Effect of laser surface remelting on the corrosion behavior of commercially pure titanium sheet

By Voevodin, N.N.; Balbyshev, V.N. & Donley, M.S.
Published in Materials Science and Engineering: A NULL 2003

Abstract

The effect of laser surface remelting on corrosion resistance and pitting potential of pure titanium (ASTM grade 2) sheets was investigated. A Nd-YAG laser was used to remelt the surface of the titanium sheets. Corrosion performance of laser surface remelted and titanium base sheets were then evaluated qualitatively and quantitatively by both potential dynamic measurements (PDM) and electrochemical impedance spectroscopy (EIS) in a 3% NaCl solution. It was found that there were significant differences in corrosion properties for the two materials. Analyses of the polarization curves obtained from the PDM illustrated that no pitting corrosion could be perceived in laser surface remelted titanium sheet, while clear pitting corrosion could be seen in the base titanium sheet. EIS diagrams also showed that laser surface remelted titanium has higher impedance than the base titanium. Both results are evidence that laser surface remelting can improve the corrosion resistance of titanium. Further observation using optical microscopy and scanning electron microscopy showed clear pitting corrosion on the surface of the base titanium sheet, while no pitting was in evidence on laser surface remelted sheets. The improved pitting corrosion resistance is obtained due to the microstructural changes caused by rapid solidification after laser remelting. The study clearly demonstrates that laser surface remelting can be a potential way to improve pitting corrosion resistance of titanium and to enlarge its application range in harsh environments.

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