Influence of Chemical Composition on Rupture Test Properties at 1500 Degrees Fahrenheit of Forged Chromium-Cobalt-Nickel-Iron Base Alloys Page: 11 of 70
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10
NACA TN 2745
Summarized Effects of Composition on Rupturre Test Properties'The effects of-individual variations of_the elements in the basic
alloy on rupture strength and elongation are summarized in figure 22.
The stresses for rupture in 100 and 1000 hours resulting from simul-
taneous variation of Mo, W, and Cb are summarized by figures 23 and 24,
respectively. Elongation was omitted in the .latter summary inasmuch
as those alloys without Cb had low elongation and all containing Cb had
high elongation.
The data for the individual variations. were presented in groups
according to the percentages present in the alloys.- The effects of.
simultaneous variations were summarized by combining Mo and W as the
independent variable because the two elements had similar and additive-_
effects. Average curves were drawn through the data for the various
Cb contents studied. This procedure may not be correct in.detail in
that the effect of Mo and W may be different. The trends, however, are
shown by the curves and probably represent the reproducibility of the
properties frQm heat to heat,
" M . - ,, ... . _MICROSTRUCTURAL EFFECTS OF COMPOSITION VARIATION
The original microstructures were examined in detail for reference 1
to help explain the effects of composition on rupture properties at
12000 F. ' In this- investigation the examination was extended to include
the structures of. the specimens from the most-prolonged tests at 15000 F.
When tested at 12000 F there was little..change in structure in
most alloys from that produced by the original solution and aging treat-
ment. After testing at-15000 F, however, the general trend was for the
precipitate particles in both the grain boundaries and matrix to be
larger. -The fractures tended to be more intergranuiar.than at 1200 F_
in those alloys which did not.have brittle-type fractures. These general
effects are shown by the structures of the basic alloy in figure 25.The following discussions briefly summarize.the structural effects
of the various compositional changes as related to the rupture properties..
Carbon
Increasing C. increased the amount of insoluble Constituent present-
after solution-treating and the amount of random precipitate which
formed on aging. The grain sizes of alloys up to 0.40 percent C were
about A.S.T.M number 5 while the 0.60-percehnt-C alloyhad a grain -sizet _
r
...
. . . . . __ -- ....- _ .- ..
. .. _~_ .- C_-
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Freeman, J. W.; Ewing, J. F. & White, A. E. Influence of Chemical Composition on Rupture Test Properties at 1500 Degrees Fahrenheit of Forged Chromium-Cobalt-Nickel-Iron Base Alloys, report, July 1952; (https://digital.library.unt.edu/ark:/67531/metadc56341/m1/11/: accessed May 8, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.