ORNL-1771 - Oak Ridge National Laboratory

loop plugged after 768 hr of operation with hot-
and cold-leg temperatures of 820 and 510°C, re-
spectively. A transverse section of the hot-leg
specimen is shown in Fig. 6.19.
A survey of the alloys which have been tesfed
revealed that the plugging time for all those in
which intermetallic compound formation is a possi-
bility (types 410 and 446 stainless steel, 2%
Si-14% Cr-84% Fe, Hastelloy B (5% Fe-28% Mo-
67% Ni),25% Mo-75% Ni, 45% Cr-55% Co, and 16%
Ni-37% Cr-47% Fe (austenite plus sigma)] was in
excess of 500 hr, the only exception being the loop
containing the 16% Ni-37% Cr-47% Fe specimens
which plugged in 456 hr. The plugging times for
loops containing the pure constituents of these
alloys were: Ni, 2 hr; Co, 80 hr; Cr, 100 hr; and
Fe, 250 hr. No mass transfer was observed in a
loop containing molybdenum specimens after 500
PERIOD ENDING SEPTEMBER 70, 1954
hr of operation. On the other hand, loops with
specimens of alloys for which there is virtually no
tendency toward compound formation (types 304
and 347 stainless steel, Inconel, and nichrome)
all plugged in less than 150 hr. On the basis of
these data, it was concluded that resistance to
muss transfer in liquid lead is considerably greater
in alloys in which intermetallic compound formation
is possible.
Future work will include tests of two alloys: one
with the composition of 50% Cr-50% Fe and the
other with approximately 50% Fe-50% Mo. These
compositions correspond closely to the composi-
tions of intermetallic compounds in types 410 and
446 stainless steel, and if the ideas presented
above are correct, both should show relatively
high resistance to mass transfer in liquid lead.
Fig. 6.19. Transverse Section of 45% Cr-55% CQ Specimen Exposed to Liquid bead at 82Q°C in the
Hot-Leg Section of a Quartz Thermal Convection Emp.
101