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Steel Making

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

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

Sulphur
SULPHUR is another element (symbol S) which is always found i...

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

The Pyrometer And Its Use
In the heat treatment of steel, it has become absolutely nece...

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...

Carbon Steels For Different Tools
All users of tool steels should carefully study the different...

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

Oil-hardening Steel
Heat slowly and uniformly to 1,450 deg.F. and forge thorough...

Refining The Grain
This is remedied by reheating the piece to a temperature slig...

Tempering Colors On Carbon Steels
Opinions differ as to the temperature which is indicated by t...

Steel Worked In Austenitic State
As a general rule steel should be worked when it is in the a...

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

Heat Treatment Of Lathe Planer And Similar Tools
FIRE.--For these tools a good fire is one made of hard foundr...

Liberty Motor Connecting Rods
The requirements for materials for the Liberty motor connecti...

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

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

Fatigue Tests
It has been known for fifty years that a beam or rod would fa...

Temperature Recording And Regulation
Each furnace is equipped with pyrometers, but the reading an...

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



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.





Next: Pyrometers

Previous: Furnace Data



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