

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

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

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

Optical System And Electrical Circuit Of The Leeds & Northrup Optical Pyrometer


For extremely high temperature, the optical pyrometer is
largely used. This is a comparative method. By means of the rheostat
the current through the lamp is adjusted until the brightness of
the filament is just equal to the brightness of the image produced
by the lens L, Fig. 123, whereupon the filament blends with or
becomes indistinguishable in the background formed by the image
of the hot object. This adjustment can be made with great accuracy
and certainty, as the effect of radiation upon the eye varies some
twenty times faster than does the temperature at 1,600 deg.F., and some
fourteen times faster at 3,400 deg.F. When a balance has been obtained,
the observer notes the reading of the milliammeter. The temperature
corresponding to the current is then read from a calibration curve
supplied with the instrument.

As the intensity of the light emitted at the higher temperatures
becomes dazzling, it is found desirable to introduce a piece of red
glass in the eye piece at R. This also eliminates any question
of matching colors, or of the observer's ability to distinguish
colors. It is further of value in dealing with bodies which do
not radiate light of the same composition as that emitted by a
black body, since nevertheless the intensity of radiation of any
one color from such bodies increases progressively in a definite
manner as the temperature rises. The intensity of this one color
can therefore be used as a measure of temperature for the body
in question. Figures 124 to 126 show the way it is read.

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