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Steel Making

Heat Treatment Of Steel
Heat treatment consists in heating and cooling metal at defin...

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

Oil-hardening Steel
Heat slowly and uniformly to 1,450 deg.F. and forge thorough...

Highly Stressed Parts
The highly stressed parts on the Liberty engine consisted of ...

Effect Of A Small Amount Of Copper In Medium-carbon Steel
This shows the result of tests by C. R. Hayward and A. B. Joh...

The Effect Of Tempering On Water-quenched Gages
The following information has been supplied by Automatic and ...

Phosphorus
PHOSPHORUS is an element (symbol P) which enters the metal fr...

Carbon-steel Forgings
Low-stressed, carbon-steel forgings include such parts as car...

Application Of Liberty Engine Materials To The Automotive Industry
The success of the Liberty engine program was an engineer...

Tempering Round Dies
A number of circular dies of carbon tool steel for use in too...

The Packing Department
In Fig. 56 is shown the packing pots where the work is packe...

Hints For Tool Steel Users
Do not hesitate to ask for information from the maker as to t...

Manganese
Manganese adds considerably to the tensile strength of steel,...

Sulphur
SULPHUR is another element (symbol S) which is always found i...

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

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

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

Carbon In Tool Steel
Carbon tool steel, or tool steel as it is commonly called, us...

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

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



Quenching






Category: CASE-HARDENING OR SURFACE-CARBURIZING

It is considered good practice to quench alloy steels from the pot,
especially if the case is of any appreciable depth. The texture
of carbon steel will be weakened by the prolonged high heat of
carburizing, so that if we need a tough core, we must reheat it
above its critical range, which is about 1,600 deg.F. for soft steel,
but lower for manganese and nickel steels. Quenching is done in
either water, oil, or air, depending upon the results desired.
The steel is then very carefully reheated to refine the case, the
temperature varying from 1,350 to 1,450 deg.F., depending on whether
the material is an alloy or a simple steel, and quenched in either
water or oil.



There are many possibilities yet to be developed with the carburizing
of alloy steels, which can produce a very tough, tenacious austenitic
case which becomes hard on cooling in air, and still retains a
soft, pearlitic core. An austenitic case is not necessarily file
hard, but has a very great resistance to abrasive wear.

The more carbon a steel has to begin with the more slowly will it
absorb carbon and the lower the temperature required. Low-carbon
steel of from 15 to 20 points is generally used and the carbon
brought up to 80 or 85 points. Tool steels may be carbonized as
high as 250 points.

In addition to the carburizing materials given, a mixture of 40
per cent of barium carbonate and 60 per cent charcoal gives much
faster penetration than charcoal, bone or leather. The penetration
of this mixture on ordinary low-carbon steel is shown in Fig. 32,
over a range of from 2 to 12 hr.





Next: Effect Of Different Carburizing Material

Previous: Carburizing Material



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