Definition and impact of overlap on the surface state after deep rolling of aluminum and steel alloys

The mechanical surface treatment by deep rolling is a widely used process in many industriai applications to increase the fatigue and wear resistance. Multiple process parameters (contact pressure, feed rate, tool diameter) can be varied to achieve an optimum treatment result. To reduce the optimization effort for finding adequate deep rolling parameters the overlapping of two subsequent deep rolled lines was calculated assuming linear-elastic (elastic overlap factor) and elastic-plastic materiai behavior by analytical calculations (Hertzian contact) and by Finite Element simulation. The impact of overlapping on the surface roughness and residuai stress state after deep rolling was experimentally investigateci for the materials EN AW 5083, S355J2+N and S690QL. A high (elastic) overlap factor of around 90% leads to surface defects for EN AW 5083 and S355J2+N. An optimum of around 60% was determined for these materials and 90% for S690QL.