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Steel Making

MANGANESE is a metal much like iron. Its chemical symbol is M...

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

The Electric Process
The fourth method of manufacturing steel is by the electric f...

Nickel may be considered as the toughest among the non-rare a...

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

Affinity Of Nickel Steel For Carbon
The carbon- and nickel-steel gears are carburized separately...

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

Rate Of Cooling
At the option of the manufacturer, the above treatment of gea...

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

Temperature Recording And Regulation
Each furnace is equipped with pyrometers, but the reading an...

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

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

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

Carbon-steel Forgings
Low-stressed, carbon-steel forgings include such parts as car...

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

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

Knowing What Takes Place
How are we to know if we have given a piece of steel the ver...

The Modern Hardening Room
A hardening room of today means a very different place from ...

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

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

Case-hardening Treatments For Various Steels


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

Next: Carburizing By Gas

Previous: Refining The Grain

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