7A04铝合金高压开关部件剥落腐蚀分析及解决措施

对产生剥落腐蚀的7A04铝合金开关拐臂进行了形貌及组织分析、硬度试验、剥落试验。研究结果表明,晶界大量散布的链珠状Mg(Zn,Cu,Al)₂相是造成拐臂发生腐蚀的主要原因。表面处理及热处理表明,双级时效后样品的硬度大约为170~185HV,而双级时效+喷丸处理后的表层100 μm区域的表面硬化更为明显,硬度提升至260HV;经过喷丸+双级热处理以后的样品抗剥落腐蚀性能最优,为PB级,可满足服役要求。

Investigation of Exfoliation Corrosion of A High-voltage Switch of 7A04 Aluminum Alloy and Corresponding Remedial Measures

Morphology and microstructure analysis, hardness test and spalling test were carried out on the crank arm of a 7A04 aluminum alloy switch with exfoliation corrosion. Results showed that the corrosion of the crank arm was primarily attributed to a large amount of bead-like Mg(Zn,Cu,Al)2 phase dispersed in the grain boundaries. Surface treatment and heat treatment suggested that the hardness of the sample was about 170～185HV after two-stage ageing. And a combined treatment of two-stage ageing and shot peening  resulted in the surface hardening enhanced to 260HV in the 100 μm region, exhibiting an optimal performance in resisting exfoliation corrosion, up to PB grade, which can meet the working requirements.