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Comparison Between Welding Defects Caused by Flux Cored and Bare Electrodes

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Comparison Between Welding Defects Caused by Flux Cored and Bare Electrodes COMPARISON BETWEEN WELDING DEFECTS CAUSED BY FLUX CORED AND BARE ELECTRODES A PROJECT BY YOUNUS ALI DEPARTMENT OF MECHANICAL ENGINEERING DHAKA UNIVERSITY OF ENGINEERING & TECHNOLOGY, GAZIPUR GAZIPUR-1700 COMPARISON BETWEEN WELDING DEFECTS CAUSED BY FLUX CORED AND BARE ELECTRODES YOUNUS ALI DEPARTMENT OF MECHANICAL ENGINEERING DHAKA UNIVERSITY OF ENGINEERING & TECHNOLOGY, GAZIPUR GAZIPUR-1700 COMPARISON BETWEEN WELDING DEFECTS CAUSED BY FLUX CORED AND BARE ELECTRODES A Project By YOUNUS ALI Department of Mechanical Engineering Dhaka University of Engineering & Technology, Gazipur Gazipur-1700 March 2016 ii COMPARISON BETWEEN WELDING DEFECTS CAUSED BY FLUX CORED AND BARE ELECTRODES A Project By YOUNUS ALI Submitted to the Department of Mechanical Engineering, Dhaka University of Engineering & Technology, Gazipur, in partial fulfillment of the requirements for the degree of MASTER OF ENGINEERING IN MECHANICAL ENGINEERING. Department of Mechanical Engineering Dhaka University of Engineering & Technology, Gazipur Gazipur-1700 March 2016 iii The project titled “Comparison Between Welding Defects Caused by Flux Cored and Bare Electrodes”, submitted by Younus Ali, Student No. 112317 (P) session 2011-2012, has been accepted as satisfactory in partial fulfillment of the requirements for the degree of Master of Mechanical Engineering on March 15, 2016. BOARD OF EXAMINERS 1. Professor Dr. Md. Kamruzzaman Supervisor and Chairman Department of Mechanical Engineering DUET, Gazipur. 2. Professor Dr. Mohammad Asaduzzaman Chowdhury Member Head, Department of Mechanical Engineering (Ex-officio) DUET, Gazipur. 3. Professor Dr. Mohammed Alauddin Member Professor, Department of Mechanical Engineering DUET, Gazipur. 4. Professor Dr. Md. Arefin Kowser Member Professor, Department of Mechanical Engineering DUET, Gazipur. 5. Professor Dr. Mohammad Mosharaff Hossain Member Head, Department of Industrial and Production (External) Engineering Rajshahi University of Engineering & Technology (RUET), Rajshahi iv Declaration I do hereby declare that this work has been done by me and neither this project nor any part of it has been submitted elsewhere for the award of any degree or diploma except for publication. Countersigned Prof. Dr. Md. Kamruzzaman Younus Ali Supervisor & Professor Department of Mechanical Engineering DUET, Gazipur. v This Project work is dedicated to My Beloved Parents vi TABLE OF CONTENTS TABLE OF CONTENTS ………………………………………………………. vii LIST OF FIGURES …………………………………………………………….. x LIST OF TABLES ……………………………………………………………... xi LIST OF SYMBOLS ……………………………………………………….….. xii ACKNOWLEDGEMENT …………………………………………….……….. xiv ABSTRACT …………………………………………………………….……… xv CHAPTER 1 INTRODUCTION …………………………………….…… 1 1.1 State of Welding …………………………………….……… 2 1.1.1 SAW ………………………………………………….…….. 2 1.1.2 Solid Wire use MIG power sources ………………………... 2 1.1.3 FCAW Process ………………………………………….….. 3 1.1.4 Flux Cored welding Wire Basics …………………….…….. 4 1.2 Description of Electrodes …………………………….…….. 4 1.2.1 Bared Electrodes ………………………….……. 4 1.2.2 Submerged Arc Electrode ………………..…….. 6 1.2.3 Flux core or Tubular Electrode ………………… 8 1.2.4 Classification of Flux-Cored Electrodes ……….. 11 CHAPTER 2 LITERATURE REVIEW ……………………………….…. 14 2.1 Welding Industry …………………………………….…….. 14 2.2 Welding Quality ……………………………………….…… 15 2.3 Welding Expenditure …………………………………….…. 17 2.4 Welding Quality Measures and Testing ……………….…… 18 2.5 Welding Processes Used …………………………………… 19 2.6 Welding Technique in welding operation ……………….…. 21 vii 2.7 Objectives of present works ………………………………... 22 2.8 Research Methodology ………………………………….….. 22 CHAPTER 3 Welding Defects & Non Destructive Testing ……………… 24 3.1 Description of defects ………………………………….…… 24 3.2 Solidification Cracking ………………………………….…. 27 3.3 Hydrogen induced cracking (HIC) …………………….…… 29 3.4 Non Destructive Testing ……………………………….…… 29 3.4.1 Visual Inspection …………………………….…… 31 3.4.2 Detection Visual Inspection …………………..….. 32 3.4.3 Liquid Penetrant Examination (LPE) ……….……. 32 3.4.4 Magnetic Particle Testing (MPT) ……………..….. 33 3.4.5 Acoustic Emission Testing (AET) …………….…. 35 3.4.6 Eddy Current Array (ECA) ………………….…… 36 3.4.7 X-Ray Inspection ………………………………..... 38 3.4.8 Radio graphic Testing ……………………………. 38 CHAPTER 4 CASE STUDY WITH DATA ANALYSIS ……………….. 41 4.1 Description of Phased Array Machine ……………………... 41 4.2 Principal of PAUT Operation …………………………….… 42 4.3 Basic Principal of DPT/LPU/DPI ……………………….…. 47 4.4 The Process of Testing ……………………………………... 48 4.5 Mild Steel Microstructure Analysis ………………………... 55 4.6 PAUT Report with Image ……………………………….…. 57 4.7 4.1 Testing Results…………………………………….. 61 viii CHAPTER 5 RESULTS AND DISCUSSION ………………………….. 63 5.1 Results ……………………………………………………… 63 5.2 Discussion ………………………………………………….. 65 CHAPTER 6 CONCLUSIONS AND RECOMMENDATION …………. 67 6.1 Conclusions ………………………………………………… 67 6.2 Recommendations …………………………………………. 68 REFERENCES ………………………………………………………………… 70 APPENDICES ………………………………………………………………… 72 ix LIST OF FIGURES No. Description Page No. Fig. 2.1 Non destructive Testing Methods 19 Fig. 2.2 Welding Processes used in companies 20 Fig. 2.3 Welding Technical in welding operation 21 Fig. 4.1 DPT solution 46 Fig. 4.2 PA Machine 51 Fig. 4.3 MIG Welding Process 51 Fig. 4.4 FCAW with CO 2 gas after testing 52 Fig. 4.5 FCAW without CO 2 gas after testing 52 Fig. 4.6 Solid Wire with CO 2 gas after testing 52 Fig. 4.7 Solid Wire without CO 2 gas after testing 53 Fig. 4.8 Butt weld by FCAW with CO 2 gas before testing 53 Fig. 4.9 Butt weld by Solid wire with CO 2 gas before testing 53 Fig. 4.10 Fillet Weld by FCAW with CO 2 gas before testing 54 Fig. 4.11 Fillet Weld by Solid wire without CO 2 Gas before testing 54 Fig. 4.12 FCAW with CO 2 gas after testing 55 Fig. 4.13 FCAW without CO 2 gas after testing 55 Fig. 4.14 Microstructure for Mild Steel (Magnification 200) 56 Fig. 4.15 Microstructure for Welded joint of FCAW (Magnification 56 200) Fig. 4.16 Microstructure for Welded joint of Solid Wire (Magnification 56 200) x LIST OF TABLES No. Description Page No. Table 4.1 Used apparatus list 45 Table 4.2 Standard as per ASTM A572 Grade 50 45 Table 4.3 Testing Data for Mechanical Properties 46 Table 4.4 Report of butt weld FCAW with CO 2 gas 57 Table 4.5 Report of butt weld FCAW without CO 2 gas 58 Table 4.6 Report of butt weld Solid wire with CO 2 gas 59 Table 4.7 Report of butt weld solid wire without CO 2 gas 60 Table 4.8 Testing Results 61 xi LIST OF SYMBOLS ABS : American Bureau of Shipping ASME : American Society of Mechanical Engineers AWS : American Welding Society AET : Acoustic Emission Testing BS : British Standard BV : Bureau Veritas CNC : Computer Numeric Control CO 2 : Carbon dioxide CT : Computed Tomography DPT : Dye Penetrate Test DR : Digital Radiography ECA : Eddy Current Array FCAW : Flux-Core Arc Welding HIC : Hydrogen induced cracking IIW : International Institute of Welding ISO : International Organization of Standards ISO / TC : International Organization of Standards Technical Committee LPG : Liquefied Petroleum Gas MPT : Magnetic Particle Testing MIG / MAG : Metal Inert Gas / Metal Active Gas OHSAS : Occupational Health and Safety Advisory Services PAUT : Phased Array Ultrasonic Test PAW : Plasma Arc Welding PEBSAL : PEB Steel Alliance Limited PPE : Personal Protective Equipment SSL : Sarker Steel Limited. RTR : Real Time Radiography RGT : Radio Graphic Test SAW : Submerged Arc Welding xii SMAW : Shielded Metal Arc Welding TIG : Tungsten Inert Gas TWI : The Welding Institute UTM : Universal Testing Machine. VI : Visual Inspection X – Ray : X – Radiation xiii ACKNOWLEDGEMENTS I could never accomplish this task without the help of so many generous people. I would like to thanks Professor Dr. Md. Kamruzzaman for giving privilege the author to demonstrate his ability by researching in the field of welding and also correcting his final script and making useful suggestions for creating the platform and accepting him on this project. Also the author thanks the supervisor for his constructive comments and directions during the course of the project and for his suggestions, advice and constant motivation before and after this project work. He listened to author’s interests and led him accordingly. He also likes to thank especially to the Head of the Department of Mechanical Engineering for the help rendered for allowing and providing shops facilities to carry out the experiment whenever required. The help extended by the CASR for providing research fund is highly acknowledged. He would also likes to thank the staff members of the Department of Mechanical Engineering of Dhaka University of Engineering and Technology for their countless supports. Many thanks go to all the institutions which availed themselves to participate in this project. Finally, the author offers his sincere thanks to all those who either directly or indirectly helped him in various ways to complete this project thesis. xiv ABSTRACT There are different welding techniques that are used to join materials effectively and efficiently considering the fact that the foreign particles, darts, grease and oil will be removed from the welded junction properly as a result the junction will acquire the higher strength bonding in between the pure materials. Flux in the flux cored electrode do this functions along with some tempering effects. A cover on the welded junction made by molten slug reduces the heat dissipation rate due to its insulating property. As a result residual stresses are eliminated. Sub-surface cracks or micro-cracks are formed usually
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