: APPLICATION OF LIBERTY ENGINE MATERIALS TO THE AUTOMOTIVE INDUSTRY
: The Working Of Steel
The material used for all gears on the Liberty engine was selected
at the option of the manufacturer from the following standard S.
A. E. steels, the composition of which are given in Table 12,
TABLE 12.--COMPOSITION OF STEELS NOS. X-3,340 AND 6,140
Steel No X-3,340 6,140
Carbon, minimum 0.350 0.350
Carbon, maximum 0.450 0.450
minimum 0.450 0.500
Manganese, maximum 0.750 0.800
Phosphorus, maximum 0.040 0.040
Sulphur, maximum 0.045 0.045
Nickel, minimum 2.750
Nickel, maximum 3.250
Chromium, minimum 0.700 0.800
Chromium, maximum 0.950 1.100
Vanadium, minimum 0.150
All gears were heat-treated to a scleroscope hardness of from 55
to 55. The heat treatment used to secure this hardness consisted
in quenching the forgings from a temperature of 1,550 to 1,600 deg.F.
in oil and annealing for good machineability at a temperature of
from 1,300 to 1,350 deg.F. Forgings treated in this manner showed a
Brinell hardness of from 177 to 217.