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

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...

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

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

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

The Quenching Tank
The quenching tank is an important feature of apparatus in c...

Pyrometers For Molten Metal
Pyrometers for molten metal are connected to portable thermoc...

Flange Shields For Furnaces
Such portable flame shields as the one illustrated in Fig. 1...

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

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

Heat Treatment Of Punches And Dies Shears Taps Etc
HEATING.--The degree to which tools of the above classes shou...

Carbon In Tool Steel
Carbon tool steel, or tool steel as it is commonly called, us...

Instructions For Working High-speed Steel
Owing to the wide variations in the composition of high-speed...

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

The Effect Of Tempering On Water-quenched Gages
The following information has been supplied by Automatic and ...

Silicon
Silicon prevents, to a large extent, defects such as gas bubb...

For Milling Cutters And Formed Tools
FORGING.--Forge as before.--ANNEALING.--Place the steel in a ...

The Care Of Carburizing Compounds
Of all the opportunities for practicing economy in the heat-t...

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



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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