Evaluating Deformation-Induced Grain Orientation Change in a Polycrystal During In Situ Tensile Deformation using EBSD

2015 ◽  
Vol 21 (4) ◽  
pp. 969-984 ◽  
Author(s):  
Thomas E. Buchheit ◽  
Jay D. Carroll ◽  
Blythe G. Clark ◽  
Brad L. Boyce
Keyword(s):  
Tensile Deformation ◽  
Electron Backscatter Diffraction ◽  
Correlation Technique ◽  
Polycrystalline Specimen ◽  
Initial Development ◽  
Orientation Change ◽  
Reference Orientation ◽  
Orientation Deviation ◽  
Backscatter Diffraction

AbstractUsing an in situ load frame within a scanning electron microscope, a microstructural section on the surface of an annealed tantalum (Ta) polycrystalline specimen was mapped at successive tensile strain intervals, up to ~20% strain, using electron backscatter diffraction. A grain identification and correlation technique was developed for characterizing the evolving microstructure during loading. Presenting the correlated results builds on the reference orientation deviation (ROD) map concept where individual orientation measurements within a grain are compared with a reference orientation associated with that grain. In this case, individual orientation measurements in a deformed grain are measured relative to a reference orientation derived from the undeformed (initial) configuration rather than the current deformed configuration as has been done for previous ROD schemes. Using this technique helps reveal the evolution of crystallographic orientation gradients and development of deformation-induced substructure within grains. Although overall crystallographic texture evolved slowly during deformation, orientation spread within grains developed quickly. In some locations, misorientation relative to the original orientation of a grain exceeded 20° by 15% strain. The largest orientation changes often appeared near grain boundaries suggesting that these regions were preferred locations for the initial development of subgrains.

In Situ Observation on the Deformation Behavior of Primary α-Ti in a Textured Ti-6Al-4V

2020 ◽  
Vol 993 ◽  
pp. 365-373
Author(s):  
Yun Xi Liu ◽  
Wei Chen ◽  
Zhi Qiang Li ◽  
Liang Liang Liu ◽  
Dong Liu
Keyword(s):  
Tensile Deformation ◽  
Electron Backscatter Diffraction ◽  
Local Texture ◽  
Slip Bands ◽  
Texture Characteristics ◽  
Schmid Factor ◽  
Dislocation Behavior ◽  
Different Strains ◽  
Backscatter Diffraction

The tensile deformation process and dislocation behavior of primary α-Ti of Ti-6Al-4V were studied by the in-situ tensile test combined with EBSD (electron backscatter diffraction). The initiation, evolution and distribution of dislocation slips at different strains were discussed. The results showed that the microtexture of the material had a significant influence on slip behavior. Typically, basal and prismatic <a> slips initiated first, but the dominant slip type was related to the local texture characteristics. Sometimes, the basal and prismatic <a> slips could still initiate when their Schmid factors were relatively low, while the pyramidal slips usually need a higher Schmid factor to initiate. With the increase of strain, the second slip system inside one grain was activated to accommodate the plastic deformation. When the deformation was localized in a specific microtextured region, basal <a> slips were dominant, but eventually the crack initiated from the <c+a> slip bands inside the grain.

scholarly journals Analysis of Strain Partitioning in Intercritically Deformed Microstructures via Interrupted Tensile Tests

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 112
Author(s):  
Unai Mayo ◽  
Nerea Isasti ◽  
José M. Rodríguez-Ibabe ◽  
Pello Uranga
Keyword(s):  
Electron Backscatter Diffraction ◽  
Tensile Tests ◽  
Correlation Technique ◽  
Strain Partitioning ◽  
High Angle ◽  
Electron Backscatter ◽  
Different Types ◽  
Final Deformation ◽  
Micro Alloyed Steel ◽  
Backscatter Diffraction

Intercritically deformed steels present combinations of different types of ferrite, such as deformed ferrite (DF) and non-deformed ferrite (NDF) grains, which are transformed during the final deformation passes and final cooling step. Recently, a grain identification and correlation technique based on EBSD has been employed together with a discretization methodology, enabling a distinction to be drawn between different ferrite populations (NDF and DF grains). This paper presents a combination of interrupted tensile tests with crystallographic characterization performed by means of Electron Backscatter Diffraction (EBSD), by analyzing the evolution of an intercritically deformed micro-alloyed steel. In addition to this, and using the nanoindentation technique, both ferrite families were characterized micromechanically and the nanohardness was quantified for each population. NDF grains are softer than DF ones, which is related to the presence of a lower fraction of low-angle grain boundaries. The interrupted tensile tests show the different behavior of low- and high-angle grain boundary evolution as well as the strain partitioning in each ferrite family. NDF population accommodates most of the deformation at initial strain intervals, since strain reaches 10%. For higher strains, NDF and DF grains behave similarly to the strain applied.

Grain Growth in Al: First Results from a Combined Study of Bulk and In-Situ Experiments Using a Columnar Structured Al Foil

2004 ◽  
Vol 467-470 ◽  
pp. 935-940 ◽  
Author(s):  
Sandra Piazolo ◽  
Vera G. Sursaeva ◽  
David J. Prior
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Electron Backscatter Diffraction ◽  
Boundary Energy ◽  
Complete Replacement ◽  
Von Neumann ◽  
In Situ Experiments ◽  
First Results ◽  
Backscatter Diffraction

First results from grain growth experiments in a columnar structured Al foil show several interesting features: (a) the grain size distribution remains heterogeneous even after up to 300 min. annealing and (b) the Von Neumann-Mullins relation is not always satisfied. To clarify the underlying reasons for these features, in-situ heating experiments within a Scanning Electron Microscope (SEM) were combined with detailed Electron Backscatter Diffraction (EBSD) analysis. These show that the movement of boundaries can be strongly heterogeneous. For example, the complete replacement of one grain by a neighbouring grain without significant change of the surrounding grain boundary topology is frequently seen. Experiments show that grain boundary energy and/or mobility are anisotropic both with respect to misorientation and orientation of grain boundary plane. Low energy and/or mobility boundaries are commonly low angle boundaries, twin boundaries and boundaries that form traces to a low index plane of at least one of the adjacent grains. As a consequence the Von Neumann-Mullins relation is not always satisfied.

scholarly journals Microstructure and Texture Evolutions During Deep Drawing of Mg–Al–Mn Sheets at Elevated Temperatures

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3608 ◽  
Author(s):  
Jae-Hyung Cho ◽  
Sang-Ho Han ◽  
Geon Young Lee
Keyword(s):  
Dynamic Recrystallization ◽  
Deep Drawing ◽  
Elevated Temperatures ◽  
Tensile Deformation ◽  
Electron Backscatter Diffraction ◽  
Texture Evolution ◽  
Grain Structure ◽  
Transmission Electron ◽  
Backscatter Diffraction ◽  
Twin Roll

Texture and microstructure evolution of ingot and twin-roll casted Mg–Al–Mn magnesium sheets were examined during deep drawing at elevated temperatures. The twin-roll casted sheets possessed smaller grain sizes and weaker basal intensity levels than the ingot-casted sheets. The strength and elongation at room temperature for the twin-roll casted sheets were greater than those of the ingot-casted sheets. At elevated temperatures, the ingot-casted sheets showed better elongation than the twin-roll casted sheets. Different size and density of precipitates were examined using transmission electron microscopy (TEM) for both ingot-casted and twin-roll-casted sheets. The deep drawing process was also carried out at various working temperatures and deformation rates, 225 °C to 350 °C and 30 mm/min to 50 mm/min, respectively. The middle wall part of cups were mainly tensile deformation, and the lower bent regions of drawn cups were most thinned region. Overall, the ingot-casted sheets revealed better deep drawability than the twin-roll casted sheets. Microstructure and texture evolution of the top, middle and lower parts of drawn cups were investigated using electron backscatter diffraction. Increased deformation rate is important to activate tensile twins both near the bent and flange areas. Ingot casted sheets revealed more tensile twins than twin-roll casted sheets. Increased working temperature is important to activate non-basal slips and produce the DRXed grain structure in the flange. Dynamic recrystallization were frequently found in the top flanges of the cups. Both tensile twins and non-basal slips contributed to occurrence of the dynamic recrystallization in the flange.

scholarly journals Novel −75°C SEM cooling stage: application for martensitic transformation in steel

Microscopy ◽  
2020 ◽  
Author(s):  
Kaneaki Tsuzazki ◽  
Motomichi Koyama ◽  
Ryosuke Sasaki ◽  
Keiichiro Nakafuji ◽  
Kazushi Oie ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Electron Backscatter Diffraction ◽  
Dislocation Slip ◽  
In Situ Observation ◽  
Contrast Imaging ◽  
Cooling Stage ◽  
Electron Channelling ◽  
Electron Backscatter ◽  
Backscatter Diffraction

Abstract Microstructural changes during the martensitic transformation from face-centred cubic (FCC) to body-centred cubic (BCC) in an Fe-31Ni alloy were observed by scanning electron microscopy (SEM) with a newly developed Peltier stage available at temperatures to  −75°C. Electron channelling contrast imaging (ECCI) was utilized for the in situ observation during cooling. Electron backscatter diffraction analysis at ambient temperature (20°C) after the transformation was performed for the crystallographic characterization. A uniform dislocation slip in the FCC matrix associated with the transformation was detected at −57°C. Gradual growth of a BCC martensite was recognized upon cooling from −57°C to −63°C.

In-situ Recrystallization Experiments Using Electron Backscatter Diffraction

2007 ◽  
Vol 13 (S02) ◽  
Author(s):  
D Prior ◽  
M Bestmann ◽  
S Piazolo ◽  
NC Seaton ◽  
DJ Tatham ◽  
...  
Keyword(s):  
Electron Backscatter Diffraction ◽  
Electron Backscatter ◽  
Backscatter Diffraction

The Observation of Slip Phenomena in Single Crystal Fe Samples During In Situ Micro-Mechanical Testing Through Orientation Imaging

2014 ◽  
Vol 20 (4) ◽  
pp. 1060-1069 ◽  
Author(s):  
Dhriti Bhattacharyya ◽  
Robert W. Wheeler ◽  
Robert P. Harrison ◽  
Lyndon Edwards
Keyword(s):  
Single Crystal ◽  
Mechanical Testing ◽  
Electron Backscatter Diffraction ◽  
Tensile Axis ◽  
Orientation Data ◽  
Direction Parallel ◽  
Entire Area ◽  
Orientation Change ◽  
Gauge Section

AbstractThis paper reports a study of local orientation change occurring within micro-scale tensile samples as a function of strain. These samples were fabricated from a thin film of single crystal bcc Fe and deformed in tension using an in situ micro-mechanical testing device inside a scanning electron microscope. Samples were loaded along the <110> direction parallel to the specimen axis, strained to different levels, and then subjected to electron backscatter diffraction scans over the entire area of the gauge section. Analysis of the surface orientation data shows that, within a necked zone of the micro-sample gauge section, there are two distinct regions of significant orientation change, in which local crystal rotations occur in opposite directions. These two regions are separated by an intermediate band that shows minimal misorientation from the original state. Crystal rotations within the two regions that develop opposite orientations are found to be consistent with classic single crystal slip, where the slip direction rotates toward the tensile axis. It is shown that increasing tensile strain causes an increasing degree of rotation away from the starting orientation. The tests also illustrate the occurrence of slip on at least two different slip systems, based on the slip traces and orientation change.

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