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Case-hardening Treatments For Various Steels
Plain water, salt water and linseed oil are the three most co...

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

Vanadium
Vanadium has a very marked effect upon alloy steels rich in c...

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

Cyanide Bath For Tool Steels
All high-carbon tool steels are heated in a cyanide bath. Wi...

Bessemer Process
The bessemer process consists of charging molten pig iron int...

Take Time For Hardening
Uneven heating and poor quenching has caused loss of many ve...

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

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

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

Connecting Rods
The material used for all connecting rods on the Liberty engi...

Complete Calibration Of Pyrometers
For the complete calibration of a thermo-couple of unknown e...

Hardening
Steel is hardened by quenching from above the upper critical....

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

Quenching Tool Steel
To secure proper hardness, the cooling of quenching of steel ...

Optical System And Electrical Circuit Of The Leeds & Northrup Optical Pyrometer
For extremely high temperature, the optical pyrometer is lar...

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

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

Leeds And Northrup Optical Pyrometer
The principles of this very popular method of measuring tempe...

Fatigue Tests
It has been known for fifty years that a beam or rod would fa...



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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