표제지
국문 요약
목차
1. 서론 12
1.1. 연구배경 12
1.2. 연구목적 18
2. 이론적 배경 19
2.1. 마그네슘 합금의 적용 및 특성 19
2.2. 셀프 피어싱 리벳팅 (Self-piercing riveting, SPR) 23
2.2.1. SPR의 원리 및 특징 23
2.2.2. SPR의 공정 매개변수 26
2.2.3. SPR 접합 만족 여부 평가 32
3. 실험 방법 34
3.1. 대상 접합 소재 34
3.2. 접합 방법 및 조건 34
3.3. 부식 시험 37
3.4. 인장 전단 시험 37
4. 실험 결과 39
4.1. 접합 만족 여부 평가 39
4.2. 접합부 영역별 코팅층 거동 43
4.3. 부식 거동 관찰 46
4.3.1. 염수 분무 시험 46
4.3.2. 염수 분무 시험 후 접합 단면 관찰 51
4.3.3. 침지 시험 53
4.3.4. OCP test 및 동전위 분극 시험 58
4.4. 인장 전단 시험 62
5. 고찰 66
5.1. 접합부에 영향을 미치는 인자와 접합 만족 조건과의 상관관계 66
5.2. 갈바닉 부식과 틈새 부식의 상관관계 69
5.3. 인장 전단 시험 후 파괴양상과 부식이 접합강도에 미치는 영향 75
6. 결론 81
7. 참고문헌 82
영문 요약 85
Table 3-1. Evaluation criteria for SPR join 35
Table 5-1. Joining result of AZ31/SGC340 67
Figure 1-1. Current status of fuel efficiency regulations on automobiles 14
Figure 1-2. A recent study by McKinsey shows that by 2030, the use of lightweight materials in automotive production will approach the levels currently used in aviation 14
Figure 1-3. Magnesium Alloy Automotive Parts Application Prospects 15
Figure 1-4. Trends in joining processes, current year beyond 2030 15
Figure 1-5. Multi-Material Integration (MMI) Body Lightweight Technology by Multi-Materials 16
Figure 1-6. Resistance spot welding process 16
Figure 1-7. Blind riveting process 17
Figure 1-8. Comparison of rivet weights of self-piercing riveting and blind riveting 17
Figure 2-1. Magnesium alloys applied to the body (a) Mg/Al, a series of six-cylinderdeveloped by BMW Crank Case (b) Magnesium sheet frame 21
Figure 2-2. Hardness comparison between AZ31 and Modified-AZ31 22
Figure 2-3. Tensile Strength Comparison of AZ31 and Modified-AZ31 22
Figure 2-4. An SPR system for laboratory use 25
Figure 2-5. Self piercing reverting process 25
Figure 2-6. Cross section of rivet 29
Figure 2-7. Rivet coverage according to the Bollhoff guidelines 29
Figure 2-8. Typical SPR rivets with countersunk head and a cross-section 30
Figure 2-9. Typical dies for SPR and a cross-section 30
Figure 2-10. An SPR joint with over-deep die (small interlock distance and joint button necking) 31
Figure 2-11. SPR joint quality and some faults 33
Figure 2-12. Possible joint defects for joining an ultra-high strength steel to an aluminium alloy by SPR 33
Figure 3-1. Cross-section bottom surface of aluminium-magnesium joints formed by SPR 35
Figure 3-2. Electro-hydraulic Portable C 36
Figure 3-3. Almac coated rivet and FM Die 36
Figure 3-4. Geometry of SPR joint specimen 38
Figure 4-1. Rivet joint cross section of A1(7.0mm), A2(7.5mm), A3(8.0mm) using FM1002117 Die 41
Figure 4-2. Rivet joint cross section of A1(7.0mm), A2(7.5mm), A3(8.0mm), B1(7.0mm), B2(7.5mm), B3(8.0mm) using FM0952123 Die 42
Figure 4-3. Behavior of Coating Layer by Rivet Joint Area (a)Rivet head, (b)Upper sheet and rivet interface 44
Figure 4-4. Schematic of the rivet coating damage during riveting process and stress concentration around the tip of rivet-leg in the shear-loading of SPR joints 45
Figure 4-5. Corrosion behavior of Rivet 7.0mm by salt spray time 47
Figure 4-6. Corrosion behavior of Rivet 7.5mm by salt spray time 48
Figure 4-7. Corrosion behavior of Rivet 8.0mm by salt spray time 49
Figure 4-8. Comparison before and after salt spraying 50
Figure 4-9. Comparison of weight loss rates before and after salt spraying 50
Figure 4-10. Optical microscope(OM) of Joint cross section after salt spray test 52
Figure 4-11. Corrosion behavior of Rivet 7.0mm by immersion time 54
Figure 4-12. Corrosion behavior of Rivet 7.5mm by immersion time 55
Figure 4-13. Corrosion behavior of Rivet 8.0mm by immersion time 56
Figure 4-14. Comparison before and after immersion 57
Figure 4-15. Comparison of weight loss rates before and after immersion 57
Figure 4-16. Electrochemical tests : open circuit tests 60
Figure 4-17. Electrochemical tests : potentiodynamic polarization curves 61
Figure 4-18. Load displacement curves (a)AZ31 (b)Modified-AZ31 (c) After salt spray tests, AZ31 and Modified-AZ31 63
Figure 4-19. Average interlock distance by rivet specification 64
Figure 4-20. Fracture shape of SPR: (a)AZ31_7.0mm, (b)AZ31_7.5mm, (c)AZ31_8.0mm (d)Modified-AZ31_7.0mm, (e)Modified-AZ31_7.5mm, (f)Modified-AZ31_8.0mm 65
Figure 5-1. The important influential factors for SPR joint quality and single-rivet joint strength 68
Figure 5-2. Comparison of potential by materials 71
Figure 5-3. Schematic diagram of galvanic corrosion and clearance corrosion on SPR joints 71
Figure 5-4. Galvanic corrosion schematic diagram at SPR 72
Figure 5-5. Crevice corrosion schematic diagram at SPR 73
Figure 5-6. Flushness of the rivet by length 74
Figure 5-7. Typical failure modes of SPR joint 77
Figure 5-8. Load/displacement curves for all batches of samples at increasing corrosion time 78
Figure 5-9. The effect of corrosion on the lap shear strength of a self- piercing riveted joint between I.F. steel and aluminium 5182 78
Figure 5-10. Corrosion products in SPR combination after corrosion test 79
Figure 5-11. Mapping image of SEM-EDS(Corrosion product) 80
Figure 5-12. XRD pattern of corrosion product after corrosion test 80