Materials Science Forum Vol. 1186

Abstract: The influence of cold rolling pass schedules on the microstructural evolution, mechanical response and stress state of a DP800 base material was investigated. A micro-alloyed S355 steel with ferritic-pearlitic microstructure was subjected to identical total thickness reductions using different numbers of pass reductions. The mechanical behavior was characterized by uniaxial tensile tests while microstructural features were analyzed using electron backscatter diffraction and light optical microscopy, with grain morphology quantified by elliptical approximations. All investigations are carried out on the deformed ferritic – pearlitic microstructure, before the final intercritical annealing to produce the final dual phase microstructure. Finite element simulations of the flat rolling process were conducted to evaluate the evolution of non-proportional stress states in terms of stress triaxiality and Lode angle parameter. The results show that varying the number of passes leads to subtle but systematic differences in strength and ductility together with pronounced grain elongation and strongly banded pearlite morphologies that challenge ellipsoidal grain representations. While the overall stress-state trajectories remain similar, increasing the number of passes results in smoother stress evolution with reduced stress peaks. These findings highlight the non-trivial role of pass scheduling in shaping deformation-induced microstructures prior to annealing.