UNIVERSITI TEKNIKAL MALAYSIA MELAKA

Transcription

1

2 UNIVERSITI TEKNIKAL MALAYSIA MELAKA BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA TAJUK: Mechanical properties determination of mild steel and stainless steel joint fabricated by MIG welding process SESI PENGAJIAN: 2009/10 Semester 2 Saya SHAHRIR BIN SAHARI 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) Disahkan oleh: Alamat Tetap: Lot 156 Kg Baru Peramu, Kuantan, Pahang Darul Makmur. Cop Rasmi: Tarikh: Tarikh: ** 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.

3 DECLARATION I hereby, declared this report entitled Mechanical properties determination of mild steel and stainless steel joint fabricated by MIG welding process is the results of my own research except as cited in references Signature :. Author s Name :. SHAHRIR BIN SAHARI Date :.

4 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: (Signature of Supervisor).. (Official Stamp of Supervisor)

5 ABSTRAK Tujuan projek ini adalah untuk menentukan prilaku mekanik dan daerah terkesan haba (HAZ) pada struktur mikro, terhadap kimpalan diantara besi baja yang mengandungi peratusan yang karbon rendah dan keluli tahan karat dengan menggunakan proses kimpalan keluli gas arka (MIG). Keluli tahan karat daripada kelas (AISI 304) dah besi baja karbon rendah (AISI 1010) telah digunakan dalam projek ini. Kedua-duanya yang berketeblan 4 mm telah dikimpal bersama logam penambah (AWS ER309) yang berbeza diameter iaitu (0.8 mm dan 1.2 mm). Mesin kimpal (WIM 210S) telah digunakan untuk tujuan tersebut, yang mana parameter terkawal adalah voltan, kelajuan suap logam penambah dan kadar alir gas pelindung. Ujian ujian mekanik yang dilaksanakan adalah ujian kekuatan tarikan, ujian keteguhan hentaman, dan ujian kekerasan. Di penghujung analisa didapati terdapat perubahan nilai kekerasan pada setiap bahagian seperti besi asas, kawasan terkesan haba dah bahagian kimpalan itu sendiri. Kekerasan yang tinggi telah dicatat pada kawasan terkesan haba di kedua- dua belah sambungan. Ujian terikan pula menunjukkan kimpalan menggunakan logam penambah berdiameter 0.8 mm adalah lebih tegar daripada 1.2 mm. Sungguhpun begitu, kesemua bahan ujian telah gagal pada kawasan terkesan haba di sebelah (AISI 1010) yang berkemungkinan disebabkan oleh kurangnya pelakuran antara logam penambah dan besi baja karbon rendah. Walaubagaimanapun, ujian struktur micro menunjukkan adanya keretakan berlaku pada bahagian HAZ tersebut yang menyumbang pada kegagalan semasa ujian keterikan. Akhir sekali, tumpuan haruslah diberikan sepenuhnya terhadap rekabentuk, procedur, spesifikasi dan teknik mengimpal besi yang berlainan jenis untuk mendapat keputusan yang baik sebelum berjaya menentukan penetapan perilaku mekanik terhadap sesuatu sambungan kimpalan. ii

6 ABSTRACT The purpose of this study is to determine the mechanical properties and the microstructure behavior at weldment and HAZ of mild steel and stainless steel joint fabricated using MIG welding process. Material from grade Austenitic stainless steel (AISI 304) and mild steel (AISI 1010) with both thickness 4 mm were used. Welding design was done in single groove butt joint and weld using 1.2 mm and 0.8 mm diameter size of filler wire (ER309). Welding machine (WIM 210S) was used with selected parameter with involved voltage, wire feed speed and gas flow rate. Mechanical properties were evaluated in tensile tests, Charpy-V toughness tests, and hardness test. In addition microstructure examinations were carried out. Base on the finding, there was changes in hardness value on base metal, weldment and HAZ area. High hardness value has been identified at both HAZ area of dissimilar weld. Tensile test show at 1.2 mm strength was weaker than 0.8 mm joint. All specimens were fracture at HAZ near AISI 1010 side because of lack of fusion. At their barrier microstructures reveal that present of crack at HAZ near AISI 1010 and show little dilution in intermetallic of dissimilar metal. No ferrite structure present because MIG welding provide rapid cooling. All the implication in the dissimilar weld disturbance and affect the whole properties. i

7

8 ACKNOWLEDGEMENTS First and foremost, I would like to thank Almighty Allah for allowing me to successfully complete this report. I also would like to convey my thanks to the all person who had contributed in ensuring a successful occurrence throughout the duration of my final year project. I also would like to take this opportunity to express my gratitude to Mr. Mohd Shukor bin Salleh as my supervisor for his guidance and support. I also want to express my whole-hearted thanks to all my friends who are also my comrades in times of need. Last but not list those mentioned, I would like to express my gratitude with highly appreciation and dedication to my family with their support morally in completing my final year project and motivate to success and complete study in Universiti Teknikal Malaysia, Melaka (UTeM). iv

9 TABLE OF CONTENTS Abstract Abstrak Dedication Acknowledgement Table of Contents List of Figures List of Tables List of Abbreviations i ii iii iv v ix xii xiii CHAPTER 1: INTRODUCTION 1.1 Introduction Project Background Problem Statement Objective Scope of Project Report Organization Project Planning 7 CHAPTER 2: LITERATURE REVIEW 2.0 Introduction Stainless Steel Typical Stainless Steel Application Austenitic (200 and 300 series) Low Carbon Steel (Mild Steel) Typical Mild Steel Application Gas Metal Arc Welding (GMAW) 13 v

10 2.3.1 MIG Metal Transfer Spray Transfer Globular Transfer Short Circuiting Transfer MIG Equipment Setup Principles of Operation Dissimilar Metal Welding Weld Metal Dilution Melting Temperature Thermal Conductivity Coefficient of Thermal Expansion Welding Stainless Steel and Mild Steel Welding Consideration Filler Wire Selection for Dissimilar Metal Buttering Process Joint Design for MIG Butt Joint Shielding Gas Variation for MIG welding Process Mechanical Properties Tensile Test Stress Strain Curves Basic Calculation Ductility Hardness Test Rockwell hardness test Impact Test Toughness Weldment Microstructure Heat Affected Zone 32 vi

11 CHAPTER 3: METHODOLOGY 3.0 Introduction Process Flow Chart Materials preparation Raw Material Equipment preparation Design of Experiment (D.O.E) Determine MIG welding Settings Procedure of Hardness Measure Machine Setup Install Filler wire Contact Tip Change Welding Experiment Cutting the Material Joint Design Process Buttering Process Tack Weld process Welding process Specimen Preparation Cutting process Tensile Specimen (ASTM E8) Hardness Specimen (ASTM 10) Microstructure Specimen (ASTM E3) Impact Specimen (ASTM E23) Experimentation Hardness Test Measurement Tensile Test Measurement Impact Test Measurement Microstructure Analysis 51 vii

12 CHAPTER 4: RESULT AND DISCUSSION 4.1 Hardness Result-D.O.E Actual Experiment Hardness Result Hardness Data Analysis Results for Tensile Test Data Collected Analysis Stress versus Strain Analysis Results for Charpy Impact Results for Microstructure Analysis Sample A -Filler wire 1.2 mm with 20X Magnifier Sample F- Filler wire 0.8 mm with 20X Magnifier Relation of the Results 67 CHAPTER 5: CONCLUSION AND RECOMMENDATION 5.0 Introduction Result overview Conclusion Recommendation 70 REFERENCES 71 APPENDICES A Gantt chat B Hardness test result B Tensile test result D Microstructure Analysis viii

13 LIST OF FIGURES 1.0 Dissimilar metal joint in Volvo S Basic principle of MIG welding Spray transfer Globular transfer Short-circuiting transfer Schematic of equipment setup for MIG Illustration operation of MIG Effect of electrode position and welding technique A Schaeffler diagram and the procedure of estimating the 21 microstructure of E309-type. 2.9 Buttering process used to assist in dissimilar welding Bevel angle, groove angle, and root opening of joints for welding Shielding gas related to weld profile for DCEP Diagram of tensile test machine Typical stress-strain curve obtained from tensile test Rockwell hardness testing technique Charpy-V notch impact apparatus Optical microstructure of parent metal Austenite 304 stainless steel Optical microstructure of parent metal plain mild steel Heat affected zone microstructure Austenitic steel side Anatomy of a weld Process Flow Chart Stainless steel plate Mild Steel Plate Filler Wire specification MIG Machine Specification 37 ix

14 3.6 Hardness measured point for D.O.E purpose Hardness test in progress Show the sequence to install the filler wire Procedure to change the MIG contact tip Beveling process Buttering process at AISI 1010 side Allocated the tack weld MIG welding in action Finish welded part with 45 degree single groove butt join type The way specimen cut from weld part Cutting the specimen for testing Standard specimen for tensile test Tensile specimen for 1.2 mm diameter filler wire Example of hardness test specimen Hardness test specimens Metallographic specimens Specimen for charpy impact test Rockwell hardness machine Hardness test process Tensile machine in progress Impact Tester Specimen with before and after impact test Image Analyzer (Buehler Omniment) Grinding and polishing equipment (Buehler) Hardness Result for 1.2 mm filler wire Hardness Result for 0.8 mm filler wire Hardness measure point Mean of hardness value on dissimilar metal joint Tension test specimen 59 x

15 4.6 Properties comparison between different size filler wire Result tension test for specimen A Result tension test for specimen F Show the Result obtain from Charpy test Physical appearance of the specimen after the test Metallographic observation on 1.2 mm (20 X) Metallographic observation on 0.8 mm (20 X) Heat Affected zone (HAZ) and weldment Solidification Crack was identifying using both filler wire. 67 xi

16 LIST OF TABLES 2.1 Minimum Mechanical Properties for annealed Alloys Nominal Compositions of Austenitic Stainless Steels Mechanical properties of selected carbon steel Composition of selected carbon steel The nominal chemical compositions of the alloy steel Mechanical properties of ER Recommended parameter for MIG using welding grade CO The variation of the MIG welding process Recommended etching solution for dissimilar metal General setting parameter for MIG welding process Best Parameter for Welding machine MIG 210S Standard specimen size for tensile experiment (From ASTM E8) Parameter for Hardness test machine Parameter for tensile test machine MIG parameter for 1.2 mm filler wire MIG parameter for 0.8 mm filler wire Specimen number for each filler wire Convert HRB value to approximate tensile strength Data of tensile test using 1.2 mm and 0.8 mm MIG filler wire Mechanical properties 69 xii

17 LIST OF ABBREVIATIONS AWS - American Welding Society AISI - American Iron and Steel Institute ASTM - American Standard Testing for Material ASME - American Society of Mechanical Engineer BHN - Brinell Hardness Number Cr - Chromium CV - Constant Voltage CO 2 - Carbon dioxide DCEP - Direct Current Electrode positive DCEN - Direct Current Electrode Negative GTAW - Gas Tungsten Arc Welding GMAW - Gas Metal Arc Welding HAZ - Heat Affected Zone MIG - Metal Inert Gas Mn - Manganese Ni - Nickel PSM - Projek Sarjana Muda SMAW - Shield Metal Arc Welding SAW - Submerge Arc Welding UTeM - Universiti Teknikal Malaysia Melaka xiii

18 CHAPTER 1 INTRODUCTION 1.1 Introduction Welding is very common technique in order to join two or more types of metal. Welding is used to join all commercial metals and alloys and to joint metal of different type of strength. Welding begin as a repair or maintenance tool and has become one of the most crucial manufacturing methods as well as the most essential construction method. Almost everything made of metal is welded. Because of its strength and versatility, welding is used in manufacture of almost all the products used in our life every day. Without welding many community cannot afford the cost of the goods and services they need to earn a living (Cary & Helzer, 2005). American welding society (AWS) has defined welding as a joining process that produce coalescence of materials by heating them to the welding temperature, with or without the application of pressure or by the application of pressure alone, and with or without the use of filler metal. Welding goes well beyond the bounds of its simple description. Welding today is applied to a wide variety of materials and products, using such advanced technologies such as lasers and plasma arcs. The future of welding holds even greater promise as methods are devised for joining dissimilar and non-metallic materials, and for creating products of innovative shapes and designs. 1

19 For an example, the famous trans-alaska pipeline, a super-tanker, the world largest moving weldment, storage tank for water supply systems, the sears Tower in Chicago would not be possible without welding. The international space station was welded together on earth and transported to space, and the final assembly welds were done in space. The shuttle itself, from the rocket engines to the external fuel tank, required specialized procedures for welding alloy aluminum without defects. Most large airplanes include much welding, even miniature components for electronic equipment and telecommunication equipment. All of these prove that welding is important in many applications (Cary & Helzer, 2005). There are many types of welding processes and also many ways to make a weld. Some welding processes do not cause spark, use electricity, or required heat. Many different energy sources can be used for welding, including a gas flame, an electric arc, a laser, an electron beam, friction, and ultrasound. While often an industrial process, welding can be done in many different environments, including open air, under water and in outer space (Cary & Helzer, 2005). 2

20 1.2 Project Background Welded dissimilar metal joints become widely accepted as the superior design option for manufactured products between their quality, reliability, and serviceability. The welding industries are working to remove reservations in areas where there is concern about welded joints due to limitations of materials, process, and ability to ensure quality. In the recent years, welding dissimilar metal joint promotes various service conditions such as resistance to corrosion, heat resistance and magnetic properties. A lot of study has been done with the dissimilar welding technology nowadays. Wagner et al. (2000) shows there were a lot of wide variety of possible applications for dissimilar material combinations. At present, the main focus in this area is aiming car body concepts for weight reduction and higher stiffness due to the locally use of aluminum sheet materials. For power train components the combination of aluminum parts with thin walled steel pipes offers the opportunity for a significant reduction of the rotating masses. Under this concern, higher product efficiency could be realized. Figure 1.0: Dissimilar metal joint in Volvo S40 (Available at: Realizing the important of welding dissimilar metal nowadays; the research about joining the material of mild steel and stainless steel fabricated by using MIG welding process has been carrying out. In contrast, this research is subjected to determine the mechanical properties of dissimilar metal joint and also to study the characteristic of the weldment area. This is important to understand behavior of dissimilar joint at the basic point of view before applying them to the real application. 3

21 1.3 Problem Statement Weld between dissimilar metals relates to the transition zone between the metal and the intermetallic compounds formed in this transition zone. For the fusion welding processes, it is important to investigate the composition of two metals involved. If there is mutual solubility of the two metals, the dissimilar joint can be made successfully. If there is little or no solubility between the two metals to be joined, the weld joint will not be successful (Cary & Helzer, 2005). Al Wadleigh (1991) derive dissimilar metals have different chemistries, so they have different physical properties such as melting temperature. Many who have involved with joining metal with different melt temperature experience frustration. The difficulties was arise when someone try to melt metal together at same weld temperature. For example mild steel and stainless steel, obviously in nature these materials have different melting point. MIG welding is widely used in many industry applications such as automotive, oil and gas, agriculture, and construction. Their versatility, rapid, economical, capable in all weld position, technique, speed and high deposition is the reason why it most used. MIG welding can operate with semiautomatic or automatic and work with most metal (Kalpakjian & Schmid, 2006). MIG welding does not require particular skill level and it is capable to be carried out by fresh welder with some basic instruction. Hence, it is provided with semiautomatic mode which is appropriate to reduce the human factor error that contributes to weld quality as well as to acquire the better result. In weld a dissimilar metal, MIG welding is twice better than SMAW in term of productivity from deposition of the welt metal on the base metal, and good consumable utilization (Cary & Helzer, 2005). 4

22 Kiling (2001) stated that scope of application of MIG welding in German is over 75% nowadays, it is being used in partial mechanized, fully mechanized and automate technique. MIG welding produce high quality weld at high speed without the used flux and limited postweld cleaning. It is very desirable for both small and high production metal joining. It frequently replaces other joining process such as riveting, brazing, silver-soldering, or resistance welding. MIG welding is better than friction welding in term of flexibility because friction welding constraint for round billet shape or pipe only. It may be used instead of the following fusion welding process; submerge arc welding, flux core and gas tungsten arc welding. However material such Mild steel and stainless steel are widely used in many applications such as construction, power plant, petrochemical, offshore, and more. Mild steel is low carbon steel that easy to form and has excellent weldability meanwhile stainless steel has popular as resistant to corrosion material and weldable with various application (Kalpakjian & Schmid, 2006). Realizing the important on joining dissimilar metal and its application in many industry nowadays it is essential to joining various of metal in order to reducing cost and meet the specification of the product. Engineer is essential to study the properties of the weld join in order to design and size the load carrying for economic and safety concern. Hence, the study on the mechanical properties determination of mild steel and stainless steel joint fabricated by MIG welding process was necessary to provide understanding of dissimilar weldments from the basic point of view. 5

23 1.4 Objective The objectives of the research are as follow: a) To study the effect on mild steel and stainless steel joint using different diameter filler wire of MIG welding. b) To evaluate weld properties through the Hardness, Tensile, and Microstructure. c) To analyze the characteristic of weldment and heat affected zone (HAZ) microstructure. 1.5 Scope of Project Here, scope act as the guidance that permits this research is doing without loss the focusing. It is capable to bring the project to their objective without run out by doing work that not relate to the objective. Welding process has done using MIG welding machine (WIM 210S). Three controlled parameter such Voltage, Wire feed and Gas flow rate was selected which respect to the welding standard and machine capability. Material used is from type (AISI 1010) mild steel and (AISI 304) stainless steel with both thickness 4 mm. the joint design was single groove butt joint with flat position (1G) by different diameter of MIG welding filler wire (ER309) which is 1.2 mm and 0.8 mm. Specimen was prepared according to AWS and ASTM respectively to study the mechanical properties such state in the objective. Other variables are not mention here become a limitation of this project scope. 6

24 1.6 Report Organization Chapter 1: Introduction a) This chapter briefly explained the background of the project study, the objective that want to achieved, the problem statement and finally whole project planning through Gantt chart. Chapter 2: Literature Review a) This chapter was collection of research information that relate to the study from any trusted resources. Chapter 3: Research Methodology a) This chapter explains the structure on how project was done Chapter 4: Result and Discussion a) The output from the study was precisely explain and discussed in this chapter. Chapter 5: Conclusion and Recommendation a) This chapter finally explains the achievement of whole project to compare with objectives. 1.7 Project Planning The purpose of the project planning was to meet the due date. Besides that, it was very important tool to manage the project smoothly and flexible. Although, Gantt chat was developed for that purpose, it shows the time line for every task and targeted plan. From Gantt chart the entire process was clearly preview, and the way to start the project was easy to understand. Hence, Gantt chart was attached at Appendix A. 7