하이브리드(Nd:YAG+MIG) 용접을 이용한 알루미늄(Al-Mg-Si)합금의 열적 거동 및 역학적 특성에 관한 연구

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Presently the consumption and application of aluminum alloys has been increased in many industrial fields, aerospace, automobiles, shipbuilding, electronics, building constructions etc. for light in weight and high strength. Therefore welding technology of aluminum alloys has already become a most important problem in industrial settings.
Aluminum alloys are light in weight materials suitable for high-speed and durability because it has a high ratio of strength to density, corrosion resistance, good toughness and metallurgical characteristics at low temperature. For example 5xxx and 6xxx series of aluminum alloys has been raised in shipbuilding due to distinguished corrosion resistance, and they are not affected by big difference of salinity or temperature.
However aluminum alloys are very active materials and has high thermal conductivity and thermal expansion coefficient. So welding defects and deformation can be generated by the high hydrogen solubility between liquid-state and solid-state. Thus when welding of aluminum alloys, high heat input and current are required in a short time.
According to increase in use of aluminum alloys, new welding technology has been required for improvement of productivity and quality, while making up the weak points of conventional welding method and process.
In this study new joining technology, laser+arc hybrid welding, was introduced and observed the weldability and feasibility in aluminum alloys for complementing the disadvantages of conventional arc welding. The 6xxx series of aluminum alloys were butt jointed by CW 3kW Nd:YAG laser+MIG hybrid welding.
Firstly characteristics of thermal distribution and residual stress distribution in weldment by hybrid welding were surveyed using numerical analysis. Secondly the optimum parameters of hybrid welding were determined based on experiments. And mechanical testing and residual stress measurement were carried out and compared with the numerical analysis.
In conclusion, application possibility of laser+arc hybrid welding to aluminum alloys are confirmed.
Alternative Title
A Study on Thermal Behavior and Mechanical characteristics in Hybrid welding (Nd:YAG Laser+MIG) of Al-Mg-Si alloys
Alternative Author(s)
Jeong, Eun-Young
조선대학교 대학원
일반대학원 선박해양공학과
Bang, Han-Sur
Awarded Date
Table Of Contents
List of Figure = Ⅱ
List of Table = Ⅲ
CHAPTER 1. Introduction = 1
1.1 Backgrounds & Purposes = 1
1.2 Materials Used = 4
1.3 Organizations & Scope of Study = 6
CHAPTER 2. Numerical Simulation of Hybrid welding = 7
2.1 Theoretical Basis for Analysis = 7
2.1.1 Heat Transfer Analysis = 7
2.1.2 Thermal elasto-plastic analysis = 11
A. Basic theory for thermal stress analysis by finite element method = 11
B. Stress and strain relation dependent upon temperature = 14
C. Temperature dependency of material properties = 19
2.2 Analysis Conditions and FE Model of Hybrid welding = 20
2.2.1 Analysis Conditions = 20
2.2.2 FE model for Hybrid welding = 22
2.2.3 Calculation of Heat Input for Analysis of Hybrid welding = 24
A. Gas Metal Arc welding = 24
B. Laser welding = 25
2.3 Results of Numerical Simulation in Hybrid welding = 26
2.3.1 Heat Distribution characteristics of Hybrid welding = 26
2.3.2 Residual Stress characteristics of Hybrid welds = 28
CHAPTER 3. Experiments of Hybrid welding = 29
3.1 Various Parameters of Hybrid welding Process = 29
3.1.1 MIG welding = 29
3.1.2 Nd:YAG Laser welding = 31
3.2 Hybrid welding Experiments = 33
CHAPTER 4. Mechanical Characteristics of Hybrid welds = 38
4.1 Hardness Test in Hybrid welds = 38
4.2 Comparison of Bead Geometry in Hybrid Welds = 40
CHAPTER 5. Conclusion = 41
Reference = 43
조선대학교 대학원
정은영. (2006). 하이브리드(Nd:YAG+MIG) 용접을 이용한 알루미늄(Al-Mg-Si)합금의 열적 거동 및 역학적 특성에 관한 연구.
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