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National Advisory Committee for Aeronautics, Technical Notes - The Effect of Temperature on Sheet Metals for Airplane Firewalls

Tests were conducted on S uncoated steels and on 20 steels
with various coatings to determine the effect of temperature on the
tensile properties and surface characteristics of the metals. The
metals were Subjected to furnace-heating tests over a range of temp-
peratures from 10000 F to 20000 F for 2%, 5, 15, and 60 minutes and
to f1ame~impingement and airplaneefire tests. The surface oxides
formed at different temperatures were noted and the'tensile strength
and ductility of the metals determined'for the various temperatures
and periods of heating. The tests showed the following results:

1. In general, all materials investigated were capable of with—
standing exposure to temperatures not exceeding 17000 F for periods
up to 15 minutes without a serious deterioration in tensile prop-
erties.

2. Stainless steel proved to be the best of the uncoated mate;
rials tested; low carbon steels containing 1 percent silicon were
better than steels without silicon. ' ‘

3. Stainless-clad plain carbon steel exhibited very little
change in properties over the most severe heating conditions.

h. Chromiumenickel-alloy coatings and aluminum coatings on
plain carbon steel sheets proved to be more resistant to high tene
peratures for periods of exposure up to 60 minutes than did coatings
of zinc or of zinc over nickel.

As a result of the shortage of critical materials, such as
steel alloys containing nickel, an investigation was conducted by
the National Bureau of Standards with cooperation from the Civil
Aeronautics Administration to find satisfactory materials to replace
these alloys, which are currently being used in airplane firewalls.
This work was requested by the National Advisory Committee for
Aeronautics.

This report covers the results-of furnace—heating, flame-
impingement, and airplane-fire tests that were conducted on
S uncoated steels and on 20 steels with coatings to determine the
effect of temperature on the tensile characteristics of the mate~
rials. Charts are presented to show the changes in tensile prop~
erties with temperature and time of heating; photographs showing
the changes in surface and in microstructure are also presented.