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was fractured only on the front 1 in. The remainder
of the extrusion appeared to be sound. A thin
layer of lnconel was found on the whole length of
the extrusion. This experiment has not, as yet,
been fully evaluated.
Nickel-Molybdenum Binary Alloys. In contrast
to the experiments with the Hastelloys, previous
extrusion experiments with vacuum melts of the
binary alloys in the cast condition showed marked
improvement in the quality and ease of fabrication.
The tendency to fracture was still apparent to a
slight degree and became progressively more
noticeable as the molybdenum content of the alloy
was increased from 20 to 24%. Two extrusions of
tube blanks of the 24% molybdenum alloy were
unsatisfactory for further reduction to small-diameter
tubing because of the large fractures and deep
defects. It was found that the defects could be
eliminated by homogeneizing the cast billets for
48 hr at 2100OF. The minimum homogeneizing time
was not determined. The data obtained in the
extrusions of the nickel-molybdenum binary alloys
are presented in Table 7.1.
PERIOD ENDlNG DECEMBER 10,1954
Since Hastelloy C could not be extrucled with
any degree of success until it was canned in
Inconel, it is concluded that lubricatioin is an
important factor in these experiments. At the
temperature of extrusion, although the alloy is
probably not molten, the grain boundary is weakened
sufficiently by the friction of the flowing metal
against the die to cause fracture. By providing
a layer of lnconel between the die and the alloy,
as by canning, the friction on the alloy is removed.
The friction could also be reduced by increasing
the extrusion temperature, but, to increase the
extrusion temperature, it wil I be necessary to
eliminate the low-melting-point impurities from the
alloys. An alternative would be to reduce the
extrusion temperature and the extrusion ratios.
The following tentative conclusions have been
drawn: (1) Vacuum melting has little effect on the
extrudability of the alloys. (2) The extriidability
of the alloy does not depend on whether it is in
the wrought or the as-cast condition. (3) Homoge-
neizing has a beneficial effect, as evidenced by
alloys of the24% Mo-76% Ni composition. (4) Poor
E 7.1. EXTRUSION DATA FOR NICKEL-MOLYBDENUM BINARY ALLOYS
Atmosphere: Houghton's salt bath No. 1550
Heating Time: tube blanks, 30 min; rod, 45 min
Billets: as-cast, 3 in. in diameter and 3 in. long, homogeneized 48 hr in helium plus hydrogen
Die: 30- to 45-deg cone die, alloy CHW
Mandrel: 1-in. stem, straight, alloy LPD
Lubrication: glass wool in container, Fiberglas sleeving on mandrel stem
Dummy Block: 70-30 brass coated with Necrolene
Temperature Extrusion
tons; minimum, 487 tons
Remarks
One tube extrusion; minor defect 2 in.
from front
24 32 68 2150 6.3 :1 One rod extrusion; failed to extruide
101