4th World Conference on
Applied Sciences, Engineering & Technology
24-26 October 2015, Kumamoto University, Japan
Finite Element Analysis of Brazing Joint on Cemented Carbide Alloy
With Low Melting Point Silver Brazing Filler Metal
MERIBE RICHARD CHUKWUMA1, KAZUYA MORI 1, KENTO TAKENOUCHI 1 ,
YUKI FIJISHITA2, TAKESHI EGUCHI2, KAZUFUMI SAKATA2
1
Graduate School of Science and Technology, Kumamoto University, Japan
2
Nakayama Seimitsu Co. Ltd, Japan
Email: [email protected], [email protected]
Abstract: Brazing joints are widely accepted in industry due to its simplicity in a variety of applications. The
strength of brazing joints determines the reliability of brazed engineering components. So the need to ascertain
the reliability or to predict its failure (without some destructive testing) becomes high. While concrete testing is
preferred conceptual testing in the form of computer aided analysis can also be beneficial. In this paper, we have
used Finite-Element Analysis software, Abaqus CAE, to investigate a joint combining cemented carbide brazed
with silver-based filler metal. In this paper, 2D analysis has been adopted because the thickness of the material
(in 2D) does not influence the final calculation results. We have applied constant loading and constant boundary
condition to explore data from the elastic and plastic strain analysis through which we were able to predict the
maximum joint strength with respect to the joint thickness. The result could be transferable to a real-life field
situation. The final results showed that there is an optimum thickness for the filler metal to obtain maximum
strength which matched the results achieved through concrete experimentation.
Keywords: Finite Element Analysis, Brazing, Cemented Carbide Alloy, Silver Brazing
Introduction:
In the field of manufacturing, dies made of superior
wear resistance materials are chosen to cut costs. One
such material is polycrystalline diamond (PCD) with
its high heat and wear resistance. The PCD is sintered
onto the cemented carbide and it is cut into be cutting
blanks as shown in Fig. 1. The cutting blank is brazed
on a parent material. Figure 2 shows an example of a
PCD punch with a very small amount of brazing
material. So the overall strength of the PCD tool
depends on the strength of the brazing.
In a previous study, the authors obtained the
relationship between the bending strength and the
brazing thickness of cemented carbide1), as shown in
Fig. 3. The difference of plots ○ and ● is the pressure
between the joints at time of brazing. From the
results of the experiment, it was found that the
strength improves when the brazing thickness is more
than 25µm.
In this paper, the brazing strength versus the
thickness of the brazing joint was analysed using a
Finite-element analysis by focusing on the deference
of material properties between the cemented carbide
and the brazing filler metal.
2. Finite-element Analysis
The authors performed a finite-element analysis in
reference to the specimen which was used (as in Fig.
4) for experiment1). The specimens were cantilever
beams whose cross sectional dimension is 4mm by
4mm. The load was applied at the position of 20mm
from the brazing joint. The mechanical properties of
the cemented carbide and the braze filler material
which was used in the experiment are shown in Table
1.
This specimen is a bending test specimen for the
experiment, however the stress distribution at the
local stress concentration part can be assumed to be
constant. Therefore, in the finite-element analysis, a
stepped tensile specimen model as shown in Fig. 5
was used. The load orientation was axial which also
created the same effect of tensile stress at the upper
part of the brazed joint (area of stress concentration).
The material properties of the model were set to be
the same as the experiment as shown in Table 1.
Fig. 1 manufacturing method of Polycrystalline
Diamond Tools
Fig. 2 Application of cemented carbide to punch
WCSET 2015041 Copyright © 2015 BASHA RESEARCH CENTRE. All rights reserved
MERIBE RICHARD CHUKWUMA, KAZUYA MORI, KENTO TAKENOUCHI,
YUKI FIJISHITA, TAKESHI EGUCHI, KAZUFUMI SAKATA
The results of the finite element analysis are shown
in Fig. 6 and Fig. 7. Figure 6 shows the magnitude of
the strain by gray level. From Fig. 6 it is found that
the strain of the cemented carbide is very small in
comparison with that of the brazing part. The reason
for this is that the young’s modulus of the cemented
carbide is seven times to the modulus of the brazing
filler material and the yield stress of the cemented
carbide is nine times to the yield stress of the brazing
filler material.
Figure 7 shows the relations of the maximum strain
and the brazing joint thickness at a stress of 400MPa.
The strain becomes small at brazing thickness of
20µm and more. This result is concordant with the
result of the experiment that the strength increases as
the brazing thickness becomes thicker until 25µm as
shown in Fig. 3.
3. Discussion
Generally, brazing joint strength increases as the
brazing thickness becomes thinner3). On the other
hand, brazing joint strength of cemented carbide with
silver brazing alloy decreases as the brazing
thickness becomes thinner as mentioned above. This
reason was considered in this discussion.
Figure 8(a) shows stress distributions in case of thick
brazing filler material. The thin line shows the stress
distribution when the brazing filler material is a
perfectly elastic body and the bold line shows the
stress redistribution by the plastic deformation at
brazing materials. It is reasonable to suppose that
fracture occurs when the stress at the whole brazing
reaches the yield stress.
Figure 8(b) shows stress distributions in case of thin
brazing filler material. Comparing the perfectly
elastic stress distributions (thin lines) in Figs. 8(a)
and 8(b), the elastic stress distribution of the thick
brazing filler is higher than that of the thin brazing
filler. Stress distribution occurred when stress on the
brazing material reach the destruction point in case of
thin brazing material. So, brazing joint strength
increases as the brazing joint thinness becomes
thicker. It is considered that this phenomenon occurs
when the strength of brazing materials is remarkably
lower than the strength of base materials.
Fig. 3 Bending strength of silver brazing versus
brazing thickness
Fig. 4 Cantilever beam specimen.
Fig. 5 Mesh pattern and boundary condition of finite
element analysis
Table 1 Mechanical property of the brazing filler
metal and cemented carbide
Young’s modulus [GPa]
Poisson’s ratio [-]
Tensile strength [MPa]
Yield strength [MPa]
Brazing
filler
metal
76
0.36
445
338
Cemented
carbide
570
0.23
1270
Fig. 6 Strain distribution (Grey level represents the
magnitude of the strain)
Proceedings of the 4th World Conference on Applied Sciences, Engineering and Technology
24-26 October 2015, Kumamoto University, Japan, ISBN 13: 978-81-930222-1-4, pp 154-156
Finite Element Analysis of Brazing Joint on Cemented Carbide Alloy
With Low Melting Point Silver Brazing Filler Metal
Conclusion:
The strength of brazing joints made of cemented
carbide and silver brazing filler was investigated by
Finite Element Analysis. According to the results, the
conclusions are as follows;
1) The degree of strain within the cemented
carbide is much smaller than that of the silver
brazing filler due to the material properties.
Fig. 7 Strain versus brazing joint thickness
2) Under a constant load, the point of maximum
strain becomes lowest with a brazing filler
thickness of 20µm. Brazing thicknesses over
20µm have almost the same effect.
3) The reason why the brazing joint strength
increases as the joint thickness becomes thinner
can be explained with the stress redistribution
due to its plastic deformation.
(a)Thick brazing filler
References:
[1] Kyogo Watanabe, Kazuya Mori, Yuki Fujishita,
Koji Kirihara, Kazufumi Sakata, High
Reliability Brazing Technique on Brazed Joint
of Cemented Carbide / Silver Solder- Japan
Society of Materials Science reliability,
destruction dynamics combination symposium
lecture memoirs (2013), pp. 105-108.
[2] Kento Takenouchi person, Kazuya Mori,
Meribe Richard, Yuki
Fujishita, Takeshi
Eguchi, Kazufumi Sakata, Improvement of
reliability of brazing joint on cemented carbide
alloy with low melting point silver brazing filler
metal- Japanese mechanics Kyushu branch
office Nagasaki lecture lecture memoirs (2015).
[3] Association of Japan of welding, JWES joining,
welding technology Q&A1000, http://wwwit.jwes.or.jp/qa/details.jsp?pg_no=0080010080
(b)Thin brazing filler
Fig. 8 Stress distributions of brazing filler
Proceedings of the 4th World Conference on Applied Sciences, Engineering and Technology
24-26 October 2015, Kumamoto University, Japan, ISBN 13: 978-81-930222-1-4, pp 154-156