U
6,195 |0.90 to 1.05|0.20 to 0.45| 0.03 | 0.03 |0.80 to 1.10| 0.15 U
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TABLE 10.--SILICO-MANGANESE STEELS
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S. A. E. | | | | | |
Specification| | | | | |
no. ----- Carbon| Manganese | | | Silicon |
|(minimum and|(minimum and|Phosphorus|Sulphur |(minimum and| Heat
| maximum) | maximum) |(maximum) |(maximum)| maximum) |treatment
-------|------------|------------|----------|---------|------------|---------
9,250 |0.45 to 0.55|0.60 to 0.80| 0.045* | 0.045 |1.80 to 2.10| V
9,260 |0.55 to 0.65|0.50 to 0.70| 0.045* | 0.045 |1.50 to 1.80| V
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* Steel made by the acid process may contain maximum 0.05 phosphorus.

LIBERTY MOTOR CONNECTING RODS

The requirements for materials for the Liberty motor connecting rods
are so severe that the methods of securing the desired qualities
will be of value in other lines. The original specifications called
for chrome-nickel but the losses due to the difficulty of handling
caused the Lincoln Motor Company to suggest the substitution of
chrome-vanadium steel, and this was accepted by the Signal Corps. The
rods were accordingly made from chromium-vanadium steel, containing
carbon, 0.30 to 0.40 per cent; manganese, 0.50 to 0.80 per cent;
phosphorus, not over 0.04 per cent; sulphur, not over 0.04 per
cent; chromium, 0.80 to 1.10 per cent; vanadium, not less than 0.15
per cent. This steel is ordinarily known in the trade as 0.35 carbon
steel, S. A. E., specification 6,135, which provides a first-rate
quality steel for structural parts that are to be heat-treated.
The fatigue resisting or endurance qualities of this material are
excellent. It has a tensile strength of 150,000 lb. minimum per
square inch; elastic limit, 115,000 lb. minimum per square inch;
elongation, 5 per cent minimum in 2 in.; and minimum reduction
in area, 25 per cent.

The original production system as outlined for the manufacturers
had called for a heat treatment in the rough-forged state for the
connecting rods, and then semi-machining the rod forgings before
giving them the final treatment. The Lincoln Motor Company insisted
from the