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

Impact Tests
Impact tests are of considerable importance as an indication ...

Application To The Automotive Industry
The information given on the various parts of the Liberty eng...

Hardening
The forgings can be hardened by cooling in still air or quen...

Air-hardening Steels
These steels are recommended for boring, turning and planing...

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

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

The Effect
The heating at 1,600 deg.F. gives the first heat treatment w...

Short Method Of Treatment
In the new method, the packed pots are run into the case-har...

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

Robert Mushet
Robert (Forester) Mushet (1811-1891), born in the Forest of D...

Separating The Work From The Compound
During the pulling of the heat, the pots are dumped upon a ca...

Tensile Properties
Strength of a metal is usually expressed in the number of pou...

Brown Automatic Signaling Pyrometer
In large heat-treating plants it has been customary to mainta...

Hardening Carbon Steel For Tools
For years the toolmaker had full sway in regard to make of st...

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

Surface Carburizing
Carburizing, commonly called case-hardening, is the art of pr...

Placing Of Pyrometers
When installing a pyrometer, care should be taken that it re...

Introduction Of Carbon
The matter to which these notes are primarily directed is the...

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



Introduction Of Carbon






Category: CASE-HARDENING OR SURFACE-CARBURIZING

The matter to which these notes are primarily directed is the
introduction of carbon into the case of the article to be hardened.
In the first place the chances of success are increased by selecting
as few brands of steel as practicable to cover the requirements of
each component of the mechanism. The hardener is then able to become
accustomed to the characteristics of that particular material, and
after determining the most suitable treatment for it no further
experimenting beyond the usual check-test pieces is necessary.

Although a certain make of material may vary in composition from
time to time the products of a manufacturer of good steel can be
generally relied upon, and it is better to deal directly with him
than with others.

In most cases the case-hardening steels can be chosen from the
following: (1) Case-hardening mild steel of 0.20 per cent carbon;
(2) case-hardening 3-1/2 per cent nickel steel; (3) case-hardening
nickel-chromium steel; (4) case-hardening chromium vanadium. After
having chosen a suitable steel it is best to have the sample analyzed
by reliable chemists and also to have test pieces machined and pulled.

To prepare samples for analysis place a sheet of paper on the table
of a drilling machine, and with a 3/8-in. diameter drill, machine
a few holes about 3/8 in. deep in various parts of the sample bar,
collecting about 3 oz. of fine drillings free from dust. This can be
placed in a bottle and dispatched to the laboratory with instructions
to search for carbon, silicon, manganese, sulphur, phosphorus and
alloys. The results of the different tests should be carefully
tabulated, and as there would most probably be some variation an
average should be made as a fair basis of each element present,
and the following tables may be used with confidence when deciding
if the material is reliable enough to be used.

TABLE 16.--CASE-HARDENING MILD STEEL OF 0.20 PER CENT CARBON

Carbon 0.15 to 0.25 per cent
Silicon Not over 0.20 per cent
Manganese 0.30 to 0.60 per cent
Sulphur Not over 0.04 per cent
Phosphorus Not over 0.04 per cent

A tension test should register at least 60,000 lb. per square inch.

TABLE 17.--CASE-HARDENING 3-1/2 PER CENT NICKEL STEEL

Carbon 0.12 to 0.20 per cent
Manganese 0.65 per cent
Sulphur Not over 0.045 per cent
Phosphorus Not over 0.04 per cent
Nickel 3.25 to 3.75 per cent

TABLE 18.--CASE-HARDENING NICKEL CHROMIUM STEEL

Carbon 0.15 to 0.25 per cent
Manganese 0.50 to 0.80 per cent
Sulphur Not over 0.045 per cent
Phosphorus Not over 0.04 per cent
Nickel 1 to 1.5 per cent
Chromium 0.45 to 0.75 per cent

TABLE 19.--CASE-HARDENING CHROMIUM VANADIUM STEEL

Carbon Not over 0.25 per cent
Manganese 0.50 to 0.85 per cent
Sulphur Not over 0.04 per cent
Phosphorus Not over 0.04 per cent
Chromium 0.80 to 1.10 per cent
Vanadium Not less than 0.15 per cent

Having determined what is required we now proceed to inquire into
the question of carburizing, which is of vital importance.





Next: Using Illuminating Gas

Previous: The Penetration Of Carbon



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