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Steel Making

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

For Milling Cutters And Formed Tools
FORGING.--Forge as before.--ANNEALING.--Place the steel in a ...

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

There is no mystery or secret about the proper annealing of d...

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

Hardening Operation
Hardening a gear is accomplished as follows: The gear is tak...

Effect Of Different Carburizing Material
[Illustrations: FIGS. 33 to 37.] Each of these different p...

Annealing Method
Forgings which are too hard to machine are put in pots with ...

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

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

Air-hardening Steels
These steels are recommended for boring, turning and planing...

Non-shrinking Oil-hardening Steels
Certain steels have a very low rate of expansion and contract...

Carburizing By Gas
The process of carburizing by gas, briefly mentioned on page ...

Heat Treatment Of Axles
Parts of this general type should be heat-treated to show the...

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

Reheating for machine ability was done at 100 deg. less than ...

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

Knowing What Takes Place
How are we to know if we have given a piece of steel the ver...

Properties Of Steel
Steels are known by certain tests. Early tests were more or l...

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

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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