Numerical analyses of cladding processes by twin-roll casting: Mg-AZ31 with aluminum alloys

Two types of cladding process by vertical twin-roll casting were analyzed in two dimensions. Mg-AZ31 sheet was cladded with molten AA3003 in Type I while molten Mg-AZ31 was cladded with two AA1100 sheets in Type II. Assuming the viscosity of a fluid and the proportional constant of the flow rule of a Mises material to be equivalent, the rigid-thermoviscoplastic finite-element method was applied to these analyses. Steady-state solutions were achieved after a number of non-steady state solutions for continuously updated configurations by using small time-steps. As a result, the Mg-AZ31 sheet was found to be pulled in tension under roll pressure and thinned with a risk of fracture in Type I. However, the Mg-AZ31 melt was found to be incompletely solidified because of low IHTC at the interface between the roll and the AA1100 sheet in Type II. Details of flow, temperature distribution, plastic deformation and possibility of fracture were predicted by the analyses.