Role of the misfit stress between grains in the Bauschinger effect for a polycrystalline material

Abstract

. (2015) Role of the misfit stress between grains in the Bauschinger effect for a polycrystalline material. Acta Materialia, http://dx.doi.org/10.1016/j.actamat. .11.021 DOI 10.1016/j.actamat.2014.11.021 ISSN 1359 Publisher: Elsevier Copyright © and Moral Rights are retained by the author(s) and/ or other copyright owners. A copy can be downloaded for personal non-commercial research or study, without prior permission or charge. This item cannot be reproduced or quoted extensively from without first obtaining permission in writing from the copyright holder(s). The content must not be changed in any way or sold commercially in any format or medium without the formal permission of the copyright holders. This document is the author's post-print version, incorporating any revisions agreed during the peer-review process. Some differences between the published version and this version may remain and you are advised to consult the published version if you wish to cite from it. AbstractThe role of misfit stress on kinematic hardening under reversed straining of a Type 316H austenitic stainless steel has been investigated by using the neutron diffraction technique combined with in-situ deformation. Initial misfit stresses, often referred to an intergranular internal stresses, were created by the tensile pre-straining at high temperature. The misfit stresses at the length-scale of grain families, measured by neutron diffraction, were shown to be a function of the magnitude of the tensile prestrain. The pre-strained specimens were further subjected to either continued (tensile) straining or reversed (compressive) straining at room temperature. In-situ neutron diffraction measurements were undertaken to monitor the change of the misfit stresses during loading. The macroscopic stress-strain behaviour was used to derive isotropic and kinematic hardening stresses developed in the pre-strained specimens. Resultsshow that the change of the transient softening stress towards a zero value is accompanied by a decrease in the change of the misfit stresses. A multi-scale selfconsistent model has been developed to assist in understanding the measured change of the misfit stresses when subjecting the material to strain reversal. An important conclusion is that the origin of the kinematic hardening of Type 316H austenitic stainless steel arises from the misfit stress between grains.

Strain hardening in Fe–16Mn–10Al–0.86C–5Ni high specific strength steel

“…Additionally, the intra-granular internal stresses also develop due to the dislocations inside the g grains, along with the "grain to grain yielding" due to the misfit plastic strains among neighboring g grains [59]. This is the reason of a very high Q back at the onset of the elasto-plastic transition as shown in Fig.…”

Effect of boundary conditions on the evolution of lattice strains in a polycrystalline austenitic stainless steel

“…In the present study, the axial stresses for each plane were calculated assuming both the hoop strain (e hh hkl ) and the radial strain (e rr hkl ) were equal to Àte zz hkl [14]. Hence, Eq.…”

“…This is due to creep occurring differently along different crystalline planes, thereby creating strain incompatibilities between grain families. The presence of intergranular stress can change the internal resistance and effective stress in materials which therefore change the material properties [13][14][15][16]. However, no work has been done to study the effect of elastic follow-up on creep behaviour along different crystalline orientations.…”

“…This 316H stainless steel was from header HYA 2D1/2 (cast 69431) that had been in service for approximately 65000 h in the temperature range of 763-803 K, followed by exposure to 823 K for 21000 h. The chemical composition of the EXLA Type 316H austenitic stainless steel is given in Table 1 [14]. A rig was built based on the three-bar model ( Fig.…”

Internal strains between grains during creep deformation of an austenitic stainless steel

“…In situ neutron diffraction is often used to measure these meso-scale internal strains/stresses in a bulk polycrystalline material [1][2][3][4]. The crystal plasticity finite element [5] or self-consistent models [1,4] developed at the length-scale of grains can be used to predict the bulk behaviour of a polycrystalline material. Self-consistent models, which provide information about the average response of different grain families, can be compared directly with neutron diffraction measurements.…”