冷却槽对自孕育法制备ZA92镁合金组织的细化作用

采用自孕育法制备新型的ZA92镁合金,研究了冷却槽对组织的细化作用,并对其机理进行了分析。结果表明:合金熔体内部的形核与冷却槽的激冷作用、熔体的流动速度及剪切力的大小有关,合适的冷却槽角度有利于晶粒的游离和增殖。熔体在流经冷却槽的过程中,其组织变化趋势为:粗大枝晶→细小枝晶→等轴晶→蔷薇状晶和近球状晶。冷却槽角度较大或较小均不利于组织的细化,当冷却槽角度在30~45°之间时,坯料组织的晶粒分布比较集中且细小,其平均晶粒尺寸在47.5~51.4μm之间。

Grain Refinement Effect of Cooling Channel on ZA92 Magnesium Alloy Prepared by Self-inoculation Method

ZA92 magnesium alloy was prepared by self-inoculation method(SIM).Refined role of cooling channel on microstructure was studied,and refined mechanism was analyzed.Results show that nucleation in melt were effected by chilling action of cooling channel,flow velocity and shear force of the melt.The suitable slope angle of cooling channel was favorable for liberation and proliferation of the grains.When the melt was flowing on the cooling channel,the microstructure evolution was coarse dendrite→fined dendrite→equiaxed grain→rose crystal→ near spherical crystal.Neither smaller nor bigger cooling channel angle was benefitial for refined grain.When cooling channel angel was between 30-45°,the distribution of grain size was more concentrated and smaller,and the average grain size was between 47.5-51.4μm