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Steel Making

Fatigue Tests
It has been known for fifty years that a beam or rod would fa...

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

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

Correction For Cold-junction Errors
The voltage generated by a thermo-couple of an electric pyrom...

Phosphorus is one of the impurities in steel, and it has been...

Although it is possible to work steels cold, to an extent de...

Classifications Of Steel
Among makers and sellers, carbon tool-steels are classed by g...

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

Mushet And Bessemer
That Mushet was "used" by Ebbw Vale against Bessemer is, perh...

Composition Of Transmission-gear Steel
If the nickel content of this steel is eliminated, and the pe...

Annealing To Relieve Internal Stresses
Work quenched from a high temperature and not afterward tempe...

Rate Of Absorption
According to Guillet, the absorption of carbon is favored by ...

Steel Can Be Worked Cold
As noted above, steel can be worked cold, as in the case of ...

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

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

Reheating for machine ability was done at 100 deg. less than ...

Standard Analysis
The selection of a standard analysis by the manufacturer is t...

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

Uses Of The Various Tempers Of Carbon Tool Steel
DIE TEMPER.--No. 3: All kinds of dies for deep stamping, pres...

Hardening High-speed Steel
In forging use coke for fuel in the forge. Heat steel slowly ...

Highly Stressed Parts


The highly stressed parts on the Liberty engine consisted of the
connecting-rod bolt, the main-bearing bolt, the propeller-hub key,
etc. The material used for parts of this type was selected at the
option of the manufacturer from standard S. A. E. steels, the
composition of which are given in Table 11.

TABLE 11.--COMPOSITION OF S. A. E. STEELS Nos. 2,330, 3,135 AND 6,130

Steel No 2,330 3,135 6,130
Carbon, minimum 0.250 0.300 0.250
Carbon, maximum 0.350 0.400 0.450
Manganese, minimum 0.500 0.500 0.500
Manganese, maximum 0.800 0.800 0.800
Phosphorus, maximum 0.045 0.040 0.040
Sulphur, maximum 0.045 0.045 0.045
Nickel, minimum 3.250 1.000
Nickel, maximum 3.750 1.500
Chromium, minimum 0.450 0.800
Chromium, maximum 0.750 1.100
Vanadium, minimum 0.150

All highly stressed parts on the Liberty engine must show, after
heat treatment, the following minimum physical properties: Elastic
limit, 100,000 lb. per square inch; elongation in 2 in., 16 per
cent; reduction of area, 45 per cent; scleroscope hardness, 40
to 50.

The heat treatment employed to obtain these physical properties
consisted in quenching from a temperature of 1,525 to 1,575 deg.F., in
oil, followed by tempering at a temperature of from 925 to 975 deg.F.

Due to the extremely fine limits used on all threaded parts for
the Liberty engine, a large percentage of rejection was due to
warpage and scaling of parts. To eliminate this objection, many
of the Liberty engine builders adopted the use of heat-treated
and cold-drawn alloy steel for their highly stressed parts. On
all sizes up to and including 3/8 in. in diameter, the physical
properties were secured by merely normalizing the hot-rolled bars
by heating to a temperature of from 1,525 to 1,575 deg.F., and cooling
in air, followed by the usual cold-drawing reductions. For parts
requiring stock over 3/8 in. in diameter, the physical properties
desired were obtained by quenching and tempering the hot-rolled bars
before cold-drawing. It is the opinion that the use of heat-treated
and cold-drawn bars is very good practice, provided proper inspection
is made to guarantee the uniformity of heat treatment and, therefore,
the uniformity of the physical properties of the finished parts.

The question has been asked many times by different manufacturers, as
to which alloy steel offers the best machineability when heat-treated
to a given Brinell hardness. The general consensus of opinion among
the screw-machine manufacturers is that S. A. E. No. 6,130 steel
gives the best machineability and that S. A. E. No. 2,330 steel
would receive second choice of the three specified.

In the finishing of highly stressed parts for aviation engines,
extreme care must be taken to see that all tool marks are eliminated,
unless they are parallel to the axis of strain, and that proper
radii are maintained at all changes of section. This is of the
utmost importance to give proper fatigue resistance to the part
in question.

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Previous: Carbon-steel Forgings

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