B. Bacroix

Estimation of recrystallized volume fraction from EBSD data

Abstract The recrystallized volume fraction is an important parameter in the study of recrystallization processes. This paper proposes a new method to estimate this parameter, based on quantitative EBSD data analysis. The principle of the method is first presented. The method is then tested on experimental EBSD data obtained on copper and brass. Estimated recrystallized volume fractions for different annealing temperatures are compared with values estimated from micro-hardness measurements. The presented method appears to be precise and very easy to implement, provided that some conditions are met; these are discussed in the final section.

Grain orientation effects in Zr702α polycrystalline samples deformed in channel die compression at room temperature

Abstract Deformation mechanisms are determined in five zirconium polycrystalline samples deformed by channel die compression at room temperature (T1–T5 textures). Slip systems are characterized by a slip trace analysis and twinning systems by a misorientation calculation between twinned and non-twinned parts of the grains, from Electron Back Scattering Diffraction (EBSD) measurements. The analysis is completed by the measurement of crystallographic texture evolutions and the examination of the stress–strain curves. Prismatic glide and {10 1 2} twinning are identified as primary deformation modes and first-order pyramidal slip {10 1 1} and basal slip as secondary slip modes. The experimental study is completed by a numerical approach using polycrystalline models which is consistent with the experimental observations.

Effect of initial textures on deformation mechanisms and texture evolutions of Zrα polycrystals deformed by channel-die compression tests

Abstract Channel die compression tests were performed at room temperature on zirconium polycrystalline samples (Zr 702) up to 40% plastic strain. Three initial textures ( T3, T4 and T5 ) with 〈c〉 axes concentrations along the die axes (ND, TD and LD) are considered. The macroscopic stress-strain curves, the active mechanisms (slip and twinning systems) and the texture evolutions obtained for T3, T4 and T5 show an anisotropic behaviour of the material. Identification of the deformation modes by EBSD (Electron Back Scattering Diffraction) indicates an important contribution of 100 prismatic glide in the different samples. Estimates of twinned volume fractions show an important activation of 102 twinning in the T5 samples. The correlation between the active mechanisms and the texture evolutions is partly explained by geometrical considerations.

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.

The Influence of Temperature on the Rolling Textures of Al Alloys in the Absence of Recrystallization

Textures measured on 2 Al alloys after hot and cold rolling are analyzed in detail. It is nshown that the texture strength and the intensity of the brass component increase with nincreasing temperature. This is in good agreement with some texture predictions.