Abstract: With the 8ns pulse width of Nd: YAG pulsed laser, AZ31B magnesium alloy is micro-textured induced by laser peening. The effects of micro-texture induced by laser peening on AZ31B magnesium alloy is studied in corrosion resistance. The morphology analysis is conducted on the micro-textured surface and the electrochemical polarization curves are investigated. The results indicate that ablation does not occur surround the micro-texture. With the increment of laser power, the depth and diameter of micro-dent increases, and with the number of peening increasing, the growth approaches a saturated value. Comparing with the untreated specimen, the corrosion potential improve by 95 mV, 123 mV, 151 mV and the corrosion current densities decrease to 36.48%, 50.26%, 60.42% with laser power of 1.0 J, 1.5 J, 2.0 J respectively under same micro-texturing density condition. For the same laser power condition, the corrosion potential improve by 145, 134, 123 mV and the corrosion current densities decrease to 50.26%, 46.19%, 49.16% respectively with the micro-texturing spacing of 1.0 mm, 1.5 mm, 2.0 mm. This suggests that the micro-texturing induced by laser peening improves the corrosion resistance of AZ31B magnesium alloy, and within the scope of the study, the higher the energy and the smaller the pitch, the better the corrosion resistance.

Key words: AZ31B magnesium alloy, electrochemical corrosion, laser optics, laser peening, micro-dent, micro-texture