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It is considered good practice to quench alloy steels from th...

Tungsten, as an alloy in steel, has been known and used for a...

Temperature For Annealing
Theoretically, annealing should be accomplished at a tempera...

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

Annealing Of Rifle Components At Springfield Armory
In general, all forgings of the components of the arms manufa...

Using Illuminating Gas
The choice of a carburizing furnace depends greatly on the fa...

Surface Carburizing
Carburizing, commonly called case-hardening, is the art of pr...

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

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

Knowing What Takes Place
How are we to know if we have given a piece of steel the ver...

Carburizing Low-carbon Sleeves
Low-carbon sleeves are carburized and pushed on malleable-ir...

There is no mystery or secret about the proper annealing of d...

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

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

Typical Oil-fired Furnaces
Several types of standard oil-fired furnaces are shown herew...

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

Testing And Inspection Of Heat Treatment
The hard parts of the gear must be so hard that a new mill f...

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

Rate Of Absorption
According to Guillet, the absorption of carbon is favored by ...

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...

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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