• Share
  • Email
  • Embed
  • Like
  • Save
  • Private Content
Improvement of tensile strength of butt welded joints prepared by vibratory welding process
 

Improvement of tensile strength of butt welded joints prepared by vibratory welding process

on

  • 308 views

 

Statistics

Views

Total Views
308
Views on SlideShare
308
Embed Views
0

Actions

Likes
0
Downloads
7
Comments
0

0 Embeds 0

No embeds

Accessibility

Categories

Upload Details

Uploaded via as Adobe PDF

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

    Improvement of tensile strength of butt welded joints prepared by vibratory welding process Improvement of tensile strength of butt welded joints prepared by vibratory welding process Presentation Transcript

    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 4, July - August (2013) © IAEME 53 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 INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING AND TECHNOLOGY (IJMET) ISSN 0976 – 6340 (Print) ISSN 0976 – 6359 (Online) Volume 4, Issue 4, July - August (2013), pp. 53-61 © IAEME: www.iaeme.com/ijmet.asp Journal Impact Factor (2013): 5.7731 (Calculated by GISI) www.jifactor.com IJMET © I A E M E
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 4, July - August (2013) © IAEME 54 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
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 4, July - August (2013) © IAEME 55 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
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 4, July - August (2013) © IAEME 56 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
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 4, July - August (2013) © IAEME 57 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
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 4, July 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 6359(Online) Volume 4, Issue 4, July - August (2013) © IAEME 58 (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
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 4, July - August (2013) © IAEME 59 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
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 4, July - August (2013) © IAEME 60 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, pp 4592-4600. 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 the welding microstructure and residual stress distribution. Proceedings of the Institution of Mechanical Engineers, Journal of Materials: Design and Applications, 215 (2). pp. 99-111. 4) Shigeru Aoki, Tadashi Nishimura and Tetsumaro Hiroi (2005) Reduction method for residual stress of welded joint using random vibration, Nuclear Engineering Design, 235,pp1441-1445. 5) Tewari, S. P. and Shanker (1993), A. Effect of longitudinal vibration on the mechanical properties of mild steel weldments. Proc. Instn Mech. Engrs, Part B, Journal of Engineering Manufacture, 207(B3), 173–177.
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 4, July - August (2013) © IAEME 61 6) Weglowska. A. and Pietras. A. (2012), Influence of the welding parameters on the structure and mechanical properties of vibration welded joints of dissimilar grades of nylons. Archives of civil and mechanical engineering 12, pp198-204. 7) P. Govinda Rao, Dr. C L V R S V Prasad, Dr.D.Sreeramulu, Dr.V. Chitti Babu And M.Vykunta Rao, “Determination Of Residual Stresses Of Welded Joints Prepared Under The Influence Of Mechanical Vibrations By Hole Drilling Method And Compared By Finite Element Analysis” International Journal of Mechanical Engineering & Technology (IJMET), Volume 4, Issue 2, 2013, pp. 542 - 553, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359. 8) U.S.Patil And M.S.Kadam, “Effect Of The Welding Process Parameter In Mmaw For Joining Of Dissimilar Metals And Parameter Optimization Using Artificial Neural Fuzzy Interface System” International Journal of Mechanical Engineering & Technology (IJMET), Volume 4, Issue 2, 2013, pp. 79 - 85, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359. 9) P.Govinda Rao, Dr.Clvrsv Prasad, Dr.S.V.Ramana And D.Sreeramulu,“Development Of Grnn Based Tool For Hardness Measurement Of Homogeneous Welded Joint Under Vibratory Weld Condition” International Journal Of Advanced Research In Engineering & Technology (IJARET) Volume 4, Issue 4, 2013, pp. 50 - 59, ISSN Print: 0976-6480, ISSN Online: 0976-6499. 10) ravi butola, shanti lal meena and jitendra kumar, “Effect Of Welding Parameter On Micro Hardness Of Synergic Mig Welding Of 304l Austenitic Stainless Steel” ” International Journal of Mechanical Engineering & Technology (IJMET), Volume 4, Issue 3, 2013, pp. 337 - 343, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359.