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Typical Oil-fired Furnaces
Several types of standard oil-fired furnaces are shown herew...

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

Gears
The material used for all gears on the Liberty engine was sel...

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

Flange Shields For Furnaces
Such portable flame shields as the one illustrated in Fig. 1...

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

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

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

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

Steel For Chisels And Punches
The highest grades of carbon or tempering steels are to be re...

Annealing Of Rifle Components At Springfield Armory
In general, all forgings of the components of the arms manufa...

Introduction Of Carbon
The matter to which these notes are primarily directed is the...

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

Correction By Zero Adjustment
Many pyrometers are supplied with a zero adjuster, by means ...

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

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

Alloying Elements
Commercial steels of even the simplest types are therefore p...

The Thermo-couple
With the application of the thermo-couple, the measurement of...

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

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



Knowing What Takes Place






Category: HARDENING CARBON STEEL FOR TOOLS

How are we to know if we have given a
piece of steel the very best possible treatment?

The best method is by microscopic examination of polished and etched
sections, but this requires a certain expense for laboratory equipment
and upkeep, which may prevent an ordinary commercial plant from
attempting such a refinement. It is highly recommended that any
firm that has any large amount of heat treatment to do, install
such an equipment, which can be purchased for from $250 to $500.
Its intelligent use will save its cost in a very short time.

The other method is by examination of fractures of small test bars.
Steel heated to its correct temperatures will show the finest possible
grain, whereas underheated steel has not had its grain structure
refined sufficiently, and so will not be at its best. On the other
hand, overheated steel will have a coarser structure, depending
on the extent of overheating.

To determine the proper quenching temperature of any particular
grade of steel it is only necessary to heat pieces to various
temperatures not more than 20 deg.C. (36 deg.F.) apart, quench in water,
break them, and examine the fractures. The temperature producing
the finest grain should be used for annealing and hardening.

Similarly, to determine tempering temperatures, several pieces
should be hardened, then tempered to various degrees, and cooled
in air. Samples, say six, reheated to temperatures varying by 100 deg.
from 300 to 800 deg.C. will show a considerable range of properties,
and the drawing temperature of the piece giving the desired results
can be used.

For drawing tempers up to 500 deg.F. oil baths of fresh cotton seed
oil can be safely and satisfactorily used. For higher temperature
a bath of some kind of fused salt is recommended.





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