低频电磁热顶铸造7050铝合金的表面质量和组织

在传统热顶铸造基础上,开发了一种新的热顶铸造结晶器,并在铸造过程中施加了低频电磁场,得出了稳定铸造φ500 mm 7050高强铝合金铸锭的工艺条件;当电磁场频率为15 Hz、磁场强度为10000 At时,铸造出了表面光滑的铸锭.采用偏光显微镜(Leica DMI)观察试样,分析试样的微观组织.实验结果表明:铸造过程中施加低频电磁场能提高铸锭的表面质量,细化铸锭的内部组织,以及抑制铸锭内部裂纹的产生.总结了低频电磁铸造改善表面质量和细化组织的原因以及低频电磁场对液穴形状的影响.

Surface Quality and Structure of 7050 Aluminum Alloy by Low Frequency Electromagnetic Hot-Top Casting

A new hot-top casting mold was developed on the basis of conventional hot-top casting, and the low-frequency (LF) electromagnetic field was applied in the process of casting. The stable technological conditions for hot-top casting of φ500 mm 7050 high-strength aluminum ingots were gotten, i.e. smooth ingots were available, when electromagnetic frequency is 15 Hz with electromagnetic intensity 10000 At. The microstructure of ingot samples were observed by Leica DMI microscope. Experimental results showed that the LF electromagnetic field can improve the surface quality of ingot with grain refining and internal cracks suppressed, and the reasons why the quality of ingots are improved and the effect of LF electromagnetic field on the shape of melt cave were summarized.