UNIVERSITI TEKNIKAL MALAYSIA MELAKA THE EFFECT OF PROCESS PARAMETERS ON SPOT WELDS STRENGTH OF 6061 ALUMINIUM ALLOY This report submitted in accordance with requirement of the Universiti Teknikal Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering (Manufacturing Process) by SHAHDAN AJIB BIN OMAR B050710221 FACULTY OF MANUFACTURING ENGINEERING 2011
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UNIVERSITI TEKNIKAL MALAYSIA MELAKA
THE EFFECT OF PROCESS PARAMETERS ON SPOT WELDS
STRENGTH OF 6061 ALUMINIUM ALLOY
This report submitted in accordance with requirement of the Universiti Teknikal
Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering
(Manufacturing Process)
by
SHAHDAN AJIB BIN OMAR
B050710221
FACULTY OF MANUFACTURING ENGINEERING
2011
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA
TAJUK: The Effect of Process Parameters on Spot Welds Strength of 6061 Aluminium Alloy
SESI PENGAJIAN: 2010/11 Semester 2 Saya SHAHDAN AJIB BIN OMAR
mengaku membenarkan Laporan PSM ini disimpan di Perpustakaan Universiti Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat kegunaan seperti berikut:
1. Laporan PSM adalah hak milik Universiti Teknikal Malaysia Melaka dan penulis. 2. Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan
untuk tujuan pengajian sahaja dengan izin penulis. 3. Perpustakaan dibenarkan membuat salinan laporan PSM ini sebagai bahan
pertukaran antara institusi pengajian tinggi. 4. **Sila tandakan (√)
SULIT
TERHAD
TIDAK TERHAD
(Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia yang termaktub di dalam AKTA RAHSIA RASMI 1972)
(Mengandungi maklumat TERHAD yang telah ditentukan oleh organisasi/badan di mana penyelidikan dijalankan)
Alamat Tetap:
165-W, Jalan Balai Besar,
Dungun, 23000
Dungun, Terengganu. Tarikh: 19 Mei 2011
Disahkan oleh:
PENYELIA PSM
(Tandatangan dan Cop Rasmi) Tarikh: 19 Mei 2011
** Jika Laporan PSM ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan dengan menyatakan sekali sebab dan tempoh laporan PSM ini perlu dikelaskan sebagai SULIT atau TERHAD.
DECLARATION
I hereby, declared this report entitled “The effect of process parameters on spot welds
strength of 6061 aluminium alloy” is the results of my own research except as cited in
references
Signature : …………………………………………….
Author’s Name : …………………………………………….
Date : …………………………………………….
SHAHDAN AJIB BIN OMAR
19 MEI 2011
APPROVAL
This report is submitted to the Faculty of Manufacturing Engineering of UTeM as a
partial fulfillment of the requirements for the degree of Bachelor of Manufacturing
Engineering (Manufacturing Process) with Honours. The member of the supervisory
committee is as follow:
……..………………………………
Supervisor
(Signature & Official Stamp of Supervisor)
i
ABSTRAK
Rintangan pengimpalan titik (RSW) ialah satu proses kimpalan logam kepingan bersama
itu menyelesaikan dengan menggunakan tekanan dan lalu satu semasa besar melalui
kawasan setempat manakala kepingan tetap bersama. Tujuan projek ini ialah untuk
menyiasat contoh-contoh microstructural dan ciri-ciri rintangan kimpal bintik pada
aluminium logam kepingan. Kepingan logam Aluminium akan digunakan. Pertindihan
bersama yang berketebalan 1 mm akan dikimpal menggunakan (SSW-2040) dengan
berbeza daya electrik, arus kimpalan, dan masa kimpalan. Analisa struktur micro akan
dilaksanakan. Sifat-sifat mekanikal akan dinilai dalam ujian-kekuatan tarikan dan ujian
kekerasan. Semua data akan dikumpul dan dianalisis. Kekerasan mungkin akan
menunjukkan nilai tinggi pada hasil kimpal kawasan. Ujian terikan pula menunujukkan
logam yg mempunyai ketebalan 1.0mm adalah lebih baik daripada logam 1.5mm kerana
ketebalannya. Penentuan pengelasan untuk rintangan pengimpalan titik mesti sesuai bagi
mendapat keputusan yang lebih baik. Kesalahan dalam pengelasan secara tak langsung
akan menjejaskan dapatan keseluruhan sama sekali.
ii
ABSTRACT
Resistance spot welding (RSW) is a welding process that joint sheet metal pieces
together by applying pressure and passing a large current through localized area while
the sheets are fixed together. The aim of this project is to investigate the microstructural
samples and characteristics of resistance spot welds on aluminum sheet metal and
examine the mechanical behavior at different welding parameters. It also evaluates the
hardness of the samples in order to determine the influence of welding parameters.
Aluminium 6061 will be used. Lap joining of plates 1mm and 1.5mm in thickness will
be weld by using (SSW-2040) with different electrode force, welding current and
welding time. Microstructure analysis will carried out. Mechanical properties will be
evaluated in tensile tests and hardness test. All the data will be collected and analyzed.
Hardness will probably show high value at weldment area. Base on the finding, tensile
test show at 1.0mm strength was better than 1.5mm thickness. The parameter of
resistance spot welding must be proper decided in order to get the better result. Improper
control the parameter of welding will be affected on the result entirely.
iii
DEDICATION
Dedicated to my beloved father, En Omar bin Hj. Mohd Shah and my lovely mother, Pn
Mahani bt Abdul Rahman who are very concern, patient and supporting. Last but not least,
to all my brothers, sisters and friends. The work and success will never be achieved without
all of you.
iv
ACKNOWLEDGEMENT
Alhamdulillah and thank to Allah S.W.T. with all His Gracious and His Merciful for
giving me strength and ability to accomplish this project research successfully. I
would like to take the utmost opportunity to express my sincere and gratitude to my
supervisor, Mr. Mohd Shukor bin Salleh who is always giving me supports and
guidance throughout the year in completing this final year project. Besides, thanks a
lot to all lecturers and staffs of Faculty of Manufacturing Engineering.
Finally, to all my fellow friends who involves direct or indirectly that always stand
strong beside me in giving opinions and supports throughout our relationship, I really
thankful and appreciate it.
v
TABLE OF CONTENT
Abstrak i
Abstract ii
Dedication iii
Acknowledgement iv
Table of Content v
List of Tables ix
List of Figures x
List of Abbreviations xii
1. INTRODUCTION 1.1 Introduction 1
1.2 Problem Statement 2
1.3 Objective 3
1.4 Scope of Project 3 1.5 Gantt chart 8
2. LITERATURE REVIEW 2.1 Introduction 4
2.2 Resistance Welding 6
2.2.1 Types of Resistance Welds 6
2.2.1.1 Lap Welding 6
2.2.2 Resistance Welding Processes 8
2.2.2.1 Spot Welds 8
2.2.3 Weld Inspection 11
2.2.4 Spot Welding Parameter 12
2.2.4.1 Current 12
2.2.4.2 Pressure 12
vi
2.2.4.3 Time 13
2.3 6061 Aluminum Alloy 13
2.3.1 Suitability of Aluminum and its Alloys for Spot Welding 14
2.3.2 Comparison of Physical Properties of Aluminum and Unalloyed Steel 16
2.3.3 Resistances during Spot Welding of Steel and Aluminium 17
2.4 Mechanical Properties 18
2.4.1 Tensile Test 18
2.4.2 Stress Strain Curves 19
2.4.3 Basic Calculation 19
2.4.4 Ductility 20
2.5 Hardness Test 22
2.5.1 Brinell Hardness Test 22
2.5.2 Rockwell Hardness Test 23
2.6 Impact Test 23
2.7 Toughness 24
2.8 Weldment Microstructure 24
2.9 Factors Influencing the Life of Electrodes 26
2.9.1 Influence of Storage Time on Life of Electrodes 26
2.10 The Process of Resistance Spot Welding 28
2.10.1 Current-Force Diagram For Spot Welding Aluminium 28
2.10.2 Recommended Values For Spot Welding With Direct Current 29
2.10.3 Example Of A Field Of Suitable Welding Parameters 30
2.10.4 Effect of Weld Spot Diameter on the Shear Strength 31
2.10.5 Correlations between Surface Pretreatment, Weld Strength and Electrode
Life 31
3. METHODOLOGY
3.1 Introduction 33
3.2 Process Flow Chart 33
3.3 Experimental 35
vii
3.4 Materials preparation 36
3.5 Equipment preparation 36
3.6 Specimens Preparation 39
3.6.1 Tensile Test Specimen 39
3.6.2 Hardness Test Specimen 40
3.7 Experimentation 41
3.7.1 Microstructure Measurement 41
3.7.2 Optical Microscope Measurement 41
3.7.3 Hardness Test Measurement 42
3.7.4 Tensile Test Measurement 43
4. RESULT AND DISCUSSION 4.1 Introduction 45
4.2 Microstructure Result 46
4.2.1 Microstructure for 1.0mm and 1.5mm thickness 46
4.3 Optical Measurement Result 47
4.3.1 Relationship between 1.0mm and 1.5mm Thickness and Optical
Measurement 48
4.4 Hardness Result 50
4.4.1 Hardness of 1.5mm thickness 51
4.4.2 Hardness of 1.0mm thickness 52
4.5 Tensile Test Result 53
4.5.1 Result of 1.0 mm thickness 54
4.5.1.2 Stress versus Strain Analysis for 1.0mm thickness 55
4.5.2 Result of 1.5 mm thickness 56
4.5.1.2 Stress versus Strain Analysis for 1.5mm thickness 57
4.5.3 Different of maximum forces for 1.0mm and 1.5mm thickness 58
viii
5. CONCLUSION AND RECOMMENDATION
5.1 Conclusion 59
5.2 Recommendation For Further Research 60
REFERENCES 61
APPENDICES A Gantt Chart
B Measurement Result Data C Conducting Experiment
ix
LIST OF TABLES
2.1 Chemical composition of Al 6061 13
2.2 Comparisons of Physical Properties of Aluminum and Unalloyed Steel
(0.15%C) at RT 16
3.1 Control parameter for spot welding process 38
3.2 Standard specimen size for tensile experiment 39
3.3 Minimum thickness requirement for Brinell hardness test 40
x
LIST OF FIGURES
2.1 How an overlapped spot weld is made 6
2.2 Cross Section of Completed Spot Weld 7
2.3 Cross Section of Completed Spot Weld 8
2.4 Principle of Stationary Spot Welding With Close-up of Operation 9
2.5 Pictorial sequence of the making of a spot weld 10