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Steel Making

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

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

Tensile Properties
Strength of a metal is usually expressed in the number of pou...

Annealing Alloy Steel
The term alloy steel, from the steel maker's point of view, r...

Heat-treating Department
The heat-treating department occupies an L-shaped building. ...

Temperatures To Use
As soon as the temperature of the steel reaches 100 deg.C. (...

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

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

Steel Can Be Worked Cold
As noted above, steel can be worked cold, as in the case of ...

Rate Of Cooling
At the option of the manufacturer, the above treatment of gea...

Pyrometers
Armor plate makers sometimes use the copper ball or Siemens' ...

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

Placing Of Pyrometers
When installing a pyrometer, care should be taken that it re...

Composition Of Transmission-gear Steel
If the nickel content of this steel is eliminated, and the pe...

The Forging Of Steel
So much depends upon the forging of steel that this operation...

The Modern Hardening Room
A hardening room of today means a very different place from ...

Crankshaft
The crankshaft was the most highly stressed part of the entir...

Tool Or Crucible Steel
Crucible steel can be annealed either in muffled furnace or b...

Calibration Of Pyrometer With Common Salt
An easy and convenient method for standardization and one whi...

Heat Treatment Of Milling Cutters Drills Reamers Etc
THE FIRE.--Gas and electric furnaces designed for high heats ...



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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