In this work, corrosion experiments on 9Cr-ODS and
CLAM steels were carried out in static Pb-Li at 873 K for
250 h. Both steels showed weight loss and softening near
the surface after the exposure. Tensile properties did not
change and creep properties degraded slightly for 9Cr-ODS steel. In contrast, CLAM steel showed hardening by
increase in tensile strength and creep rupture time, and
decrease in minimum creep rate and reduction of area.
The metallurgical analyses showed that the both steels
were non-uniformly corroded by preferential corrosion at
grain and sub-grain boundaries. Near the surface,
carbides were lost and Cr was depleted to several tens of
Pm depth. The depletion was heavier for 9Cr-ODS than
for CLAM. The corrosion mechanism was proposed to be
a loss of protective oxide layer followed by dissolution of
Cr in matrix into liquid Pb-Li. The more pronounced
corrosion effect on 9Cr-ODS than on CLAM may be due
to finer grain and sub-grain size enhancing preferential
attack by Pb-Li at the boundaries, or lack of Mn in 9Cr-ODS, which can form protective layers for CLAM.
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