Measured resolved shear stresses and Bishop-Hill stress states in individual grains of austenitic stainless steel

Abstract

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Analysis of Grain-Resolved Data from Three-Dimensional X-Ray Diffraction Microscopy in the Elastic and Plastic Regimes

“…Polycrystal plasticity calculations reveal that the origin of the deviations of the expected orientation dependence of stress state lies in a lowering of the plastic work, when grains near <321> and <100> orientations do not deform with an axisymmetric tensile strain as normally assumed in the Bishop-Hill model [17]. Finite element based crystal plasticity simulations using the experimentally determined grain map as input reproduce the grain orientation dependence of the measured stress states well.…”

“…Inspection of individual grains reveals a dominance of the stress state indicated by the grey colour in Fig. 4 but also a number of grains in the expected Bishop-Hill stress states of the <111> and <110> orientations [17]. The theoretically expected Bishop-Hill stress state of the <321> orientation is the one corresponding to the <110> orientation.…”

“…The four systems with high shear stresses at 0.1% are still the ones with the highest values, although the stress on the other four systems are higher than at 0.1%. Inspection of the stress states of individual grains reveals that some are in the Bishop-Hill state, some are in the applied uniaxial state and some lie in between [17]. For the grains near the <321> orientation the average stress state is qualitatively similar to that at 0.1% with large variations in the stress level of the individual slip systems.…”

“…The fact that this is the level for all stress components ensures high accuracy also after rotation of the stress tensor to other coordinate systems. In all such rotations in the subsequent sections, the uncertainties are recalculated (see [17] for details).…”

“…The figure presents the mean values for a number of grains in the immediate vicinity of the ideal orientations. Examples for individual grains may be found in [17].…”