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Steel Making

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

Carburizing Low-carbon Sleeves
Low-carbon sleeves are carburized and pushed on malleable-ir...

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

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

Quality And Structure
The quality of high-speed steel is dependent to a very great ...

Critical Points
One of the most important means of investigating the properti...

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

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

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

Carbon Tool Steel
Heat to a bright red, about 1,500 to 1,550 deg.F. Do not ham...

Manganese
Manganese adds considerably to the tensile strength of steel,...

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

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

Fatigue Tests
It has been known for fifty years that a beam or rod would fa...

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

Heat-treating Equipment And Methods For Mass Production
The heat-treating department of the Brown-Lipe-Chapin Company...

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

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

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

Protective Screens For Furnaces
Workmen needlessly exposed to the flames, heat and glare 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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