Abstract
Residual stresses originating from elasto-plastic deformation during mechanical processing can be analyzed post-process with various known methods. A new measurement method to measure and evaluate the strain and stress fields in situ under the contact point during a deep rolling process was developed to describe the dependence of the residual stresses from the internal material load. Using synchrotron radiation at European Synchrotron Radiation Facility (ESRF) (ID11), diffraction measurements were performed in transmission geometry during dynamical loading with different process parameters. The strain and stress fields were analyzed with high spatial resolution in an 8 mm × 4 mm area around the contact point during the process using a 13-mm tungsten carbide roller on samples of AISI 4140H steel. Fast data acquisition allowed the reconstruction of full two-dimensional (2D) strain and stress maps. These could be used to determine the response from the initial material state in front of the roller to the mechanically loaded region with plastic deformation up to the processed material with the resulting residual stresses. This comprehensive analysis was then used to link the internal material load with the resulting residual stresses in the final material state.
Highlights
The study of surface modifications achieved through processes with mechanical impact is generally based on the measurement of residual stresses and other material modifications ex situ after the process
A new measurement method to measure and evaluate the strain and stress fields in situ under the contact point during a deep rolling process was developed to describe the dependence of the residual stresses from the internal material load
The deep rolling process gives a very specific set of contact parameters leading to the plastification of the surface and inducing material modifications several millimeters inside of the specimen, which was measured for static indentation in a previously published study by Meyer et al [6], where it was shown that the loading and residual stress fields are symmetric without sample movement
Summary
The study of surface modifications achieved through processes with mechanical impact is generally based on the measurement of residual stresses and other material modifications ex situ after the process. The deep rolling process gives a very specific set of contact parameters leading to the plastification of the surface and inducing material modifications several millimeters inside of the specimen, which was measured for static indentation in a previously published study by Meyer et al [6], where it was shown that the loading and residual stress fields are symmetric without sample movement. The measurement of the loading state within the material and its resulting material modifications, which can be extracted from the analysis shown in this study, is part of a new approach described by Brinksmeier et al [7] to develop a mechanism-based prediction of metal processing This approach makes the prediction of the material end state from the applied internal material load possible, which is connected to the fields studied in this analysis since both the internal material load, transition zone, and residual stress end state have been measured for specific contact parameters
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