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Steel Making

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

Protectors For Thermo-couples
Thermo-couples must be protected from the danger of mechanica...

Leeds And Northrup Optical Pyrometer
The principles of this very popular method of measuring tempe...

Effects Of Proper Annealing
Proper annealing of low-carbon steels causes a complete solu...

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

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

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

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

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

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

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

Lathe And Planer Tools
FORGING.--Gently warm the steel to remove any chill, is parti...

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

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

Protective Screens For Furnaces
Workmen needlessly exposed to the flames, heat and glare from...

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

A Satisfactory Luting Mixture
A mixture of fireclay and sand will be found very satisfactor...

Lathe And Planer Tools
TO FORGE.--Gently warm the steel to remove any chill is parti...

Manganese
Manganese adds considerably to the tensile strength of steel,...

Typical Oil-fired Furnaces
Several types of standard oil-fired furnaces are shown herew...



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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