Introducing Residual Stresses on Sheet Metals by Slide Hardening under Stress Superposition

Abstract

The fatigue strength and product life of the components can be improved by introducing compressive residual stresses using mechanical surface treatment. Appling stress superposition is an option to be used in metal forming to reduce the process force. In this work experimental investigations to analyze the influence of stress superposition on residual stresses of sheet metal parts by a slide hardening process were carried out. The flat and elastically pre-bended specimens (i.e. stress-superimposed specimen) were processed with a slide diamond tool under different loading forces. The residual stress generated through the thickness of the sheet metal was similar for the flat and the pre-bended specimens. The superimposed stress by elastic bending of the sheet metal led to higher compressive residual stress compared to the flat specimen under the same loading force. Nevertheless, the contour of the pre-bended specimen showed more bulking compared to the flat specimen. The mechanical characteristics determined by hardness measurements showed no significant improvement when applying stress superposition.