Modification of GMAW Welds of AA۶۰۶۱-T۶ Aluminum Alloy by Friction Stir Processing

In this study two plates of AA۶۰۶۱-T۶ aluminum alloy welded by gas metal arc welding technique. Then the FSP process was conducted on as-welded samples without removing the weld caps. Results showed that FSP modifies the microstructure and remove fusion weld defects. Friction stir processing resulted in the increase of homogenous corrosion rate and the decrease of polarization resistance. Corrosion rate and polarization resistance of GF۱۰۰-۹۰۰ sample was ۰.۰۱۸ mm/year and ۱۸.۷ kΩ, respectively, whereas corrosion rate and polarization resistance of as weld sample was ۰.۰۱۵ mm/year and ۱۱.۹۴ kΩ, respectively. Variation in rotational speed from ۷۵۰ to ۱۰۵۰ rpm and traveling speed from ۵۰ to ۲۰۰ mm/min resulted in minor changes (approximately ۱μm) in the grain size of nugget zone. The increase in rotational speed and the reduction in travel speed improved the homogeneity, increased the size of weld nugget zone, decreased the grain size of nugget zone, reduced the corrosion potential to more negative potential and increased the homogenous corrosion rate. Results also showed that pitting corrosion was a major corrosion mechanism of all samples. The FSP process resulted in the distribution of cathode inclusions and homogenous pitting corrosion. The FSP process resulted in the reduction of the depth of pits and therefore increasing the pitting corrosion resistance

کلیدواژه ها:

Gas metal arc welding (GMAW) ، Friction stir processing ، Microstructure ، Pitting corrosion. ، جوشکاری تحت گاز محافظ ، فرایند اصطکاکی اغتشاشی ، ریز ساختار ، خوردگی حفره ای