Influence of Gradients in the Elastic Anisotropy on the Reliability of Residual Stresses Determined by the Hole Drilling Method

Abstract

Metal forming processes often involve large strain gradients which results in heterogeneous deformation and consequently residual stresses. Furthermore the strain gradients also generate variations in the deformation texture and related properties. For materials with a significant crystallographic elastic anisotropy such as ferritic steel, these textures may have a substantial effect on the reliability of the determination of residual stresses. In the present investigation this influence is examined for the hole drilling method by a combination of experiments and finite element simulations.

Manufacturing‐induced material properties of linear flow split and linear bend split profiles

“…Furthermore, it is also apparent that the flanges not only feature gradients in grain size and shape, but also in the crystallographic textures. The nature of these textures and resulting effects has been investigated in detail for different steels . The texture gradients are the result of the heterogeneous plastic deformation within the process zone.…”

“…The reasons for that are in part the different manufacturing‐induced properties such as the gradient in yield strength and the elastic anisotropy. An investigation on the residuals stresses of profiles produced from X6Cr17 steel sheets has shown that these graded properties have to be taken into account in order to obtain accurate stress distributions . Therefore, the residual stresses within flanges were determined using finite element (FE)‐models of the drilling process, which include local flow curves and local stiffness tensors.…”