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Manganese
MANGANESE is a metal much like iron. Its chemical symbol is M...

The Penetration Of Carbon
Carburized mild steel is used to a great extent in the manufa...

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

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

Non-shrinking Oil-hardening Steels
Certain steels have a very low rate of expansion and contract...

Restoring Overheated Steel
The effect of heat treatment on overheated steel is shown gra...

Heating
Although it is possible to work steels cold, to an extent de...

Short Method Of Treatment
In the new method, the packed pots are run into the case-har...

Effect Of Different Carburizing Material
[Illustrations: FIGS. 33 to 37.] Each of these different p...

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

Vanadium
Vanadium has a very marked effect upon alloy steels rich in c...

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

Brown Automatic Signaling Pyrometer
In large heat-treating plants it has been customary to mainta...

Oil-hardening Steel
Heat slowly and uniformly to 1,450 deg.F. and forge thorough...

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

The Effect Of Tempering On Water-quenched Gages
The following information has been supplied by Automatic and ...

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

Alloying Elements
Commercial steels of even the simplest types are therefore p...

Drop Forging Dies
The kind of steel used in the die of course influences the he...

Heating Of Manganese Steel
Another form of heat-treating furnace is that which is used ...



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.





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Previous: Heating



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