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ANP PROJECT PROGRESS REPORT
THERMAL-CONVECTION LOOP TESTS OF
INCONEL CASTINGS
J. H. Devon E. A. Kovacevich
In order to evaluate the use of lnconel castings
for large, intricate sections required in the ART,
three standard inconel thermal-convection loops
with cast lnconel inserts in the hot legs were
operated for 500 hr. The castings, whose compo-
sitions are given in Table 3.1.3, contained approxi-
mately 1.2% manganese, 2% niobium, and 1 to 2%
silicon. Inserts 321 and 322, which had the
lowest and the highest silicon contents, re-
spectively, were tested in loops which circulated
the fuel mixture (No. 30) NaF-ZrF4-UF, (50-46-4
mole %) at 150O0F, while the remaining insert,
323, with an intermediate silicon content, was
136
tested in a loop which circulated sodium at cd
15OOOF. .
As shown in Table 3.?.4, very severe corrosion
of the cast specimens was found in the loops
which circulated the fuel mixture. The attack
occurred not only in the form of the subsurface
voids that are typical of the attack of wrought
Inconel, but, in addition, very deep intergranular
penetrations appeared, which reached in the worst
case to a depth of 70 mils, as shown in Fig. 3.1.3.
These intergranular penetrations, although a
result of rapid attack of grain-boundary con-
stituents, were aided considerably by the porosity
and the shrinkage cracks present in all the castings
in the as-received condition, as shown in Fig. 3.1.4.
The casting containing 1% silicon was found to be
TABLE 3.1.3. CHEMICAL ANALYSES OF CAST INCONEL INSERTS TESTED IN
STANDARD INCONEL THERMAL-CONVECTION LOOPS
Cast lnconel Insert
Chemical Analyses (wt %)
No. Ni* cu Fe Si Mn C Cr Nb S
32 1 70.49 0.01 8.20 1.04 1.22 0.23 16.67 2.08 0.005
322 69.79 0.03 8.20 1.93 1.17 0.22 16.51 2.09 0.006
323 70.44 0.02 8.10 1.34 1.16 0.22 16.67 2.00 0.004
*Obtained by difference analysis.
TABLE 3.1.4. RESULTS OF METALLOGRAPHIC EXAMINATION OF INCONEL THERMAL-CONVECTION
LOOPS OPERATED WITH CAST INCONEL INSERTS IN THE HOT LEGS
Operating time: 500 hr
Maximum fluid temperature: 1500°F
Meta
Loop
I lographic Results
Insert
Circulated Fluid
No. No. Hot-Leg Attack Cold-Leg Attack
876 32 1 NaF-ZrF4* Cast section, 25 mils Light surface roughening with
(50-46-4 mole %) Weld interface, 70 mils a metal deposit present
877 322 Na F-ZrF4-U F4* Cast section, 23 mils Light surface roughening with
(50-46-4 mole %) Weld interface, 25 mils evidence of metal crystals
878 Control Na F-Zr F4-U Fa* 10 mils
(50-46-4 mole %)
No attack
879 323 Sodium No attack No attack; no deposits
*Fuel mixture No. 30.
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