Effect of friction stir welding on corrosion behavior of pure copper in 3.5 wt.%NaCl solution

摘要

This study aims at investigating the effect of friction stir welding on the corrosion behavior of pure copper in 3.5wt.% NaCl solution. To this end, pure copper was welded with rotation speed of 500 rpm and welding speeds of 20, 28 and 40mmmin~(-1). The microstructures of pure copper and welded pure copper were studied by X-ray diffraction and scanning electron microscopy. Furthermore, the corrosion behavior of the samples in 3.5wt.% NaCl solution was investigated by the use of Tafel polarization and electrochemical impedance spectrometry tests. X-ray diffraction patterns showed that after performing welding process, only three peaks related to pure copper appear which indicates the absence of unwanted phases including oxides. Also, scanning electron microscopy results indicated that friction stir welding leads to reduction of the grain size of pure copper. These observations were in consistence with the results of the corrosion behavior, evidencing that the corrosion behavior improved with decreasing the grain size.