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| Effects of Sulfate-reducing Bacteria on Marine Corrosion of Weld Joints of EH40 |
| Received:July 13, 2018 Revised:October 25, 2018 |
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| DOI：10.7643/ issn.1672-9242.2018.10.009 |
| KeyWord:sulfate reducing bacteria EH40 steel welding microbiologically influenced corrosion |
| Author | Institution |
| CHEN Chao |
1. Institute of Oceanology, Chinese Academy of Science, Qingdao , China; 2. Qingdao National Laboratory for Marine Science and Technology, Qingdao , China; 3. University of Chinese Academy of Science, Beijing , China |
| WU Jia-jia |
1. Institute of Oceanology, Chinese Academy of Science, Qingdao , China; 2. Qingdao National Laboratory for Marine Science and Technology, Qingdao , China |
| ZHANG Dun |
1. Institute of Oceanology, Chinese Academy of Science, Qingdao , China; 2. Qingdao National Laboratory for Marine Science and Technology, Qingdao , China |
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| Abstract: |
| Objective To study differences of corrosion of EH40 weld joints in base metal zone, heat affected zone and weld zone in sterile and SRB systems. Methods The metallurgical microscope observation, weight loss method, electrochemical methods, scanning electron microscopy (SEM) and energy dispersive X ray analysis (EDS) were applied. Results Microstructure of weld zone was composed of block lath ferrite (BLF) and widmanstatten structure (W). The heat affected zone was composed of coarse grain heat affected zone (CGHAZ) and fine grain heat affected zone (FGHAZ); the base metal zone was composed of BLF, acicular ferrite(AF) and some pearlite. Corrosion rate decreased in the order of weld zone (0.0026 mm/a)> mixed zone (0.0023 mm/a)>base metal (0.0019 mm/a) when there was no SRB. When SRB was introduced, corrosion rate decreased in the order of weld zone (0.0037 mm/a)>mixed zone (0.0034 mm/a)>base metal (0.0030 mm/a). Furthermore, localized corrosion attack was observed in the heat affected zone. Conclusion The weld area is easier to corrode than the base material zone, causing accelerated corrosion from small anode and large cathodes. The heat affected zone is likely to suffer from localized corrosion. SRB could accelerate corrosion in the three zones. |
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