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

Effects Of Proper Annealing
Proper annealing of low-carbon steels causes a complete solu...

Case-hardening Treatments For Various Steels
Plain water, salt water and linseed oil are the three most co...

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

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

Carbon-steel Forgings
Low-stressed, carbon-steel forgings include such parts as car...

Carburizing By Gas
The process of carburizing by gas, briefly mentioned on page ...

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

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

The Influence Of Size
The size of the piece influences the physical properties obta...

Care In Annealing
Not only will benefits in machining be found by careful anne...

Gears
The material used for all gears on the Liberty engine was sel...

The Packing Department
In Fig. 56 is shown the packing pots where the work is packe...

Properties Of Alloy Steels
The following table shows the percentages of carbon, manganes...

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

Heat Treatment Of Punches And Dies Shears Taps Etc
HEATING.--The degree to which tools of the above classes shou...

Heat-treating Equipment And Methods For Mass Production
The heat-treating department of the Brown-Lipe-Chapin Company...

Heat Treatment Of Milling Cutters Drills Reamers Etc
THE FIRE.--Gas and electric furnaces designed for high heats ...

The Effect Of Tempering On Water-quenched Gages
The following information has been supplied by Automatic and ...

Carbon Tool Steel
Heat to a bright red, about 1,500 to 1,550 deg.F. Do not ham...



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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