The Influence of the Process Conditions on the Thermo-Mechanical Fatigue Damage of the Rolls in the Twin-Roll Casting Process of Aluminum Alloys

Twin-roll casting is a technology for the production of thin strips directly from liquid metal by combining continuous casting with hot rolling in a single step. The thermo-mechanical cyclic interaction with the solidifying strip causes fatigue crack formation at the outer surface of the rolls. A 2D FEM model with Eulerian boundary conditions and the interference fit load on the rolls was defined. The influence of the roll–strip thermal contact, the inlet temperature of the liquid aluminum, the efficiency of the water cooling and the production rate on the fatigue damage of the rolls was analyzed with a parametric study. The maximum temperature of the rolls, the maximum contact pressure, the accumulated plastic strain and the equivalent strain computed (considering a multiaxial out-of-phase fatigue criterion) were considered to investigate the thermo-mechanical fatigue load on the rolls. The results showed that, in the considered range, the most influential parameters on the fatigue mechanism are the heat contact conductance coefficient, which dominates the thermo-mechanical load, and the tangential velocity of the rolls, which contributes to the thermal field and determines the roll–strip mechanical contact interaction.