电磁调质A356合金的组织研究

The Research on the Microstructure of Electromagnetic Modifying Casting A356 Aluminum Alloy

采用低频电磁场对水平连续铸造方法制备A356合金锭坯,通过金相显微镜观察,比较了磁场频率和电流大小对亚共晶区内初生-αAl形貌、晶粒大小的影响,通过扫描电镜分析,确定电磁场对Si在铝中晶内含量的影响。结果表明:与普通电磁铸造比较,低频电磁铸造可以细化晶粒,获得细小的-αAl组织和共晶组织。随着磁场频率降低,晶粒细化更加明显。而电流的增加也可以使晶粒细化,从而获得-αAl非枝晶组织和细小均匀的共晶组织。施加低频电磁场,可以提高Si在铝中的晶内含量,使共晶区域和晶界变窄,且Si的分布更加均匀。

The effect of low frequency electromagnetic field on the microstructure of aluminum alloy is researched in this paper. It is found through experimental and theoretical analysis that low frequency electromagnetic field can increase the content in the aluminum radix and improve the microstructure of the alloy. On the basis of theoretical analysis, the technology of aluminum alloy dectromagnetic casting under the effect of low frequency electromagnetic field is confirmed, so that the cast ingot with slender and homogeneous grains increasing the solid solubility of solute element is achieved. The following conclusions can be gotten through experimental and theoretical analysis： using lower frequency electromagnetic field and choosing proper intensity can not only improve the quality of the surface of the cast ingot , but also can refine the grains obviously and change the dimension of non-dendrites so that improve the microstructure of the cast ingot. Low frequency electromagnetic field can also increase the content of silicon dement in aluminum radix and reduce the degree of macro segregation of the alloy so that it improves the microstructure and the quality of surface of materials. Slender α-Al and eutectic structure can achieved through choosing processing parameter.