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Steel Making

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

Tempering Round Dies
A number of circular dies of carbon tool steel for use in too...

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

Annealing Method
Forgings which are too hard to machine are put in pots with ...

Testing And Inspection Of Heat Treatment
The hard parts of the gear must be so hard that a new mill f...

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

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

Connecting Rods
The material used for all connecting rods on the Liberty engi...

For Milling Cutters And Formed Tools
FORGING.--Forge as before.--ANNEALING.--Place the steel in a ...

Quenching The Work
In some operations case-hardened work is quenched from the bo...

Mushet And Bessemer
That Mushet was "used" by Ebbw Vale against Bessemer is, perh...

Heat-treating Department
The heat-treating department occupies an L-shaped building. ...

Preparing Parts For Local Case-hardening
At the works of the Dayton Engineering Laboratories Company, ...

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

Temperature For Annealing
Theoretically, annealing should be accomplished at a tempera...

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

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

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

Quality And Structure
The quality of high-speed steel is dependent to a very great ...

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

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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