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Steel Making

Preventing Carburizing By Copper-plating
Copper-plating has been found effective and must have a thick...

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

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

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

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

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

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

The Quenching Tank
The quenching tank is an important feature of apparatus in c...

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

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

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

The Leeds And Northrup Potentiometer System
The potentiometer pyrometer system is both flexible and subst...

S A E Heat Treatments
The Society of Automotive Engineers have adopted certain heat...

Preparing Parts For Local Case-hardening
At the works of the Dayton Engineering Laboratories Company, ...

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

Silicon
Silicon prevents, to a large extent, defects such as gas bubb...

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

Hardening High-speed Steels
We will now take up the matter of hardening high-speed steels...

Standard Analysis
The selection of a standard analysis by the manufacturer is t...

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



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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