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Steel Making

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

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

Refining The Grain
This is remedied by reheating the piece to a temperature slig...

Reheating for machine ability was done at 100 deg. less than ...

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

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

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

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

Affinity Of Nickel Steel For Carbon
The carbon- and nickel-steel gears are carburized separately...

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

The Pyrometer And Its Use
In the heat treatment of steel, it has become absolutely nece...

The Theory Of Tempering
Steel that has been hardened is generally harder and more br...

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

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

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

Sulphur is another impurity and high sulphur is even a greate...

The Care Of Carburizing Compounds
Of all the opportunities for practicing economy in the heat-t...

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...

High-carbon Machinery Steel
The carbon content of this steel is above 30 points and is ha...

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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