电磁连铸对镁合金显微组织及腐蚀性能的影响

Effects of Electromagnetic Continuous Casting on Microstructure and Corrosion Resistance of Magnesium Alloy

对电磁连铸生产的AZ31镁合金铸坯的晶体结构、金相组织和材料耐腐蚀性能进行了研究。结果表明,电磁连铸未改变镁合金铸坯相的组成,电磁连铸坯晶粒细小,树枝晶破碎,分布在块状α-Mg相周边的β-Mg17Al12相均匀连续。质量分数为5%的NaCl盐雾腐蚀试验结果表明,电磁连铸生产的AZ31镁合金铸坯的腐蚀速率比普通连铸下同牌号铸坯下降29.4%,其主要原因是连续分布的网状β-Mg17Al12相有效阻碍了镁合金的腐蚀。

The effects of electromagnetic continuous casting on the phase constituent,microstructure and corrosion resistance of magnesium alloy AZ31 were investigated.The results reveal that although the change of phase constituent in electromagnetic continuous casting AZ31 magnesium alloy can not be observed,the grain size in the billet is refined with broken dendrites and uniform continuous β-Mg17Al12 phase distributed around bulk α-Mg phase.Compared with that of the billets in conventional continuous casting,the corrosion rate of AZ31 magnesium alloy billets in electromagnetic continuous casting is decreased by 29.4 % in 5% NaCl salt spray testing,which is attributed to the continuously distributed net β-Mg17Al12 phase effectively controlling the corrosion of Mg alloy.