7A04-T6铝合金在氯化钠溶液中的腐蚀行为及其对拉伸性能的影响

Corrosion Behavior of AA7A04-T6 in NaCl Solution and Its Influence on Tensile Strength

采用激光共聚焦显微镜研究了7A04-T6铝合金在3.5%NaCl溶液中腐蚀形貌随时间的演变;对浸泡试样进行了失重计算和拉伸性能测试,并观察了拉伸断口形貌。结果表明,在初始两周,金属化合物周围的沟逐渐加深并向四周扩展,这是失重的主要原因,此时腐蚀对拉伸性能影响较小;随后,腐蚀产物在金属表面的沉积,腐蚀面积的增加以及暴露出来的金属化合物粒子数量的增多导致腐蚀失重速度加快;金属间化合物周围的沟连在一起并向基体深入,造成拉伸试样颈缩现象弱化,延伸率下降。

The corrosion behavior of AA7A04-T6 in 3.5 % NaCl solution was studied. Weight loss was measured, the corrosion morphology was observed using scanning laser confocal microscopy. Tensile tests were used to study the influence of corrosion on the tensile strength of the specimens. The results show that the weight loss rate was low in the first two weeks, then enhanced by synergism of the deposition of corrosion product on the surface and the increase in both reaction area and newly exposed intermetallic particles. Corrosion led to the disappearance of necking phase in tensile tests gradually.