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   Home - Steel Making - Categories - Manufacturing and the Economy of Machinery

Steel Making

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

Piston Pin
The piston pin on an aviation engine must possess maximum res...

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

Preventing Carburizing By Copper-plating
Copper-plating has been found effective and must have a thick...

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

Nickel-chromium
A combination of the characteristics of nickel and the charac...

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

The Pyrometer And Its Use
In the heat treatment of steel, it has become absolutely nece...

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

Hardness Testing
The word hardness is used to express various properties of me...

Restoring Overheated Steel
The effect of heat treatment on overheated steel is shown gra...

William Kelly's Air-boiling Process
An account of Bessemer's address to the British Association w...

Chromium
Chromium when alloyed with steel, has the characteristic func...

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

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

Quenching
It is considered good practice to quench alloy steels from th...

Short Method Of Treatment
In the new method, the packed pots are run into the case-har...

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

Annealing Work
With the exception of several of the higher types of alloy s...

High-chromium Or Rust-proof Steel
High-chromium, or what is called stainless steel containing f...



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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