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

The Pyrometer And Its Use
In the heat treatment of steel, it has become absolutely nece...

Hardness Testing
The word hardness is used to express various properties of me...

Refining The Grain
This is remedied by reheating the piece to a temperature slig...

Non-shrinking Oil-hardening Steels
Certain steels have a very low rate of expansion and contract...

Correction By Zero Adjustment
Many pyrometers are supplied with a zero adjuster, by means ...

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

Making Steel Balls
Steel balls are made from rods or coils according to size, st...

Detrimental Elements
Sulphur and phosphorus are two elements known to be detrimen...

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

Liberty Motor Connecting Rods
The requirements for materials for the Liberty motor connecti...

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

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

Take Time For Hardening
Uneven heating and poor quenching has caused loss of many ve...

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

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

Hints For Tool Steel Users
Do not hesitate to ask for information from the maker as to t...

Steel Worked In Austenitic State
As a general rule steel should be worked when it is in the a...

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

Tempering Round Dies
A number of circular dies of carbon tool steel for use in too...



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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