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用电化学实验、浸泡实验与慢应变速率拉伸实验研究铸造AZ91镁合金在不同浓度比例的CO_3~(2-)/HCO_3~-溶液体系中的应力腐蚀(SCC)行为。结果表明,随着溶液pH值的升高,AZ91镁合金的应力腐蚀敏感性降低。点蚀是AZ91镁合金在该实验体系下的裂纹萌生源,随着实验时间的延长,萌生于点蚀底部的微裂纹会逐渐扩展形成主裂纹,主裂纹靠吞并其前端的微裂纹向前扩展,直至发生SCC失效。
The stress corrosion (SCC) behavior of the as-cast AZ91 magnesium alloy in CO_3 ~ (2 -) / HCO_3 ~ solution system with different concentrations was studied by electrochemical experiments, immersion experiments and slow strain rate tensile tests. The results show that with the increase of solution pH, the stress corrosion susceptibility of AZ91 magnesium alloy decreases. Pitting corrosion is the source of crack initiation of AZ91 magnesium alloy under the experimental system. With the extension of experimental time, the micro-cracks initiated at the bottom of pitting corrosion will gradually expand to form the main crack. The main crack propagates forward by the micro-cracks Until SCC failure occurs.