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Steel Making

Detrimental Elements
Sulphur and phosphorus are two elements known to be detrimen...

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

Annealing Of Rifle Components At Springfield Armory
In general, all forgings of the components of the arms manufa...

Impact Tests
Impact tests are of considerable importance as an indication ...

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

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

Steel Worked In Austenitic State
As a general rule steel should be worked when it is in the a...

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

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

Double Annealing
Water annealing consists in heating the piece, allowing it to...

Chromium when alloyed with steel, has the characteristic func...

S A E Heat Treatments
The Society of Automotive Engineers have adopted certain heat...

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

Hardness Testing
The word hardness is used to express various properties of me...

Crucible Steel
Crucible steel is still made by melting material in a clay or...

Armor plate makers sometimes use the copper ball or Siemens' ...

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

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

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

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

Steel Worked In Austenitic State


As a general rule steel should
be worked when it is in the austenitic state. (See page 108.) It
is then soft and ductile.

As the steel is heated above the critical temperature the size of
the austenite crystals tends to grow rapidly. When forging starts,
however, these grains are broken up. The growth is continually
destroyed by the hammering, which should consequently be continued
down to the upper critical temperature when the austenite crystals
break up into ferrite and cementite. The size of the final grains
will be much smaller and hence a more uniform structure will result
if the mother austenite was also fine grained. A final steel
will be composed of pearlite; ferrite and pearlite; or cementite
and pearlite, according to the carbon content.

The ultimate object is to secure a fine, uniform grain throughout
the piece and this can be secured by uniform heating and by thoroughly
rolling it or working it at a temperature just down to its critical
point. If this is correctly done the fracture will be fine and
silky. Steel which has been overheated slightly and the forging
stopped at too high a temperature will show a granular fracture.
A badly overheated or burned steel will have iridescent colors
on a fresh fracture, it will be brittle both hot and cold, and
absolutely ruined.

Next: Steel Can Be Worked Cold

Previous: Heating

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