New method of direct chill casting of Al-6Si-3Cu-Mg semisolid billet by annulus electromagnetic stirring

The electromagnetic direct chill (EMDC) casting process is a well-established production route for aluminum alloy ingot, however, the skin effect restricts the casting diameter. In order to avoid this problem, annulus electromagnetic direct chill (A-EMDC) casting process has been developed. A three-dimension finite element computational model of A-EMDC casting process was established by using ANSYS Magnetic-Nodal programs and FLOTRAN CFD programs. Microstructures of A-EMDC casting semi-solid Al-6Si-3Cu-Mg alloy billets were investigated. Two pairs of vortexes occur within the crystallizer with opposite direction in A-EMDC. The annulus gap is advantageous to increasing circulate flow, reducing the temperature gradient as well as shallowing liquid sump depth. The microstructure obtained by A-EMDC is globular or rosette-like, and the microstructure is homogeneous in the billet.