ORNL-1771 - Oak Ridge National Laboratory

ANP QUARTERLY PROGRESS REPORi
UNCLASSIFIED
1041, , Y-12934
Fig, F.13. Brcassd Air-Nozzle BBawk, Note
bonding at the points of tangency of the stainless
steel rods.
using threaded molybdenum joints, whish were then
protected from oxidation by the USC of welded cover
plates. h t h loops failed early in corrosion tests
hemuse of ftac:urc of the COYW plates and leakage
frcm the joints.
It is believed :hot overheating of the cover plates
occurred while the loops were being initially heated
by olectricul resistance. Since no metallurgical
bond existed between the molybdenum and the
cladding, separation became inore pronounced with
increased tsnipernfUre, unti I fincpl ly a1 I the current
was being ctxrried by iha rather thin COVE?' plates,
Future molybdcnum Ptre;inol-convection loops will
be made from arc-melted molybdenum, which is
weldable, and the heavy nickel electrodes required
foi resistance hcating will be welded directly to
the molybdenum tuhc instead of to the cladding.
Columbium clad with type 310 stainless steel has
been fabricated into a theriiicrl-convection loop by
-
heliarc wc!dli?g in air. lhis lsop will be tested as
soon as thc accessory parts are available.
122
Inconel-Type Alloys
Eight tlierrnal-convection loops of Inconel-type
I
alloys were fabricated. I he compositions and room
temperature properties of the alloys are given in
Table 7.4. The alloys are being studied as a part
of the effort to obtain alloys with better high-
temperature corrosion resistance than that of Inconel.
TABLE 7.4. PRDPERTIES OF HIGH-PURITY
IN CON EL- T YP E Ab QQYS *
-
Nomina I lensile Yield
Heat E longati on
Composition Strength Point
No, (%I
(wt %) (psi) (psi)
14 18 Cr, 7 Fe, 75 NI 85,000 41,500 49
15 10 Cr, 15 Fe, 75 Ni 77,700 38,800 44
16 5 Cr, 20 ke, 75 Ni 72,700 34,200 41
17 io G, 7 Fe, 83 NI 76,000 36,000 44
18 5 Cr, 10 ke, 75 Ni,
10 Mn
- __
*hta obtained from the Superior Tube Company.
Nick91-Molybdenurn-Bnse Alloys
The nickel-molybdenum-base alloys are also being
studied as port of the effort to obtain alloys with
better high-temperature strength and corrosion re-
sistance than are offered by Inconel. These re-
quirements are met by Hastelloy B; however, some
difficulties have been encountered in attempts to
fabricate this material. In castings and in fusion
welds, o whole range of composition results because
of severe coring during freezing, and thus the
properties of the fabricated specimen vary from one
area to another. Even long-time high-temperature
aging trentinents of such material will not produce
on equilibrium structure. The aging treatment also
results in a great increase in hardness with a
corresponding decrease in ductility. At temperatures
between 1200 and 1800"F, the wrought material
exhibits its poorest ductility because of hot short-
ness, which cun arise from trace impurities or the
precipitation of an age-hardening constituent, which
is probably the case for t-lastelloy 8. Thus the
temperature range of poorest ductility of Hastelloy
R coincides with the temperature range of con-
templated use in high-temperature circu lating-fuel
reactors. Hastelloy B is not recommended for use
in air at temperatures above 1400°F becaose of