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ORNL-2780.txt
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[ SRSl VN ]
[ A )
| PSS ]
A7
ORNL
MASTER COPY
ORNL=-2780
UC-25 - Metallurgy and Ceramics
THE MECHANICAL PROPERTIES OF INOR-8
R. W. Swindeman
OAK RIDGE NATIONAL LABORATORY
operated by
UNION CARBIDE CORPORATION
‘ for the
U.S. ATOMIC ENERGY COMMISSION
. Available from the
$1.75
Office of Technical Services
Printed in USA. Price
Department of Commerce
Washington 25, D.C,
LEGAL NOTICE
This report was prepared as an account of Government sponsored work. Neither the United States,
nor the Commission, nor any person acting on behalf of the Commission:
A. Makes ony warranty or representation, expressed or implied, with respect to the accuracy,
completeness, or usefulness of the information contained in this report, or that the use of
any information, apparatus, method, or process disclosed in this report may not infringe
privately owned rights; or
B. Assumes any liabilities with respect to the use of, or for domages resulting from the use of
any information, apparatus, method, or process disclosed in this report.
As used in the above, "‘person octing on behalf of the Commission'' includes ony employee or
contractor of the Commission, or employee of such contractor, to the extent that such employee
or contractor of the Commission, or employee of such contractor prepares, disseminates, or
provides access to, any information pursuant to his employment or contract with the Commission,
or his employment with such contractor.
CORNL-2780
Metallurgy and Ceramics
TID-4500 (15th ed.)
Contract No. W-T4O5-eng-26
METALLURGY DIVISION
THE MECHANICAL PROPERTTES OF INOR-8
R. W. Swindeman
DATE ISSUED
JAN 19 1961
OAK RIDGE NATTIONAL IABORATCRY
Oak Ridge, Tennessee
Operated by
UNLON CARBIDE CORPORATION
for the
U. S. ATOMIC ENERGY CCOMMISSION
THE MECHANICAL PROPERTIES OF INOR-8
R. W. Swindeman
ABSTRACT
Tensile, creep, and relaxation tests were performed on INOR-8, a nickel-
base alloy developed for use in the Molten-Salt Reactor. The mechanical
properties are summarized and discussed in relation to the composition,
microstructure, and environment.
The results indicate that the minimum strength properties of INOR-8
are sufficient to permit the use of workable design stresses up to 1300°F,
although certain areas are pointed out where additional information is
desirable.
INTRODUCTION
The chemical, metallurgical, and nuclear properties required of a
structural material for use in the Molten-Salt Reactor brought about the
(ref l) As soon as
development of a nickel-base alloy, designated INOR-8.
commercial heats of this material became available, mechanical properties
studies were initiated by several laboratories. This report summarizes the
results obtained by the Mechanical Properties Group of the Metallurgy
Division at the Oak Ridge National Laboratory.
The testing program had two major objectives. The first was to obtain
design data for INOR-8 under conditions similar to those in the Molten-Salt
Reactor, while the second was to study the effect of various metallurgical
factors on the strength and ductility of the alloy. Most of the testing was
done on two heats of material, designated SP 16 and SP 19. The program
l'I‘. K. Roche, The Influence of Composition Upon the 1500°F Creep-Rupture
Strength and Microstructure of Molybdenum-Chromium-Iron-Nickel-Base Alloys,
ORNL-2524 (June 2L, 1958).
_3_
included tensile, creep, and relaxation tests at temperatures in the range of
interest for the Molten-Salt Reactor. The program is supplemented by
mechanical properties data obtained by several other groups at the Qak Ridge
National Iaboratory, the Haynes-Stellite Company,2 and the Battelle Memorial
Institute.3
Because the range of testing techniques and conditions was broad, this
report has been separated into sections covering each type of test. Repre-
sentative data are shown and the variations discussed. More detailed data
are supplied in the Appendix. Where pertinent, the mechanical properties
data obtained by other investigators will be discussed.
MATERTAT
Procurement and Chemistry
Five heats of wrought material have been tested. These are SP 16,
SP 19, M-1566, 8M-1, and 1327. Two heats, SP 16 and SP 19, were supplied
by the Haynes-Stellite Company and were air melted. Two other air-melted
heats, M-1566 and 8M-1, were procured from the Westinghouse Electric Company.
Heat 1327 is identical to 8M-1, except that it was vacuum-arc remelted.
The chemical analyses of these heats are presented in Table I. The
composition specified for INOR-8 is also given and a comparison of the analyses
reveals that the most significant variation occurs in the carbon content which
ranges from 0.02% for SP 16 to 0.1L4% for 8M-1 and 1327. Only SP 19 and M-1566
are within the present carbon specifications.
Annealing Response and Microstructure
The annealing treatment was chosen to be above the anticipated brazing
temperature but below the temperature where excessive grain growth occurs.
For most heats this treatment was for 1 hr at 2100°F. Heat SP 16 developed
a coarse-grain size under these conditions, however, and the temperature was
reduced to 2000°F for most of the test series on this heat. Even this treat-
ment produced a relatively coarse-grain size.
The variations in the ASTM grain-size numbers and the Rockwell B hardness
numbers corresponding to the annealing treatment are shown in Table II. Rod
stock of SP 19 exhibits two grain sizes, AST™ 1-3 and 5-7, corresponding to
2Developmental Data on Hastelloy Alloy N, Haynes-Stellite Company,
(May, 1959).
3r. @. Carlson, Fatigue Studies of INOR-8, BMI-1354 (June 26, 1959).
TABLE I. The Chemical Composition of Five Heats of INOR-8 (Wt %)
Element Specification SP 16 SP 19 M-1566 8M-1 1327
Molybdenum 15 - 19 15.82 16.65 16.1 6.2 17.2
Chromium 6 - 8 6.99 T.43 7.9 T.47 7.0
Iron 5 max .85 4.83 k.2 6.1 5.1
Carbon 0.0k - 0.08 0.02 0.06 0.08 0.1k 0.1k
Manganese 0.8 max 0.3k .48 0.66 0.69 0.73 i
Silicon 0.55 max 0.32 0.0k 0.20 0.2 0.19
Tungsten 0.50 max 0.35 - -- -- - .
Cobalt 0.2 max 0.51 0.51 - -- --
Titanium/Aluminum 0.50 max o -- 0.08 0.08 0.07
Copper 0.50 max -- 0.02 -- -— -
Sulfur 0.01 max -- 0.015 0.004 0.006 0.001
Phosphorus 0.01 max - 0.010 0.002 0.009 0.001
Boron 0.01l max 0.02 - 0.03 == -- - -
Nickel Balance Balance Balance Balance Balance Balance
TABLE II. The Grain Size and Hardness of Annealed INOR-8
Annealing Carbon Range of Range of
Treatment Content ASTM Grain- Rockwell B
(°F) (hr) Heat Geometry (Wt %) Size Number Hardness Number
2000 1 SP 16 Sheet 0.02 2 - U 76 - 86
2000 1 SP 16 Rod 0.02 2 - U 80 - 88
2100 1 SP 16 Sheet 0.02 2 - 3 76 - 86
2100 1 SP 16 Rod 0.02 2 -3 76 - 8k
2100 1 SP 19 Sheet 0.06 L -6 86 - 91
2100 1 SP 19-1 Rod 0.06 1 -3 86 - 91
2100 1 SP 19-3 Rod 0.06 5 =7 88 - 100
2100 1 M-1566 Sheet 0.08 5 -7 87 - 93
2100 1 M-1566 Red 0.08 5 -7 87 - 90
2100 1 8M-1 Sheet 0.14 5 - 7 90 - 93
2100 1 1327 Sheet 0.1k 5 -7 89 - 92
- g -
two different rods designated SP 19-1 and SP 19-3, respectively. With the
exception of SP 19-1 the high carbon heats have the finest grain size and
highest hardness numbers.
Photomicrographs of the annealed sheet specimens are shown in Figs. 1
through 5. The microstructures reveal an equiaxed grain structure with
stringers and clusters of a second phase through the grains and along the
grain boundaries. This phase has been identified as a (Ni, Mo)6 C carbide
and appears to increase with increasing carbon content. The size, number,
and distribution of these carbides vary from heat to heat.
TENSILE PROPERTIES
Equipment and Procedure
Tensile tests were performed in air on sheet and rod material. The
sheet specimens were 0.063-in. thick, 0.5-in. wide, with a 3-in. uniform
gage length. A detailed description of the specimen design has been pre-
sented by Douglas and Manly.5
Rod specimens were of the standard ASTM design
for 0.505- or 0.357-in.~diam gage sections. Tests were performed on a
Baldwin-Southwark hydraulic testing machine having a 120,000-1b capacity.
In all cases the extension rate was 0.05 in. per min.
Results
Typical Data: A series of tensile curves for INOR-8 rod specimens
(SP 16 annealed at 2000°F) is shown in Fig. 6. At elevated temperatures it
is evident that yielding takes place quite abruptly and very little work
hardening occurs during the initial stages of plastic flow. The stress at
the proportional limit and the 0.2% offset yield strength (indicated by the
dash on the tensile curve) exhibit very little temperature dependence between
1000 and 1400°F. This type of behavior was observed for all of the heats
tested. The tensile strength and elongation are considerably more temperature
dependent, as illustrated in Fig. 7.
%A. E. IaMarche, Pilot Plant Development of a Nickel-Molybdenum-Base
High Temperature Alloy, Report No. 2-98848-190, Materials Manufacturing
Department of Westinghouse Electric Company, Blairsville, Penn. (May, 1958).
5D. A. Douglas and W. D. Manly, A Laboratory for the High-Temperature
Creep Testing of Metals and Alloys in Controlled Environments, ORNL-2053
(Sept. 18, 1956).
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. 5 Heat 1327 Amnealed 1 Hr at 2100
Fig
UNCLASSIFIED
ORNL-LR-DWG 46327
50,000
45,000
40,000
35,000
30,000
25,000
STRESS (psi)
_8-[.-
20,000
15,000
10,000
5000
fOOo - IS
fEOOoF.
1
~L3000,
\ 4000 &
\ SOO op
\ 800°F
Fig. 6 1Initial Portion of the Tensile Curves for INOR-8
(SP 16 Annealed at 2000°F) Rod Specimens.
STRAIN
)
-3
TENSILE OR YIELD STRESS (psix 10
140
120
100
80
60
40
20
UNCLASSIFIED
ORNL-LR-DWG 40206
70
> [>
ELONGATION
60
T TENSILE STRENGTH
) A
50
40
30
0.2% YIELD STRENGTH
20
(0]
200 400 600 800 1000 1200 1400
TEMPERATURE (°F)
Fig. 7 Tensile Properties of INOR-8 (SP 16) 0.505-in. Rods
Annealed 1 hr at 2000°F.
1600
(%)
ELONGATION IN 3in.
-E-[_
- 14 -
Effect of Composition and Grain Size: The tensile properties for sheet
specimens of four heats—SP 16, SP 19, M-1566, and 8M-1 (data for SP 19 and
8M-1 are for 0.045-in.-thick sheet and were taken from a test series performed
for Inouye6) are presented in Figs. 8, 9, and 10. The data shown in Fig. 8
indicate that the tensile strengths do not vary greatly from heat to heat.
Although high-carbon and fine-grained heats are slightly stronger than
coarse-grained and low-carbon heats, the tensile strengths for all heats of
the sheet specimens fall within a narrow scatterband.
Figure 9 shows the variation in the yield strength from heat to heat.
Heat 8M-1, high in carbon with a fine-grain size, exhibits the highest yield
strength; while SP 16, low in carbon and coarse grained, is the weakest. -
Values range from 25,000 psi to 38,000 psi at 1300°F.
Tensile elongation data are presented in Fig. 10. The elongation is
constant up to 1000°F, but rapidly drops to a minimum value near 1500°F, the
highest temperature investigated. The elongation decreases with increasing
carbon content and/or decreasing grain size with the exception of M-1566.
Heat M-1566 is the least ductile above 1000°F. A summary of these and
additional tensile data are given in Tables A-1 and A-2 in the Appendix.
Effect of Notches: Tests were performed on notched-rod specimens of
SP 19-3 at several temperatures. These specimens had a gage diameter of
0.357 in. and a notch radius of 0.005 in.
As in the case of most metals, the effect of the notch is to increase
the ultimate tensile strength; but at the lower temperatures, the increase
for INOR-8 is only slight. The notched to unnotched strength ratiocs at room
temperature, 1000, 1200, and 1500°F are 1.08, 1.07, 1.13, and 1.38,
respectively. Data for these tests are presented in Table A-3 of the Appendix.
Effect of Aging: A few aging tests were performed on notched specimens
of SP 19-~3. The selected treatments were 200 hr at 1200°F, Lo hr at 1650°F,
and 4 hr at 1800°F. Data are summarized in Table A-3 of the Appendix. The
results do not indicate any significant aging effect, although the notch
strength ratios are very close to unity below 1500°F.
—
H. Tnouye, Met. Ann. Prog. Rep. Sept. 1, 1959, ORNL-2839, p. 195.
140
120
100
®
O
TENSILE STRESS (psi x 10 )
()
(@]
40
20
UNCLASSIFIED
ORNL-LR-DWG 40207
0.063-in. THICK SHEETS
V22
A
AN
222870
é%
O 5.P. 16 ‘<&
® S.P. 19
A 8 M1
A M1566
4
200 400 600 B0OO 1000 1200 1400 1600 1800
TEMPERATURE (°F)
Fig. 8 Temperature Dependence of the Ultimate Tensile
Strength for INOR-S8.
_g-[_
60
50
D
o
YIELD STRESS (psi x 10 °)
[8Y]
o
N
o
10
UNCLASSIFIED
ORNL- LR-DWG 40208
0.063-in. THICK SHEET
L .y
‘\\\
\\
‘\ \\
™~ [~
.\ "'\
S S -~
) \\ "c-..._
. ™ o~ --...\
T — ——
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-~ AT
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\ -
s ~
\
-—_:‘_;\T_—.; Y
Q v
O S.P. 16
® S P 19
A8 M1
A M1566
200 400 600 800 1000 1200 1400 1600
Fig. 9 Temperature Dependence of the 0.2% Offset
TEMPERATURE (°F)
Yield Strength for INOR-8.
1800
- 9"[-
ELONGATION IN 2-in. (%)
60
50
40
30
20
10
UNCLASSIFIED
ORNL-LR-DWG 40209
0.063-in. THICK SHEETS
”— ——— —y
A — -
i I S —_——
O S.P. 16 \A
® S.P 19
A 8MI
A M1566
\\‘~
200 400 600 800 1000 1200 1400 1600
TEMPERATURE (°F)
¥Fig. 10 Temperature Dependence of Tensile Elongation.
1800
_LT_
- 18 -
Data are also reported in Table A-3 of the Appendix for smooth rods of
coarse-grained SP 19-1 aged 40 hr at 1650°F. No change in the strength
properties is evident, but the elongation at 1500°F has increased from 20
to 50%. This improvement appears to be associated with coarsening of the
carbides and evidence of this coarsening is presented in the section of the
report covering creep.
Effect of Carburization: A few tensile tests were performed on smooth-
and notched-rod specimens of SP 19-3 which had been carburized in sodium-
graphite for LO hr at 1650°F. This treatment resulted in a high-carbon case
which penetrated to a depth of about 0.010 in. Data for smooth rods are
compared to noncarburized material in Fig. 11. Up to 1200°F carburization
results in a slight increase in the yield strength and a decrease in the
tensile strength, elongation, and reduction in area. Data for notched
specimens parallel this behavior with the notch strength ratio being less
than unity when the ratio is in respect to the unnotched-uncarburized
specimens. Summary data are reported in Table A-3 of the Appendix.
Fracture Characteristics and Microstructure: Metallographic studies
were performed on the rod specimens of SP 19-3. This study revealed that the
temperature at which the ductility begins to drop corresponds to the tempera-
ture at which grain-boundary fracture begins to occur. Below 1000°F, the
fracture is predominately transgranular as shown in Fig. 12, while above this
temperature the fracture becomes intergranular as indicated by Fig. 13. The
effect of carburization on fracture is to change the low-temperature mechanism
to one of intergranular fracture. Figures 14 and 15 show the fracture at the
surface for carburized and noncarburized specimens tested at room temperature.
The intergranular fracture which occurs at room temperature in the carburized
zone becomes transgranular in the interior of the specimen where no carburiza-
tion occurs.
CREEP PROPERTIES
Program
Creep tests were performed in molten salt and alr between 1100 and 1800°F.
Since the maximum temperature for long-time service was not expected to exceed
1300°F, most of the tests were conducted in the 1100 to 1300°F temperature
TENSILE AND YIELD STRENGTH (psi)
140,000
120,000
100,000
80,000
60,000
40,000
20,000
UNCLASSIFIED
ORNL-LR-DWG 47361
Fig. 11 Effect of Surface Carburization on the Tensile
Properties of INOR-8 (SP 19) Rod Specimens.
v O A © NON- CARBURIZED
Y m A o CARBURIZED WITH 0.040-in. CASE
60
O
‘———___:\
/TENSILE STRENGTH (o,e)
| e 50
[m]
: \i, I
I 40
A
[ ]
73 30
ELONGATION \
(0.8) / 3 REDUCTION
&\ IN AREA
L A \ | "
—— 20
A Y SNy
f P— Y Y
0.2% OFF SET YIELD “
STRENGTH (V.¥)
U\ 10
0
o) 200 400 600 800 1000 1200 1400 1600 1800
TEMPERATURE (°F)
ELONGATION AND REDUCTION IN AREA (%)
_6-[_
INCHES
ig. 12 Heat SP 19-3 Annealed 1 Hr at 2100°F. Tensile tested at
room temperature. Etchant: Aqua Regia. 100X.
= ol -
& 7o e :
1 * 7 Y-30905
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e Lty 5
= -
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e g i P oy
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’ o / o . ¢ ‘ . - -
| e o {( & LY o Je » tepo®
Fig. 13 Heat SP 19-3 Annealed 1 Hr at 2100°F. Tensile tested at
1500°F. Etchant: Aqua Regia. 100X.
INCHES
INCHES
. ) 1 1 oy : ~ ~\0 gl |
ig. 14 Heat SP 19-3 Annealed 1 Hr at 2100"F. Tensile tested at
room temperature. tchant: Aqua Regia. 100X.
|
no
)
|
FPig. 15 Heat SP 19-3 Annealed 1 Hr at 2100°F. Carburized in Sodium—
Graphite for 40 hr at 1650°F. Tensile tested at room