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

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

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

Hardening Operation
Hardening a gear is accomplished as follows: The gear is tak...

Pickling The Forgings
The forgings were then pickled in a hot solution of either ni...

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

The Thermo-couple
With the application of the thermo-couple, the measurement of...

Critical Points
One of the most important means of investigating the properti...

Tempering Colors On Carbon Steels
Opinions differ as to the temperature which is indicated by t...

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

Crucible Steel
Crucible steel is still made by melting material in a clay or...

Uses Of The Various Tempers Of Carbon Tool Steel
DIE TEMPER.--No. 3: All kinds of dies for deep stamping, pres...

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

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

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

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

Placing The Thermo-couples
The following illustrations from the Taylor Instrument Compan...

Carburizing Material
The simplest carburizing substance is charcoal. It is also th...

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

Hardening High-speed Steels
We will now take up the matter of hardening high-speed steels...



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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