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Fig. 18.3. Hastellay N Containing 14C Annealed 1 hr at 240OOF. Autoradiographs made in situ on lightly etched
surface using Kodak NTE liquid emulsion; 312-hr exposure. Reduced 38%.
The thin film of precipitate in Fig. 18.5a is of N. However, the zirconium addition appears to
the face-centered cubic type with “Ti 20’’ existing be very desirable from the standpoint of improving
as the “spines” and polyhedral particles. The the resistance of the material to embrittlement
threadlike morphology of the face-centered cubic by neutron irradiation. For this reason, we are
precipitate is seen in Fig. 18.Sh.
continuing studies to determine how we can im-
The final objectives of this work are to identify prove the weldatility of zirconium-bearing alloys.
all precipitates present and to correlate their for- One tool that we are using in our study is the
mation with the mechanical behavior ot the alloy. Gleeble. The Gleeble permits us to assess the
hot ductility of the base material as it is being
18.4. HOT-DUCTILITY STUDIES
OF ZI RCONIUM-BEARING MODlFlED
HASTELLOY N
subjected to a thermal cycle simulating that received
by the heat-affected zone (HAZ) of a weldment.
Specimens are fractured, on heating, at increas-
D. A. Canonico
ing temperatures until they no longer exhibit any
~
Our previous work4 has shown that zirconium
4Meta1s and Ceramics Div. Ann. Progr. Rep. J~me 30,
additions cause weld-metal cracking in Hastelloy I 96 7, ORNT .-4 1 70.