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National Advisory Committee for Aeronautics, Technical Notes - Investigation of Properties of AISI Type 310B Alloy Sheet at High Temperatures

The alloy haNing a composition of 25 percent chromiumb 20 percent
nickel, and 2 percent silicon (AISI Type 310B alloy) is known to'be
subject to low ductility in the temperature range from 12000 to 114000 F.
The present investigation was undertaken to determine by means of ten?
sile tests whether service at 17000 to 18000 F, such as that in combus-
tion chaMbers of Jet engines, would cause further loss of ductility
resulting in brittleness at 12000 to 1hoo° F. In addition, tensile
tests were made on samples after heating at 19000 to 21000 F for short
time periods. Rupture tests were also made at 17000 F and, to a limited
extent, at 18000 F. Three heats of stock were used in order to evaluate
heat-to-heat reproducibility and the relative effects of annealing,
coldrworking, and hot-rolling as initial treatments.

Elongation in the tensile test, the criterion of brittleness used,
was found to be a minimum at about 13000 F. Elongation at 13000 F was
markedly increased by short periods of prior heating at temperatures
from 17000 to 2000° F. Prolonged exposure at 17000 or 18000 F also
increased elongation at 1300° F. The cold-rolled and hot-rolled sheet
had considerably higher tensile strength than the annealed'sheet from
900° to 18000 F. The cold-rolled stock had the lowest ductility.

Both carbon content and prior treatment influenced the rupture
properties, but not so greatly as had been expected. Sheet containing
0.16 percent carbon had considerably higher rupture strength than
0.05-percent-carbon sheet. Annealed sheet had higher rupture strength
than hot-rolled or cold-rolled sheet, except at short time periods.

The alloy having a composition of 25 percent chromium, 20 percent
nickel, and 2 percent silicon (AISI Type 3103 alloy) has oxidation
resistance and strength properties suitable for sheet applications at
high temperatures in gas turbines. Its rupture strength at 1700°
and 1800° F compares favorably with that of several more highly alloyed
sheet materials. (See reference 1.) It is, however, subject to low
ductility in the temperature range from 12000 to lh00° F as the result
of precipitation reactions and probably the formation of sigma phase.