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Steel Making

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

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

Case-hardening Treatments For Various Steels
Plain water, salt water and linseed oil are the three most co...

Corrosion
This steel like any other steel when distorted by cold worki...

Flange Shields For Furnaces
Such portable flame shields as the one illustrated in Fig. 1...

Temperature Recording And Regulation
Each furnace is equipped with pyrometers, but the reading an...

Correction By Zero Adjustment
Many pyrometers are supplied with a zero adjuster, by means ...

Annealing Work
With the exception of several of the higher types of alloy s...

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

Hardening Operation
Hardening a gear is accomplished as follows: The gear is tak...

An Automatic Temperature Control Pyrometer
Automatic temperature control instruments are similar to the ...

High Speed Steel
For centuries the secret art of making tool steel was handed ...

Annealing Of High-speed Steel
For annealing high-speed steel, some makers recommend using g...

Classifications Of Steel
Among makers and sellers, carbon tool-steels are classed by g...

Phosphorus
Phosphorus is one of the impurities in steel, and it has been...

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

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

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

Uses Of The Various Tempers Of Carbon Tool Steel
DIE TEMPER.--No. 3: All kinds of dies for deep stamping, pres...

Annealing
ANNEALING can be done by heating to temperatures ranging from...



Steel Worked In Austenitic State






Category: THE FORGING OF STEEL

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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