Khảo sát ảnh hưởng của biên dạng chân đến độ bền kéo của hàn khuấy ma sát

VIETNAM NATIONAL UNIVERSITY HO CHI MINH CITY HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY TRA NGOC TIEN DAT INVESTIGATION ON THE EFFECT OF PIN PROFILE ON TENSILE STRENGTH OF FRICTION STIR WELDING Major Subject: Engineering Mechanics Codes: 8520101 MASTER THESIS HO CHI MINH CITY, January 2023 THIS RESEARCH IS COMPLETED AT HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY – VNU HCM Instructor: Ass Prof PhD Vu Cong Hoa PhD Duong Dinh Hao Examiner 1: PhD Mai Duc Dai Examiner 2: PhD Nguyen Tuong Long Master’s thesis is defended at HCMC University of Technology, VNU HCM on January 11, 2023 The Board of Master’s thesis defense council includes: Chairman: Prof PhD Ngo Kieu Nhi Secretary: PhD Pham Bao Toan Counter-Argument member 1: PhD Mai Duc Dai Counter-Argument member 2: PhD Pham Tan Hung Council Member: PhD Nguyen Tuong Long Verification of the chairman of the master’s thesis defense council and the Dean of the Faculty of Applied Science after the thesis is correct (if any) CHAIRMAN OF THE COUNCIL (Full name and signature) DEAN OF FACULTY OF APPLIED SCIENCE (Full name and signature) i VIETNAM NATIONAL UNIVERSITY HCMC VNUHCM UNIVERSITY OF TECHNOLOGY SOCIALIST REPULIC OF VIETNAM Independent – Liberty – Happiness MASTER’S THESIS ASSIGNMENTS I Full name: Tra Ngoc Tien Dat Leaner ID: 2070067 Date of birth: 10/10/1997 Place of birth: Quang Ngai Major: Engineering mechanics Major ID: 8520101 TITLE: INVESTIGATION ON THE EFFECT OF PIN PROFILE ON TENSILE STRENGTH OF FRICTION STIR WELDING/ KHẢO SÁT ẢNH HƯỞNG BIÊN DẠNG CHỐT HÀN ĐẾN ĐỘ BỀN KÉO MỐI HÀN MA SÁT KHUẤY II ASSIGMENTs: - III Research about the principle of friction stir welding process Design and fabricate friction stir welding tools with different pin profile Initialize the simulation model for friction stir welding process in Abaqus software - Conduct the friction stir welding experiment with aluminum alloy AA6061T6 - Evaluate and analyze the effect of pin profiles on the tensile strength of the welds and other mechanical properties ASSIGMENT DELIVERY DATE: September 05, 2022 IV ASSIGMENT COMPLETING DATE: December 18, 2022 V INSTRUCTOR: Ass Prof PhD VU CONG HOA PhD DUONG DINH HAO Ho Chi Minh City, January 11, 2023 INSTRUCTOR (Full name and signature) INSTRUCTOR (Full name and signature) Ass Prof PhD Vu Cong Hoa PhD Duong Dinh Hao ii HEAD OF DEPARTMENT (Full name and signature) DEAN OF FACULTY (Full name and signature) Ass Prof PhD Vu Cong Hoa Ass Prof PhD Truong Tich Thien iii LỜI CẢM ƠN Lời đầu tiên, xin chân thành cảm ơn đến hai người thầy hướng dẫn luận văn PGS TS Vũ Cơng Hồ TS Dương Đình Hảo Cảm ơn hai thầy cho định hướng, phương pháp nghiên cứu, hỗ trợ nhiệt tình suốt thời gian thực đề tài Tôi xin gửi lời cảm ơn đến: - Bộ môn Cơ kỹ thuật, khoa Khoa học ứng dụng, trường Đại học Bách Khoa TP HCM cung cấp kiến thức kinh nghiệm thời gian năm theo học - Thầy PGS TS Trần Hưng Trà phịng thí nghiệm Hàn ma sát khuấy, trường Đại học Nha Trang, hỗ trợ việc thực thí nghiệm hàn, việc đánh giá chất lượng mối hàn - Những đồng nghiệp, bạn bè Khoa Cơ khí, trường Đại học Bách Khoa, hỗ trợ việc thiết kế, chế tạo chốt hàn Cuối cùng, xin gửi lời cảm ơn đén gia đình, người thân, ln đồng hành, hỗ trợ suốt thời gian qua Người thực Trà Ngọc Tiến Đạt iv ABSTRACT Friction stir welding is now widely applied in material joining applications, in many fields such as aerospace, marine, railway In this method, tool pin profile has great impact on the quality of the weld This study will present the investigation on the effect of different pin profiles on the quality of FSW joint, particularly in tensile strength The numerical model is developed with Coupled Eulerian Lagrangian technique in Abaqus software The heat generation is validated by experimental work The evaluation of mechanical properties of the weld, including tensile strength, bending strength and hardness was performed The macrostructure and microstructure analysis were also conducted As a result, FSW joint had been successful made in which investigated tools with joint efficiency around 78% However, the effect of different tool pin profiles on the tensile strength is not clearly observed The numerical model is good for prediction the temperature distribution in FSW process with a quite accuracy compared with experimental results v TÓM TẮT LUẬN VĂN THẠC SĨ Hàn ma sát khuấy ngày áp dụng rộng rãi ứng dụng hàn hay kết nối vật liệu với nhau, ứng dụng ngành hàng không, vũ trụ, tàu thuỷ, … Trong phương pháp hàn ma sát, biên dạng chốt hàn đóng vai trị quan trọng việc tạo mối hàn đạt chất lượng Luận văn trình bày khảo sát ảnh hưởng biên dạng chốt hàn khác lên chất lượng mối hàn ma sát, cụ thể độ bền kéo Mơ hình mơ số xây dựng phần mềm Abaqus, sử dụng kỹ thuật mơ hình hố Coupled Eulerian Lagrangian Sự sinh nhiệt trình hàn, kiểm tra kết thí nghiệm Cơ tính mối hàn, gồm độ bền kéo, độ bền uốn độ cứng mối hàn đánh giá Việc khảo sát cấu trúc thô đại cấu trúc tế vi mối hàn thực Với biên dạng đầu hàn dùng khảo sát này, mối hàn ma sát khuấy tạo với chất lượng đạt yêu cầu, với hiệu suất hàn khoảng 78% Tuy nhiên, ảnh hưởng biên dạng chốt hàn khác chưa thấy rõ Mơ hình mơ cho phân bố nhiệt độ trình hàn ma sát khuấy với độ tin cậy cao vi GUARANTEE I hereby declare that the master’s thesis, “Investigation on The Effect of Pin Profile on Tensile Strength of Friction Stir Welding” is my independent scientific study The numerical and experimental data in this thesis was conducted based on my effort, with strong support from Assoc Prof Vu Cong Hoa and Dr Duong Dinh Hao All references have been clearly cited The research data in the topic is honest and absolutely not copy or use the results of other research topics If there is a copy found, I will fully assume all responsibility Author Tra Ngoc Tien Dat vii CONTENT CONTENT vii List of Figures .x List of Tables xiii CHAPTER INTRODUCTION 1.1 Background 1.2 Problem statement 1.3 Scope .3 1.4 Work Plan and Objectives: 1.5 Organization of the Thesis .3 CHAPTER LITERATURE REVIEW 2.1 Fundamentals of Friction Stir Welding 2.2 Heat Generation in Friction Stir Welding .9 2.3 Friction Stir Welding Tool 2.4 Coupled Eulerian Lagrangian Formulation 12 2.4.1 Lagrangian and Eulerian Analysis [13] .12 2.4.2 Using Coupled Eulerian – Lagrangian Formulation in FSW 13 2.5 Evaluation of FSW Weld Properties 14 2.5.1 FSW Quality-related Parameters .14 2.5.2 Tensile Strength 16 2.5.3 Bend Testing 17 CHAPTER MODELING DESCRIPTION .18 3.1 Tool Pin Profile Design .18 viii 3.2 Geometric Modeling 19 3.3 Material Model 19 3.4 Meshing .21 3.5 Contact Interaction and Boundary Conditions 22 3.6 Mass Scaling Technique 24 CHAPTER EXPERIMENTAL WORK 26 4.1 Aluminum Alloy 6061 – T6 26 4.2 Tool Fabrication 27 4.3 Fabrication of FSWed butt-joint 27 4.4 Analysis process 29 4.4.1 Temperature distribution 29 4.4.2 Microstructure 29 4.4.3 Hardness distribution 30 4.4.4 Tensile and bending test 31 CHAPTER RESULT AND DISCUSSION 33 5.1 Temperature Distribution 33 5.1.1 Heat generation 33 5.1.2 Numerical Model Validation .38 5.2 Inspection of the butt-joints 39 5.3 Microstructure .42 5.4 Hardness distribution 44 5.5 Tensile Strength Testing Result 44 5.6 Bend Testing Result 48 CHAPTER CONCLUSION AND FUTURE WORK 52 45 Tensile Stress (MPa) 250 Tool Tool Tool Tool 200 150 100 50 0 Tensile Strain (%) Figure 5-18 Stress-strain curve of specimens produced by various tools Figure 5-19 Fracture position of tested specimens (welded by Tool 1) 46 Figure 5-20 Fracture position of tested specimens (welded by Tool 2) Figure 5-21 Fracture position of tested specimens (welded by Tool 3) Figure 5-22 Fracture position of tested specimens (welded by Tool 4) 47 Test result of different weld joints is also compared with the strength of base material This work is to evaluate the term “joint efficiency”, which can be defined as the strength of the joint compared to the parent material The results of tensile strength test are summarized in Table Table Tensile strength test results (in MPa) Tool Tool Tool Tool Tool 198.73 197.26 196.87 195.97 195.67 195.15 196.87 195.42 199.77 192.75 191.09 194.47 Average 198.06 195.05 194.94 195.28 Specimen Base metal 248.12 Tensile strength values of FSW joints by different pin profiles can be seen in the Figure 5-23 The number above the bar indicates the joint efficiency 300 Tensile strength (MPa) 250 100.0% 200 79.8% 78.6% 78.6% 78.7% Tool Tool Tool Tool 150 100 50 Base metal Tool pin profile Figure 5-23 Tensile strength property comparison and joint efficiency of the welds In general, the joint efficiency in cases in this investigation are quite similar The values are around 78-80% With the typical joint efficiency of AA6061 weld with 48 FSW technology is 70%, it can conclude that these welds are successful made It means the tool design, process parameter applying in the experiment are properly selected However, the effect of different pin profiles on the tensile strength of the welds is not clearly seen 5.6 Bend Testing Result Figure 5-24 After bending specimens - Face bend Figure 5-25 After bending specimens – Root bend The following charts show the bend testing result of different cases Forcedisplacement curve of face bend, root bend and base metal bend are shown in one graph to visualize the differentiation 49 Tool 700 Bending load (N) 600 500 400 300 Base metal Face bend #1 Face bend #2 Root bend #1 Root bend #2 200 100 0 10 15 20 Displacement (mm) Figure 5-26 Force – Displacement Bending Curve of Tool Tool 700 Bending load (N) 600 500 400 300 Base metal Face bend #1 Face bend #2 Root bend #1 Root bend #2 200 100 0 10 15 20 Displacement (mm) Figure 5-27 Force – Displacement Bending Curve of Tool 50 Tool 700 Bending load (N) 600 500 400 300 Base metal Face bend #1 Face bend #2 Root bend #1 Root bend #2 200 100 0 10 15 20 Displacement (mm) Figure 5-28 Force – Displacement Bending Curve of Tool Tool 700 Bending load (N) 600 500 400 300 Base metal Face bend #1 Face bend #2 Root bend #1 Root bend #2 200 100 0 10 15 20 Displacement (mm) Figure 5-29 Force – Displacement Bending Curve of Tool 51 Table 10 Bend testing results (in MPa) Base metal 443.11 Face bend Face bend Root bend Root bend Tool 356.81 317.23 306.96 350.83 Tool 265.79 342.1 252.29 202.38 Tool 279.75 211.86 360.6 244.67 Tool 305.6 281.24 273.87 222.05 Similar to the tensile test, in bending test, we also compare the bending properties of the joints to the base metal Maximum Bending Stress of FSW samples welded by different pin profiles (Number above the bar indicate percentage with base metal) 500 443.11 Max Bending Stress (MPa) 450 FACE BEND 400 350 76% 74% 69% 68% 300 51% 250 55% ROOT BEND 66% 56% BASE METAL 200 150 100 50 Tool Tool Tool Tool Tool pin profile Figure 5-30 Bending properties of FSW joints with pin profiles 52 CHAPTER 6.1 - CONCLUSION AND FUTURE WORK Summary the Results The study provided four tool designs with different pin profiles for Friction Stir Welding for AA6061-T6 butt joint These tools worked well with aluminum plate with 3mm thickness, result in joint efficiency of the welds around 78% - The Coupled Eulerian Lagrangian numerical model is successful developed in Abaqus Mass scaling technique is used to reduce the computation effort - The evaluation of mechanical properties of the weld is conducted with tensile, bending test, hardness measurement, and microstructure analysis - The tensile strength of four specimens produced by different tool pin profiles are quite similar, with the value is about 78-80% with the value of base metal The fracture position is at HAZ region in four cases This result can be explained by the hardness distribution, and the microstructure analysis - Tool pin profile No.1 (cylindrical thread) produced the welded specimen with the highest bending strength 6.2 Conclusion This investigation comes out with several results as follow: - A Coupled Eulerian Lagrangian numerical model was successfully created and proved to be reliability in prediction the temperature distribution of FSW - The successful fabrication of FSW process for AA6061-T6 butt-joint was performed, with process parameters as follow: ▪ Rotational speed: 800 RPM ▪ Welding speed: 100mm/min ▪ Tool penetration: 0.2mm ▪ Four tool designs in the thesis, made by H13 steel - Within the conducted experiments, the different pin profiles have indistinctive effect on the tensile strength of FSW joints (quite similar tensile strength in 53 four cases) Since four tool pin profiles have the same dynamic volume, it can conclude that this value directly affects the joint efficiency of the weld - The flat features on the tool pin profile produced higher temperature value than feature-less tool 6.3 Limitation There are also some limitations in this thesis: - Welding forces had not been investigated with various tool pin designs So that the tool wear in different tool design could not be evaluated or predicted - There are some “weird” values in the temperature distribution plotted by numerical result 6.4 Recommendation for Future Work The potential works of this thesis: - Conduct the simulation with finer mesh - Analyze other available results in numerical model - Review and the remove the noise value in temperature data in experiment - Conduct new experiment set up with force measurement system, to evaluate the welding force of different tools - Apply the concept of pin profile design in other studies with various material, thickness, joint type 54 REFERENCES [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] R.S Mishra, P.S De and N Kumar Friction Stir Welding and Processing Springer International Publishing, 2014 K Elangovan and V Balasubramanian “Influences of pin profile and rotational speed of the tool on the formation of friction stir processing zone in AA2219 aluminium alloy.” Mater Sci Eng A, vol 459, pp 7–18, 2007 J Marzbanrad, M.Akbari and P Asadi “Characterization of the influence of tool pin profile on microstructural and mechanical 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