표제지
목차
Abstract 9
I. 서론 12
1. 연구 배경 12
2. 이론적 배경 16
2.1. 부식의 정의 16
2.2. 알루미늄의 부식 개요 16
2.3. 부식의 원인 17
2.4. 부식의 종류 17
2.4.1. 균일 부식(Uniform Attack) 17
2.4.2. 갈바닉 부식(Galvanic Corrosion) 17
2.4.3. 틈 부식(Crevice Corrosion) 20
2.4.4. 공식(Pitting Corrosion) 21
2.4.5. 입계 부식(Intergranular Corrosion) 22
2.4.6. 응력 부식 균열(Stress Corrosion Cracking) 22
2.5. 갈바닉 부식에 대한 이해 23
2.5.1. 기본 이론 23
2.5.2. 면적의 영향 24
2.5.3. 갈바닉쌍에서의 분극저항 25
2.6. 금속의 피로 거동 이해 28
2.6.1. 피로파괴의 정의 28
2.6.2. 피로파괴를 야기하는 요인 29
2.6.3. 피로파괴 메커니즘 29
II. 실험 방법 31
1. 실험 재료 및 시편 31
2. 부식 실험 38
3. 염수 분무 시험 43
4. 인장 실험 46
5. 피로 시험 50
5.1. 실험 환경 및 장비 50
5.2. 반복 하중하의 피로 실험 51
III. 실험 결과 및 고찰 53
1. 부식 실험 53
2. 인장 시험 55
3. 피로 시험 결과 및 고찰 57
IV. 결론 62
참고 문헌 63
Table 1. Boeing Airplanes in Service 14
Table 2. Classification of Dissimilar Metals for Design 20
Table 3. Combination of Alloy and Stress Corrosion Cracking Environment 23
Table 4. Chemical Composition(wt.%) of Al 6013 31
Table 5. Mechanical Properties 32
Table 6. Chemical Composition(wt.%) of Al 7075 33
Table 7. Mechanical Properties 34
Table 8. Net Tension Properties in Air Condition 48
Table 9. Net Tension Properties after 25 days Salt Spray 50
Table 10. Corrosion Potential of Test Materials 54
Table 11. Tension Properties of Specimens Atmosphere Condition and Pre_exposure (3.5 % NaCl Salt Spray after 25 days) 56
Fig. 1. Typical Causes and Sources of Corrosion 19
Fig. 2. Corrosion Cell 20
Fig. 3. Pitting Corrosion of Al 7050-T73 Forging 22
Fig. 4. Polarization Curve of Galvanic Potential between Two Different Materials 26
Fig. 5. Polarization Curve of Several Materials at 3.5% NaCl 27
Fig. 6. S-N Curve (MIL-HDBK-5H, 7075-T6) 30
Fig. 7. Net Tension Test Specimen 34
Fig. 8. Microstructure of Al 6013-T62, L-surface 35
Fig. 9. Microstructure of Al 7075-T6, L-surface 35
Fig. 10. Microstructure of Al 2117-T4, ST-surface 36
Fig. 11. Microstructure of Al 7050-T73, ST-surface 36
Fig. 12. Microstructure of Nickel-Copper Alloy, ST-surface 37
Fig. 13. Apparatus of Corrosion Test 39
Fig. 14. Polarization Curve of Al 6013-T62 at 3.5% NaCl Solution 40
Fig. 15. Polarization Curve of Al 7075-T6 at 3.5% NaCl Solution 40
Fig. 16. Polarization Curve of Al 2117-T4 at 3.5% NaCl Solution 41
Fig. 17. Polarization Curve of Al 7050-T73 at 3.5% NaCl Solution 41
Fig. 18. Polarization Curve of Nickel-copper alloy at 3.5% NaCl Solution 42
Fig. 19. Equipment of Salt Spray Test Chamber 44
Fig. 20. Salt Spray Chamber Inside View 45
Fig. 21. One of Salt Spray Test Specimen after 15 days Exposure 45
Fig. 22. Equipment of Tension Test 46
Fig. 23. Specimens after Net Tension Test 47
Fig. 24. Stress/strain Curve of Al 6013-T62 48
Fig. 25. Stress/strain Curve of Al 7075-T6 49
Fig. 26. Fatigue Test Equipment (Instron 8872) 51
Fig. 27. Polarization Curve of Test Specimens at 3.5% NaCl Solution 53
Fig. 28. Corrosion Potential of Test Materials 54
Fig. 29. Allowable Stress of Al 6013-T62 Atmosphere Condition and Pre_exposure (3.5% NaCl Solution Salt Spray 25 days) 56
Fig. 30. Allowable Stress of Al 7075-T6 Atmosphere Condition and Pre_exposure (3.5% NaCl Solution Salt Spray 25 days) 57
Fig. 31. Fatigue Life of AL6013-T62 with Atmosphere Condition and Pre_exposure (3.5% NaCl Solution Salt Spray 38 days) 58
Fig. 32. Fatigue Life of AL7075-T6 with Atmosphere Condition and Pre_exposure (3.5% NaCl Solution Salt Spray 38 days) 59
Fig. 33. Fracture Analysis of Al 6013-T62 after 38 days Salt Spray 60
Fig. 34. Fracture Analysis of Al 7075-T6 after 38 days Salt Spray 61