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Steel Making

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

Heat Treatment Of Axles
Parts of this general type should be heat-treated to show the...

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

Furnace Data
In order to give definite information concerning furnaces, fu...

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

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

Open Hearth Process
The open hearth furnace consists of a big brick room with a l...

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

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

Connecting Rods
The material used for all connecting rods on the Liberty engi...

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

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

Chrome-nickel Steel
Forging heat of chrome-nickel steel depends very largely on ...

Temperatures To Use
As soon as the temperature of the steel reaches 100 deg.C. (...

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

Plant For Forging Rifle Barrels
The forging of rifle barrels in large quantities and heat-tre...

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

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

Highly Stressed Parts
The highly stressed parts on the Liberty engine consisted of ...

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

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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