Wootz steel project by electron backscatter diffraction

The data is from an electron backscatter diffraction (EBSD) study of the microstructure of high carbon ‘Wootz’ steel. The objective of the study is to infer an unknown thermomechanical history from observation and analysis of the final microstructure in various ancient artefacts (swords and tools), and then compare the findings with heat treatments of the ancient artefacts and modern attempts at duplication of the structure. Electron backscatter data reveals the orientation relationships between various phases in the material, particularly cementite and ferrite.

Electron backscatter diffraction (EBSD) map of AZ31 compressed to 1% strain at room temperature in a direction parallel to the extrusion direction

The collection contains an EBSD map of AZ31 compressed to 1% strain at room temperature in a direction parallel to the extrusion direction. The map was collected as part of an investigation into the role of twinning in the occurrence of a yield point elongation during deformation.

Wootz steel project by electron backscatter diffraction

The data is from an electron backscatter diffraction (EBSD) study of the microstructure of high carbon ‘Wootz’ steel. The objective of the study is to infer an unknown thermomechanical history from observation and analysis of the final microstructure in various ancient artefacts (swords and tools), and then compare the findings with heat treatments of the ancient artefacts and modern attempts at duplication of the structure. Electron backscatter data reveals the orientation relationships between various phases in the material, particularly cementite and ferrite. The dataset is randomly structured and organised. The data is automatically generated by an electron backscattered diffraction system attached to a field emission scanning electron microscope. The dataset uses proprietary software (cannot be copied or distributed without complying with licensing agreements): Oxford HKL Channel 5. As the native formats are binary they cannot be read with standard software.

Grain boundary segregation in Fe-Mn-C twinning-induced plasticity steels studied by correlative electron backscatter diffraction and atom probe tomography

We report on the characterization of grain boundary (GB) segregation in an Fe-28Mn-0.3C (wt.%) twinning-induced plasticity (TWIP) steel. After recrystallization of this steel for 24 h at 700 °C, ∼50% general grain boundaries (GBs) and ∼35% Σ3 annealing twin boundaries were observed (others were high-order Σ and low-angle GBs). The segregation of B, C and P and traces of Si and Cu were detected at the general GB by atom probe tomography (APT) and quantified using ladder diagrams. In the case of the Σ3 coherent annealing twin, it was necessary to first locate the position of the boundary by density analysis of the atom probe data, then small amounts of B, Si and P segregation and, surprisingly, depletion of C were detected. The concentration of Mn was constant across the interface for both boundary types. The depletion of C at the annealing twin is explained by a local change in the stacking sequence at the boundary, creating a local hexagonal close-packed structure with low C solubility. This finding raises the question of whether segregation/depletion also occurs at Σ3 deformation twin boundaries in high-Mn TWIP steels. Consequently, a previously published APT dataset of the Fe-22Mn-0.6C alloy system, containing a high density of deformation twins due to 30% tensile deformation at room temperature, was reinvestigated using the same analysis routine as for the annealing twin. Although crystallographically identical to the annealing twin, no evidence of segregation or depletion was found at the deformation twins, owing to the lack of mobility of solutes during twin formation at room temperature.

Electron backscattering diffraction analysis of an ancient wootz steel blade from central India

The electron backscattering diffraction technique was used to analyse the nature of carbides present in an ancient wootz steel blade. Bulky carbides, pro-eutectoid carbide along the prior austenite grain boundaries and fine spheroidized carbides were detected. Electron backscattering diffraction was employed to understand the texture of these carbides. The orientations of the cementite frequently occur in clusters, which points to a common origin of the members of the cluster. For the bands of coarse cementite, the origin is probably large coarse particles formed during the original cooling of the wootz cake. Pearlite formed earlier in the forging process has led to groups of similarly oriented fine cementite particles. The crystallographic texture of the cementite is sharp whereas that of the ferrite is weak. The sharp cementite textures point to the longevity of the coarse cementite throughout the repeated forging steps and to the influence of existing textured cementite on the nucleation of new cementite during cooling.

Electron backscattering diffraction analysis of a reconstructed wootz damascus steel blade

The historical impact and subsequent fame of wootz weaponry in the ancient world has created interest in what has come to be seen as an advanced material even by modern standards. Ancient wootz artifacts are classed as high carbon (hypereutectoid) crucible steels and are characterised by high strength, hardness and wear resistance, but especially by their attractive surface pattern.

Recrystallization textures in course grained low carbon and interstitial free steels

The microstructures and textures of coarse grained cold rolled, partially recrystallized and fully recrystallized low carbon and interstitial free steel were examined by optical microscopy, scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). The recrystallization textures of the two grades are markedly different, with the low carbon steel having a predominantly Goss {11O}<OOl> texture and the interstitial free steel having a <1ll>/1ND texture with a strong {III }<112> component. One possible explanation for the texture difference is that less severe localization of flow during deformation of interstitial free steels causes less Goss nuclei to be generated. While some support for this view is provided by the results presented in this paper, the results suggest that another mechanism may be at least partially responsible. Examination of micro
shear bands on the surface of pre-polished samples showed that a higher proportion of micro shear bands remained active at high rolling reductions in the low carbon steel, compared with the interstitial free grade. Regions of Goss orientation within bands that have ceased to operate rotate to
near-{ III }<112> orientations with further deformation. Consequently, the recrystallization texture of coarse grained interstitial free steels can be rationalized by a reduction in the availability of Goss nuclei and an increase in the availability of {Ill }<112> nuclei due to a "Goss to {Ill }<112>" rotation within micro shear bands that have ceased to operate.

On the production of randomly-oriented recrystallization nuclei for selective growth experiments

The ideal starting condition for selective growth experiments is one having a layer of randomly-oriented nuclei adjacent to a matrix with negligible orientational variation but sufficient stored energy to promote growth. In practice, cutting or deformation processes are used in an attempt to approximate these ideal conditions, but the degree to which this is achieved has not been rigorously quantified. In this work, Fe-3wt%Si single crystals were cut or deformed using six different processes. The variation in texture with distance from the cut or deformed surface was measured using electron backscatter diffraction (EBSD) in a field emission gun scanning electron microscope (FEG-SEM) in order to assess the ability of each process to create conditions suitable for selective growth experiments. While grooving with a machine tool produced the best spread of orientations at the cut surface, the suitability of this process is diminished by the presence of a differently-textured deformed layer between the cut surface and the single crystal matrix. Grinding produced a less ideal distribution of orientations at the cut surface, but the presence of these orientations in a very thin layer adjacent to the matrix makes this process preferable for preparing crystals for selective growth experiments, provided the results are corrected for the deviation in the distribution of nuclei orientations from a random distribution.

Observation of deformation modes in Mg-3Al-1Zn

Since magnesium alloys are the lightest metallic materials, they are very attractive for automotive and aerospace industries. The main problem of these alloys is limited ductility due to a shortage of independent slip systems. In order to improve the formability in these alloys, an understanding of the deformation modes is required. In the present work, different slip systems were investigated in rolled Mg-3Al-IZn by means of in situ tensile tests in the SEM. These permitted electron backscatter diffraction (EBSD) and electron backscatter diffraction imaging (QBSD) to be carried out during the test. The results show that non-basal slip systems are active at room temperature.

In-situ investigation of twinning behaviour in Mg-3Al-1Zn

Magnesium alloys are attractive for automotive and aerospace industries, due to their low density. One problem with these alloys is their limited formability at room temperature. Twinning plays a dominant role in deformation behaviour and it can be expected that an increased understanding of twinning will help improve formability. In the present work, the behaviour of different twinning systems in as-cast Mg-3AI-IZn is investigated using in-situ tensile tests in a scanning electron microscope. Electron backscatter diffraction and back scatter electron imaging were carried out during the tests. The results show both "tension" and "compression" twinning are active at room temperature and that twinning and untwinning occur both during loading and unloading.

Modeling the flow behavior, recrystallization, and crystallographic texture in hot-deformed Fe-30 Wt Pct Ni Austenite

The present work describes a hybrid modeling approach developed for predicting the flow behavior, recrystallization characteristics, and crystallographic texture evolution in a Fe-30 wt pct Ni austenitic model alloy subjected to hot plane strain compression. A series of compression tests were performed at temperatures between 850 °C and 1050 °C and strain rates between 0.1 and 10 s⁻¹. The evolution of grain structure, crystallographic texture, and dislocation substructure was characterized in detail for a deformation temperature of 950 °C and strain rates of 0.1 and 10 s⁻¹, using electron backscatter diffraction and transmission electron microscopy. The hybrid modeling method utilizes a combination of empirical, physically-based, and neuro-fuzzy models. The flow stress is described as a function of the applied variables of strain rate and temperature using an empirical model. The recrystallization behavior is predicted from the measured microstructural state variables of internal dislocation density, subgrain size, and misorientation between subgrains using a physically-based model. The texture evolution is modeled using artificial neural networks.