Investigate strategies for moving heat sources in the process of heating metal on a flat surface

MINISTRY OF EDUCATION AND TRAINING HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY AND EDUCATION FACULTY FOR HIGH QUALITY TRAINING CAPSTONE PROJECT ELECTRONICS AND TELECOMMUNICATIONS ENGINEERING TECHNOLOGY INVESTIGATE STRATEGIES FOR MOVING HEAT SOURCES IN THE PROCESS OF HEATING METAL ON A FLAT SURFACE LECTURER: PGS TS PHẠM SƠN MINH STUDENT: NGÔ ĐỨC TÀI LÊ MINH NHI HOÀNG MẠNH THẮNG S K L 01 8 Ho Chi Minh City, 2023 MINISTRY OF EDUCATION AND TRAINING UNIVERSITY OF TECHNICAL AND EDUCATION HO CHI MINH CITY FACULTY OF HIGH QUALITY TRAINING ⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯ MECHANICAL ENGINEERING TECHNOLOGY GRADUATION THESIS INVESTIGATE STRATEGIES FOR MOVING HEAT SOURCES IN THE PROCESS OF HEATING METAL ON A FLAT SURFACE Instructor: PGS TS PHẠM SƠN MINH Student: NGÔ ĐỨC TÀI ID: 19144074 LÊ MINH NHI ID: 19144061 HOÀNG MẠNH THẮNG ID: 19144070 Course year: 2019 - 2023 Ho Chi Minh city, July 2023 UNIVERSITY OF TECHNICAL AND EDUCATION HO CHI MINH CITY FACULTY OF HIGH QUALITY TRAINING MECHANICAL ENGINEERING TECHNOLOGY ⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯ COURSES: GRADUATION THESIS ` GRADUATION THESIS INVESTIGATE STRATEGIES FOR MOVING HEAT SOURCES IN THE PROCESS OF HEATING METAL ON A FLAT SURFACE Instructor: PGS TS PHẠM SƠN MINH Student: NGÔ ĐỨC TÀI ID: 19144074 LÊ MINH NHI ID: 19144061 HOÀNG MẠNH THẮNG ID: 19144070 Course year: 2019 - 2023 Ho Chi Minh city, July 2023 HCM UNIVERSITY OF TECHNOLOGY AND EDUCATION SOCICALIST REPUBLIC OF VIETNAM Independent - Freedom – Happiness FACULTY OF HIGH QUALITY TRAINING Courses: graduation thesis GRADUATION THESIS MISSIONS Semester / academic year: 2022 – 2023 Instructor: PGS TS PHẠM SƠN MINH Students: NGÔ ĐỨC TÀI 19144074 Contact: 0388060002 LÊ MINH NHI 19144061 Contact: 0981478011 HOÀNG MẠNH THẮNG 19144070 Contact: 0767046782 Number of topic: 22223DT69 Name of topic: Investigate strategies for moving heat sources in the process of heating metal on a flat surface Initial Data and Documents: - Luận văn thạc sĩ: NGHIÊN CỨU ẢNH HƯỞNG THÔNG SỐ HÀN ĐẮP ĐẾN ĐỘ BÊN KÉO CỦA LỚP ĐẮP – Nguyễn Cơng Chính - Welding and Repair Options - Using CNC Machines and TIG Welding Main Content of the Project: - Overview of Welding and Repair Technology - Understanding the parameters of welding by layer - Performing welding on various samples corresponding to different options Expected Deliverables - Realistic product model - Analytical report Date assigned to the project: March 15, 2023 The deadline for project submission: July 15, 2023 English  Vietnamese  Protection presentation: English  Vietnamese  Presentation language: The report: i HEAD OF DEPARTMENT (Sign, write full name) SENIOR MANAGER (Sign, write full name)  Allowed to defend the graduation thesis (Instructor sign, full name) ii INSTRUCTOR (Sign, write full name) COMMITMENT - Name of topic: Investigate strategies for moving heat sources in the process of heating metal on a flat surface - Students: - Ngô Đức Tài 19144074 Contact: 0388060002 Lê Minh Nhi 19144061 Contact: 0981478011 Hoàng Mạnh Thắng 19144070 Contact: 0767046782 Graduation thesis submission date: Commitment: "I hereby declare that this graduation thesis is the result of my own research and work I have not copied from any published articles without proper citation If any violation occurs, I take full responsibility." Ho Chi Minh City, 27 July, 2023 Signature iii SPECIAL THANKS We would like to express our sincere and profound gratitude to the teachers at the University of Technical Education in Ho Chi Minh City for their guidance, teaching, and invaluable support throughout the implementation of our graduation project titled “Investigating Heat Source Movement Strategies in the Process of Heating Metal on a Flat Surface” We deeply appreciate the dedication and assistance provided by our esteemed instructors during this period First and foremost, we would like to express our gratitude to the teachers for imparting the knowledge and skills necessary for us to successfully complete this project The knowledge we have gained not only helped us grasp the theoretical foundations but also supported us in conducting experiments and analyzing dat We would also like to express our gratitude to Ph.D Pham Son Minh, Ph.D Tran Minh The Uyen, Ph.D Nguyen Van Thuc, Mr Truong Thanh Cong, and Mr Nguyen Van Mang for providing us with the necessary materials and equipment to conduct the experiments Thanks to their support, we were able to carry out the experiments accurately and reliably Furthermore, we deeply appreciate the advice, guidance, and support provided by the teachers throughout the project The valuable input and contributions from the instructors have helped us improve our project to the best of our abilities Once again, we would like to express our gratitude for the excellent facilities provided by the university, including state-of-the-art laboratories, diverse research materials, and a friendly learning and working environment All of these have created a conducive atmosphere for us to conduct our experiments and research effectively iv ABSTRACT Investigate strategies for moving heat sources in the process of heating metal on a flat surface( Khảo sát phương án di chuyển nguồn nhiệt trình nung nóng kim loại đắp phẳng) The research project focuses on studying the process of heating metal on a flat surface and investigating various heat source movement strategies during this process The objective of the research is to understand and evaluate the effectiveness of different heat sources movement options to enhance the heating process of metal on a flat surface To achieve this objective, the research utilizes an experimental approach to conduct experiments with different heat source movement strategies These strategies may involve horizontal, vertical, rotational, or combined movements of the heat source during the process of heating the metal During the experimental process, parameters such as temperature, pressure, flow rate, and uniformity are measured and recorded to analyze and evaluate the effectiveness of each heat source's movement strategy In conclusion, the graduation project aims to research and evaluate different heat source movement strategies in the process of heating metal on a flat surface, with the goal of improving the efficiency and quality of metal production processes v TABLE OF CONTENTS GRADUATION THESIS MISSIONS i COMMITMENT iii SPECIAL THANKS iv ABSTRACT v TABLE OF CONTENTS vi LIST OF TABLES x LIST OF FIGURES xi LIST OF ABBREVIATIONS xiii CHAPER 1: INTRODUCTION 1.1 Put the problem 1.2 Research situation in Viet Nam 1.3 Research situation of orther contries 1.4 Graduation project goals 1.5 Objects, research scope of the topic 1.5.1 Research subjects 1.5.2 Research scope of the topic 1.6 Research method 1.6.1 Theoretical research 1.6.2 Experimental study 1.7 The scientific and practical significance of the graduation project topic 1.7.1 Scientific significance 1.7.2 Practical significance 1.8 Limitations of the research 1.9 Structure of the thesis CHAPTER 2: OVERVIEW OF RESEARCH TOPIC 2.1 Overview of additive manufacturing technology vi 2.2 Classification of AM technology 2.3 Some materials used in AM technology 2.4 TIG electrodes welding in a protective gas environment 2.4.1 General concept of TIG welding in a protective gas environment 2.4.2 Features of TIG welding 10 2.4.3 Advantages and disadvantages of Tig welding 11 2.5 Welding materials and equipment 12 2.5.1 Welding materials 12 2.5.2 Tungsten electrode 14 2.6 TIG weld formation and organization 22 2.7 General rules in the manufacture of tensile specimens: 23 CHAPTER 3: THEORETICAL BASIS 25 3.1 Tensile strength test method 25 3.1.1 Theoretical basis of tensile testing 25 3.1.2 Test conditions 26 3.1.3 Definitions of elongation 27 3.2 Methods of checking microorganism 29 3.2.1 Theoretical basis 29 3.2.2 Quantitative metallographic method 29 3.2.3 Conduct experiments 30 3.3 Method of Scanning Electron Microscopy (SEM) 31 3.3.1 Theoretical basis 31 3.3.2 Operating Principles of SEM 32 3.3.3 Structure of the Scanning Electron Microscope (SEM) 32 CHAPTER 4: RESEARCH, DESIGN, AND FABRICATION OF TENSILE TEST SAMPLES 33 4.1 Testing weld profiles for optimal welding parameters 33 4.1.1 Purpose 33 vii From the above calculation results, we can draw a stress diagram representing options for welding profiles: Figure 6.3 Stress diagrams of different options Figure 6.4 Histogram showing the particle-level frequencies of the different alternatives 53 6.1.2 Evaluation of experimental results Figure 6.5 Tensile strength comparison chart of samples and 2mm steel plate Figure 6.6 Comparison chart of the elongation of the samples and the original 2mm steel plate after breaking Comment: Based on the tensile strength, it is observed that compared to the original JIS G-3141 SPCC steel with a minimum tensile strength of 270 MPa, almost all samples of the welding methods have higher tensile strength than the original steel plate However, when considering the elongation at break, most of the welded samples have lower elongation compared to the original steel plate The main reason for this difference is the melting process of the steel 54 using the TIG welding torch, which is essentially a heat process During this process, the steel plate is melted and cooled, causing an impact on the crystal structure and microstructure of the steel This results in the formation of a weld with a new crystal structure, which may lead to changes in the size and shape of the grains in the steel, causing lower elongation When evaluating the elongation of the welding methods, each method consists of test samples Some results are unstable, so the average tensile strength of the samples for each method is taken The D heat source movement method yields the highest average tensile strength, followed by the N movement method, the DT movement method, and finally the HC movement method, which yields the lowest average tensile strength For the D heat source movement method, satisfactory results are achieved as the steel is melted in a long straight line, ensuring that the welding force is applied evenly and consistently along the length of the sample This avoids the concentration of welding force and imbalance in the welding pool, resulting in better load-bearing capacity for the test samples Next, the particle size distribution (grain size) is considered, which is also one of the significant factors affecting the mechanical strength of the weld When the grain size is small, the weld tends to be more homogeneous and has more uniform properties, leading to higher tensile strength However, larger grain sizes may produce a weld with higher ductility, increasing the risk of crack formation and reducing the overall strength The D movement method has a particle size distribution mainly in grades and 9, with a higher concentration in grade Although most are at grade 8, a considerable number of particles are also in grades and This yields the best tensile strength among the movement methods The N movement method has a particle size distribution mainly in grades 7, 8, and 9, with the highest concentration in grade 8, followed by grades and The test samples from this method show relatively good tensile strength The DT movement method has a particle size distribution mainly in grades 7, 8, and 9, with the highest concentration in grade 8, and a considerable number of particles in grades and The test samples from this method exhibit relatively good tensile strength The HC movement method has a particle size distribution mainly in grades 7, 8, and 9, with the highest concentration still in grade However, the number of particles in grade is higher than that in grade 9, significantly affecting the tensile strength of the test samples In conclusion, the D heat source movement method shows the best results with higher tensile strength due to the evenly distributed welding force and the smaller grain size distribution The other methods also exhibit satisfactory tensile strength, but the HC movement method, with a higher concentration of larger grain sizes, leads to slightly lower tensile strength compared to the others 6.2 Tensile strength parameters at the positions of the options: When conducting a survey on heat source migration to create weld samples for durability testing, the way the heat source is moved is the main cause of the difference in mechanical properties in the samples, but there are still some causes The resulting 55 difference despite the same heat source migration scheme such as cooling time, surface conditionof the material, presence of impurities, etc 6.2.1 Option 1: Move the heat source in a long straight line (D) Figure 6.7 Comparison chart of tensile strength and elongation of D profiles Figure 6.8 Histogram showing the particle-level frequencies of the different alternatives The D movement method, which involves moving the heat source in a straight line to melt the steel plate, yields the following observations based on the tensile strength, grain size, and elongation results of the samples: - Sample has the highest tensile strength, reaching 501.06 MPa, and also the highest elongation, exceeding 40% This indicates that the high heat input and uniform grain size distribution have resulted in strong bonding and good elasticity properties, enabling the sample to withstand high loads and exhibit significant elongation before fracture The presence of grain sizes 7, 8, and has led to a more homogeneous distribution and improved mechanical properties of the material - Sample has a tensile strength of 430.58 MPa and an elongation of 20.88% Although its tensile strength and elongation are higher than those of Sample 1, they are lower than those of Sample The heterogeneity in the grain size distribution may have caused uneven distribution and weaker bonding within the sample, affecting its tensile strength and elongation - Sample has the lowest tensile strength, only reaching 330.73 MPa, and an elongation of 15.5% This sample exhibits the poorest performance among the samples in the D 56 movement method When evaluating the sample through SEM micrographs, some common TIG welding defects such as cracks and gas porosity can be observed in its internal structure In conclusion, the D heat source movement method with the highest heat input and uniform grain size distribution has yielded the best results in terms of tensile strength and elongation Sample 2, with the highest tensile strength and elongation, demonstrates superior bonding and mechanical properties On the other hand, Sample 1, with the lowest tensile strength and elongation, shows the poorest performance and reveals typical TIG welding defects The grain size distribution plays a crucial role in determining the mechanical properties of the weld, and a more homogeneous distribution leads to improved performance 6.2.2 Option 2: Move the heat source in a short straight line (N) Figure 6.9 Comparison chart of tensile strength and elongation of N profiles Figure 6.10 Histogram showing the particle-level frequencies of the different alternatives In the N movement method, which involves moving the heat source in short straight lines to melt the steel plate, we observe the following results based on the tensile strength, grain size, and elongation of the samples: - Sample has the highest tensile strength, reaching 471.27 MPa, and also the highest elongation, exceeding 16% Grain sizes 7, 8, and show a more homogeneous distribution, resulting in improved mechanical properties of the material The majority of the grains are concentrated at size 8, which contributes to the relatively good tensile strength of the sample - Sample has a tensile strength of 451 MPa and an elongation of 10.94% Although its tensile strength and elongation are higher than those of Sample 3, they are lower than those of Sample The grain size distribution still oscillates around size 8, which provides a decent tensile strength and elongation for the sample 57 - Sample has the lowest tensile strength, only reaching 272.22 MPa, and an elongation of 6.28% This sample exhibits the poorest performance among the samples in the N movement method However, the grain size distribution still concentrates at sizes 7, 8, and 9, with the highest frequency at size In conclusion, the N heat source movement method with short straight lines has shown varying results among the samples Sample demonstrates the best performance with the highest tensile strength and elongation due to a more homogeneous grain size distribution Sample also exhibits decent tensile strength and elongation However, Sample has the lowest tensile strength and elongation, but still maintains a relatively good performance due to a concentrated grain size distribution at sizes 7, 8, and 9, especially at size 6.2.3 Option 3: Move the heat source in a short cross profiles (HC) Figure 6.11 Comparison chart of tensile strength and elongation of HC profiles Option 3: Move the heat source in a short cross profiles (HC) Figure 6.12 Histogram showing the particle-level frequencies of the different alternatives In the HC movement method, which involves moving the heat source in long straight lines to melt the steel plate, we observe the following results based on the tensile strength, grain size, and elongation of the samples: - Sample has the highest tensile strength, reaching 433 MPa, and also the highest elongation, exceeding 15% This indicates that the high temperature melting process and the high grain size have resulted in a strong bond and good elasticity, allowing the specimen to withstand high loads and have a large elongation before fracturing Grain sizes 7, 8, and show a more homogeneous distribution, leading to improved mechanical properties of the material - Sample has a tensile strength of 355 MPa and an elongation of 10.9% Although its tensile strength and elongation are higher than those of Sample 1, they are lower than those 58 of Sample The non-uniformity in grain size distribution may create unevenness in the distribution of grain sizes and weak bonds within the specimen, affecting its tensile strength and elongation - Sample has the lowest tensile strength, only reaching 207 MPa, and an elongation of 5.9% This sample exhibits the poorest performance among the samples in the D movement method When evaluating the sample through SEM micrographs, we observe some common defects of TIG welding, such as cracks and gas porosity inside the specimen In summary, the HC heat source movement method with short straight lines has shown varying results among the samples Sample demonstrates the best performance with the highest tensile strength and elongation due to a more homogeneous grain size distribution Sample also exhibits decent tensile strength and elongation However, Sample has the lowest tensile strength and elongation, and the SEM analysis reveals common defects of TIG welding inside the specimen These results suggest that the HC movement method may require further optimization to achieve more consistent and desirable mechanical properties in the welded specimens 6.2.4 Option 4: Move the heat source in a short curved profiles (DT) Figure 6.13 Comparison chart of tensile strength and elongation of DT profiles Figure 6.14 Histogram showing the particle-level frequencies of the different alternatives At the DT movement plan, which involves moving the heat source along a straight path to melt the steel plate, we observed the following results for tensile strength, grain size, and elongation of the samples: - Sample had the highest tensile strength, reaching 496 MPa, and also the highest elongation, over 38% This indicates that the high heat input and uniform grain distribution resulted in a strong bond and good elasticity, allowing the sample to withstand high loads and 59 exhibit significant elongation before failure Grain sizes and achieved uniformity in their distribution, contributing to improved mechanical properties of the material - Sample had a tensile strength of 358.62 MPa and an elongation of 16.8% Although its tensile strength and elongation were higher than those of Sample 1, they were lower than those of Sample The uneven grain distribution may have led to an inconsistent bond within the sample, affecting its tensile strength and elongation - Sample had the lowest tensile strength, only reaching 305 MPa, and an elongation of 11% It presented the weakest results among the samples of the D movement plan When evaluating the sample through SEM images, common TIG welding defects such as cracks and gas porosity were observed within the sample In summary, the DT movement plan yielded different results among the samples Sample performed the best with the highest tensile strength and elongation, thanks to the uniform grain distribution and strong bonding Sample also had relatively good tensile strength and elongation, mainly due to the presence of grain size 8, which exhibited favorable mechanical properties On the other hand, Sample showed the lowest tensile strength and elongation, likely attributed to the presence of grain sizes 7, 8, and with a higher proportion of grain size These observations indicate that the DT movement plan, with its curved path for heat input, has an impact on the microstructure and mechanical properties of the welded samples The quality of the welds can be influenced by factors such as heat input, grain size, and uniformity, leading to different mechanical properties in the welded joints 60 CONCLUSION - RECOMMENDATIONS Through the process of completing the Graduation Thesis, the group has fulfilled the stated requirements and compiled this report in the correct format with both form and content, including the importance, objectives, tasks, and an overview of the topic In general, the content of the Graduation Thesis has addressed the following key issues: - Application of mathematical, scientific, and technical knowledge, as well as social sciences, demonstrated through the calculation and statistical analysis of data obtained from the tensile strength testing of welded samples, thereby identifying the advantages and disadvantages of each heat source movement method on the flat surface - Execution/analysis/synthesis/evaluation, demonstrated through the statistical analysis of data on tensile strength and elongation, and calculating the grain size distribution to preliminarily assess the strength of each sample - Capacity for improvement and development, shown through comments on the movement methods based on tensile strength and grain size data for each heat source movement method - Utilization of technical tools and specialized software, demonstrated through experiments with equipment such as CNC machines, TIG welding machines, microscopes, and tensile testing machines After completing this topic, the achieved results can be applied to ensure the quality and performance of the metal 3D printing process Some real-world applications include: - Time and energy optimization: Surveying the heat source movement options helps optimize the metal 3D printing process, reducing time and energy consumption, thus lowering production costs - Ensuring product quality: Adjusting and accurately controlling the heat source movement process ensures the quality of metal 3D printed products, enhancing product quality by ensuring accuracy and uniformity - Reducing product defects: By surveying and applying suitable heat source movement methods, it is possible to minimize unwanted product defects in practice - Surveying the heat source movement on the flat surface plays an essential role in researching and developing new metal 3D printing methods, leading to significant advancements and improvements in the metal manufacturing industry Finally, the process of completing the topic has yielded specific outcomes, including: - Calculation and statistical results on the tensile strength of four heat source movement methods, enabling an evaluation of the strengths and weaknesses of each method 61 - Microscopic observations of 12 representative samples for the four heat source movement methods, allowing an assessment of their microstructures and grain frequency in the samples - SEM images of 12 representative samples for the four heat source movement methods, taken at the fracture location after the tensile tests, to evaluate the samples If compared with JIS G3141 SPCC steel plate, almost all the approaches result in higher tensile strength than the initial product The reason lies in the fact that during the welding process, the steel undergoes melting and gradual cooling, causing the metal molecules to rearrange and form a new crystal structure The TIG welding technique employs a non-consumable electrode to generate an arc, which helps eliminate some impurities and positively affects the mechanical properties of the weld joint However, during the investigation, there were still a few samples with lower tensile strength than the original steel plate, possibly due to welding flaws such as gas porosity, cracks, or slag inclusions Nevertheless, when considering elongation, most samples exhibited lower elongation than the initial steel plate, which is beneficial for practical applications when using 3D metal printing in complex structures or products Lower elongation in the weld joint helps avoid unwanted deformations, enhances structural stability, and reduces the risk of developing defects that can lead to decreased durability After conducting experimental investigations on various heat source movement options, including observing the microstructure of the samples, performing tensile strength tests, and synthesizing SEM images, we have obtained the processed parameters in chapters and as mentioned above From this, we can identify the advantages and disadvantages of the different approaches through the experimental process The approach with the heat source moving in a long straight line (D) yields samples with the highest tensile strength and highest elongation It is considered an efficient option with numerous applications and the highest durability This approach is suitable for manufacturing components with simple shapes but requiring high strength and deformation resistance The approach with the heat source moving in a short horizontal straight line (N) results in samples with relatively high tensile strength but low elongation It is evaluated as having good strength but poor deformation resistance It is suitable for applications in manufacturing L-shaped plate details, equipment shells, etc Similarly, the approach with the heat source moving in a short diagonal line (HC) also produces relatively high tensile strength but poor elongation results 62 The approach with the heat source moving in a circular path (DT) is a unique and favorable option The results for elongation and tensile strength are both very good This approach can be widely applied to create complex-shaped components that require high strength and deformation resistance Challenges: - The first challenge is controlling the welding temperature If the temperature is too high, it can cause unwanted sample deformations, but if it's too low, it may result in weak and inconsistent welds - TIG welding process generates a strong arc that emits harmful ultraviolet rays, which can negatively affect health Strict protective measures must be followed - The sample's surface must be kept clean, free from dust, rust, oil, etc - Constant attention is required to the welding current of the welding machine and the CNC machine in the experimental system Solutions and Mitigations: - Properly manage the cooling and rest time of the sample to avoid overheating and warping - After completing to layers, use a grinding machine to clean the surface from slag to prevent product defects - Recommendations: When conducting mechanical tests on the samples, more precise measurements and multiple microscopic and mechanical tests should be performed to provide a more objective understanding of the impact of the welding method on the manufacturing process 63 REFERENCES [1] Lê Thuận Nguyên, Tổng quan công nghệ in 3D kim loại, Zebra Technologies, 15 Jun 2019 [2] Lê Văn 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