This document summarizes research on improving the tensile strength of butt welded joints prepared using vibratory welding. Researchers designed a vibratory setup to induce mechanical vibrations into the weld pool during manual metal arc welding. Testing was conducted on mild steel butt joints welded with and without vibration at different voltages. Results showed that tensile strength increased with higher vibration amplitude and acceleration. Metallographic analysis found that vibration caused dendrites to break up into smaller dendrites, refining the microstructure and improving properties compared to joints welded without vibration. In conclusion, tensile strength was highest in joints prepared with vibratory welding compared to conventional welding without vibration.

1. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 4, July - August (2013) © IAEME
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IMPROVEMENT OF TENSILE STRENGTH OF BUTT WELDED JOINTS
PREPARED BY VIBRATORY WELDING PROCESS
P. Govindarao1
, Dr. P. Srinivasarao 2
, Dr. A. Gopalakrishna 3
and C V sriram 4
1
Associate Professor, Dept. of Mechanical Engineering, GMRIT, Rajam, Andhra Pradesh,
2
Professor, Dept. of Industrial Engineering, GITAM University, Vishakhapatnam, Andhra Pradesh
3
Professor, Dept. of Mechanical Engineering, JNTU Kakinada, Andhra Pradesh
4
Dept. of Mechanical Engineering, Andhra University, Andhra Pradesh
ABSTRACT
Vibration techniques have been used in welding for improving the mechanical properties of
metals in the last few decades. In the present work vibratory setup has been used for inducing
mechanical vibrations into the weld pool during welding. The designed vibratory setup produces the
required frequency with the amplitude and acceleration in terms of voltages. An increase in the
tensile strength of the weld pieces in to the heat affected zone (HAZ) has been observed. The
increase in mechanical properties is attributed to, as the weld pool solidifies, grains are not only
limited in size but also dendrites are broken before they grow large in size. Refined microstructure
has been observed. The above mechanism is responsible for the improvement in tensile strength of
weld pieces welded with vibratory setup compared to without vibration during welding.
I. INTRODUCTION
In manual metal arc welding (MMA) process, an arc is drawn between a coated consumable
electrode and the work piece. The metallic core-wire is melted by the arc and is conveyed to the weld
pool as molten drops. The electrode coating is also melting to form a gas shield around the arc and
the weld pool. Slag is formed on the surface of the weld pool, and the slag must be removed after
each layer. Manual Metal Arc welding is still a widely used hard facing process. Due to the low cost
of the equipment, the low operating costs of the process and the ease of transporting the equipment,
this flexible process is ideally suited to repair work benefits of MMA Welding are: Flexible, Low
Cost, and ease of Repairs. Butt welding is used to connect parts which are nearly parallel and don't
overlaps. It can be used to run a processing machine continuously, as opposed to having to restart
such machine with a new supply of metals. Butt-welding is an economical and consistent way of
joining process without using supplementary components. Usually, a butt-welding joint is made by
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slowly heating up the two weld ends with a weld plate and then combine them under specific
pressure. This process suitable for prefabrication and manufacturing special fittings afterward, the
material is usually ground down to a smooth finish and either sent on its way to the processing
machine, or sold as a completed product.
Lakshminarayanan A.K. and Balasubramanian. V [1] described about improvement in tensile
properties of 409M ferritic stainless steel welded joints in comparison with base metal. Ductility and
impact toughness of welded joints also tested for the welded joints.
Lu Qinghua, Chen Ligong and Ni Chunzhen [2] discussed about the applications of vibration
during submerged arc multi-pass welding to improve welded valve quality. The reduction in residual
deformation and stress due to vibratory weld conditioning is discussed. The enhancement of the
impact property in the weld metal due to vibratory weld conditioning is described.
Munsi A S M Y, Waddell A J and Walker C A[3] discussed about the effect of vibratory
stress on the welding microstructure and residual stress distribution of steel welded joints. The 25
percent improvement in hardness of weld joint is also discussed.
Shigeru Aoki, Tadashi Nishimura and Tetsumaro Hiroi [4] discussed about a method for
reducing the residual stress using random vibrations during welding. The residual stress in the
quenched butt-welded joint is measure by paralleled beam X-ray diffractometer with scintillation
counter.
Tewari S P and Shanker A.[5] described about improvements on yield strength, ultimate
tensile strength and breaking strength on shielded metal arc welded joints due to vibratory conditions
like longitudinal vibration and frequency. The drop in percentage of elongation due to the vibratory
conditions is discussed.
Weglowska. A, and Pietras A [6] described the influence of the welding parameters on the
mechanical properties of vibration welded joints such are tensile properties and microscopic
behaviour of dissimilar grades of nylons.
II EXPERIMENTAL WORK
The MMA welding process is an arc welding process which produces coalescence of metal
by heating them with an arc between a covered metal electrode and the work. Shielding is obtained
from decomposition of the electrode covering. Pressure is not used during the operation and the filler
metal is obtained from the electrode. The MMA welding process can be used for welding most
structural and mild steels. These include low-carbon or alloy steels; low-alloy, heat treatable steels;
and high-alloy steels such as stainless steels. This welding process can be used in all positions flat,
vertical, horizontal and requires only the simplest equipment. Thus, MMA welding lends itself very
well to field work
Material Used:
Mild Steel, It is composed of (in weight percentage) 0.9% Carbon (C), 7.5-10.0% manganese
(Mn), 1.00% Silicon (Si), 17.0-19.0% Chromium (Cr), 4.0-6.0% Nickel (Ni), 0.06% Phosphorus (P),
0.03% Sulphur (S), and the base metal Iron (Fe). Fig.1. shows a typical specimen used in the current
study.
Fig 1 Specimen piece

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Equipment Used:
Fig 2 shows the experimental setup of the vibrator machine, its properties and welding
process used for laying down the vibratory welding bead
Fig.2 Experimental setup
Vibratory Setup for Welding
With an aim of improving the mechanical properties of weld joints through inducing of
favourable changes in the weld microstructures, an auxiliary vibratory set up capable of inducing
mechanical vibrations into the weld pool during manual metal arc welding is designed and
developed. Different frequencies and with different amplitude are applied along the weld length,
just trailing behind the welding arc so that weld pool could be mechanically stirred in order to induce
favourable micro structural effects. This setup produces the required frequency with the amplitude
in terms of voltages.
Butt welding by MMA welding Process
In the current investigation, 5 mm thick mild steel butt joints are used. Low and high heat
input combinations are used to study the effect of mechanical vibrations. Figs.3 and 4 depict the
joining of two mild steel strips during and after the welding process.
Fig.3 During welding

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Fig.4 After welding
Butt Welded Joint at different voltages of Vibromotor:
The prepared butt welded joints are under the low heat input (90-110 Amp).There are 2
umber of passes to fill the gap, in which 1 main passes and 1is root pass. During the root pass there
is no role of vibratory setup. After the root pass, vibratory setup come into action and moved just
behind the arc and make a disturbance during the solidification of weld bead. Table 1 and Table 2
illustrate the parameters variation with respect to acceleration & amplitude during the process
Table 1 Parameters variation with respect to acceleration during the analysis
Table 2 Parameters variation with respect to amplitude during the analysis
Tensile Testing: Tensile test has been conducted in UTM for Different test Specimens which are
prepared under the influence of mechanical vibration. Following fig. 4 and 5 shows the line diagram
and sample of actual tensile test specimen respectively.
Voltage Input to the
Vibromotor (Volts)
70 V 150 V 230 V
Accelerations of the tip
of the specimens (m/s2
)
18.3 32.6 49.1
16.4 31.1 49.7
19.9 30.4 48.7
17.7 28.4 45.3
18.6 28.3 51.9
19.3 29.7 50.8
RMS Value 18.4 30.33 49.29
Voltage Input to the
Vibromotor (Volts)
70 V 150 V 230 V
Amplitude at the tip of
the specimen (mm)
0.238 0.274 0.350
0.233 0.269 0.348
0.230 0.266 0.347
0.235 0.270 0.349
0.242 0.275 0.352
0.240 0.273 0.351
RMS Value 0.236 0.273 0.350

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Fig. 4 Line diagram of a tensile test specimen
Figure 5 Tensile Test Specimen before testing in UTM
Figure 6 Tensile test specimen (without vibration) after testing in UTM
Figure 7 Tensile test specimen (with vibration at 70 Volts input to the vibromotor) after testing
Figure 8 Tensile test specimen (with vibration at 150 Volts input to the vibromotor) after testing

6. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976
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Figure 9 Tensile test specimen (with vibration at 230 Volts input to the vibromotor) after testing
III RESULTS AND DISCUSSION
Tensile strength of a welded joint is increased with respect to the
and acceleration of the specimens in terms of voltage input to the vibromotor. And also tensile
strength of welded joints prepared with vibration is more compared to wi
and graphs 1, 2 and 3 shows about the
acceleration in terms of voltage input to the vibromotor
Tensile testing Results are shown in following table
Voltage input to the
vibromotor
Amplitude in mm
(RMS)
Acceleration in m/s
(RMS)
Tensile Strength
Mpa
Graphs:
Voltage input to
Graph. 1 Variation of Tensile Strength with respect to Voltage input to vibromotor
500
550
600
650
700
0
TensileStrength(Mpa)
International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976
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(with vibration at 230 Volts input to the vibromotor) after testing
III RESULTS AND DISCUSSION
e strength of a welded joint is increased with respect to the increase in the amplitude
and acceleration of the specimens in terms of voltage input to the vibromotor. And also tensile
strength of welded joints prepared with vibration is more compared to without vibration. The table 3
about the variation of tensile strength with respect to the amplitude and
acceleration in terms of voltage input to the vibromotor.
shown in following table 3
input to the Without
Vibration
70 V 150 V 230 V
in mm 0 0.236 0.273 0.350
in m/s2
0 18.4 30.33 49.29
Tensile Strength
530 596.7 620.25 651
Voltage input to the Vibromotor (Volts)
Variation of Tensile Strength with respect to Voltage input to vibromotor
70 V 150 V 230 V
International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
August (2013) © IAEME
(with vibration at 230 Volts input to the vibromotor) after testing
increase in the amplitude
and acceleration of the specimens in terms of voltage input to the vibromotor. And also tensile
thout vibration. The table 3
with respect to the amplitude and
Variation of Tensile Strength with respect to Voltage input to vibromotor

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Graph. 2 Variation of Tensile Strength with respect to the amplitude of the specimen
Graph.3 Variation of Tensile Strength with respect to the Acceleration of the specimen
IV METALLURGICAL STUDY OF SPECIMENS
Metallographic study shows that during conventional butt welding the uniform long
dendrites which show that a uniform solidification process took place with uniform dendrites shown
in the fig.10 and fig.11 with acceleration and amplitude kept constant during welding current
respectively. Long dendrites show Corse structure of the weld joint. The microstructure shows the
uniform solidification process. Under vibratory conditions with acceleration and amplitude kept
changing, the microstructure of vibratory butt-weld joints, long dendrites get fragmented and
break in to small dendrites and forms a new nucleation sites. Here dendritic fragmentation took
place due to which fine structures form. This enhances the hardness and tensile strength of weld
joints
500
520
540
560
580
600
620
640
660
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
TensileStrength(Mpa)
Amplitude of the Specimen
Tensile Strength Vs Amplitude
500
520
540
560
580
600
620
640
660
0 5 10 15 20 25 30 35 40 45 50
TensileStrength(Mpa)
Acceleration of the Specimen
Voltage Vs Acceleration

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Fig 10: Microstructure of manual
metal arc welding Without vibration.
Fig 11: Microstructure of manual metal
arc welding With vibration.
V CONCLUSIONS
Tensile strength of the welded joints prepared under the influence of mechanical vibrations is
found to be more compared to welded joints prepared without vibration. This is attributed to, as the
weld pool solidifies, grains are not only limited in size but also dendrites are broken up before they
grow large in size. The microstructure of the weld metal is observed to be improved. Therefore the
tensile strength and hardness are improved in welded joints prepared under the influence of vibration
compared to without vibration. Further, the tensile strength of welded joint has also been increased
with respect to the increase in the voltage input to the vibromotor. There is also an improvement in
the tensile strength with the increase in the acceleration and amplitude of the specimens.
REFERENCES
1) Lakshminarayanan A.K. and Balasubramanian. V (2010) an assessment of microstructure
hardness, tensile and impact strength of friction stir welded ferritic stainless steel joints, 31,
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2) Lu Qinghua, Chen Ligong and Ni Chunzhen (2006) Improving welded valve quality by
vibratory weld conditioning, Materials Science and Engineering A 457, pp246-253.
3) Munsi, A.S.M.Y. and Waddell, A.J. and Walker, C.A. (2001) the effect of vibratory stress on
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Mechanical Engineers, Journal of Materials: Design and Applications, 215 (2). pp. 99-111.
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Manufacture, 207(B3), 173–177.

9. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
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6) Weglowska. A. and Pietras. A. (2012), Influence of the welding parameters on the structure
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