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Steel Making

Detrimental Elements
Sulphur and phosphorus are two elements known to be detrimen...

Carbon Steels For Different Tools
All users of tool steels should carefully study the different...

Pyrometers
Armor plate makers sometimes use the copper ball or Siemens' ...

Calibration Of Pyrometer With Common Salt
An easy and convenient method for standardization and one whi...

Making Steel Balls
Steel balls are made from rods or coils according to size, st...

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

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

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

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

Heat-treating Department
The heat-treating department occupies an L-shaped building. ...

The Theory Of Tempering
Steel that has been hardened is generally harder and more br...

Plant For Forging Rifle Barrels
The forging of rifle barrels in large quantities and heat-tre...

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

Silicon
SILICON is a very widespread element (symbol Si), being an es...

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

Nickel
Nickel may be considered as the toughest among the non-rare a...

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...

Conclusions
Martien was probably never a serious contender for the honor ...

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

Rate Of Absorption
According to Guillet, the absorption of carbon is favored by ...



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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