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Steel Making

A Satisfactory Luting Mixture
A mixture of fireclay and sand will be found very satisfactor...

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

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

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

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

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

Pickling The Forgings
The forgings were then pickled in a hot solution of either ni...

Cutting-off Steel From Bar
To cut a piece from an annealed bar, cut off with a hack saw,...

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

Composition And Properties Of Steel
It is a remarkable fact that one can look through a dozen tex...

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

Hardening Carbon Steel For Tools
For years the toolmaker had full sway in regard to make of st...

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

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

Manganese adds considerably to the tensile strength of steel,...

This steel like any other steel when distorted by cold worki...

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

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

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

Heat Treatment Of Gear Blanks
This section is based on a paper read before the American Gea...

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.

Next: Correction For Cold-junction Errors

Previous: Leeds And Northrup Optical Pyrometer

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