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

Chrome-nickel Steel
Forging heat of chrome-nickel steel depends very largely on ...

Bessemer Process
The bessemer process consists of charging molten pig iron int...

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

Instructions For Working High-speed Steel
Owing to the wide variations in the composition of high-speed...

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

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

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

Flange Shields For Furnaces
Such portable flame shields as the one illustrated in Fig. 1...

Effect Of Different Carburizing Material
[Illustrations: FIGS. 33 to 37.] Each of these different p...

Heavy Forging Practice
In heavy forging practice where the metal is being worked at...

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

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

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

Nickel
Nickel may be considered as the toughest among the non-rare a...

Brown Automatic Signaling Pyrometer
In large heat-treating plants it has been customary to mainta...

Compensating Leads
By the use of compensating leads, formed of the same materia...

Protective Screens For Furnaces
Workmen needlessly exposed to the flames, heat and glare from...

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

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



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.





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Previous: Furnace Data



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