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Steel Making

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

Quenching Tool Steel
To secure proper hardness, the cooling of quenching of steel ...

Liberty Motor Connecting Rods
The requirements for materials for the Liberty motor connecti...

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

Nickel may be considered as the toughest among the non-rare a...

Pyrometers For Molten Metal
Pyrometers for molten metal are connected to portable thermoc...

Forging High-speed Steel
Heat very slowly and carefully to from 1,800 to 2,000 deg.F....

Gas Consumption For Carburizing
Although the advantages offered by the gas-fired furnace for ...

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

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

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

Making Steel Balls
Steel balls are made from rods or coils according to size, st...

Mushet And Bessemer
That Mushet was "used" by Ebbw Vale against Bessemer is, perh...

Quenching The Work
In some operations case-hardened work is quenched from the bo...

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

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

Tempering Colors On Carbon Steels
Opinions differ as to the temperature which is indicated by t...

Shrinking And Enlarging Work
Steel can be shrunk or enlarged by proper heating and cooling...

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

Hints For Tool Steel Users
Do not hesitate to ask for information from the maker as to t...

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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