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Steel Making

Heating Of Manganese Steel
Another form of heat-treating furnace is that which is used ...

Using Illuminating Gas
The choice of a carburizing furnace depends greatly on the fa...

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

A Chromium-cobalt Steel
The Latrobe Steel Company make a high-speed steel without tun...

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

Correction For Cold-junction Errors
The voltage generated by a thermo-couple of an electric pyrom...

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

Judging The Heat Of Steel
While the use of a pyrometer is of course the only way to hav...

Heating
Although it is possible to work steels cold, to an extent de...

Heat Treatment Of Milling Cutters Drills Reamers Etc
THE FIRE.--Gas and electric furnaces designed for high heats ...

Steel Before The 1850's
In spite of a rapid increase in the use of machines and the ...

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

Gas Consumption For Carburizing
Although the advantages offered by the gas-fired furnace for ...

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

The Care Of Carburizing Compounds
Of all the opportunities for practicing economy in the heat-t...

Annealing Method
Forgings which are too hard to machine are put in pots with ...

Temperature For Annealing
Theoretically, annealing should be accomplished at a tempera...

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

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

Chrome-nickel Steel
Forging heat of chrome-nickel steel depends very largely on ...



Case-hardening Treatments For Various Steels






Category: CASE-HARDENING OR SURFACE-CARBURIZING

Plain water, salt water and linseed oil are the three most common
quenching materials for case-hardening. Water is used for ordinary
work, salt water for work which must be extremely hard on the surface,
and oil for work in which toughness is the main consideration. The
higher the carbon of the case, the less sudden need the quenching
action take hold of the piece; in fact, experience in case-hardening
work gives a great many combinations of quenching baths of these
three materials, depending on their temperatures. Thin work, highly
carbonized, which would fly to pieces under the slightest blow if
quenched in water or brine, is made strong and tough by properly
quenching in slightly heated oil. It is impossible to give any
rules for the temperature of this work, so much depending on the
size and design of the piece; but it is not a difficult matter to
try three or four pieces by different methods and determine what
is needed for best results.

The alloy steels are all susceptible of case-hardening treatment;
in fact, this is one of the most important heat treatments for such
steels in the automobile industry. Nickel steel carburizes more
slowly than common steel, the nickel seeming to have the effect
of slowing down the rate of penetration. There is no cloud without
its silver lining, however, and to offset this retardation, a single
treatment is often sufficient for nickel steel; for the core is not
coarsened as much as low-carbon machinery steel and thus ordinary
work may be quenched on the carburizing heat. Steel containing
from 3 to 3.5 per cent of nickel is carburized between 1,650 and
1,750 deg.F. Nickel steel containing less than 25 points of carbon,
with this same percentage of nickel, may be slightly hardened by
cooling in air instead of quenching.

Chrome-nickel steel may be case-hardened similarly to the method just
described for nickel steel, but double treatment gives better results
and is used for high-grade work. The carburizing temperature is the
same, between 1,650 and 1,750 deg.F., the second treatment consisting
of reheating to 1,400 deg. and then quenching in boiling salt water,
which gives a hard surface and at the same time prevents distortion
of the piece. The core of chrome-nickel case-hardened steel, like
that of nickel steel, is not coarsened excessively by the first
heat treatment, and therefore a single heating and quenching will
suffice.





Next: Carburizing By Gas

Previous: Refining The Grain



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