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Steel Making

Hints For Tool Steel Users
Do not hesitate to ask for information from the maker as to t...

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

William Kelly's Air-boiling Process
An account of Bessemer's address to the British Association w...

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

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

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

The Effect
The heating at 1,600 deg.F. gives the first heat treatment w...

Tool Or Crucible Steel
Crucible steel can be annealed either in muffled furnace or b...

Properties Of Steel
Steels are known by certain tests. Early tests were more or l...

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

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

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

Placing The Thermo-couples
The following illustrations from the Taylor Instrument Compan...

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

Standard Analysis
The selection of a standard analysis by the manufacturer is t...

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

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

Forging High-speed Steel
Heat very slowly and carefully to from 1,800 to 2,000 deg.F....

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

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



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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