SIMULATION OF SOLIDIFICATION AND VISCOPLASTIC STRESSES DURING VERTICAL SEMICONTINUOUS DIRECT CHILL CASTING OF ALUMINUM-ALLOY

A method to simulate temperature and stress fields in solidifying cylindrical ingots during the vertical semicontinuous direct chill casting process is presented in this paper. As the first approximation of the whole process, a steady state in the casting ingot with enough length is examined, and the steady heat conduction equation with heat generation due to solidification incorporated with material flow is solved by the finite element method. Based on the obtained temperature distribution, elastic-viscoplastic stresses were also calculated to obtain residual stresses. Here, material parameters appearing in the constitutive equation were determined by the data of tensile stress-strain curves under some strain rates at several temperature levels close to the melting temperature. Calculated temperature and residual stress fields were compared with the experimental data to verify the analytical procedure, and discussions are also given on the effect of operating conditions on the fields.