Analysis of residual stresses in the Roll Hemming Process using the Barkhausen Magnetic Noise

Abstract

Hemming is a manufacturing process, consisting on folding a sheet metal onto itself or another sheet metal. In this work, Magnetic Barkhausen Noise (MBN) was implemented for the identification of residual stresses and their variations through the stages of Roll Hemming process. Initially, the inspection process over hemmed ASTM A36 specimens is detailed. For this study, a S6519 probe was selected to perform measurements at 5 different regions on the specimens’ edges, obtaining average values of intensity of MBN for each stage of Roll Hemming process. The variation of the obtained results was identified and discussed. Finally, the analysis of the absence or presence of residual stresses and their effect on the magnetic behavior of the material is presented. Obtained results allow us to determine the feasibility of MBN implementation for the inspection of hemmed parts in production lines.