Note: Descriptions are shown in the official language in which they were submitted.
122557Z
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HIGH ENERGY BEAM THERMAL PROCESSING OF ALPHA
ZIRCONIUM ALLOYS AND THE RESULTING ARTICLES
CROSS-REFERENCE TO RELATED APPLICATION
Zircaloy alloy fabrication methods and resultant
products which also exhibit improved high temperature, high
pressure steam corrosion resistance are described in related
Canadian Application Serial No. 419,843, assigned to the
same assignee. This related application describes a process
in which a conventional beta treatment is followed by
reduced temperature alpha working and annealing to provide
an alpha worked product having reduced precipitate size, as
well as enhanced high temperature, high pressure steam
corrosion resistance.
BACKGROUND OF THE INVENTION
The present invention relates to alpha zirconium
alloy intermediate and final products, and processes for
their fabrication. More particularly, this invention is
especially concerned with Zircaloy ~ alloys having a
particular microstructure, and the method of producing this
microstructure through the use of high energy beam heat
treatments, such that the material has improved long term
corrosion resistance in a high temperature steam
environment.
The Zircaloy alloys were initially developed as
cladding materials for nuclear components used within a
i~,
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high temperature pressurized water reactor environment
(U.S. Patent No. 2,772,964). A Zircaloy-2 alloy is an
alloy of zirconium comprising about 1.2 to 1.7 weight
percent tin, about 0.07 to 0.20 weight percent iron, about
0.05 to 0.15 weight percent chromium, and about 0.03 to
0.08 weight percent nickel. A Zircaloy-4 alloy is an
alloy of zirconium comprising about 1.2 to 1.7 weight
percent tin, about 0.12 to 0.18 weight percent iron, and
about 0.05 to 0.15 weight percent chromium (see U.S.
Patent No. 3,148,055).
In addition variations upon these alloys have
been made by varying the above listed alloying elements
and/or the addition of amounts of other elements. For
example, in some cases it may be desirable to add silicon
to the Zircaloy-2 alloy composition as taught in U.S.
Patent No. 3,097,094. In addition oxygen is sometimes
considered as an alloying element rather than an impurity,
since it is a solid solution strengthener of zirconium.
Nuclear grade Zircaloy-2 or Zircaloy-4 alloys
are made by repeated vacuum consumable electrode melting
to produce a final ingot having a diameter typically
between about 16 and 25 inches. The ingot is then condi-
tioned to remove surface contamination, heated into the
beta, alpha + beta phase or high temperature alpha phase
and then worked to some intermediate sized and shaped
billet. This primary ingot breakdown may be performed by
forging, rolling, extruding or combinations of these
methods. The intermediate billet is then beta solution
treated by heating above the alpha + beta/beta transus
temperature and then held in the beta phase for a speci-
fied period of time and then quenched in water. After
this step it is further thermomechanically worked to a
final desired shape at a temperature typically below the
alpha/ alpha + beta transus temperature.
For Zircaloy alloy material that is to be used
as tubular cladding for fuel pellets, the intermediate
billet may be beta treated by heating to approximately
. .
~Z557Z
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1050C and subsequently water ~uenched to a temperaturebelow the alpha + beta to alpha transus temperature. This
beta treatment serves to improve the chemical homogeneity
of the billet and also produces a more isotropic texture
in the material.
Depending upon the size and shape of the inter-
mediate product at this stage of fabrication, the billet
may first be alpha worked by hea~ing it to about 750C and
then forging the hot billet to a size and shape appro-
priate for extrusion. Once it has attained the desiredsize and shape (substantially round cross-section), the
billet is prepared for extrusion. This preparation in-
cludes drilling an axial hole along the center line of the
billet, machining the outside diameter to desired dimen-
sions, and applying a suitable lubricant to the surfacesof the billet. The billet diameter is then reduced by
extrusion through a frustoconical die and over a mandrel
at a temperature of about 700C or greater. The as-
extruded cylinder may then be optionally annealed at about
700C. Before leaving the primary fabricator, the ex-
truded billet may be cold worked by pilgering to further
reduce its wall thickness and outside diameter. At this
stage the intermediate product is known as a TREX (Tube
Reduced Extrusion). The extrusion or TREX may then be
sent to a tube mill for fabrication into the final
product.
At the tube mill the extrusion or TREX qoes
through several cold pilger steps with anneals at about
675-700 between each reduction step. After the final
cold pilger step the material is given a final anneal
which may be a full recrystallization anneal, partial
recrystallization anneal, or stress relief anneal. The
anneal may be performed at a temperature as high as
675-700C. Other tube forming methods such as sinking,
rocking and drawing, may also completely or partially
substitute for the pilgering method.
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Thin-walled members of Zircaloy-2 and Zircaloy-4
alloys, such as nuclear fuel cladding, processed by the
above-described conventional techniques, have a resultant
structure which is essentially single phase alpha with
intermetallic particles (i.e. precipitates) containing Zr,
Fe, and Cr, and including Ni in the Zircaloy-2 alloy. The
precipitates for the most part are randomly distributed,
through the alpha phase matrix, but bands or "stringers"
of precipitates are frequently observed. The larger
precipitates are approximately 1 micron in diameter and
the average particle si2e is approximately 0.3 microns
(3000 angstroms) in diameter.
In addition, these members exhibit a strong
anisotropy in their crystallographic texture which tends
lS to preferentially align hydrides produced during exposure
to high temperature and pressure steam in a circumferen-
tial direction in the alpha matrix and helps to provide
the required creep and tensile properties in the circum-
ferential direction.
The alpha matrix itself may be characterized by
a heavily cold worked or dislocated structure, a partially
recrystallized structure or a fully recrystallized struc-
ture, depending upon the type of final anneal given the
material.
Where final material of a rectangular cross
section is desired, the intermediate billet may be pro-
cessed substantially as described above, with the excep-
tion that the reductions after the beta solution treating
process are typically performed by hot, warm and/or cold
rolling the material at a temperature within the alpha
; phase or just above the alpha to alpha plus beta transus
temperature. Alpha phase hot forging may also be per-
formed. ~xamples of such processing techni~ues are des-
cribed in U.S. Patent No. 3,645,800.
It has been reported that various properties of
Zircaloy alloy components can be improved if beta treating
is performed on the final size product or near final size
~55 7~
5 48,331
product, in addition to the conventional beta treatment
that occurs early in the processing. Examples of such
reports are as follows: United States Patent No.
3,865,635, United States Patent No. 4,238,251 and United
States Patent No. 4,279,667. Included among these reports
is the report that good Zircaloy-4 alloy corrosion proper-
ties in high temperature steam environments can be
achieved by retention of at least a substantial portion of
the precipitate distribution in two dimensional arrays,
especially in the alpha phase grain boundaries of the beta
treated microstructure. This configuration of precipi-
tates is quite distinct from the substantially random
array of precipitates normally observed in alpha worked
(i.e. below approximately 1450F) Zircaloy alloy final
product where the beta treatment, if any, occurred much
earlier in the breakdown of the ingot as described above.
The extensive alpha working of the material after the
usual beta treatment serves to break up the two dimen-
sional arrays of precipitates and distribute them in the
random fashion typically observed in alpha-worked final
product.
It has been found that conventionally processed,
alpha worked Zircaloy alloy cladding (tubing) and channels
(plate) when exposed to high temperature steam such as
that found in a BWR (Boiling Water Reactor) or about 450
to 500C, 1500 psi steam autoclave test have a propensity
to form thick oxide films with white nodules of spalling
corrosion product, rather than the desirable thin contin-
uous, and adherent substantially black corrosion product
needed for long term reactor operation.
Where beta treating is performed on the final
product in accordance with U.S. Patent 4,238,251 or U.S.
Patent 4,279,667, the crystallographic anisotropy of the
alpha worked material so treated tends to be diminished
and results in a higher proportion of the hydrides formed
- in the material during exposure to high temperature, high
pressure a~ueous environments being aligned substantially
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parallel to the radial or thickness direction of the
material. Hydrides aligned in this direction can act as
stress raisers and adversely affect the mechanical perfor-
mance of the component.
In addition the high temperatures utilized
during a beta treatment process, especially such as that
described in U.S. Patent 4,238,251, can create significant
thermal distortion or warpage in the component. This is
especially true for very thin cross-section components,
such as fuel clad tubing.
Through the wall beta treating the component,
before the last cold reduction step, as described in U.S.
Patent 3,865,635, may result in increased difficulty in
meeting texture-related properties in the final product
since only a limited amount of alpha working can be pro-
vided in the last reduction step.
BRIEF SUMMARY OF THE INVENTION
In accordance with one aspect of the present
invention it has been found that the high temperature
steam corrosion resistance of an alpha zirconium alloy
body can be significantly improved by rapidly scanning the
surface of the body with a high energy beam so as to cause
at least partial recrystallization or partial dissolution
of at least a portion of the precipitates.
Preferably the high energy beam employed is a
laser beam and the alloys treated are selected from the
groups of Zircaloy-2 alloys, Zircaloy-4 alloys and zircon-
ium-niobium alloys. These materials are preferably in a
cold worked condition at the time of treatment by the high
energy beam and may also be further cold worked sub-
sequently.
In accordance with the present invention inter-
mediate as well as final products having the microstruc-
tures resulting from the above high energy beam rapid
scanning treatments are also a subject of the present
invention and include, cylindrical, tubular, and rectang-
ular cross-section material.
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7 48,331
In accordance with a second aspect of the
present invention the high temperature, high pressure
steam corrosion resistance of an alpha zirconium alloy
body can also be improved by beta treating a first layer
of the body which is beneath and adjacent to a first
surface of said body so as to produce a Widmanstatten
grain structure with two dimensional linear arrays of
precipitates at the platelet boundaries in this first
layer, while also forming a second layer containing alpha
recrystallized grains beneath the first layer. The mater-
ial so treated is then cold worked in one or more steps to
final size, with intermediate alpha anneals between cold
working steps.
Preferably any intermediate alpha or final alpha
anneals performed after high energy beam beta treatment
are performed at a temperature below approximately 600~C
to minimize precipitate coarsening. It has been found
that Zircaloy bodies surface beta treated in accordance
with this aspect of the invention are easily cold worked.
It has also been found that typically both the alpha
recrystallized layer as well as the beta treated layer
when processed in accordance with the present invention
possess good high temperature, high pressure steam cor-
rosion resistance.
Preferably the beta treating is performed by a
rapidly scanning high energy beam such as a laser beam.
In one embodiment of this aspect of the invention, the
degree of cold working after beta treating may be suffi-
cient to redistribute the two dimensional linear arrays of
precipitates in a substantially random manner while retain-
ing good high temperature, high pressure steam corrosion
resistance.
Beta treated and one-step cold worked alpha
zirconium bodies in accordance with this second aspect of
the invention are characterized by two microstructural
layers. Both layers have anisotropic crystallographic
textures; however, it is believed that the outermost
.:~Z;ZS5 ~Z
8 48,331
layer, that is, the layer that received the beta treat-
men~, is less anisotropic than the inner layer. This
difference, however, diminishes as the number of cold
working steps and intermediate anneals after beta treating
increases.
These and other aspects of the present ir.vention
will become more apparent upon review of the drawings in
conjunction with the detailed description o~ the inven-
tion.
BRIEF DESCRIPTION OF THE DRAWINGS
Figures 1 and 2 show optical micrographs of
micro-structures produced by laser treating Zircaloy-4
tubing in accordance with one embodiment of the present
invention.
Figures 3A and 3B show optical micrographs of a
Widmanstatten basket-weave structure produced by laser
treating Zircaloy-4 tubing.
Figures 4A and 4B show transmission electron
micrographs of typical microstructures found in the embodi-
ment shown in Figures 1 and 2.
Figure 5 shows optical and scanning electron
microscope micrographs of typical microstructures present
in the as-laser treated tube according to ~he present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In one embodiment of the present invention it
was found that scanning of final size Zircaloy-4 tubing by
a high power laser beam would provide high temperature,
high pressure steam corrGsion resistance even though a
Widmanstatten basket-weave microstructure was not achieved.
It was found that material processed as described in the
following examples could achieve high temperature, high
pressure steam corrosion resistance even though optical
metallographic examination of the material revealed it to
have partially or fully recrystallized microstructural
regions with a substantially uniform precipitate distribu-
tion typical of that observed in conventionally alpha
worked and annealed 2ircaloy tubing.
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The laser treatments utilized in this illustra-
tion of the present invention are shown in Table I. In
all cases a 10.6 ~ wavelength, 5 kilowatt laser beam was
rastered over an area of 0.2 in. x 0.4 in. (0.508 cm x
1.08 cm) of conventionally fabricated, stress relief
annealed, final size Zircaloy-4 tubing, the tubing having
a mechanically polished (400-600 grit) outer surface, was
simultaneously rotated and translated through the beam
area under the conditions shown in Table I. As the tube
rotation and tube withdrawal rates decreased, more energy
was transmitted to the specimen surace and higher tempera-
tures were attained. This relationship of tube speed to
energy is illustrated by the increase in specific surface
energy (that is energy striking a square centimeter of the
tube surface) with decreasing tube rotation and tube
withdrawal rates as shown in Table I. ~lthough the treat-
ment chamber was purged with argon at a rate of about 150
cubic feet/hour, most tubes were covered with a very light
oxide coating upon exit from the chamber.
Representative sections of each treatment condi-
tion were metallographically polished to identify any
microstructural changes that had occurred. Results ob-
tained from optical metallography are listed in Table II,
where it can be seen that no obvious microstructural
effects were discerned until the rotation speed had been
reduced to below 285 rpm, at which recrystallization
occurred (241 rpm). At the next slowest speed (196 rpm)
the whole tube was transformed to a Widmanstatten basket-
weave structure, Figure 3. Similar Widmanstatten struc-
tures were also observed at a rotation speed of 147 rpm.
The structures produced at rotation speeds of 241 rpm and
285 rpm are shown in Figures 1 and 2, respectively. The
only visible difference between the structures was that
the 241 rpm sample had a fine recrystallized grain
structure, whereas, the 285 rpm sample did not. Faster
rotation speeds resulted in structures which were opti-
cally indistinguishable from the 285 rpm sample. In no
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case was a beta treated structure produced solely in an
outer layer of the tubing. Both the 196 rpm sample, as
,r.,'~ well as the 147 rpm sample, had Widmanst'atten basket-weave
structures (Figures 3A and 3B~ extending through the wall
thickness. Microhardness measurements performed on these
specimens indicated that significant so~tening occurred
only in samples where the rotation speed was less than 241
rpm.
Sections of the laser treated tubing were
10 pickled in 45% H20, 4S% HN03 and 10% XF to remove the
oxide that had formed during the processing, and were
subsequently corrosion tested in 454C (850F), 1500 psi
steam to determine the effect of the various treatments on
high temperature corrosion resistance. After five days
corrosion exposure, all samples that had experienced
rotation rates greater than 285 rpm had disintegrated,
while those with comparable or slower rotation rates had
black shiny oxide films. A summary of the corrosion data
obtained after 30 days exposure in 45~C steam is pre-
sented in Table III, as are data obtained on beta-annealed
+ water quenched Zircaloy-4 control coupons which were
included in the exposures. It can be seen that the laser
treated tubing generally had lower weight gains than the
beta treated Zircaloy-4 control coupons. For comparison,
conventionally processed cladding disintegrates after 5-10
days in the corrosion environment utilized.
Because beta-treated Zircaloy-4 with a Widman-
statten microstructure has good corrosion resistance in
454C steam, it was anticipated, on the basis of optical
metallography, that the laser treated specimens with the
Widmanstatten structure (Figure 3) would also have good
corrosion resistance. However, the change from cata-
strophic corrosion behavior to excellent corrosion be-
havior that occurred between rotation rates of 332 rpm and
2~5 rpm was not expected on the basis of optical metal-
lography and forms the basis of this embodiment of the
present invention. In order to determine what specific
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microstructural changes were responsible for this phenom-
ena, transmission electron microscopy (TEM) samples were
prepared from the 332-241 rpm tubing. The structures that
are characteristic of these specimens are shown in Figures
4A and 4B. (The dark particles shown in these micrographs
are not indigenous precipitates, but are oxides and hy-
dride artifacts introduced during TEM specimen prepara-
tion.) All of the samples had areas which were well
polygonized (Figures 4A, area X) and/or recrystallized
(Figure 4B). The structures were quite similar, in over-
all appearance, to cold-worked Zircaloy-4 that had been
subjected to a relatively severe stress relief anneal.
Precipitate structures were typical of those in normally
processed Zircaloy-4 tubing, although many precipitates
were more electron transparent than normally expected,
indicating that partial dissolution may have occurred. No
qualitatively discernible difference between the specimens
which had poor corrosion resistance and good corrosion
resistance was noted. It is however theorized that dis-
solution of intermetallic compounds may result in enrich-
ment of the matrix in Fe and/or Cr, thereby leading to the
improved corrosion resistance observed.
In accordance with the present invention the
above examples clearly illustrate that laser treating of
Zircaloy-4 tubing so as to provide an incident specific
surface energy at the treated surface of between approx-
imately 288 and 488 joules per centimeter s~uared can
produce Zircaloy-4 material which forms a thin, adherent
and continuous oxide film upon exposure to high tempera-
ture and high pressure steam. Based on these corrosiontest results it is believed that Zircaloy-4 material so
treated will possess good corrosion resistance in boiling
water reactor and pressurized water reactor environments.
While these materials in accordance with this
invention possess the corrosion resistance of Zircaloy-4
having a Widmanstatten structure, it advantageously is
believed to substantially retain the anisotropic texture
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12 4~,331
produced in the alpha working of the material prior to
laser treating, making it less susceptible to formation of
hydrides in undesirable orientation with respect to the
stresses seen by the component during service.
While the invention has been demonstrated using
a laser beam, other high energy beams and methods of rapid
heating and cooling may also be suitable.
The values of specific surface energy cited
above in accordance with the invention may of course vary
with the material composition and factors, such as section
thickness and material surface condition and shape, which
may affect the fraction of the incident specific surface
energy absorbed by the component.
It is also believed that the subject treatments
are also applicable to other alpha zirconium alloys such
as Zircaloy-2 alloys and zirconium-niobium alloys. It is
also believed that the excellent corrosion resistance
obtained by the described high energy beam heat treatment
can be retained after further cold working and low tempera-
ture annealing of the material.
The material to be treated may be in a coldworked (with or without a stress relief anneal) or in a
recrystallized condition prior to laser treatment.
In other embodiments of the present invention
conventionally processed Zircaloy-2 and Zircaloy-4 tubes
are scanned with a high energy laser beam which beta
treats a first layer of tube material beneath and adjacent
to the outer circumferential surface, producing a Widman-
statten grain and precipitate morphology in this layer
while forming a second layer of alpha recrystallized
material beneath this first layer (see Figure 5) . The
treated tubes are then cold worked to final size and have
been found to have excellent high temperature, high pres-
sure steam corrosion resistance. The following examples
are provided to more fully illustrate the processes and
products in accordance with these embodiments of the
present invention.
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Note, as used in this application, the term
scanning refers to relative motion between the beam and the
workpiece, and either the beam or the workpiece may be
actually moving. In all the examples the workpiece is moved
past a stationary beam.
The laser surface treatments utilized in these
illustrations of the present invention are shown in Table
IV. In all cases a continuous wave CO2 laser emitting a
10.6 ~ wavelength, 12 kilowatt laser beam was utilized. An
annular beam was substantially focused onto the outer
diameter surface of the tubing and irradiated an arc
encompassing about 330 of the tube circumference. The
focused arc had a diameter equal to the tube diameter and a
length of 0.1 inch. The materials were scanned by the laser
by moving the tubes through the ring-like beam. While being
treated in a chamber continually being purged with argon,
the tubes were rotated at a speed of approximately 1500
revolutions per minute while also being translated at the
various speeds shown in inches per minute (IPM) in Table IV,
so as to attain laser scanning of the entire tube O.D.
surface. The variation in translation speeds or withdrawal
or scanning speeds were used to provide the various levels
of incident specific surface energy (in joules/centimeter
squared) shown in Table IV. Under predetermined conditions
of laser scanning, as the specific surface energy increases
the maximum temperature seen by the tube surface and the
maximum depth of the first layer of Widmanstatten structure,
both increase. Rough estimates of the maximum surface
temperature reached by the tube were made with an optical
pyrometer and are also shown in Table IV. While these
values are only rough estimates they can be used to compare
one set of runs to another and they complement the
calculated specific surface energy values since the latter
are known to be effected by interference of the chamber
atmospheric conditions on laser workpiece energy coupling.
The tubes treated included conventionally pro-
cessed cold pilgered Zircaloy-2 and Zircaloy-4 tubes having
a 0.65 inch diameter x 0.07 inch wall thickness,
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and a 0.7 inch diameter x 0.07 inch wall thickness,
respectively. The tubes had a mill pickled surface.
Ingot chemistries of the material used for the various
runs are shown in Table V.
After the beta treatment the tubes were cold
pilgered in one step and processed (e.g. centerless ground
and pickled) to final size, 0.4~4 inch diameter x 0.0328
inch wall thickness, and 0.374 inch diameter x 0.023 inch
wall thickness for the Zircaloy-2 and Zircaloy-4 heats,
respectively.
Representative sections from various runs were
then evaluated for microstructure, corrosion properties,
and hydriding properties. Microstructural evaluation
indicated that for the runs shown in Table IV the Widman-
statten structure originally produced in the .070 inchwall typically extended inwardly from the surface to a
depth of from 10 to 35 percent of the wall thickness,
depending upon the beta treatment temperature. The abso-
lute value of these` first layer depths, of course, de-
creased significantly due to the reduction in wall thick-
ness caused by the final cold pilgering.
Lengths of tubing from the various runs were
then pickled and corrosion tested in high temperature,
high pressure steam and the data are as shown in Tables VI
and VII. It will be noted that in all cases the samples
processed in accordance with this invention had signifi-
cantly lower weight gains than the conventionally alpha
worked material included in the test standards. It was
noted, however, that in some cases varying degrees of
accelerated corrosion wer~ observed on the laser beta
treated and cold worked samples (see Table VI 1120C, and
1270-1320C materials). These are believed to be an
artifact of the experimental tube handling system used to
move the tube under the laser beam which allowed some
portions of tubes to vibrate excessively while being laser
treated. These vibrations are believed to have caused
portions of the tube to be improperly beta treated result-
` ` i2;~5572
48,331ing in a high variability in the thickness of the beta
treated layer around the tube circumference in the affected
tube sections, causing the observed localized area~ of high
corrosion. It is therefore believed that these incidents of
accelerated corrosion are not inherent products of the
present invention, which typically produces excellent
corrosion resistance.
Oxide film thickness measurements performed on the
corrosion-tested laser-treated and cold-worked Zircaloy-4
samples from the tests represented in Table VI surprisingly
indicated that the inside diameter surface, as well as the
outside diameter surface, both had equivalent corrosion
rates. This was true for all the treatments represented in
Table VI except for the 1120C treatment, where the inner
wall surface had a thicker oxide film than the outer wall
surface.
Based on the preceding high temperature, high
pressure steam corrosion tests it is believed that these
alpha Zirconium alloys will also have improved corrosion
resistance in PWR and BWR environments.
The mechanical property characteristics and
hydriding characteristics of the treated materials were
found to be acceptable.
In this invention since only a surface layer of
the intermediate tube is beta treated, it is believed that
the crystallographic texture of the final product can be
more easily tailored to provide desired final properties
compared to the method disclosed in U.S. Patent No.
3,865,635. In this invention both the alpha working before
and after the surface beta treatment can be used to form the
desired texture in the inner layer of the tube.
Both good outside diameter and inside diameter
corrosion properties have been achieved by laser surface
treating and cold working according to this invention,
without resort to the precipitate size control steps of
Canadian Application Serial No. 419,843 prior to
the laser treating step, as demonstrated by the
1'~2557~
16 48,331
preceding examples. However, in another embodiment of the
present invention, the process of the copending applica-
tion, utilizing reduced extrusion and intermediate anneal-
ing temperature, may be practiced in conjunction with the
high energy beam beta treatments of this invention. In
this embodiment, the high energy beam surface treatment
would be substituted for the intermediate anneal at step
5, 7 or 9, of the copending application. The intermediate
product, in the surface beta treated condition, would have
an outer layer having a Widmanstatten microstructure
adjacent and beneath one surface, and an inner layer,
beneath the outer layer, having recrystallized grain
structure with the fine precipitate size of the copending
application. Subsequent working and annealing in accord-
ance with the present invention would produce a final
product having a substantially random precipitate distri-
bution and a fine precipitate size in its inner layer.
In applying the present process to Zirconium-
niobium alloys it is preferred that the material be aged
at 400-600C after cold working. This aging will occur
during intermediate and final anneals performed on the
material after the laser surface treatment.
The above examples of this invention are only
illustrative of the many possible products and processes
coming within the scope of the attached claims.
l;~Z557~
17 48, 331
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TABLE II
ZIRCALOY-4 LASER HEAT TREATME~TS
Rotation
RateTranslation Optical Microhardness
(rpm) Rate (in/min) Microstructural Observations (kg/mm )
485 145.5~o Observable Effect 219
473 142 " 228
4S5 136.5 " 215
430 129 " 228
407 122 " 222
376 113 " 224
332 100 " 223
285 85.5 " 207
241 72Fine Recrystallized Structure 222
196 59~Tidmanstatten Structure 196
147 44l~idmanstatten Structure 196
TABLE III
454C (850F) CORROSIO~ DATA OBTAINED ON
LASER TREATED ZIRCALOY-4 TUBING EXPOSED FOR 30 DAYS
~lean ~'eight Gain
Sample(mg/dm2)
285 rpm 168
241 rpm 217
196 rpm 207
147 rpm 211
Beta-Annealed (9;0C) ~ 262
~'ater Quenched
55~7~
lg 48, 331
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21 48,331
TABLE V
INGOT CHEMISTRY OF ZIRCALOY TUBES
PROCESSED IN ACCORDANCE WITH THE INVEN~ION
Zircaloy-4 Heat A Zircaloy-4 Heat B ~ircaloy-2
Run Nos. 23-43 ~un Nos. 44-48Run Nos. 49-63
Sn1.46-1.47 w/o 1.42-1.52 w/o 1.44-1.63 w/o
Fe.22-.23 w/o .19-.23 w/o .14-.16 w/o
Cr.11-.12 w/o .lO-.12 w/o .11-.12 w/o
Ni ~50 ppm C35 ppm .05-.06 w/o
Al42-46 ppm 39-58 ppm ~35 ppm
B <0.5 ppm < 0.25 ppm < 0.2 ppm
Ca NR <15 ppm NR
Cd<0.5 ppm <0.25 ppm ~0.2 ppm
C115-127 ppm 125-165 ppm 10-40 ppm
Cl <10 ppm 7-11 ppm <~0 ppm
Co<~0-13 ppm <~0 ppm ~10 ppm
Cu <10 ppm <25-44 ppm <25 ppm
Hf52-53 ppm <80-84 ppm 51-57 ppm
Mn <~0 ppm <25 ppm <25 ppm
20 Mg <~O ppm <~O ppm <10 ppm
Mo <20 ppm ~2; ppm ~25 ppm
Pb NR <25 ppm NR
Si 52-54 ppm 60-85 ppm 99-119 ppm
Nb <50 ppm <50 ppm NR
Ta100 ppm <100 ppm NR
Ti18-48 ppm <25 ppm ~25 ppm
U<0.5 ppm <1.8 ppm ~1.8 ppm
U235 .002-.004 ppm .010 ppm NR
V<20 ppm <25 ppm NR
W<50 ppm <50 ppm <50 ppm
Zn~50 ppm NR NR
H2-18 (12-17) ppm 5-7 ppm (<~2) ppm
N35-40 (35-43) ppm 40 ppm (21-23) ppm
01100-1140 (1100-1200) ppm1200-1400 ppm (1350-1440) ppm
Values reported typically represent the range of analyses
determined from various positions on the ingot.
Values in parentheses represent the range of analyses as
determined on TREX.
NR = not reported
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22 48, 331
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