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Steel Making

The Forging Of Steel
So much depends upon the forging of steel that this operation...

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

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

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

Making Steel Balls
Steel balls are made from rods or coils according to size, st...

Blending The Compound
Essentially, this consists of the sturdy, power-driven separa...

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

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

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

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

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

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

ANNEALING can be done by heating to temperatures ranging from...

Steel For Chisels And Punches
The highest grades of carbon or tempering steels are to be re...

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

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

Molybdenum steels have been made commercially for twenty-five...

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

Correction By Zero Adjustment
Many pyrometers are supplied with a zero adjuster, by means ...

Annealing In Bone
Steel and cast iron may both be annealed in granulated bone. ...

Correction For Cold-junction Errors


The voltage generated by a thermo-couple of an electric pyrometer is
dependent on the difference in temperature between its hot junction,
inside the furnace, and the cold junction, or opposite end of the
thermo-couple to which the copper wires are connected. If the
temperature or this cold junction rises and falls, the indications
of the instrument will vary, although the hot junction in the furnace
may be at a constant temperature.

A cold-junction temperature of 75 deg.F., or 25 deg.C., is usually adopted
in commercial pyrometers, and the pointer on the pyrometer should
stand at this point on the scale when the hot junction is not heated.
If the cold-junction temperature rises about 75 deg.F., where base metal
thermo-couples are used, the pyrometer will read approximately 1 deg.
low for every 1 deg. rise in temperature above 75 deg.F. For example, if the
instrument is adjusted for a cold-junction temperature of 75 deg., and
the actual cold-junction temperature is 90 deg.F., the pyrometer will
read 15 deg. low. If, however, the cold-junction temperature falls below
75 deg.F., the pyrometer will read high instead of low, approximately
1 deg. for every 1 deg. drop in temperature below 75 deg.F.

With platinum thermo-couples, the error is approximately 1/2 deg. for
1 deg. change in temperature.

Next: Correction By Zero Adjustment

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

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