ORNL-2106 - the Molten Salt Energy Technologies Web Site

ANP PROlECT PROGRESS REPORT
the extrusion conditions for the special compositions.
Two billets, T-23012 and T-23014, were
extruded slowly at 2200°F with a 3/-in.-dia
mandrel at an extrusion ratio of 5.41. Bo d alloys
responded satisfactori ly, but the mandrel broke
within the tube blank in each case. With a decreased
rate of extrusion the billet remained in
contact with the mandrel for an excessive length
of time, and the resultant overheating of the tool
caused a subsequent decrease in its ultimate
strength. The utilization of a 1-in.-dia mandrel
alleviated this problem. The final results of slow
extrusion of these alloys at 22OOOF are presented
in Table 3.3.5. Extrusions 1 through 5, shown
in Fig. 3.3.4, are representative of the good tube
blanks obtained from these special compositions.
The tube blanks have been sent to the Superior
Tu be Company for redrawing to 0.500-in.-OD,
0.035-in.-wall tubing.
TABLE 3.3.5. RESULTS OF THE FINAL EXTRUSIONS
OF SPECIAL ALLOYS PREPARED BY THE
INTERNATIONAL NICKEL COMPANY
Mandrel size: 1 in. dio
Nunber of
Alloy Extrusion Extruded ~ccessful
No. Ratio Shape Ex ir us ions
T-230 11 21 Tube blank 2
T-23012 7:l Tube blank 1
T-23013 21 Tube blank 2
T-23014 7:l Tube blank 1
T-23015 7:l Tube blank 2
T-230 11 6.25: 1 Rod 1
T-23012 6.25: 1 Rod 1
T-23013 6.25: 1 Rod 1
T-23014 6.25: 1 Rod 1
T-23015 6.25~1 Rod 1
Hot rolling of the extruded rods was only moder-
ately successful. The rolling temperature was
varied between 1925 and 2100°F, and the
scheduled reduction was approximately 10% per
pass. In general, the lower temperature proved
to be more satisfactory for minimizing edge
cracking. Each alloy was hot rolled to 0.250-in.
strip, pickled, annealed at 205OoF for 1 hr, and
1 64
cold finished to 0.065-in. strip with an intermediate
anneal at 2050°F for 4 hr. Final an- s
nealing of each alloy was scheduled to yield a
grain size of ASTM 6-7. Alloy T-23015 edge-
cracked severely during hot rolling. The other
alloys for which edge cracking did not interfere
with the machining of sound test specimens will
be evaluated for strength.
Battelle Memorial Institute Compositions. - In
cooperation with Battelle Memorial Institute in the
development of nickel-molybdenum-base alloys for
h igh-temperature use, extrusion experiments were
conducted on three promising compositions with
the intention of producing seamless tubing for
corrosion testing. A total of 10 forged billets
representing portions of 220-lb air-melted heats
was fabricated. The results of the experiments
are presented in Table 3.3.6.
Although fast extrusion at a ratio of 5.4:1 re-
sulted in cracking on the inside, all these tube
blanks are being salvaged at the Superior Tube
Company by drilling the as-extruded tube blank
and thus increasing the inside diameter from to
1 in. before tubing reducing. Tube No. 6, shown
in Fig. 3.3.4, is representative of a good extrusion
obtained from these alloys. As is typical of most
of these h igh-strength n ic kel-molybdenum-base
alloy extrusions, a certain amount of surface
roughening was found on the inside, but it was
not so severe as it appears to be in Fig. 3.3.4.
Slight conditioning of the blanks before redrawing
will eliminate these defects. The cause of this
roughening is not completely understood at this
time, but it may be related to the surface condition
of the billet before extrusion or to lubrication
practice during extrusion. All the blanks are
being fabricated to 0.500-in.-OD, 0.035-in.-waII
tubing.
ORNL Compositions. - The basic nickel-
molybdenum alloy containing 15 to 20% mo-
lybdenum possesses corrosion resistance on a par
with that of Hastelloy B, better ductility and
fabricability, but poorer strength properties. Con-
sequently, alloy additions to the basic composition
are required for improving the strength properties.
The elements being investigated as strengtheners
are Ti, AI, W, Nb, Cr, Fe, V, and C. In order to
determine the effect of these elements individually
on corrosion resistance and to establish the
maximum quantity of each element that can he
a
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