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| CORROSION MECHANISM ON TOP SURFACE OF FRICTION STIR WELDED JOINT OF 2024 ALUMINUM ALLOY |
| KANG Ju1, DONG Chunlin1, LUAN Guohong1,HE Miao1, FU Ruidong2 |
1. Beijing Aeronautical Manufacturing Technology Research Institute, China FSW Center, Beijing 100024
2. State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 |
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Abstract In this paper, based on the analysis to surface microstructure of FSW AA2024 joint, the corrosion evolution behavior was revealed by a quasi-in-situ observation method. Besides, the corrosion mechanism of the FSW joint was investigated by combining TEM, DSC and electrochemical analysis. The results show that FSW makes the corrosion resistance decrease, which is characterized by the facts that the most corrosion in the SAZ (shoulder active zone) and the pitting corrosion initially originates in dissolving of the $S$ phase (Al2CuMg). TEM observations indicate that crystal defects density increases in the welded joints causing the more different electrochemical properties between grains and grain boundaries. The S phase particles are broken and partially redissolved during the FSW process in the SAZ. When the corrosion happens, the broken S phase particles increase the pitting corrosion density of the SAZ. In addition, the activity of the SAZ is enhanced due to the doped Mg.
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Received: 11 June 2010
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Corresponding Authors:
KANG Ju
E-mail: kangjusin@163.com
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