EVALUATION OF ULTRASONIC DISSIMILAR BONDS BY ULTRASONIC … · by ultrasonic testing as...
Transcript of EVALUATION OF ULTRASONIC DISSIMILAR BONDS BY ULTRASONIC … · by ultrasonic testing as...
Proceedings of the 6th International Conference on Mechanics and Materials in Design,
Editors: J.F. Silva Gomes & S.A. Meguid, P.Delgada/Azores, 26-30 July 2015
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PAPER REF: 5664
EVALUATION OF ULTRASONIC DISSIMILAR BONDS BY
ULTRASONIC TESTING IMMERSION METHOD
C-SCOPE MODE
H. Abdel-Aleem1(*)
, S. A. Khodir1
Welding Technology and Inspection Lab., Central Metallurgical Res. & Develop. Institute (CMRDI), Egypt (*)Email: [email protected]
ABSTRACT
Ultrasonic bonding is very useful technique for bonding dissimilar metals which brittle
intermetallic compounds are easily developed on conventional fusion welding process. The
possibility of evaluations of ultrasonic bonds by ultrasonic testing was discussed in detail. In
order to evaluate the quality bonds it is necessary to obtain the correlation between the results
by ultrasonic testing as non-destructive test and mechanical properties, tensile shear strength
in this work as a destructive test. It was confirmed that ultrasonic testing (C-scope mode) was
useful to evaluate the bonding situations of the bonds by ultrasonic bonding when the
appropriate threshold level was selected. In this study it was found that threshold level of 200
had a good correlation between the results of ultrasonic testing and tensile shear test.
Keywords: Ultrasonic testing C-scope mode, ultrasonic bonds, tensile shear test, SEM.
INTRODUCTION
Nowadays it is difficult to find any fields without ultrasonics. It has many applications in
material science, chemical science, medical fields and many industries. For example, in
material science ultrasonics have many applications in both macro- and micro-scales. It has
been used to detect some internal defects and cracks inside the materials. In addition, the
physical properties of ultrasonics are used to get some information about the internal
structures of the materials. For example, it is possible to observe the characteristics of
feathery crystals in aluminum welds by using a scanning acoustic microscope (SAM) without
etching the materials. By using ultrasonics, we can get some useful information, which are
difficult to get by other measuring techniques such as electromagnetic waves, X-rays and
electron beam, etc. So recently ultrasonics are essential techniques in the modern industries
(ASNT handbook. 1991 and M. Katoh, 1997)
Ultrasonic bonding is a low temperature welding process. Frictional heat generated by the
process only raises the temperature of the parts beyond approximately one-third of their
melting temperatures. Since little heat is generated, no cooling water for tooling is required,
and the parts do not melt or anneal. This low temperature in bonding process is very
important in dissimilar welding such as aluminum to copper, aluminum to stainless steel and
aluminum to steel. Fusion welding generates intermetallic compounds that reduce the ductility
of some dissimilar combinations bonds as in the case of the aluminum / copper, aluminum /
stainless steel and aluminum / steel joining. Since ultrasonic bonding does not cause melting
these intermetallic compounds are not developed in bonding of those materials.
This work is mainly concerned with the bonding of dissimilar metals by ultrasonic bonding
and their materials evaluation. Many researchers have made valuable contributions for
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understanding of dissimilar ultrasonic bonds (J. Wanger, 1992, Y. Watanabe, 1996, T. Adams
1997 , M. Katoh, 2002 and J. Villafuerate, 2003). They focused their studies on the influence
of bonding conditions on the properties of ultrasonic bonds, observing the existence of
intermetallic compounds, and the evaluation the of bonds quality by different mechanical tests
and microscopic observations near bond interfaces. However, evaluations of ultrasonic bonds
by nondestructive methods were not emphasized in their studies (G. Flood, 1997 and 1999,
M.J. Greitmann 1997, and S. Morita, 1997). The authors tried to evaluate ultrasonic bonds
quantitatively by ultrasonic testing (C-scope mode). Moreover, they tried to find a correlation
between the result of ultrasonic testing and a tensile shear test as mechanical test.
MATERIAL USED AND EXPERIMENTAL PROCEDURES
In this study both similar and dissimilar metals bonded combinations were used. There were
three metals combination 1050W/1050N as similar combination with artificial flaw while the
other two combinations are 5052/ SUS304 and 5052/SPCC respectively used as dissimilar
combinations.
It is natural that aluminum surface is covered with a thin oxide film. In this study a symbol
“N” is used to represent a specimen without anodically-oxidized film that is a sheet as
received, while a symbol “W” is used to represent the specimen with an anodically-oxidized
film. Aluminum 1050N and 1050W are commercially pure aluminum. The thickness of the
oxide film was changed to t0 = 4, 15 and 30 µm with an anodizing method by changing the
anodizing time. The combination of similar metal with artificial flaw is 1050W (t 1.5 mm) to
1050N (t 1.5 mm). oxide films with different thickness represent the artificial flaw inside
bond area after bonding.
For the dissimilar materials combinations, there were two combinations, aluminum 5052
(t 1.5 mm) was bonded for two different materials, stainless steel SUS304 (t 1mm) and cold
reduced carbon steel SPCC (t 1mm) respectively. Table 1 shows the chemical composition of
the material used in this study.
Table 1 - Chemical composition of materials used (mass %)
5052
Si Fe Cu Mn Mg Zn Cr Ti Al
0.09 0.270 0.027 0.049 2.19 0.005 0.19 0.015 Bal.
SPCC
C Si Mn P S Ni Cr Ti Fe
0.05 0.004 0.18 0.01 0.01 - - - Bal.
SUS304
C Si Mn P S Ni Cr Ti Fe
0.06 0.85 1.25 0.035 0.020 8.00 18.00 - Bal.
The width and the length of each specimen are 20 and 100 mm, respectively. Before the
bonding, the specimens were cleaned by ultrasonic cleaning in acetone. After that the bonding
was performed using an ultrasonic welding machine and lap joints (over lapped length: 20
mm) were obtained near the center of the lapped. In case of 1050N/1050W combination,
aluminum sheets with the anodically-oxidized films were set in the upper side, which
contacted a horn of the machine, while aluminum sheets without the anodically-oxidized
films were set in the lower side, which was contacted an anvil. While in case of two other
combinations 5052/SUS304 and 5052/SPCC, steel sheets were set in upper side (horn) and
aluminum 5052 sheets to lower side (anvil). Figure 1 shows an example of bond shape and
dimensions of a specimen to be bonded.
Proceedings of the 6th International Conference on Mechanics and Materials in Design,
Editors: J.F. Silva Gomes & S.A. Meguid, P.Delgada/Azores, 26-30 July 2015
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Fig. 1 - An example of Shape and dimensions of a specimen to be bonded (5052/SPCC)
Table 2 shows conditions of the ultrasonic bonding. For each combination, bonding pressure
and amplitude were kept constant. The value of the amplitude shown here is the one of free
horn tip vibration without load. The vibration direction was parallel to the specimen surface.
Input energy (Ei) for the bonding was changed by 4 steps for the 1050W/1050N and by 5
steps for 5052/SUS304 and 5052/SPCC combinations, respectively. When the value of input
energy (Ei) is input into the machine, it is automatically controlled by the area surrounded by
a power vs. bonding time curve during the bonding.
Table 2 - Conditions of ultrasonic bonding
Combination of materials
Input energy
Ei (J)
Pressure
P (MPa)
Amplitude
A (µµµµm)
Horn tip diameter
D (mm)
1050W/1050N
(N: no oxide film, W: with oxide
film)
Thickness of oxide film
t0 (µµµµm) = 4, 15 and 30
350
0.31
68
7
400
450
500
5052/SUS304
600
0.27
50
6
800
1000
1200
1400
5052/SPCC
800
0.27
50
6
1000
1200
1400
1500
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First, macrostructures of the specimens were observed as bonded. After that, the cross-
sections of the bonds were microscopically observed using an optical microscope. The
distributions of constituent elements and the existence of intermatallic compounds near the
bonding interface were analyzed by EPMA. Moreover, the bonding situation was evaluated
by ultrasonic testing (immersion method, C-scope mode) using ultrasonic imaging equipment
(AT 7000 fabricated by Hitachi Construction Machine Co.,Ltd). For each combination
mechanical properties of the bonds were evaluated by performing tensile shear test.
RESULTS
Features of bonds and their cross sections
Figure 2 shows some examples of macroscopic features of the bonded specimens at different bonding conditions. Knurling marks are observed on the top of the bonded specimens due to
the horn of the ultrasonic bonding machine. The tip diameter of the horn was selected based
on preliminary experiments. This depends on the maximum capacity of the machine.
1050N/1050W (t0 = 15 µm, Ei = 500 J)
Fig. 2 - An examples of macroscopic features of the specimens bonded
In all bonding conditions and each bonding combination, there were flashes around circular
bond areas. The flash around the bond area increased with the increase in bonding energy.
Since the knurling marks and the flash around the bonding area make the specimen surface
rough, it is difficult to transmit ultrasonic waves through these sides of the specimens in
ultrasonic testing, as will be mentioned later. Good bonding was obtained by using the
appropriate range of input bonding energies. When the input bonding energy exceeded the
range a hole was developed in the bond area. We could not also use the input bonding energy
less than the range because it was not enough to bond the materials ( H. Abdel-Aleem 2003
and 2004) .
Figure 3 shows examples of cross-sectional microstructures near the bond interface of the
dissimilar combinations at different bonding conditions, and smooth interface and no un-
bonded region nor intermetallic compounds were observed in the microstructures in these
figures.
Proceedings of the 6th International Conference on Mechanics and Materials in Design,
Editors: J.F. Silva Gomes & S.A. Meguid, P.Delgada/Azores, 26-30 July 2015
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Ei = 1000J Ei = 1400J
Fig. 3 - Examples of microstructures near the bond interfaces of 5052/SUS304 and 5052/SPCC
Results by Electronic Probe Micro Analyzer (EPMA)
Figure 4 (a) and (b) show the results of line analysis for 1050N/1050W 5052/SUS304
combinations. The constituent elements mutually diffuse each other by a few micrometers near the bond interface. In the case of 5052/SUS304, Al and Mg in 5052 diffuse to SUS304 ,
while in the SUS304 side, Fe, Ni, and Cr diffuse to 5052 side. In the case of 5052/SPCC
combination, Al and Mg in 5052 diffuse to SPCC, while in the SPCC side Fe diffuses to 5052
side, Fe diffuse to 5052 side.
Both results of microstructure and EPMA showed that there no intermettalic compound was
observed near the bond interface.
(a) 1050N/1050W (b) 5052/SUS304
Fig. 4 - Result of line analysis near the bond interfaces
SPCC
5052
100 μμμμm
5052
SUS304100 μμμμm
10 μμμμm
Cr
Ni
Mg
Al
Fe
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Ultrasonic testing
The major aim of nondestructive evaluation of materials is quantitative prediction of their
mechanical properties. Ultrasonic waves are well known for its ability to evaluate and create
images of internal structures. Recent advances in ultrasonic technology have demonstrated the
use of ultrasonic waves for evaluating several important welding variables (S. Morita, 1997,
M.J. Grietmann, 1997 and H. Abde;-Aleem 2003, 2004 and 2005).
Ohashi et al. have reported that echo height in ultrasonic testing from the interface of a joint
diffusion-welded depended strongly on the dimensions of the individual flaws distributing
near the interface, and for a given interface echo height the joint had higher strength with the
decrease in the individual flaw size (Ohashi 1997). They also showed that the joint strength
was a function of real bonded area estimated fractographically, irrespective of the flaw size.
They discussed the phenomenon using the result of A-scope image because it was not easy to
obtain quantitative data over the bonded region at that time. In this section, the author tried to
evaluate the bonds by ultrasonic testing. Images obtained here show the situation of bond
interfaces and the distribution of the oxide film since they reflect ultrasonic waves.
S. Rokhlin et al. have introduced a concept for nondestructive evaluation of spot welds (S.
Rokhlin, 1985). This concept was based on ultrasonic measurement of the spot weld diameter
(nugget diameter) which is then used for failure load prediction. They have reported that
ultrasonic waves could be used to estimate shear strength of spot welds.
In this work, we tried to evaluate ultrasonic bonds quantitatively by ultrasonic testing.
Moreover, we tried to find a correlation between the result of ultrasonic testing and a tensile
shear test.
Working sensitivity in ultrasonic testing is affected by the combination of ultrasonic testing
equipment and a probe frequency. In order to perform ultrasonic testing under the same
condition it is necessary to define the standard echo height using the standard test block and
adjust the working sensitivity using the echo height. The working sensitivity was set to 100 %
by using the back wall echo from the upper sheet of the specimen bonded. When a probe
frequency over than 20MHz was used, the ultrasonic transmission loss becomes larger on the
specimen surface. No such a phenomenon was observed when a 10 MHz probe was used.
Usually, 2 or 5 MHz probe is used for the conventional ultrasonic testing. The resolution for
detecting a flaw becomes better when a higher frequency probe is used. Hence, the frequency
was decided to be 10 MHz in this work.
In the ultrasonic testing equipment, the flaw echo heights are represented by the difference in
color tones of 16 levels. Good and bad bond areas are represented by blue and red,
respectively. Depending on the bond quality, the color of the bond area should be in the range
between blue and red. The region of the base metal was represented by red because the
transmitted waves were reflected from the back wall of the base metal and their heights are
largest. The region of water (immersion coupling) was represented by blue because there was
no reflection from it.
Figure 5 (a) and (b) show the comparison of C-scope images as bonded with that after
grinding the surface of the specimen. This specimen was for 1050N/1050W combination.
First, the ultrasonic waves were tried to transmit from the specimen surface, which contacted
the anvil. It is not possible, however, to get a good result because the specimen surface is not
smooth enough as shown in the upper figure of Fig.5 (a) and most of ultrasonic waves were
scattered from the surface. After smoothing the surface by grinding, good results could be
Proceedings of the 6th International Conference on Mechanics and Materials in Design,
Editors: J.F. Silva Gomes & S.A. Meguid, P.Delgada/Azores, 26-30 July 2015
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obtained and it was possible to detect the existence of flaws due to the oxide films in the bond
area as shown in Fig.5 (b). Hence, it was necessary to remove the influence of the roughness
of the specimen surface to apply ultrasonic testing for evaluating ultrasonic bonds.
(a) As bonded (b) After grinding
Fig. 5 - Comparison of C-scope image as bonded with that after grinding the surface
Figure 6 shows an example of the results of ultrasonic testing C-scope image for
5052/SUS304 and 5052/SPCC combinations. The color of the good bonded region becomes
yellow green, not blue in cases of 5052/SUS304 and 5052/SPCC combinations, because there
is a big difference in acoustic impedance (Z) between two base metals in each combination
(Z5052 = 16.9×106 kg/m
2s, ZSUS304 = 45.45×10
6 kg/m
2s and ZSPCC = 46.8 ×10
6 kg/m
2s). This
leads to the result that a reflection coefficient from the good interface of 5052/SUS304 is
0.475 and for the bonding interface of 5052/SPCC is 0.468. Therefore, there is some
reflection can be obtained even if the good bond is obtained at the interface.
(a) 5052/SUS304 (Ei = 1400 J) (b) 5052/SPCC (E
i = 1200 J)
Fig. 6 - Example of C-scope images from the bonds of 5052/SUS304 and 5052/SPCC combinations
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Figure 7 (a), (b), (c) and (d) show examples of C-scope images from the bond interfaces for
the anodically-oxidized film thickness of 0, 4, 15 and 30 µm, respectively, in 1050W/1050N
(Ei=400J). The area of dark blue region corresponding to the good bonding decreased with the
increase in the oxide film thickness for the same input energy. It was possible to evaluate the
bonds with the oxide film by ultrasonic testing. Then the authors tried to evaluate
quantitatively the ratio of good bond area. For this, it is convenient to binarize the C-scope
images by using the appropriate threshold echo height level.
(a) t0 = 0 µm (b) t
0 = 4 µm
(c) t0 = 15 µm (d) t
0 = 30 µm
Fig. 7 - Examples of C-scope images from the bond interfaces for different oxide film thicknesses in
1050W/1050N (Ei = 400 J)
It is possible to obtain quantitatively the ratio of good bonded area in the bond area by
analyzing this image. For this purpose it is convenient to binarize the image by using the
appropriate threshold level. Figure 8 shows examples of images of good bond area
represented by gray, after binarizing the original image of C-scope mode at different threshold
echo height levels (hereafter referred to as threshold level; in this equipment 256 levels from
0 (blue) and 255 (red)). It is possible to obtain the ratio of good bond area by obtaining the
area represented by gray. Features in the bond area change depending on threshold levels.
Figure 9 shows the relation between the ratio of good bond area and threshold level for the
5052/SUS304 combination. The ratio of good bond area smoothly increases with the increase
in the threshold level, it was also the same for 5052/SPCC and 5052N/5052Wcombinations.
Proceedings of the 6th International Conference on Mechanics and Materials in Design,
Editors: J.F. Silva Gomes & S.A. Meguid, P.Delgada/Azores, 26-30 July 2015
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Level 140 Level 160
Level 180 Level 200
Fig. 8 - Examples of C-scope images of good bond area after binarizing the original images at different threshold
level (5052/SPCC, Ei = 1200 J)
Fig. 9 - Relation between the ratio of good bond area and threshold level (5052/SUS304, E
i = 1400 J)
In order to evaluate the quality of bonds it is necessary to obtain the correlation between the
results by ultrasonic testing and mechanical properties, tensile shear strength in this work, by
a destructive test. The feature of fracture surface at good bond area after a tensile shear test
should be ductile, that is, dimple patterns should be observed. The feature at bad bond area,
however, should be brittle, that is, no dimple pattern should be observed. Hence, it is possible
0 40 80 120 160 200 2400
20
40
60
80
100
Threshold level
Ratio o
f good b
ond a
rea (%
)
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to decide the appropriate threshold level by comparing the features of the fracture surfaces by
SEM and contours obtained by binarizing the C-scope images at different threshold levels.
Figure 10 shows the contours at different threshold levels including the contour by the
macrostructure of the bond after the tensile shear test for 5052/SPCC combination (Ei = 1200
J). The location marked X1, X2, X3 and X4 show the area corresponding to the boundaries
between ductile and not-ductile area observed by SEM. Figure 11 (a), (b), (c) and (d) show
SEM images of the locations of X1, X2, X3 and X4 shown in Fig.10, respectively. The best
correspondence is obtained in the threshold level of 200. The same method was used to
determine the appropriate threshold level in case of 5052/SUS304 and 1050W/1050N
combinations. Hence, the good bond area was decided by using the result when binarized at
the threshold level of 200 in this work for 51050W/1050N, 5052/SUS304 and 5052/SPCC
combinations.
Fig. 10 - Contours at several threshold levels including the contour by the macrostructure of the bond after the
tensile shear test (Ei = 1200 J
(a) Location X1 (b) Location X2
(c) Location X3 (d) Location X4
Fig. 11 - SEM images of the locations of X1, X2, X3 and X4 shown in Fig. 10
Proceedings of the 6th International Conference on Mechanics and Materials in Design,
Editors: J.F. Silva Gomes & S.A. Meguid, P.Delgada/Azores, 26-30 July 2015
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Figure 12 (a) and (b) show the relation between the ratio of good bond area and input energy
at the threshold level of 200 for 1050W/105N, 5052/SUS304 and 5052/SPCC combination,
respectively. Three specimens were used for each bonding condition for ultrasonic testing.
Though the data varied widely, the ratio of good bond area was more than 75 % in average
except for the case of input energy Ei = 600J in the case of 5052/SUS304 combination (in this
case input energy is too low to obtain good bonding). It is necessary to deform the softer
metal well in dissimilar combinations in ultrasonic bonding to obtain good bonds. The ratio of
good bond area tended to increase with the increase in the input energy.
(a) 1050W/1050N (threshold level 200) (b) 5052/SUS304
(c) 5052/SPCC
Fig. 12 - Relation between the ratio of good bond area and input energy (threshold level of 200)
Tensile shear test
Tensile shear test was performed for the same specimens after performing ultrasonic testing to
evaluate the mechanical properties of bonds. In every case for each combination, the fracture
was observed along the bonding interface as shown in Fig. 13. Figure 14 (a), (b) and (C) show
the relation between the maximum tensile shear load and input energy for 1050W/1050N,
5052/SUS304 and 5052/SPCC combinations, respectively. Though the data varies, the
maximum tensile shear load tended to increase with the increase in the input energy.
600 800 1000 1200 1400 16000
20
40
60
80
100
Input energy, Ei (J)
Ratio o
f good b
ond a
rea (%
)
400 600 800 1000 1200 1400 160020
40
60
80
100
Input energy, Ei (J)
Ratio o
f good b
ond a
rea (%
)
300 400 500 60040
50
60
70
80
90
100
Input energy, Ei (J)
Ratio o
f good b
ond a
rea (%
)
t0 = 0μμμμm
t0 = 4μμμμm
t0 = 15μμμμm
t0 = 30μμμμm
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1050W/1050N
Fig. 13 - Examples of macroscopic features of the specimens after
(a) 1050W/1050N
Fig. 14 - Relation between
The tensile shear strength was obtained by using
shear load and the ratio of good bond area which was obtained ultrasonically
shear strength was obtained by dividing the
area obtained ultrasonically. Figure 15 shows the relation between tensile shear strength and
input energy for 1050N/1050W,
The result shown in Fig. 15 shows that the
that of the base metal (5052) independently of the input energy. This means that there is a
good correlation between the maximum tensile shear load and the ratio of good bond area by
ultrasonic testing. The tensile shear strength is larger than that in 5052/5052 combination
140 MPa depending on the bonding energy),
1000
2000
3000
4000
Maxim
um
tensi
le s
hear load, F
max (N
)
Al without oxide
Al with oxi
10 m
300 400 500500
1000
1500
2000
2500
Input energy, Ei (J)
Maxim
um
tensi
le shear load, F
max (N
)
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5052/SUS304
Examples of macroscopic features of the specimens after the tensile
(a) 1050W/1050N (b) 5052/SUS304
(c) 5052/SPCC
Relation between the maximum tensile shear load and input energy
was obtained by using the results of both the maximum
of good bond area which was obtained ultrasonically
shear strength was obtained by dividing the maximum tensile shear load by the good bond
Figure 15 shows the relation between tensile shear strength and
1050N/1050W, 5052/SUS304 and 5052/SPCC combinations, respectively
Fig. 15 shows that the strength estimated corresponds to about 75% of
that of the base metal (5052) independently of the input energy. This means that there is a
good correlation between the maximum tensile shear load and the ratio of good bond area by
ensile shear strength is larger than that in 5052/5052 combination
140 MPa depending on the bonding energy), [15] probably because an oxide film of 5052 is
600 800 1000 1200 1400 1600
1000
2000
3000
4000
Input energy, Ei (J)
10 mm
5052
SUS304SPCC
ide
m
500 600
(J)
t0 = 0 μμμμm
t0 = 4 μμμμm
t0 = 15μμμμm
t0 = 30μμμμm
5052/SPCC
tensile shear test
(b) 5052/SUS304
energy
the maximum tensile
of good bond area which was obtained ultrasonically. The tensile
tensile shear load by the good bond
Figure 15 shows the relation between tensile shear strength and
and 5052/SPCC combinations, respectively.
strength estimated corresponds to about 75% of
that of the base metal (5052) independently of the input energy. This means that there is a
good correlation between the maximum tensile shear load and the ratio of good bond area by
ensile shear strength is larger than that in 5052/5052 combination (75-
probably because an oxide film of 5052 is
5052
10 mm
Proceedings of the 6th International Conference on Mechanics and Materials in Design,
Editors: J.F. Silva Gomes & S.A. Meguid, P.Delgada/Azores, 26-30 July 2015
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more easily destroyed by the harder dissimilar metal, that is, SUS304 or SPCC in this work.
M. Hiraishi reported that surface segregation of Mg retarded the good bonding of Al-Mg alloy
sheets in ultrasonic bonding and the adhesion of alcohol on the bonding surface was effective
to improve the strength of bonds (M. Hiraishi, 2003) .In the case of 1050W/1050N, the tensile
shear strength was independent of the input energy and this means that there was good
correlation between the results of the good bond area and the maximum tensile shear load.
The strengths in t0 = 0 and 4 µm were nearly the same and this shows that the oxide film of
about 4 µm did not influence the bond quality. When t0 increased to 15 and 30 µm, the
strength decreased. The strength in t0 =30 µm was about half of the base metal. It was made
clear that the higher tensile shear strength was obtained in the dissimilar metals combination
than in the similar metals combination.
(a) 1050N/1050W (b) 5052/SUS304
(b) 5052/SPCC
Fig. 15 - Relation between tensile shear strength and input energy (threshold level of 200)
CONCLUSION
- Ultrasonic testing immersion method C-scope mode was useful to evaluate the ultrasonic
bondons.
- It was necessary to remove the influence of the roughness of the specimen surface to apply
ultrasonic testing for evaluating ultrasonic bonds.
- In this study it was found that the threshold level of 200 had a good correspondence to the
result of the observation of the fractured surface using SEM.
- There was a correlation between the results of ultrasonic testing and mechanical properties,
tensile shear strength in this work when the appropriate threshold level was selected
600 800 1000 1200 1400 16000
100
200
300
Input energy, Ei (J)
Tensi
le s
hear s
trength
, ττ ττB (M
Pa)
ττττB of 5052 (Base metal)
400 600 800 1000 1200 1400 16000
100
200
300
Input energy, Ei (J)
Tensi
le shear
stre
ngth
, ττ ττB (M
Pa)
ττττB of 5052 (Base metal)
300 400 500 6000
20
40
60
80
100
Input energy, Ei (J)
Tensi
le shear str
ength
, ττ ττB (M
Pa)
ττττB of 1050 ( base metal)
t0 = 0μμμμm
t0 = 4μμμμm
t0 = 15μμμμm
t0 = 30μμμμm
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ACKNOWLEDGMENTS
We would like to express our sincere gratitude to Mr. M. Sudo in Branson Ultrasonic
Division of Emerson Japan Corporation for performing ultrasonic bonding of the specimens.
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