近液相线半连续铸造AZ91D镁合金微观组织研究

Study on the microstructure of AZ91D magnesium alloy by the near-liquidus semi-continuous casting

用近液相线半连续铸造法制备出具有球状和蔷薇状晶粒的AZ91D合金坯料 .考察了铸造速度对合金微观组织的影响 ,以及对铸锭边部和中心组织差异的影响 .实验结果表明 ,随铸造速度的增加 ,铸锭逐渐趋向枝晶化 ,边部和中心组织差异经历了由小到大 ,再由大到小的变化 .

The ingots with spherical and rosettic grains are obtained by means of near-liquidus semi-continuous casting method. The effects of casting rate on the microstructure of ingots and the microstructural differitiations between edge and center are investigated. The results indicate that dendriticization become greater with the increasing of casting rate. The microstructural differentiations between the edge and the center undergo the changes from small to great and then to small extent. The mechanism of effects of casting rate is analysed.