Effects of Cu, Sb and welding microstructure on the galvanic corrosion of steel weldment in sulfuric and hydrochloric acid solution : 황산 염산 복합환경에서 용접재의 갈바닉 부식에 미치는 구리, 안티모니 및 용접조직의 영향

다국어 초록 (Multilingual Abstract)

This study examines the effects of Cu, Sb and welding microstructure on the galvanic corrosion of weldment using two types of filler metals in sulfuric and hydrochloric solution. Cu, Sb improved the corrosion resistance of weldment by the formation of protective layer and suppressed the anodic dissolution of the substrate. The welding microstructure affected the corrosion resistance by influencing the reaction at electrolyte/metal interface and the stability of protective layer. These factors lead to different galvanic corrosion behaviour of two weldments with time.

목차 (Table of Contents)

• 1. Introduction 7
• 2. Literature review 11
• 2.1. Basic principles of corrosion 11
• 2.1.1. Fundamentals of corrosion 11
• 2.1.2. Forms of corrosion 13
• 2.2. Corrosion of steel weldment 18
• 2.2.1. Factors influencing on corrosion of weldment 18
• 2.2.2. Forms of corrosion of weldment 19
• 2.3. Flue gas desulfurization system and corrosion 22
• 2.3.1. Flue gas desulfurization system 22
• 2.3.2. Chemical reactions in the flue gas desulfurization system 23
• 2.3.3. Corrosion mechanism of flue gas desulfurization system 25
• 2.4. Microstructure of steel weldment 27
• 2.4.1. Structures of steel weldment 27
• 2.4.2. Microstructure transformations in weld metal 31
• 2.5. Theory of work function 40
• 2.6. Corrosion test method 42
• 2.6.1. Tafel extrapolation 42
• 2.6.2. Electrochemical impedance spectroscopy (EIS) 45
• 2.6.3. Zero resistance ammeter (ZRA) 49
• 3. Experimental 50
• 3.1. Specimen and solution preparation 50
• 3.2. Potentiodynamic polarization tests 53
• 3.3. EIS tests 53
• 3.4. ZRA tests 54
• 3.5. Microstructure observation 55
• 3.6. EBSD / EFM / SKPM measurements 56
• 3.7. Rust analyses 58
• 4. Results and discussion 59
• 4.1. Potentiodynamic polarization tests 59
• 4.2. EIS tests 62
• 4.3. Galvanic corrosion test 68
• 4.4. Microstructure observation 72
• 4.5. Work functions in the microstructure 77
• 4.6. Rust analysis after immersion test 85
• 5. Conclusions 91
• 6. References 92
• 논문요약 97