激光喷丸诱导镁合金表面微织构的电化学腐蚀性能

Electrochemical Corrosion Behaviors of Magnesium Alloy Micro-textured Induced by Laser Peening

利用脉宽为8 ns的Nd:YAG脉冲激光对AZ31B镁合金表面进行激光喷丸处理,研究激光喷丸诱导微织构对AZ31B镁合金耐腐蚀性能的影响,进行表面微织构的形貌分析,测量试样表面的动电位极化曲线。结果表明,激光喷丸产生的微织构周围未出现烧蚀现象,其微凹坑的直径和深度随激光能量的增加而增大,随喷丸次数的增加呈现先增大后趋于饱和趋势。与未处理试样相比,在相同微织构间距下,激光能量为1.0 J、1.5 J、2.0 J时试样的自腐蚀电位分别向正移95 m V、123 m V、151 m V,自腐蚀电流密度分别减少36.48%、50.26%、60.42%;在相同激光能量下,微织构间距为1.0 mm、1.5 mm、2.0 mm试样的自腐蚀电位分别向正移145 m V、134 m V、123 m V,自腐蚀电流密度分别减少50.26%、46.19%、44.34%。研究表明激光喷丸诱导的微织构提高了AZ31B镁合金表面的耐腐蚀性,且激光能量越高,喷丸间距越小,抗腐蚀性能越好。

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.