Surface Integrity of AISI 4140 After Deep Rolling with Varied External and Internal Loads

In Situ X-ray Diffraction Analysis of Stresses during Deep Rolling of Steel

“…This also leads to an increase in the affected depth of the residual stresses. These main results from the experimental in situ measurement correspond well with trends observed in ex situ measured residual stress dependence on the contact parameters by Meyer et al [2] as well as with simulated fields distribution of loading stresses in finite element modeling by Sayahi et al [14].…”

“…The highest equivalent stress values below the contact point for each contact force tended to plateau at a value of around 1050 MPa, corresponding to around~73% of the yield strength for this material state. Comparatively, the generated residual stress distributions in Figure 5, which were taken from enlarged views of the region at −4.5 mm to −3.5 mm in Figure 2b for different contact forces, showed an increase in depth and in the amount of introduced compressive stresses in the σ yy component in the surface zone as well as in increase in the counterbalancing tensile residual stresses in the deeper region, which is consistent with the ex situ measurement of residual stresses for different contact forces by Meyer et al [2]. However, compared to the loading state, there was only small improvement since the stresses also tended to plateau at −200 MPa.…”

“…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. For the plastic deformation induced in machining with turning or deep rolling tools, several in-depth studies have investigated the surface state after hard turning, as conducted by M'saoubi et al [1], and the deep rolling process, as conducted by Meyer et al [2]. Thus, specific knowledge about the influence of contact parameters in mechanical machining and the resulting residual stresses is available.…”

In-Situ Analysis of Material Modifications During Deep Rolling by Synchrotron X-Ray Diffraction Experiments

“…2a. This shows that these two modifications are directly connected, as already found in ex-situ measurements by Meyer et al [1]. A maximum increase of FWHM is detected behind the roller, which then decreases again.…”

“…Analysis of surface residual stresses and of depth profiles generated by deep rolling is possible ex-situ after the process through standard methods such as X-Ray Diffraction (XRD), hole drilling techniques and other methods. It is well known that compressive residual stresses may be introduced several hundred micrometers into the material, depending on the process parameters, as shown by Meyer and Kaemmler [1]. These are connected with improved near surface hardness and an increased fatigue resistance for processed parts, as found by Nikitin and Altenberger [2].…”