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Steel Making

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

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

Furnace Data
In order to give definite information concerning furnaces, fu...

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

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

Surface Carburizing
Carburizing, commonly called case-hardening, is the art of pr...

Properties Of Alloy Steels
The following table shows the percentages of carbon, manganes...

Heavy Forging Practice
In heavy forging practice where the metal is being worked at...

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

The Electric Process
The fourth method of manufacturing steel is by the electric f...

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

Piston Pin
The piston pin on an aviation engine must possess maximum res...

Lathe And Planer Tools
FORGING.--Gently warm the steel to remove any chill, is parti...

Composition And Properties Of Steel
It is a remarkable fact that one can look through a dozen tex...

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

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

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

Preventing Decarbonization Of Tool Steel
It is especially important to prevent decarbonization in such...

Preventing Cracks In Hardening
The blacksmith in the small shop, where equipment is usually ...

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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