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Steel Making

Rate Of Cooling
At the option of the manufacturer, the above treatment of gea...

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

Preventing Carburizing By Copper-plating
Copper-plating has been found effective and must have a thick...

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

Affinity Of Nickel Steel For Carbon
The carbon- and nickel-steel gears are carburized separately...

Shrinking And Enlarging Work
Steel can be shrunk or enlarged by proper heating and cooling...

Lathe And Planer Tools
FORGING.--Gently warm the steel to remove any chill, is parti...

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

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

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

Carbon In Tool Steel
Carbon tool steel, or tool steel as it is commonly called, us...

Crankshaft
The crankshaft was the most highly stressed part of the entir...

Ebbw Vale And The Bessemer Process
After his British Association address in August 1856, Besseme...

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

Cyanide Bath For Tool Steels
All high-carbon tool steels are heated in a cyanide bath. Wi...

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

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

The Leeds And Northrup Potentiometer System
The potentiometer pyrometer system is both flexible and subst...

Vanadium
Vanadium has a very marked effect upon alloy steels rich in c...

Manganese
MANGANESE is a metal much like iron. Its chemical symbol is M...



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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