Development of
Nickel-Chromium-Silicon Base
Filler Metals
Alloying with small amounts of phosphorus
decreases
melting temperatures
during development
on
low melting boron-free brazing filler metals for high temperature
service
BY E. LUGSCHEIDER, O. KNOTEK A N D K. KLOHN
Introduction
For some applications—mainly in the
nuclear industries—boron-free nickel
base filler metals are prefered. O n e of
the important filler metals used in
these fields in West Germany is the
nickel-chromium-silicon filler metal
BNi-5. This nickel base filler metal,
containing 19 wt-% chromium and 10.2
wt-% silicon, has a considerably high
liquidus temperature of about 1408 K
or 1135 C (2075 F) in comparison to
boron-containing filler metals such as
BNi-2, BNi-3 or BNi-4. 1
Although the suggested brazing
temperature of BNi-5 is high, this filler
metal is used in non-nuclear industries
because of the possibility to get very
ductile joints using a heat treatment
after brazing. The brittle silicide hard
phases of the brazing gap can be eliminated during the diffusion heat treatment because of the high solid solubility of silicon in the base metal. 2 This
most important improvement of joint
ductility for high strength components
is very difficult in cases using boridecontaining filler metals because of the
very low solid solubility of boron in
the base metal.In developing boron-free low melting nickel base filler metals, the melting behavior of nickel-chromium silicon alloys (depending on the chromium and silicon content) has been
investigated systematically. Further,
the influence of low content of phosphorus on the melting and flowing
behavior has been examined.
Selected Ni-Cr-Si and Ni-Cr-Si-P
alloys were used for brazing experiments. Their strength properties were
tested using the AWS single-lap standard method. 1 The ability of the investigated alloys for high temperature
brazing filler metal is discussed.
Properties of Ni-Cr-Si and
Ni-Cr-Si-P Alloys
Melting Behavior of Ni-Cr-Si Alloys
In the nickel-rich part of the Ni-Cr-Si
system, the filler metal BNi-5 is the
only alloy used in high temperature
brazing. BNi-5 (19 wt-% Cr, 10.2 wt-%
Si, bal. Ni) has a liquidus temperature
of 1408 K or 1135 C (2075 F). Systematic
investigations on the melting behavior
of ternary alloys dependent on the
chromium and silicon content should
show if there are concentration areas
of lower melting temperatures.
The element silicon is essentially
responsible for reducing the melting
point of Ni-Cr-Si alloys. O n the other
hand, silicon stabilizes brittle silicide
hard phases distributed in the nickel
solid solution. 3 Therefore, a compromise has to be made between lowering the melting point and raising the
volume of hard phases; this leads to an
upper limit corresponding to a silicon
content of about 10 to 15 wt-% in the
filler metal. The decrease of the melt-
Paper presented during the Ninth International AWS-WRC Brazing Conference held
in New Orleans, Louisiana, during April 4-6,
1978.
E. LUGSCHEIDER, O. KNOTEK AND K.
KLOHN are with the Institut fur Werkstoffkunde, Technical University, Aachen, West
Germany.
ing points of ternary Ni-Cr-Si alloys
can only be given by nonvariant reactions influenced by eutectic reactions
of the binary systems.
In the nickel-silicon binary system
one eutectic reaction exists at significant silicon concentrations. The eutectic is formed between nickel solid
solution and the silicide Ni.,Si at 11.5
wt-% silicon and 1423 K or 1150 C (2102
F). Ni3Si results by a peritectic reaction
between the melt and the silicide
Ni-,Si, at a temperature of 1438 K or
1165 C (2129 F).1
In the nickel-chromium binary system, only one eutectic reaction exists
between the solid solutions of nickel
and chromium at 49 wt-% chromium
and at a temperature of about 1618 K
or 1345 C (2453 F).3 Besides its importance for the melting characteristic of
the alloys, silicon improves the flowing behavior and-similarly to the
chromium—the corrosion and 'oxidation resistance.
The determination of the melting
behavior of nickel-base alloys was
done by differential thermal analysis.
The test conditions were an argon
atmosphere and heating and cooling
rates of 5 K (i.e., 5 C or 9 F) per minute.
The results, are shown in Fig. 1, w h i c h
indicates the relationship between the
liquidus temperature and the concentration of the alloying elements in the
nickel-rich part of the system nickelchromium-silicon.
About 350 samples prepared by
induction heat melting under argon
inert gas atmosphere were investigated. Raw materials for the preparation of these alloys were nickel,
chromium, nickel silicides and chrom-
W E L D I N G RESEARCH S U P P L E M E N T I 319-s
14
28
•
A
0
40
55
45
40
45
chromium ——
Ni
BNi-5
BNi21.5Cr11.6Si
ot - % 60
55-wt.-% 60
Fig. 1—Liquidus temperature of nickel-chromium-silicon alloys dependent on the composition in the concentration range of
0-40 wt-% chromium and 0-14 wt-% silicon. Dark lines are projections of melting grooves
ium silicides, all of at least 99.8% purity.
Figure 1 shows that—in the investigated concentration range of 0-40
wt-% chromium, 0-14 wt-% silicon,
and the balance nickel—a ternary
eutectic exists at a temperature below
1350 K or 1077 C (1971 F). The ternary
eutectic is given by the point of intersection between melting grooves
(dark lines in Fig. 1) and was found at
20 at.-% chromium and 21.3 at.-% silicon; this corresponds to 20.5 wt-%
chromium and 11.8 wt-% silicon.
a
2600
F
2500
The melting grooves are the lines of
intersection of the melting planes
(planes of primary crystallization). The
plane of the primary crystallization of
the nickel solid solution slopes steadily from the melting temperature of
nickel to the temperature of the ternary eutectic for 376 K/C (676 F). In other
words, the temperature of the primary
crystallization of the nickel solid solution decreases with increasing concentrations of silicon and c h r o m i u m , but
the influence of silicon is much more
pronounced as shown by the isoliqui-
Figure 2 shows such sections at
constant chromium content of 19
wt-% containing the filler metal c o n centration of BNi-5—and of 20 and 21
wt-% chromium. All sections are near
the concentration of the ternary eutectic. The dependence of the liquidus
temperature on the silicon content in
Fig. 2 indicates that a small change of
Cr = const 19 wt. - %
o
Cr = const. 2 0 w t . - %
A
Cr = const 21 w t - %
dus curves drawn in steps of 50 K, i.e.,
50 C (90 F).
The melting planes in concentration
areas with silicon contents of more
than about 11 wt-% show a slope
similar to the part of the melting plane
at high nickel concentration. Of great
importance for developing Ni-Cr-Si
filler metals is the strong influence of
the composition on the liquidus temperature in concentration ranges near
the ternary eutectic. This fact can be
better demonstrated by concentration-temperature sections.
15
2400
2300
2200
F
CD
2200
2100
a
i
2100
|
2000
QJ
2000
n-5
1900
1300
BNi 21.5Cr 11.6Si
1900h
1300
0
_L
4
_L
8
12
0
2
4
6
A BNi20.3Cr11.5Si 0.5P
1800h
_L
16
8
20 a t . - %
silicon — » -
28
10 - w t - % 14
s i l i c o n ——
Fig. 2—Liquidus temperature of nickel-chromium-silicon alloys
with constant chromium content ol 19, 20 and 21 wt-%, dependent
on the silicon content
320-s I O C T O B E R 1978
1700
1200
J
L
2
3 wt. % 4
phosphorus —•»-
Fig. 3—The influence of phosphorus on the liquidus temperature oi
an alloy with 20.4 wt-% chromium, 11.6 wt-% silicon, balance
nickel
1500
2003
199;
1832 -
1500
F
1368
1363
1273
K
1000
CD
1000
F/g. 4—Wett/ng ang/e of f///er meta/ 8N/
20.30 77.55/ 0.5P on stainless steel at 1343
K, 1070 C (1958 E)
500 " 500
3? -
the composition of filler metal BNi-5
leads to alloys w i t h liquidus temperatures of about 58 K/C (104 F) below
the liquidus temperature of BNi-5. For
further investigations an alloy near the
ternary eutectic w i t h 21.5 wt-% chromium, 11.6 wt-% silicon and balance
nickel was selected.
Melting Behavior of Ni-Cr-Si-P Alloys
Besides the elements silicon and
boron, phosphorus is also an effective
element to lower the melting temperature of nickel base alloys as it is k n o w n
from the melting behavior of the filler
metals BNi-6 and BNi-7. 1 In Fig. 3 the
influence of phosphorus on the liquidus temperature of the approximate
ternary eutectic alloy w i t h 20.4 wt-%
chromium, 11.6 wt-% silicon and
balance nickel is shown. The graph
demonstrates that only small amounts
of phosphorus of about 0.5 wt-% give
an additional decrease of the melting
point of alloys in concentration areas
of the ternary eutectic.
The alloy w i t h 20.3 wt-% chromium,
11.5 wt-% silicon, 0.5 wt-% phosphorus, and balance nickel has a liquidus
temperature of 1333 K or 1060 C (1940
F). This means that this boron-free
filler metal BNi 20.3Cr 11.6Si 0.5P
which was selected for further investigations has a 75 C or 75 K (135 F) lower
liquidus temperature than the filler
metal BNi-5 and a similar melting
behavior in comparison to used boron-containing filler metals.
Further investigations in alloying NiCr-Si alloys with phosphorus show
that a decrease of the silicon content
in the alloy in respect to lowering the
hard phases requires higher amounts
of phosphorus of about 3 wt-% to give
similar melting behavior to alloy BNi
20.3Q H.6Si 0.5P. For instance, an
alloy with 14.8Q 8Si 3Fe 3P balance
nickel has a melting range of 1269 K or
996 C (1825 F) to 1336 K or 1063 C
(1945 F).
Flow Behavior and Structure of BNi 21.5Cr
11.6Si and BNi 20.30 11.5Si 0.5P
Besides melting characteristic, the
273
0
30
60
90
120
time —
150 mm 180
Fig. 5.—Time-temperature cycle during vacuum brazing
flow behavior is a very important property for the manufacturing of high
temperature filler metals." As a characteristic value for the wettability, the
contact angle was measured between
the liquid filler metal and a plain base
metal surface at different temperatures. The investigations were made
under vacuum ( < 10~* torr) in the
temperature range of 1323 K or 1050 C
(1922 F) to 1383 K or 1110 C (2030 F).
The base metal was stainless steel (W.
No. 1.4541, X 10 CrNiTi 18 9).
The filler metals BNi 21.5Cr 11.6Si
and BNi 20.3Cr 11.5Si 0.5P w i t h liquidus temperatures of 1358 K or 1085 C
(1985 F) and 1333 K or 1060 C (1940 F)
show good wettability even at temperatures below their liquidus temperature, whereby the phosphorus-containing alloy indicates a slightly better
flow behavior. The wetting angles in
the investigated temperature range for
both alloys in any case were below 3
deg as seen in Fig. 4.
The structure of the alloy BNi 21.5Cr
11.6Si is the same as that of filler metal
BNi-5. The main silicide Ni 5 Si 2 is distributed in the nickel solid solution.
Additionally, very small amounts of a
ternary silicide Cr 3 Ni 5 Si a (n-phase) like
in the case of BNi-5 were found. 7
The phosphorus-containing alloy
BNi 20.3Cr 11.5Si 0.5P has a structure
similar to that of BNi-5. Also, small
amounts of the nickel phosphide Ni,P
are added because of the very little
solid solubility of phosphorus in the
nickel matrix. 2
Brazing Experiments
W i t h selected filler metals BNi
21.5Cr 11.6Si and BNi 20.3Cr 11.5Si
0.5P, brazing experiments were made
to get the optimuTn brazing temperature in regard to their diffusion behavior and joint strength.
The AWS single-lap standard method was used to determine strength
properties. 1 The ratios of overlap to
thickness were 0.5 to 6. The clearance
was 25 /tm (0.001 in.). The brazing was
done in an electric heated vacuum
furnace at a vacuum better than
1.33 X 10 '2 Pa ( 1 0 J torr) according to
the brazing cycle shown in Fig. 5. This
brazing cycle w i t h a brazing time of 10
min and a diffusion heat treatment at
1273 K or 1000 C (1832 F) for 60 min
after brazing, is typical for processing
the filler metal BNi-5 in nuclear industries to get ductile joints. 8
The base metal used was stainless
steel (W. No. 1.4541, X 10 CrNiTi 18 9)
w i t h a yield strength of 214 N / m m 2 (31
ksi) and an ultimate tensile strength of
575 N / m m 2 (83.4 ksi). Both values were
determined after the base metal was
heat treated in the same way as the
brazed joints. The filler metals were
used as powders and placed w i t h
cement.
The results of the strength tests of
joints brazed w i t h the filler metal BNi
21.5Cr11.6Si at temperatures of 1363 K
or 1090 C (1994 F) and 1368 K or 1095 C
(2003 F) are shown in Fig. 6. It can be
seen that, at both brazing temperatures, the tensile stress of the joints is
slightly above the ultimate tensile
strength of the base metal at ratios of
overlap to thickness greater than
about 1.5. At the brazing temperature
of 1368 K or 1095 C (2003 F), the joints
fail at any ratios in the base metal
except the joints with ratios of 2 and 6
where w e find brazing defects in the
brazing gap. In any case, the tensile
stress of the joints is above the yield
strength of the base metal w h i c h indicates a good ductility of the brazing
seam.
loints brazed at a temperature of
1343 K or 1070 C (1958 F) have tensile
stresses above the yield strength of the
base metal. However, the values are in
general lower. The reason can be that
this brazing temperature in connection w i t h the diffusion heat treatment
is not sufficient to eliminate silicide
W E L D I N G RESEARCH S U P P L E M E N T I 321-s
i 100
I KSI
80
«
•
600
N
mm2
\
V /
xf
200
p
YS. base metal
^
•£>•••••£
A
_
n
> - " •
V•'SSklgfe4
K
40
0L
1
•
I /
400
20
/
f
I
A
I
i
i
1
i
1
2
3
4
5
6
overlap distance, ratio of overlap to thickness ——
Fig. 7-M'tcrograph of a joint brazed at 1343
K, 1070 C (1958 F). Base
metal-stainless
steel; filler metal-BNi
21.5Cr 77.65/; clearance-25 nm (0.001 in.)
Fig. 6—AWS single-lap standard method. Base metal—stainless steel (W. No.
1.4541, X 10 CrNiTi 18 9); filler metal-BNi
21.5Cr 11.6SI; clearance-25 nm (0.001
in.); vacuum < 1.33 x 10 - Pa (10-' torr); brazing cycle-See Fig. 5:
Brazing
Average unit shear stress
Average unit tensile stress
'v-'.
V
temperature
1363 K, 1090 C
(1994 F)
7368 K, 1095 C
(2003 F)
V
A
D
Open symbols represent failure in the filler metal; filled symbols represent
in the base metal
,. . V failure
*-1 * j * :-.
11.5Si 0.5P at 1363 K o r 1090 C (1994 F)
a n d 1368 K, 1095 C (2003 F) are s h o w n
in Fig. 9. It seems t h a t t h e t e n s i l e stress
of these j o i n t s also at a r a t i o o f o v e r l a p
t o t h i c k n e s s o f 1.5 is e q u a l t o t h e
u l t i m a t e t e n s i l e s t r e n g t h o f t h e base
metal ( c o m p a r e to Fig. 6 ) . Because o f
t h e fact t h a t s a m p l e s w i t h r a t i o s o f 2, 4
and 6 f a i l e d in t h e f i l l e r m e t a l , f u r t h e r
tests s h o u l d be m a d e t o c o n f i r m t h e
d e p e n d e n c e s h o w n in Fig. 10. O n t h e
other h a n d , joints w i t h o v e r l a p ratios
b e l o w 1 s h o w f a i l u r e i n t h e base m e t a l .
A l t h o u g h b r a z i n g tests at l o w e r b r a z -
100
KSI
:^j&-'•-•"- ,-'
r
::-.m - .:,,-•'
.: -'Iff-'--.
•>••'.
phases o f t h e b r a z i n g g a p b y d i f f u sion—Fig. 7. For t h e m o s t p a r t , j o i n t s
b r a z e d at a t e m p e r a t u r e o f 1363 K, 1090
C (1994 F) or 1368 K, 1095 C (2003 F)
a c c o r d i n g t o t h e b r a z i n g c y c l e in Fig. 5
s h o w n o s i l i c i d e phases in t h e b r a z i n g
g a p - F i g . 8. T h e r e f o r e , f o r t h e f i l l e r
m e t a l B N i 21.5Cr 11.6Si a b r a z i n g
t e m p e r a t u r e of 1368 K, 1095 C (2003 F)
s h o u l d be s u g g e s t e d if h i g h j o i n t
s t r e n g t h has t o b e r e q u i r e d .
T h e results o f t h e s t r e n g t h tests o f
joints brazed w i t h t h e p h o s p h o r u s containing filler metal BNi
20.3Q
" ^
.
'
*
-~
<!)•&
•
Fig. 8—Micrograph of a joint brazed at 1363
K, 1090 C (1994 F). Base
metal-stainless
steel; filler metal-BNi
21.SO 11.6SI; clearance-25 nm (0.001 in.)
ing t e m p e r a t u r e s — f o r i n s t a n c e , at 1343
K, 1070 C (1958 F ) - d e m o n s t r a t e d a
g o o d f i l l i n g o f j o i n t s at gaps o f 25 jitm
(0.001 in.) (Fig. 1 0 ) , t h e s u g g e s t e d b r a z ing t e m p e r a t u r e f o r t h e f i l l e r m e t a l B N i
2 0 . 3 Q 11.5Si 0.5P s h o u l d b e 1363 K or
1090 C (1994 F) t o 1368 K o r 1095 C
(2003 F).
In a n y case, n o o p t i m i z a t i o n o f t h e
v a l u e o f t h e c l e a r a n c e has
been
done.
bOO
80 - N
mm2
60
400
Summary
In d e v e l o p i n g b o r o n - f r e e n i c k e l base l o w m e l t i n g , h i g h t e m p e r a t u r e
40
200
'"',£& *. •
20
0
°0
1
2
3
4
5
overlap distance, ratio of overlap to thickness ——
Fig. 9- -AWS single-lap standard method.
7.4547 X 10 CrNiTi 18 9); filler metal-BNi
(0.007 in.); vacuum < 7.33 X 10- Pa (10*
Base metal—stainless steel (W.
20.30 77.55/ 0.5P; clearance-25
torr); brazing cycle-see Fig. 5:
Brazing
1363 K, 1090 C
Average unit shear stress
Average unit tensile stress
(1994 F)
v
o
temperature
7368 K, 1095 C
(2003 F)
D
Open symbols represent failure in the filler metal; filled symbols represent
in the base metal
322-s I OCTOBER 1978
No.
ju/n
failure
Fig. 10— Micrograph of a joint brazed at 1343
K, 1070 C (1958 F). Base
metal-stainless
steel; filler metal-BNi
20.30 77.55/ 0.5P;
clearance—25 jim (0.001 in.)
Table 1-Characterization of New Filler Metals in Comparison to BNi-5 and BNi-1
Suggested
Tern perature""
Filler metal
Nominal c o m p o s i t i o n , wt-%
Solidus
BNi 21.5Cr11.65i
21.5Cr, 11.6Si, bal. Ni
BNi 20.3Cr11.5SiO.5P
20.3Cr, 11.5Si, 0.5P, bal. Ni
BNi -5
19Cr, 10.2Si, bal. Ni
BNi -1
14Cr, 3B, 4.5Si
4.5Fe, 0.7C, bal. Ni
1335
(1944
1317
(1911
1353
(1975
1250
(1790
brazing filler metals for applications in
nuclear industries, the melting behaviors of nickel-chromium-silicon alloys
in the concentration range of 0-40
wt-% chromium, 0-14 wt-% silicon,
and the balance nickel were investigated systematically.
The lowest liquidus temperature of
1350 K or 1077 C (1971 F) in this
nickel-rich area was found at a ternary
eutectic concentration of 20.5 wt-%
chromium, 11.8 wt-% silicon, the
balance nickel. This means that a small
change of the concentration of filler
metal BNi-5 [19 wt-% Cr, 10.2 wt-% Si,
the balance Ni; T L = 1408 K, 1135 C
(2075 F) ] leads to a 58 K/C (104 F)
lower melting filler metal. Alloying
with small amounts of phosphorus
indicates an additional decrease of the
melting temperature to values of 1333
K or 1060 C (1940 F).
For testing the brazing behavior and
the joint strength, t w o alloys—BNi 21.5
Cr 11.6Si and BNi 20.3O 11.5Si
0.5P—which are characterized in Table
1—were selected. Both alloys have a
structure and diffusion behavior similar to that of BNi-5 and show good
flowing behavior on stainless steel
with wetting angles between 0-3 deg
K
F)
K
F)
K
F)
K
F)
Brazing
range""
Liquidus
1358
(1985
1333
(1940
1408
(2075
1311
(1900
1343-1383
(1958-2030
1343-1383
(1958-2030
1423-1478
(2100-2200
1338-1478
(1950-2200
K
F)
K
F)
K
F)
K
F)
dependent on the temperature.
Strength tests using the AWS single
lap standard method show that, at
higher overlap ratios for joints of stainless steel brazed w i t h both filler
metals, tensile stresses equal the ultimate tensile strength of the base
metal.
The suggested brazing temperature
for the investigated filler metals is 1368
K or 1095 C (2003 F). This means that
these boron-free filler metals give
ductile high strength joints at a brazing
temperature 95 K/C (171 F) and 80 K/C
(144 F) below the brazing temperature
normally used for processing the
boron-free filler metal BNi-5 or the
boron-containing filler metal BNi-1.
Compared to other well k n o w n
boron-containing filler metals, the
alloys BNi 21.5Q 11.6Si and BNi 20.3Q
11.5Si 0.5P should have higher oxidation and corrosion resistance because
of the higher content of chromium
and silicon.
Acknowledgments
This paper is based on work
performed under research and devel-
brazing
temperature'"'
K
F)
K
F)
K
F)
K
F)
1368
(2003
1368
(2003
1463
(2175
1448
(2150
K
F)
K
F)
K
F)
K
F)
opment administration contract No.
3584 of the Arbeitsgemeinschaft Industrieller Forschungsvereinigungen e.
V., West Germany.
References
1. Brazing Manual, American Welding
Society, 3rd Edition, 1976.
2. Hansen, M., and Anderko, K., Const, of
Binary Alloys, McGraw Hill, 1958.
3. Knotek, O., Lugscheider, E., and Eschnauer, H., Hartlegierungen zum Verschleissschutz, Stahleisen, DCisseldorf FRG,
1975.
4. Lugscheider, E., Reimann, H., and
Knotek, O., Monatsh. f. Chem. 106 (1975), p.
1155.
5. Shunk, F. A., Const, of Binary Alloys,
McGraw Hill, 1969.
6. Lugscheider, E., and Iversen, K., "Investigations on the Capillary Flow of Brazing Filler Metal BNi 5," Welding lournal, 56
(10), Oct. 1977, Research Suppl., pp. 319-s to
324-s.
7. Gladishevskii, E. I., and Borusevic, L.
K., Russ. I. Inorg. Chem., 8 (1963) p. 998.
8. Iversen, K„ and Lohe, H., DVS-Bericht
No. 15 (1970).
9. Nicrobraz, Eng. Data Sheet No. 2.1.1.
Rev. H, Wall Colmonoy Corp., Detroit,
Mich., 1974.
AWS Filler Metal Specifications
AWS A5.25-78, Specification for Consumables Used for Electroslag Welding of Carbon and High Strength Low
Alloy Steels and AWS A5.26-78, Specification for Consumables Used for Electrogas Welding of Carbon and High
Strength Low Alloy Steels are now available.
The classification system used in the specifications follows as closely as possible the standard pattern used in
other AWS filler metal specifications. This allows the user to more readily select the proper filler materials.
However, the inherent nature of electroslag and electrogas welding has necessitated specific changes to more
ably classify the electrodes.
Each specification contains 24 pages and they are saddle-stitched, soft cover, 8V2 x 11 in., three-hole
punched, priced at $5.00 per copy. Discounts: 25% to A and B members; 20% to book stores, public libraries and
schools; 15% to C and D members. Send your orders to the American Welding Society, 2501 N.W. 7th St., Miami,
FL 33125. Florida residents add 4 % sales tax.
W E L D I N G RESEARCH S U P P L E M E N T I 323-s
plan now plan n o w p l a n n O W
t O a t t e n d to a t t e n d to attend
The 10th International AWS-WRC
Brazing Conference
at Cobo Hall in Detroit, Michigan
during
Tuesday, Wednesday and Thursday
April 3-5, 1979
— Co-Sponsors—
American Welding Society
Welding Research Council
—Organized
By—
The AWS C3 Committee on Brazing
and Soldering
And held in conjunction with the
60th Annual Meeting of the
American Welding Society
and the
1979 AWS Welding Show
Featured at the C o n f e r e n c e : presentations
by experts on n e w a p p l i c a t i o n s and
significant research and d e v e l o p m e n t
findings.
Featured at the 1979 A W S W e l d i n g Show:
exhibits and d e m o n s t r a t i o n s stressing
n e w brazing e q u i p m e n t and process
d e v e l o p m e n t s 4- a b o o t h m a n n e d by
AWS brazing experts to assist the visitor
in the s o l u t i o n of brazing f a b r i c a t i o n
problems.
324-s I OCTOBER 1978