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

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

Carbon In Tool Steel
Carbon tool steel, or tool steel as it is commonly called, us...

Annealing
There is no mystery or secret about the proper annealing of d...

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

Heavy Forging Practice
In heavy forging practice where the metal is being worked at...

Heat Treatment Of Steel
Heat treatment consists in heating and cooling metal at defin...

Application Of Liberty Engine Materials To The Automotive Industry
The success of the Liberty engine program was an engineer...

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

Molybdenum
Molybdenum steels have been made commercially for twenty-five...

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

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

Composition Of Transmission-gear Steel
If the nickel content of this steel is eliminated, and the pe...

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

S A E Heat Treatments
The Society of Automotive Engineers have adopted certain heat...

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

Annealing Of Rifle Components At Springfield Armory
In general, all forgings of the components of the arms manufa...

Carburizing Low-carbon Sleeves
Low-carbon sleeves are carburized and pushed on malleable-ir...

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

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



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.





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Previous: Refining The Grain



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