순동 용가재를 이용한 AA1050 알루미늄과 1180MPa 고강도강 GMAW 접합부의 미세조직 및 기계적 특성 연구

다국어 초록 (Multilingual Abstract)

As the joining Carbon Neutrality begins in worldwide, almost country try to solve the environmental problems and enforce the environmental regulations. Accordingly, the automobile industry is inevitably required to reduce the automotive exhaust emissions and enhance the fuel efficiency by reducing the weight of the automobile body(lightweight body) and increasing the strength of parts. Among the various fuel efficient improvement technologies, making lightweight body has great advantages, in which it has short application cycle and occurred less cost compared to other technologies. Accordingly, the lightweight body technology becomes essential element for improving fuel efficiency.
To make lightweight body, there have been countless studies of Al/Fe dissimilar joining around the world. However, the biggest problem of those studies is the formation of Al-Fe intermetallic compound(IMC) layer which makes the weld metal to be broken on that layer. Therefore, in this study, Al/Fe dissimilar joining using GMAW(Gas Metal Arc Welding) with pure copper(cu) filler metal was tried to make lightweight. To solve the pre-study issues, this study was firstly tried to develop filler metal alloy and get the idea of using pure copper filler metal which made no IMC between Fe-Cu and also made the weld metal to be low hardness with the high content of copper. Therefore, this study tried to identify the pure copper filler wire’s effect, check the microstructure and mechanical properties by increasing travel speed, and find the best welding condition based on the results of the experiment. After GMAW with increasing travel speed; 5, 7, 8, 8.5, 9mm/s, this study could have the conclusions; as the travel speed increased, the temperature gradient values and the crystal cooling rate values were rised with heavy cu weight;Cu sink in Al-Cu coexist area. This made the low content of Al-Cu eutectic and hypereutectic structure and high content of dendrite α-Al structure in Al-based weld zone(Weld Zone Ⅱ). From the above travel speed 8mm/s, the hardness of Weld Zone Ⅱ is lower than below the 7mm/s and the results of tensile test for fracture is occurred in Al base metal.

목차 (Table of Contents)

• 제 1 장 서론 1
• 1.1 연구 배경 및 목적 1
• 1.2 국내·외 연구 동향 12
• 제 2 장 이론적 배경 14
• 2.1 GMAW 원리 및 특성 14
• 2.2 모재(알루미늄, 스틸) 소재 특성 18
• 2.3 순동 용가재 소재 특성 23
• 2.4 금속간화합물 24
• 2.5 용접 속도와 응고의 상관관계 27
• 제 3 장 실험 방법 33
• 3.1 시편 준비와 용접 방법 33
• 3.2 용접부 형상과 미세조직 관찰 및 성분 분석 38
• 3.3 기계적 특성 시험 40
• 3.3.1 경도시험 40
• 3.3.2 상온 인장시험 41
• 제 4 장 실험 결과 및 고찰 42
• 4.1 용접 속도별 비드 및 용접부 형상 42
• 4.2 용접 속도별 미세조직 및 성분 분석 결과 48
• 4.3 용접 속도별 기계적 특성 60
• 4.3.1 경도시험 결과 60
• 4.3.2 상온 인장시험 결과 62
• 제 5 장 결론 67
• 참고 문헌 70
• Abstract 75