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Steel Making

Separating The Work From The Compound
During the pulling of the heat, the pots are dumped upon a ca...

Manganese adds considerably to the tensile strength of steel,...

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

Introduction Of Carbon
The matter to which these notes are primarily directed is the...

Hardening High-speed Steel
In forging use coke for fuel in the forge. Heat steel slowly ...

Correction For Cold-junction Errors
The voltage generated by a thermo-couple of an electric pyrom...

It is considered good practice to quench alloy steels from th...

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

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

Martien was probably never a serious contender for the honor ...

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

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

Pickling The Forgings
The forgings were then pickled in a hot solution of either ni...

Temperatures To Use
As soon as the temperature of the steel reaches 100 deg.C. (...

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

The Electric Process
The fourth method of manufacturing steel is by the electric f...

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

Composition And Properties Of Steel
It is a remarkable fact that one can look through a dozen tex...

Robert Mushet
Robert (Forester) Mushet (1811-1891), born in the Forest of D...

Hardening High-speed Steels
We will now take up the matter of hardening high-speed steels...

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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