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

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

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

Refining The Grain
This is remedied by reheating the piece to a temperature slig...

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

Suggestions For Handling High-speed Steels
The following suggestions for handling high-speed steels are ...

Forging High-speed Steel
Heat very slowly and carefully to from 1,800 to 2,000 deg.F....

Cutting-off Steel From Bar
To cut a piece from an annealed bar, cut off with a hack saw,...

Annealing In Bone
Steel and cast iron may both be annealed in granulated bone. ...

Steel For Chisels And Punches
The highest grades of carbon or tempering steels are to be re...

Shrinking And Enlarging Work
Steel can be shrunk or enlarged by proper heating and cooling...

An Automatic Temperature Control Pyrometer
Automatic temperature control instruments are similar to the ...

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

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

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

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

Annealing
ANNEALING can be done by heating to temperatures ranging from...

Ebbw Vale And The Bessemer Process
After his British Association address in August 1856, Besseme...

The Penetration Of Carbon
Carburized mild steel is used to a great extent in the manufa...

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



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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