Method for welding beryllium

A method is provided for joining beryllium pieces which comprises: depositing aluminum alloy on at least one beryllium surface; contacting that beryllium surface with at least one other beryllium surface; and welding the aluminum alloy coated beryllium surfaces together. The aluminum alloy may be deposited on the beryllium using gas metal arc welding. The aluminum alloy coated beryllium surfaces may be subjected to elevated temperatures and pressures to reduce porosity before welding the pieces together. The aluminum alloy coated beryllium surfaces may be machined into a desired welding joint configuration before welding. The beryllium may be an alloy of beryllium or a beryllium compound. The aluminum alloy may comprise aluminum and silicon.

TECHNICAL FIELD 
This invention relates to a method for welding beryllium. 
BACKGROUND ART 
There have been developed various methods for joining pieces of beryllium. 
These methods include: partially merging a welding film of silver, gold, 
nickel or copper onto a reinforcing unit of stainless steel which is then 
diffusion welded onto the beryllium (U.S. Pat. No. 5,161,179); diffusion 
bonding the beryllium pieces by coating at least one surface of at least 
one of the beryllium pieces with nickel, contacting the beryllium pieces, 
exposing the pieces to lower than ambient environmental pressure, and then 
under pressure heating the surfaces while decreasing the applied pressure 
(U.S. Pat. No. 3,964,667); and brazing or diffusion-welding beryllium 
pieces with one of a family of brazing alloys of aluminum with magnesium, 
or rare earth, or silicon, or tin, or copper, or palladium, or gallium, or 
silver, or bismuth or strontium (U.S. Pat. No. 4,040,822). 
It is difficult to join very thin pieces of beryllium to each other because 
the heat of welding or brazing deteriorates the mechanical strength of the 
thin beryllium pieces. It is difficult to join pieces of beryllium thicker 
than about 0.1 inches to each other. Attempts to autogeneously weld 
beryllium in thicknesses common for industrial uses results in cracking of 
the beryllium. 
It would be advantageous to be able to quickly and easily join beryllium 
pieces using a welding process so that strong, lightweight aircraft, space 
components or satellite parts could be fabricated from beryllium. There is 
still a need for ways of joining beryllium pieces directly to each other 
without regard for the thickness of the beryllium pieces. 
It is an object of this invention to provide a method for joining pieces of 
beryllium. 
It is another object of this invention to provide a method of fabricating 
parts from beryllium. 
Additional objects, advantages and novel features of the invention will be 
set forth in part in the description which follows, and in part will 
become apparent to those skilled in the art upon examination of the 
following or may be learned by practice of the invention. The objects and 
advantages of the invention may be realized and attained by means of the 
instrumentalities and combinations particularly pointed out in the 
appended claims. 
DISCLOSURE OF INVENTION 
To achieve the foregoing and other objects, and in accordance with the 
purposes of the present invention, as embodied and broadly described 
herein, there has been invented a method for joining beryllium pieces 
comprising: 
(a) depositing aluminum alloy on at least one beryllium surface; 
(b) contacting said at least one beryllium surface with at least one other 
beryllium surface; 
(c) welding said at least one beryllium surface to said at least one other 
beryllium surface. 
After deposition of the aluminum alloy on at least one beryllium surface, 
the beryllium surface or surfaces which have been coated with the aluminum 
alloy can be subjected to pressure and elevated temperature to 
substantially reduce the porosity of the aluminum alloy coating or 
coatings. 
After deposition of the aluminum alloy on at least one beryllium surface, 
the aluminum alloy can be machined or otherwise formed into a desired weld 
joint shape.

BEST MODES FOR CARRYING OUT THE INVENTION 
It has been discovered that pieces containing a substantial amount of 
beryllium can be joined by depositing an aluminum alloy onto one or more 
of the faying surfaces before joining the beryllium pieces by welding the 
surfaces together. 
The methods of this invention can be used to join pieces of elemental 
beryllium or alloys of beryllium which contain minor amounts of one or 
more other metals or compounds. For example, the beryllium alloy or 
compound could contain one or more of iron, aluminum, beryllium oxide, 
carbon, magnesium or silicon. 
It has been discovered that a great variety of aluminum alloys can be 
successfully used in the process of this invention. The aluminum alloys 
are particularly advantageous because the aluminum alloys are also 
relatively strong, lightweight metals useful in the same environments in 
which beryllium is used. The aluminum alloys contemplated as useful in 
this invention include alloys of aluminum with from about 10 to about 15 
weight percent silicon. The aluminum alloys can additionally comprise an 
amount in the range from greater than 0 to about 1.5 weight percent of one 
or more other components including, but not limited to, iron, copper, 
manganese, magnesium, and zinc. A combination of one or more aluminum 
alloys can be used on one or more of the beryllium surfaces. 
Generally presently most preferred are depositions of aluminum alloy onto 
the surfaces of the beryllium pieces that are to be joined by employing an 
aluminum alloy consumable electrode in an inert gas metal arc welding 
process. An electric arc is struck between the consumable electrode and 
the beryllium. An inert gas, such as argon or mixtures of argon and 
helium, shields the arc and the aluminum alloy electrode from air. The 
choice of gas depends upon the nature of the joint being welded and the 
particular aluminum alloy being used. 
Electrode diameter chosen will depend upon the voltage level being used and 
the position of the pieces to be welded. Heat from the electric arc melts 
the aluminum alloy from the electrode onto the surfaces of the beryllium 
which are to be joined. 
After deposition of the aluminum alloy on at least one of the beryllium 
surfaces to be joined and prior to contacting the beryllium surfaces to be 
joined with each other, at least one of the beryllium surfaces can be 
subjected to pressure above one atmosphere and to elevated temperatures to 
reduce the porosity of the deposited aluminum alloy or alloys. This hot 
isostatic pressing step, if used, is presently most preferably carried out 
using temperatures in the range from about 400.degree. C. to about 
600.degree. C. and pressures in the range from about 8 KSI to about 30 
KSI. 
After the deposition of the aluminum alloy onto at least one of the 
beryllium surfaces to be joined and prior to contacting the beryllium 
surfaces to be joined with each other, one or more of the aluminum alloy 
coated beryllium surfaces is machined to a weld joint shape. The invention 
method can be used to make butt joints (which can be beveled), step 
joints, fillet welds or other joints. "J" joints can be machined into step 
joint shapes prior to contacting and welding the surfaces or the joints 
can be machined into step joint shapes after deposition of aluminum alloy 
on the surfaces and prior to joining the surfaces. 
The figures which are part of this specification show three examples of 
types of joints which can be made using the present invention. FIG. 1A 
shows two pieces of beryllium 2a and 2b which have had aluminum alloy 4a 
and 4b applied by spray deposition onto the ends to be joined. After 
machining, the aluminum alloy 6a and 6b is in a butt joint configuration. 
FIG. 2A shows two pieces of beryllium 10a and 10b which have had aluminum 
alloy depositions 12a and 12b applied to the surfaces to be joined. After 
machining, the aluminum alloy depositions 14a and 14b are in a step joint 
configuration. 
FIG. 3A shows two pieces of beryllium 18a and 18b which have "J" joint 
configurations 20a and 20b. After spray deposition of aluminum alloy 22a 
and 22b onto the ends to be joined, the aluminum alloy coated ends are 
machined so that the aluminum alloy depositions 20a and 20b are in a step 
joint configuration, as shown in FIG. 3B. 
The aluminum alloy coated surfaces of the pieces of beryllium to be welded 
are then placed into contact with each other and welded. Any of the 
traditional welding methods such as gas tungsten arc welding, electron 
beam welding, resistance welding, flash welding, or laser beam welding can 
be used. 
FIGS. 1C, 2C and 3C show examples of welds of the types of joint which can 
be made using the present invention. FIG. 1C shows the same two pieces of 
beryllium 2a and 2b from FIGS. 1A and 1B after the machined aluminum alloy 
depositions 6a and 6b have been contacted and electron beam welded with 
the electron beam weld 8 in the characteristic configuration for a weld of 
that type. 
FIG. 2C shows the same two pieces of beryllium 10a and 10b from FIGS. 2A 
and 2B after the machined aluminum alloy depositions 14a and 14b have been 
contacted and electron beam welded with the electron beam weld 16 in the 
characteristic configuration for a weld of that type. 
FIG. 3C shows the same two pieces of beryllium 18a and 18b from FIGS. 3A 
and 3B after the machined aluminum alloy depositions 20a and 20b have been 
contacted and electron beam welded with the electron beam weld 26 in the 
characteristic configuration for a weld of that type. 
The following examples will demonstrate the operability of the invention. 
EXAMPLE I 
The beryllium used in this example was an alloy with the composition shown 
in Table 1. 
TABLE 1 
______________________________________ 
Composition of Beryllium Alloy Used in Runs in Example I 
The beryllium alloy was commercially available from Brush 
Welman Corporation as 5.2008 inch diameter Be disks. 
Minimum Maximum 
Component Weight % Weight % 
______________________________________ 
Beryllium 98.0 
Beryllium oxide 1.5 
Aluminum 0.07 
Iron 0.12 
Carbon 0.10 
Magnesium 0.08 
Silicon 0.08 
Sulfur 0.04 
Uranium 0.04 
Other elements, each 0.04 
______________________________________ 
The beryllium alloy was commercially available from Brush Welman 
Corporation as 5.2008 inch diameter Be disks. Six rings of beryllium 
(Samples 1 through 6) having inside diameters of 4.936 inches, outside 
diameters of 5.1 inches and lengths of 0.538 inch were cleaned by the 
following sequence of steps: Blue Gold and ultrasonic degreasing for 3 
minutes at 60.degree. C.; alkaline soaking for 3 minutes; pickling in 
HNO.sub.3 /HF until bright; deionizing in a water rinse; and finally, air 
drying. 
A 0.35 inch diameter 4047 aluminum alloy (718 aluminum) shielded metal 
inert gas welding wire electrode commercially available from Washington 
Alloy Company was used for the aluminum alloy deposition. This aluminum 
alloy electrode contained from 11.0 to 13.0 weight percent silicon, a 
maximum of 0.8 weight percent iron, a maximum of 0.30 weight percent 
copper, a maximum of 0.15 weight percent magnesium, 0.10 weight percent 
magnesium, a maximum of 0.20 weight percent zinc, and up to 0.15 weight 
percent other materials, with the rest of the alloy being aluminum. 
The aluminum alloy was deposited onto the surfaces of the six beryllium 
rings to be joined with one pass of the welder over each of the beryllium 
surfaces to be joined. This resulted in a coating of aluminum alloy 
approximately 0.05 inches thick on the beryllium surfaces. The coating was 
allowed to cool in the fixture. 
Then the beryllium rings with the aluminum alloy deposition were tested for 
porosity of the aluminum alloy coating with a 300 kV X-ray system. The 
X-rays were examined visually for porosity using a 5X hand held magnifying 
glass. The porosity of each of the rings was as reported in the second 
data column in Table 2. 
TABLE 2 
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Porosity of Aluminum Alloy Deposition Layer 
After testing for porosity, the 6 rings were placed in a hot 
isostatic press with a 17 inch diameter by 30 inch long hot zone 
and subjected to 30 KSI pressure of argon at 500.degree. C. for one 
hour. 
Maximum Pore Maximum Pore Maximum Pore 
Diameter, in. 
Diameter, in. 
Diameter, in. 
Sample 
(First Test) (Second Test) 
(Third Test) 
______________________________________ 
1 0.01 0.01 0.003 
2 0.01 0.01 0.003 
3 0.01 0.01 0.003 
4 0.01 0.01 0.003 
5 0.01 0.01 0.003 
6 0.01 0.01 0.003 
______________________________________ 
After testing for porosity, the 6 rings were placed in a hot isostatic 
press with a 17 inch diameter by 30 inch long hot zone and subjected to 30 
KSI pressure of argon at 500.degree. C. for one hour. 
The rings were once again tested for porosity in the same manner using the 
same equipment described above after the hot isostatic press treatment to 
verify porosity reduction. 
The results of the second porosity test were as shown in the third data 
column of Table 2. 
Each of the beryllium rings with the aluminum alloy deposition were then 
machined using standard turning equipment into a butt or step weld joint 
configuration as shown in FIGS. 1B and 2B. 
The machined rings were X-rayed for a third time in the manner described 
above to determine post machining porosity of the aluminum alloy 
deposition layer. The results were as reported in the four data column in 
Table 2. 
A vacuum high voltage electron beam welder rated at 150 kV and 50 mA was 
used to join the beryllium rings. Welding parameters used varied depending 
upon the thickness of the joint made and were as shown in Table 3. 
TABLE 3 
______________________________________ 
Electron Beam Weld Parameters Used in First Six Runs 
Travel 
speed Focus 
Run Voltage, kV 
Current, mA in/min 
Condition 
______________________________________ 
1 90 7.5 10 sharp + 0.012 
2 100 7.5 30 sharp + 0.01 
3 100 8.0 20 sharp + 0.12 
4 100 9.5 20 sharp + 0.01 
5 100 9.5 20 sharp + 0.01 
6 100 9.5 20 sharp + 0.01 
______________________________________ 
The resulting 3 welded pans which were each made from 2 of the rings were 
x-rayed using a 300 kV X-ray system. The X-rays were examined visually for 
porosity using a 5X hand held magnifying glass. No porosity was detectable 
with this visual inspection. 
The parts were visually inspected. Each of the three welded pans exhibited 
an excellent surface appearance. Some "suck-back" (excess material from 
the weld extruding from the opposite side of the beryllium pieces from the 
side on which the weld applied) was observed. 
These results demonstrate that the methods of this invention can be 
successfully used to obtain sound, welded joints between beryllium pieces 
in a relatively simple and economical procedure. 
EXAMPLE II 
Twelve more rings of the same beryllium alloy used in Example I were tested 
to demonstrate the effect of multiple depositions of aluminum alloy on the 
surfaces of the beryllium to be joined prior to electron beam welding. The 
twelve beryllium rings (Samples 7 through 18) with 4.936-inch inside 
diameter, 5.1-inch outside diameter, and 0.538 inch-length were processed 
in exactly the same manner and using the same equipment as the six 
beryllium rings in Example I with the exception that after the first 
deposition of aluminum alloy, a second deposition was made on the surface 
of the first deposition of aluminum alloy. The second deposition of 
aluminum alloy was applied in the same manner as the first using the same 
equipment and same aluminum alloy consumable electrode. The resulting 
aluminum alloy coatings were a total of approximately 0.1 inch thick and 
had the porosities reported in Table 4. 
TABLE 4 
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Porosity of Aluminum Alloy Deposition Layer 
Maximum Pore Maximum Pore Maximum Pore 
Diameter, in. 
Diameter, in. 
Diameter, in. 
Sample 
(First Test) (Second Test) 
(Third Test) 
______________________________________ 
8 0.01 0.01 0.003 
9 0.01 0.01 0.003 
10 0.01 0.01 0.003 
11 0.01 0.01 0.003 
12 0.01 0.01 0.003 
13 0.01 0.01 0.003 
14 0.01 0.01 0.003 
15 0.01 0.01 0.003 
16 0.01 0.01 0.003 
17 0.01 0.01 0.003 
18 0.01 0.01 0.003 
______________________________________ 
The test runs made in Example II further demonstrate the operability of the 
invention. These runs also demonstrate that when a thicker layer of 
aluminum alloy is desired on the beryllium pieces before contacting and 
welding the beryllium pieces, the aluminum alloy can be deposited in 
sequential layers onto the beryllium pieces. 
The welding process of this invention provides a quick and easy way to join 
pieces of beryllium. Using the process of this invention enables deeper 
welds in beryllium pieces to be made than could be made using other 
conventional methods. Once beryllium pieces are joined using the process 
of this invention, the surfaces of the articles can be further finished by 
machining over the weld or by use of other finishing processes known in 
the art. However, the process of this invention results in joined 
beryllium articles which do not require machining or further finishing 
before most uses. The process can be carried out using simple, lightweight 
equipment; generally, an alternating current or direct current power 
supply, power cables, and welding torch are all that are required. 
While the articles of manufacture and methods of this invention have been 
described in detail for the purpose of illustration, the inventive 
articles of manufacture and methods are not to be construed as limited 
thereby. This patent is intended to cover all changes and modifications 
within the spirit and scope thereof. 
INDUSTRIAL APPLICABILITY 
The methods of this invention can be used to fabricate parts for use in 
many applications that require materials with a high strength to weight 
ratio and which have high thermal conductivity. Beryllium parts made using 
the methods of this invention can be used as structural components in 
aircraft, satellites and space applications.