Residual stress and stored energy during recrystallisation in polycrystalline copper

Abstract

A general X-ray multireflection method was applied to determine the stress level in deformed and recrystallised polycrystalline copper samples. Different reflections hkl were simultaneously used in the fitting procedure. The anisotropic diffraction elastic constants were calculated using the self consistent model and crystallographic texture. A significant decrease of the first order residual stresses was observed during recovery and recrystallisation. Diffraction peak widths and intensities were also examined for a few characteristic texture components during the recrystallisation process. Independently, synchrotron radiation and electron backscatter diffraction techniques were used to determine the stored energy in the examined material. The main result is that residual stress components start to reduce already before the recrystallisation process. The stored energy is strongly orientation dependent. It has the lowest value in the cubic texture component, which is dominating one in recrystalisation texture.

Residual stress field in steel samples during plastic deformation and recovery processes

“…are measured for more than one hkl reflection. Then, so called multireflection method for data analysis can be used to determine the stress field from equivalent lattice parameters, defined as <a(φ,ψ)> {hkl} = [32,46]. In the absence of the second order stresses and in the case of a quasi-isotropic sample (without texture), the equivalent lattice parameters <a(φ,ψ)> {hkl} measured in L 3 direction ( Fig.…”

“…In the absence of the second order stresses and in the case of a quasi-isotropic sample (without texture), the equivalent lattice parameters <a(φ,ψ)> {hkl} measured in L 3 direction ( Fig. 2) are given by the well known relation [3,4,32 . They depend on a chosen reflection hkl but do not depend on the orientation of the scattering vector (φ,ψ) defining direction of strain measurement.…”

“…Thermal relaxation of the first and the third order stresses was already deeply studied [32][33][34][35], while the evolution of the second order stresses during recovery process was not yet investigated. In the present work our methodology of stress determination is applied to study the evolution of a stress field in cold rolled ferritic and austenitic steels subjected to thermal treatment at different temperatures.…”

Local residual stresses and microstructure within recrystallizing grains in iron

“…Measurements carried out using laboratory X-rays or neutron diffraction have, however, shown the presence of residual stresses in partially recrystallized samples (e.g., [16][17][18][19]). These results are, nevertheless, averaged over the whole gauge volume, i.e., over a large number of recrystallizing grains and also their surrounding deformed matrix.…”