The knowledge of residual stresses in rails due to roll straightening has become increasingly important for the evaluation of the fatigue behaviour of rails. The residual stresses are induced both by the bending process and the roll contact leading to a very complicated distribution especially near those parts of the surface where the roll contact had taken place. So far, no clear picture has emerged with respect to the residual stress field, either from experiments or from simulations. This study intends to clarify the residual stress distribution by simulation with a fully three‐dimensional model taking into account both the bending and contact process. This work shows that especially in those areas where the roll contact happens compressive residual longitudinal stresses appear on the surface. Furthermore, a very steep gradient of the residual longitudinal stress distribution near the surface is observed which is reported also in very recent X‐ray and neutron diffraction experimental investigations.

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The presented skin pass model was developed for offline calculations in order to predict rolling forces and rolling torques very accurately over a wide range of applications including very thin and hard strips. The model takes into account radial (non-circular arc) as well as circumferential displacements of the work roll contour. This approach ensures an improved modelling of temper rolling, as the circumferential work roll displacements allow for the existence of slip as well as no slip zones inside the roll bite. The formation of a neutral zone instead of a neutral point is a consequence of this approach. The effect of circumferential displacements increases with decreasing strip thickness and draft in combination with higher friction (between work roll and strip) and cannot be neglected in such cases. The new model automatically detects the appearance of 'contained plastic flow'. Furthermore, the model offers the big advantage that the 'rollability' can be determined accurately, too. The simulation results were compared with finite element method (FEM) simulation results and were verified and calibrated against practical process data from an industrial skin pass mill. Excellent agreement between measured and predicted rolling forces and rolling torques was achieved. The developed model covers all specified requirements for a modern state of the art skin pass model. In the face of the trend to harder and thinner strips, the new skin pass model represents an applicable design tool to satisfy the most demanding customer requirements.

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