OPTIMIZATION OF MIG WELDING PROCESS PARAMETERS ON MECHANICAL PROPERTIES OF
Al-MS-SS MATERIALS
NIK NUR FATIHAH BINTI CHE HASSAN
UNIVERSITI MALAYSIA PERLIS 2013
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Optimization Of Mig Welding Process Parameters On Mechanical Properties Of Al-MS-SS Materials
by
NIK NUR FATIHAH BINTI CHE HASSAN (1332420848)
A thesis submitted in fulfillment of the requirements for the degree of Master of Science Manufacturing System Engineering
School of Manufacturing Engineering UNIVERSITI MALAYSIA PERLIS
2013
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1 THESIS DECLARATION FORM
UNIVERSITI MALAYSIA PERLIS
DECLARATION OF THESIS
Author’s full name : NIK NUR FATIHAH BINTI CHE HASSAN Date of birth : 02 / 12 / 1988 .
Title : OPTIMIZATION OF MIG WELDING PROCESS
PARAMETERS ON MECHANICAL PROPERTIES OF Al-MS- SS MATERIALS
Academic Session : 2013 .
I hereby declare that this thesis becomes the property of Universiti Malaysia Perlis (UniMAP) and to be placed at the library of UniMAP. This thesis is classifies as:
CONFIDENTAL
RESTRICTED
OPEN ACCESS
(Contains confidential information under the Official Secret Act 1972)
(Contains restricted information as specified by the organization where research was done)
I agree that my thesis is to be made immediately available as hard copy or on-line open access (full text)
I, the author, give permission to the UniMAP to reproduce this thesis in whole or in part for the purpose of research or academic exchange only (except during a period of _____ years, if so requested above).
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Date : ______________
Certified by:
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2 ACKNOWLEDGEMENTS
Alhamdulillah, thanks to God Almighty for His blesses and strength that He has gave to me to finish my research. Even though I had faced many challenges during my research that make my research progression becomes low as well as my motivation.
However, thanks to Allah S.W.T and Prophet Muhammad S.A.W, finally I got strength to move on and capable to finish my research with the support from others.
First of all, I would like to express sincere gratitude to my supervisor, Prof. Dr.
Bhuvenesh Rajamony, who providing valuable guidance and suggestions until this research completed. Their supervisions and support truly help me to keep this research going smoothness and concerned and showing interest in my research and also offering valuable suggestion during various stages of my studies. My special thanks also go to the Dean of School Manufacturing Engineering, Dr Khairul Azwan Ismail for his valuable support and also to Dr. Noorhafiza Muhammad as a coordinator post graduate for all information and as a reference person about the dissertation.
My grateful thanks also go to the Technical Staff of Universiti Malaysia Perlis at Ulu Pauh Laboratory, who had become the back bone of my experimental work. Without their tremendous technical support, I cannot manage to complete this project on the time.
I would like to give my sincere appreciations to my colleagues for many enjoyable scientific discussions and personal conversations and every else former and current of manufacturing group members. Their time, expertise and warm friendship were very much appreciated.
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I wish to thank My Brain15 by the Ministry of High Education for financially supported during my degree MSc. Manufacturing System Engineering starting from January 2013 until December 2013.
Finally, I want to express my appreciations to my beloved parents, Che Hassan Bin Zakaria and Tuan Noraini Binti Tuan Yusoff for their love and encouragement. I also want to thank you my siblings and family members for their advice and support. Thank you very much for supporting me every step of the way.
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TABLE OF CONTENTS
PAGES
DECLARATION OF THESIS ii
ACKNOWLEDGEMENT iii
TABLE OF CONTENTS v
LIST OF TABLES x
LIST OF FIGURES xii
LIST OF ABBREVIATIONS xiv
ABSTRAK xvi
ABSTRACT xvii
CHAPTER 1 INTRODUCTION 1.1 Background of Project 1 1.2 Problem Statement 3 1.3 Objectives 4 1.4 Scopes of the Project 4
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1.5 Limitations of the Project 5
1.6 Significant of Findings 5
1.7 Report Structures 6
1.8 Summary of the Chapter 7
CHAPTER 2 LITERATURE REVIEW
2.1 Introduction 8
2.2 MIG Welding Process 9
2.3 Material Selection 11
2.3.1 Ferrous Metal Alloys 12
2.3.1.1 Mild (Low-Carbon) Steel 12
2.3.1.2 Stainless Steel 12
2.3.2 Non-Ferrous Metal Alloys 13
2.3.2.1 Aluminum Alloys 13
2.4 Welding Parameters Selection 13
2.5 Mechanical Properties Analysis 15
2.6 Heat-Affected Zone (HAZ) 16
2.7 Design of Experiment (DOE) 18
2.7.1 Application DOE in MIG Welding 18
2.7.2 Application DOE Method in Different Welding Process Parameter 19
2.7.3 Application DOE Method in Another Area 19
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2.8 Summary of the Chapter 20
CHAPTER 3 METHODOLOGY 3.1 Introduction 21
3.2 Design of Experiment 23
3.2.1 Taguchi Approach 23
3.2.2 Orthogonal Array (OA) 24
3.2.3 Signal-To-Noise Ratio 25
3.2.4 Taguchi Approach Compared with Classical Approach 25
3.3 Equipments for Experiment 26
3.3.1 MIG Welding Machine 27
3.3.2 Ultimate Tensile Strength (UTM) 29
3.3.3 Vickers Micro Hardness Test 31
3.3.4 Scanning Electron Microscope (SEM) 33
3.4 Scheme of Investigation 34
3.4.1 Selection of Material 34
3.4.2 Identify Important Welding Process Parameter 36
3.4.3 Find the Upper and Lower Limits (range) of the Identified Process Parameter 37
3.4.4 Select the Orthogonal Array (design of matrix) 37
3.4.5 Conduct the Experiments as per the Selected Orthogonal Array 38
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3.4.6 Record the Quality Characteristics (Mechanical Properties) 39
3.4.7 Find the Optimum Condition for Maximizing the Mechanical Properties 40
3.4.8 Conduct the Confirmation Test 41
3.5 Summary of the Chapter 41
CHAPTER 4 RESULTS AND DISCUSSION 4.1 Introduction 42
4.2 Experimental Results 43
4.2.1 Ultimate Tensile Strength 43
4.2.2 Vickers Micro Hardness Tester 48
4.3 Predicted Optimum Conditions and Optimum Values 51
4.3.1 Signal to Noise (S/N) Ratio Graph 54
4.3.2 Analysis of Variance (ANOVA) for Main Effects 57
4.4 Confirmation/ Validation Test 60
4.4.1 Scanning Electron Microscope (SEM) 61
4.5 Weld Troubleshooting 65
4.6 Summary of the Chapter 65
CHAPTER 5 CONCLUSION 5.1 Introduction 66
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5.2 Research Findings 66
5.3 Research Contribution 70
5.4 Future Work Recommendations 71
REFERENCES 72
APPENDIX A-1: Gas Metal Arc Welding Guidelines 77
APPENDIX A-2: List of Equation of Signal-to-Noise(S/N) Ratio 79
APPENDIX A-3: Vickers Hardness Equation 80
APPENDIX B-1: Calculation Predicted Optimum Condition 81
LIST OF PUBLICATION 84
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LIST OF TABLES
TABLES TITLE PAGES
Table 3.1 The standard orthogonal arrays 24
Table 3.2 The advantages and disadvantages of Taguchi approach 26
Table 3.3 Modes of metal transfer for steel wire in an argon 20% co2 shielding gas 28
Table 3.4 Chemical composition of parent material and wire electrode material 35
Table 3.5 Level chosen for input parameter 37
Table 3.6 Taguchi’s L4 (23) orthogonal array 37
Table 3.7 L4 (23) orthogonal array using +1 and -1 38
Table 3.8 Taguchi L4 (23) orthogonal array for input parameter 38
Table 4.1 Results of tensile test 45
Table 4.2 Estimated times to reached UTS point 46
Table 4.3 Layout experiment with two level factors with interaction for Aluminum (UTS) 47
Table 4.4 Results of micro hardness test 49 Table 4.5 Layout experiment with two level factors with interaction for
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Aluminum (HV) 50
Table 4.6 Results of MSD and S/N ratio for Aluminum 52
Table 4.7 Results of MSD and S/N Ratio for Mild Steel 52
Table 4.8 Results of MSD and S/N Ratio for Stainless Steel 52
Table 4.9 Predicted optimum values for Aluminum 53
Table 4.10 Predicted optimum values for Mild Steel 53
Table 4.11 Predicted optimum values for Stainless Steel 54
Table 4.12 Summary of S/N ratio values for UTS and micro hardness 57
Table 4.13 Results ANOVA of main effects for UTS 59
Table 4.14 Results ANOVA of main effects for micro hardness 60
Table 4.15 Summary of confirmation tests 61
Table 4.16 The depth of penetration 64
Table 5.1 Summary of UTS testing 68
Table 5.2 Summary of hardness test 69
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LIST OF FIGURES
FIGURES TITLE PAGES
Figure 2.1 MIG welding process 10
Figure 2.2 Modes of metal transfer 11
Figure 2.3 The separating region of welding area 17
Figure 3.1 Flowchart of methodology process 22
Figure 3.2 The MIG welding machine 27
Figure 3.3 The stress versus strain curve 30
Figure 3.4 UTM Shimadzu model AG-X 31
Figure 3.5 Vickers micro hardness tester model CS-3000 33
Figure 3.6 Scanning electron microscope model Hitachi TM-3000 34
Figure 3.7 Sample for UTM 36
Figure 3.8 Sample for hardness 36
Figure 3.9 Sample for SEM 36
Figure 3.10 Butt joints welding 38
Figure 3.11 Failure specimen UTS test 39
Figure 3.12 Point of hardness measurement by Vickers hardness test 39
Figure 3.13 SEM analysis materials 40
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Figure 4.1 The example of Stainless Steel samples number 3 was failed in the weld
metal region 44
Figure 4.2 The stress versus strain graphs for Mild Steel (sample number 4) 44
Figure 4.3 Interaction plot for UTS of factors C and G for Aluminum 47
Figure 4.4 The region of the weld area for Vickers hardness test 48
Figure 4.5 Interaction plot for hardness of factors V and G for Aluminum 50
Figure 4.6 The predicted optimum condition of UTS and micro hardness for Aluminum 55
Figure 4.7 The predicted optimum condition of UTS and micro hardness for Mild Steel 55
Figure 4.8 The predicted optimum condition of UTS and micro hardness for Stainless Steel 56
Figure 4.9 SEM image of Aluminum 62
Figure 4.10 SEM image of Mild Steel 63
Figure 4.11 SEM image of Stainless Steel 63
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LIST OF ABBREVIATIONS
C Carbon Mn Manganese P Phosphorous
S Sulphur
O Oxygen
Si Silicon Al Aluminum Ti Titanium
Cr Chromium Ni Nickel
Co Cobalt Mo Molybdenum N Nitrogen
Cu Copper W Tungsten
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Sn Tin Fe Iron
Zn Zinc
Mg Magnesium
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Kimpalan Optimum MIG Parameter Ke Atas Sifat-Sifat Mekanikal Bahan Al- MS- SS
ABSTRAK
Aplikasi proses kimpalan dalam industri kebanyakan melibatkan ketahanan sesuatu objek untuk menahan daya yang dikenakan. Oleh yang demikian, daya tegangan dan kekuatan sambungan kimpalan mestilah diambil kira. Kimpalan gas lengai logam digunakan untuk menyambungkan dua kepingan spesimen keluli lembut, keluli tahan karat dan aloi aluminum berdasarkan kapada parameter yang telah dipilih. Spesimen yang digunakan adalah ketebalan 3mm. analisis kekuatan tegangan dan kekerasan telah dijalankan ke atas permukaan kawasan yang telah dikimpal. Analisis daya ketahanan diuji menggunakan Ultimate Tensile Machine dan kekerasan (Vickers Hardness Test) yang paling tinggi dicatatkan. Kaedah Taguchi digunakan untuk menyusun atur eksperimen bagi mendapatkan nilai optimum untuk setiap analisis yang diuji. Keputusan daripada analisis Graf nisbah Signal-to-Noise yang paling tinggi untuk setiap parameter memberi keputusan kepada nilai optimum untuk setiap jenis bahan. Analisis of Variance dilakukan untuk mengenal pasti peratusan parameter yang mempengaruhi kepada daya ketegangan sesuatu bahan. Ujian pengesahan dilakukan berdasarkan parameter optimum yang telah dianalisis dan mendapati terdapat ralat antara ramalan nilai optimum dan nilai eksperimen yang sebenar. Walau bagaimanapun, analisis struktur permukaan telah dilakukan dengan menggunakan Scanning Electron Microstructure untuk menyokong kepada keputusan eksperimen. Imej yang ditunjukkan dalam analisis menunjukkan kesan penembusan logam kimpalan di antara kepingan bahan berbeza untuk setiap bahan yang dikaji. Imej specimen keluli lembut menunjukkan penembusan paling tinggi berbanding yang lain. Penemuan-penemuan nilai optimum dan jadual keputusan yang diperolehi boleh digunakan sebagai rujukan untuk pelbagai aplikasi kimpalan gas lengai dalam industry berkaitan.
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Optimization of MIG Welding Process Parameters on Mechanical Properties of Al- MS- SS
ABSTRACT
Applications of welding process in the industry mostly involve the resistance of an object to resist the force applied. As such, the tensile strength and hardness of welding must be considered. The Metal Inert Gas welding is used to joint two plates of Aluminum, Mild Steel and Stainless Steel in butt joint type based on the selected parameters. The specimens used are 3mm thickness. Analysis of tensile strength using Ultimate Tensile Machine and hardness (Vickers Hardness Test) has been carried out on the surface of welding area. The highest values of tensile strength and hardness test were recorded. Taguchi method is used for design of experiment in order to obtain the optimum value for each analysis tested. The highest of Signal-to-Noise ratio graph for each parameter provide results of optimal values for each type of material. Analysis of Variance was carried out to identify the percentage of parameters contributions to the tension of a material. Confirmation tests carried out on the basis of optimum parameter which has been analyzed and found there was an error between predictions of optimal value and the actual experimental values. However, microstructure analysis has been done to support the results of the experiment. The images of penetration shown by Scanning Electron Microscope for Mild steel specimen are the highest penetration than others. The findings of the optimal value and table of results obtained can be used as a reference for various applications for metal inert gas welding in industry.
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CHAPTER 1
INTRODUCTION
1.1 Background of Study
Welding is a manufacturing process, which is carried out for joining of metals.
Modern welding is a technology based on heat sources, in which, there are many methods capable of being used to raise the metal locally to a temperature suitable for welding.
Statement by Houldcroft and John (1989), it is a highly efficient, economical and adaptable method of joining compared to late nineteenth century, the only welding process used by blacksmith by heaping and heating coals around the part to make a joint. Metal Inert Gas (MIG) welding is one of the most widely used processes in industry. MIG is the one type of Gas Metal Arc Welding (GMAW) in which Argon or Helium is used as an inert gas. The equipment of MIG welding comprises the power source which is direct current (DC), the wire feed unit, the flexible conduit with a torch and control devices to start and stop the wire feed, welding current and gas flow.
According to research by Sapakal and Telsang (2012), they stated that welding parameters play a very significant role in determining the quality of a weld joint. In reality weld geometry directly affects the complexity of weld structure. Therefore, controlling welding parameters affecting the arc and welding should be carried out and their changing
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conditions during the process must be known prior to obtain optimum results. The quality of the joint can be defined in terms of properties such as mechanical properties.
Mechanical testing is an important aspect of weld ability study. A mechanical property is the properties that reveal the reaction, either elastic or plastic, of a metal to an applied stress. For example, mechanical properties testing are tensile strength, yield strength, elongation, reduction of area, hardness, impact strength, and bend ability.
Esme (2009) stated the following:
The weld strength is measured by a number of standardized destructive tests, which subject the weld to dissimilar types of loading. Some of these are tensile, torsion, impact, fatigue and hardness. It is very significant to select welding process parameters for obtaining optimal weld strength. Generally, the welding process parameters are determined based on experience or from a handbook. However, this does not ensure that the selected welding process parameters can give the optimal or near optimal weld strength for that particular welding machine and environment.
Studying the design parameters one at a time of by trial and error is a common approach to design optimization (Phadke, 1989). However, this leads either to a very long and expensive time span for completing the design or to premature termination of design process due to budget or schedule pressures. Taguchi’s approach provides a systematic and efficient method to determine near optimum design parameter for performance and cost.
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1.2 Problem Statement
Common engineering materials such as aluminum, mild steel, stainless steel, nickel alloy and titanium alloys are known for better-quality resistance to heat and corrosion as well as low thermal expansion properties. These properties make it useful in industries that require parts to retain stability as well as the ability to resist corrosion over a wide range of temperatures (Mitterer, 2000; Rusinek, 2007; Baddoo, 2008). These materials are suitable for aerospace, automotive and electronic industries. These industries depend increasingly on higher geometric accuracies and micro or nano structured surfaces to meet the growing need for improving performance and reliability.
However, it is partially acceptable in industrial application due to difficulties in welding especially when utilizing conventional gas or arc welding. Therefore, for many industries the above requirements is leading to capabilities of conventional welding methods and machine tools being eclipsed by new processes and machine systems which at this time at the research stage. Furthermore, the advances in the field MIG welding have accepted in the application of this technology to the manufacture of those materials.
This research used aluminum, mild steel and stainless steel because there is a limited result that study and compare the tensile strength and hardness for these three materials which are required parts to retain stability. This study is focused on a semi automatic machine operation which applies MIG welding process.
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1.3 Objectives
The objectives of this study highlighted below:
i. To analyze quality characteristics of the weld on mechanical properties such as ultimate tensile strength, micro hardness and microstructure for weld butt joint.
ii. To identify optimum setting of the best combination welding parameters for MIG welding through experimental study of soft non-ferrous metal like 1100 Aluminum alloy.
iii. To identify optimum setting of the best combination welding parameters for MIG welding through experimental study of hard ferrous metal like AISI 1017 Mild Steel and AISI 302 Stainless Steel.
1.4 Scopes of the Project
The scopes of the study:
i. The welding method was perpendicular butt joint which is commonly used in industries.
ii. Parameter selection in the MIG welding experiment was based on available data.
iii. Mechanical properties test are used as a quality measurement for tensile strength and micro hardness.
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iv. Manual and semi-automatic ways of welding are generally used in small industries to weld three different materials.
1.5 Limitations of the Project
Limitations of the study are as follow:
i. Electrode diameter of MIG welding machine is 0.8 mm.
ii. Plate thickness provided is 3mm for aluminum, mild steel and stainless steel.
iii. The parameter range not used in the high level of machine specification because of the thickness of the plate is too thin. If the high level of range applied, the plate will burn.
1.6 Significant of Findings
The best parameter setting of MIG welding can be acquired from the experimental results. The settings were used to obtain optimal welding performance in order to maximize quality characteristic of the welding area. The result of experiments can give advantage to manufacturing industries which use manual and semi-automatic MIG welding operation.
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1.7 Report Structures
Chapter 1 is briefly described about the introduction which consists background of the study, problem statement, objective and scope. This background of study will discuss about the welding process which are the main manufacturing process in this research followed by the problem statement. The objective also mentions earlier in this chapter to make clear what the purpose this research in done and what the outcome of the research.
Scopes are listed to make the research become in deeper and more specific.
Chapter 2 is a literature review of the Metal Inert Gas (MIG) process, material selection, parameter selection and design of the experiments Taguchi application. These sections discuss details on the previous process, method and application related to this study. Much information gathered in this chapter and will be used in this study.
Chapter 3 is mainly about the procedure and theory behind the tools. The flowchart of methodology is given in this chapter to show how this study is done from beginning until the end. Besides that, the equipment and method selection for this study are discussed in details. The scheme of investigation is explained in detailed.
Chapter 4 presents the experimental results, analysis and discussion. The calculations, graphs and table of results are shown in this section. Starting with experimental results show in tables, analysis graph Signal-to-Noise (S/N) ratios and Analysis of Variance (ANOVA). The discussions about the results are evaluated and conclude.
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