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采用金相、SEM、EDS和XRD等方法分析了海南电网刀闸铝合金部件的腐蚀失效原因。结果表明,刀闸杆所采用的挤压态LY12铝合金材料,其基相中含有使得该合金具有较高晶间腐蚀倾向的Cu Al2强化相,且基体材料中存在有可以显著降低合金力学性能的光亮晶粒组织,在晶间腐蚀与应力的协同作用下,产生了较为严重的剥蚀现象;在海岛环境中Cl及工业污染中S的影响下,刀闸底座表面的镀锡层优先脱落,基体外露,但Al及铝合金基体表面自然形成的钝化膜会继续起到腐蚀防护的作用。在海南地区,Al-Cu合金完全不适用,而Al-Si合金可以安全使用。
The causes of corrosion failure of the aluminum alloy parts of the knife gate of Hainan Power Grid were analyzed by means of metallography, SEM, EDS and XRD. The results show that the extruded LY12 aluminum alloy used in the knife bar has a Cu Al2 reinforced phase in the base phase that causes the alloy to have a high intergranular corrosion tendency, and the matrix material can significantly reduce the mechanical properties of the alloy Under the influence of Cl and industrial pollution in the island environment, the tin plating on the surface of the knife base is preferentially shedding, The substrate is exposed, but the passivation film naturally formed on the Al and Al alloy substrate surfaces will continue to function as corrosion protection. In Hainan, Al-Cu alloys are completely unsuitable, while Al-Si alloys are safe to use.