Microstructures and mechanical characteristics of electromagnetic casting and direct-chill casting 2024 aluminum alloys

Electromagnetic casting (EMC) technology depends on the electromagnetic force to prevent the metal from touching the mold, leaving the ingot surface very smooth. As a result, the surface imperfections, such as oscillation and subsurface segregation etc. caused by a mold of direct-chill casting (DCC), are avoided. Moreover, the electromagnetic stirring makes the structure become more homogeneous over the entire cross-section. In this paper, 2024 aluminum alloys made by EMC and DCC were analyzed by optical microscope and scanning electron microscope, solution heat treatment and artificial aging was given to investigate the mechanical properties such as hardness, wear resistance and fatigue. Results showed EMC ingots had fine and uniform grain structure, which made the EMC ingots have high hardness and good fatigue. The hardness of EMC specimens increased one time than DCC ones and the fatigue was three times as high as DCC ones in as-cast state. The EMC specimens also expressed an excellent characterization in wear resistance; the weight loss was only a half of DCC specimens.