The evolution with strain of the stored energy in different texture components of cold-rolled IF steel revealed by high resolution X-ray diffraction

Abstract

is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. During the deformation of low carbon steel by cold-rolling, dislocations are created and stored in grains depending on local crystallographic orientation, deformation, and deformation gradient. Orientation dependent dislocation densities have been estimated from the broadening of X-ray diffraction lines measured on a synchrotron beamline. Different cold-rolling levels (from 30% to 95% thickness reduction) have been considered. It is shown that the present measurements are consistent with the hypothesis of the sole consideration of screw dislocations for the analysis of the data. The presented evolutions show that the dislocation density first increases within the α fiber (={hkl}b110N) and then within the γ fiber (={111}buvwN). A comparison with EBSD measurements is done and confirms that the storage of dislocations during the deformation process is orientation dependent and that this dependence is correlated to the cold-rolling level. If we assume that this dislocation density acts as a driving force during recrystallization, these observations can explain the fact that the recrystallization mechanisms are generally different after moderate or large strains.

The influence of the cube component on the mechanical behaviour of copper polycrystalline samples in tension

“…The normalization is necessary due to the fact that the counting parameters are not always the same, since they depend on the actual spread of the scanned peak as well as on the intensity of the diffracting orientation. It is worth mentioning that the signal to noise ratio varies between 10 2 in the worst case to 10 3 in most of the cases, which is acceptable, although this ratio is somewhat higher than when obtained from synchrotron measurements [40]. It is also interesting to note that the peaks associated with the (96 % CRannealed at 200°C) sample present some asymmetry.…”

“…It is especially clear for the material tested after 96% rolling and annealing, for which, due to the relative high percentages of the two considered orientations, the XRD values seem to be statistically much more significant than after 73% rolling and annealing. Also, it is clear that is systematically lower than , since both GND and SSD types of dislocations are taken into account by XRD [40]. It is rather striking that the estimates of these two densities and , while obtained with different procedures based on simplifying assumptions, are consistent with some values of and obtained in copper deformed in tension up to a slightly larger strain (40%) through TEM measurements [12] if we consider that we have in the present case, .…”

“…It is worth recalling that this soobtained dislocation density does include both the so-called geometrically necessary dislocations (GND), which generally constitute "hard" subgrain boundaries as well as the socalled statistically stored dislocations (SSD) which are dispersed within the dislocation cells which are thus considered to be "softer" zones. It has been recently shown that, when the densities of these two populations are roughly equal, the resulting X-ray profiles are symmetrical [40], the asymmetry produced by the harder zones being compensated by the one produced by the softer zones. The observed asymmetry mentioned above could thus be due to different populations of these two types of dislocations in the present case.…”

An evaluation of diffraction peak profile analysis (DPPA) methods to study plastically deformed metals

“…The only parameters that are adequately measured by both DPPA and other methods are the dislocation density and the crystal size. For the dislocation density the results show some agreement [7][8][9][10]. Whereas for the crystal size, the values show agreement for un-deformed samples [11][12][13], but for sample with strain present such as deformed samples there can be problems, and in most cases the sizes are significantly smaller than found by other methods [1,11,14,15].…”

Quasi in-situ analysis of geometrically necessary dislocation density in α-fibre and γ-fibre during static recrystallization in cold-rolled low-carbon Ti-V bearing microalloyed steel

“…Dillamore et al [25] reported stored energy in alpha fibre is in the order of SE{100}<011> < SE{112}<011> < SE{111}<011> based on the subgrain misorientation measurements. With an increase in rolling reduction, the intensity of both fibres is enhanced [26,27]. Wauthier-Monnin et al carried out dislocation density analyses for alpha and gamma fibres for different rolling strains (between 15 % and 93 %).…”