Orientation Distribution Function Analysis Research Articles

Correlation of microstructure, texture, and mechanical properties of friction stir welded Joints of AA7075-T6 plates using a flat tool pin profile

This study investigates the influence of square and hexagon tool pin profiles on the butt joint of AA7075-T6 plates through friction stir welding. In contrast to the AA7075-T6 base metal with a grain size of 32.736 μm, both square (4.43 μm) and hexagon (5.79 μm) pin profiles led to a significant reduction in grain size within the stir zone (SZ) of the weld cross-section. The SZ region exhibited a gradient in recrystallization and a notable fraction of high angle grain boundaries, attributed to continuous dynamic recrystallization influenced by variations in temperature and strain rate. Pole figure analysis revealed predominant shear texture elements (B/ B‾ and C) with minor A1*/A2* and A/ A‾, indicating elevated strains within the SZ. Orientation distribution function (ODF) analysis identified recrystallization texture elements such as Goss {110} <001>, cube {001} <101>, and P {011} <112>, along with shear texture components F {111} <112> and rotating cube (H) {001} <110>. Tensile and nanoindentation analyses demonstrated that the weld joint using a square-shaped pin profile exhibited higher strength, elongation, and elastic modulus compared to other weld joints. These findings suggest that the square tool pin geometry enhances material flow and grain refinement during welding, thereby improving the mechanical properties of the joint.

Microstructure, properties and crystallographic orientation of novel austenitic Fe–26Mn-3.4Cr-0.4C steel under hot torsion process

An experimental austenitic twin-induced plasticity (TWIP) steel was deformed under hot torsion tests. Two different total equivalent strains (2.2 and 2.6) were employed in order to raise its yield strength while keeping reasonable toughness. The material was isothermally strained at 900 °C with a low strain rate of 0.05 s−1. The effects of torsional deformation on the microstructure, texture and mechanical properties of the TWIP steel were investigated and compared with the as-received samples. X-Ray Diffraction (XRD) measurements were performed to identify the phases present in the metal before and after the thermomechanical process. Scanning electron microscopy (SEM), Electron backscatter diffraction (EBSD), Orientation distribution function (ODF) analysis and tensile experiments complemented the investigation of this research. The main deformation mechanism changed from conventional sliding inside the grain to nucleated twinning from the grain boundaries, which led to the decrease of the grain size to less than 1 μm (UFG - Ultrafine Grains). The results indicate that the transition in the deformation mechanisms is dependent on grain size associated with the flow profile of the material. This was due to changes in the dislocation density within the grain and the movement of dislocations around the yield point. No martensitic transformation was detected during the strain and neither from the twinning mechanism in the microstructure after the torsion deformation. The best balance between high strength and good ductility (920 MPa and 52%) was obtained after the total equivalent strain of 2.6. It was verified that the employed thermomechanical schedule affects the displacement of the substructure with the formation of sub-grains influencing the hardening behavior, texture and yield strength of the metal.

Tensile overload-induced texture effects on the fatigue resistance of a CoCrFeMnNi high-entropy alloy

The present study investigates the crystallographic-texture effects on the improved fatigue resistance in the CoCrFeMnNi high-entropy alloys (HEAs) with the full-size geometry of the American Society for Testing and Materials (ASTM) Standards E647-99. We exploited X-ray nano-diffraction (XND) mapping to characterize the crystal-deformation levels ahead of the crack tip after stress unloading under both constant- and tensile-overloaded-fatigue conditions. The crack-tip blunting-induced much higher deformation level was concentrated surrounding the crack-tip which delays the fatigue-crack growth immediately after a tensile overload. The predominant deformation texture orientation in the Paris regime was investigated, using electron backscatter diffraction (EBSD) and orientation distribution function (ODF) analyses. The twinning formation-driven shear deformation gave rise to the development of the Goss-type texture within the plastic deformation regime under a tensile-overloaded-fatigue condition, which was attributed to enhance the crack deflection and thus the tensile-induced crack-growth-retardation period in the CoCrFeMnNi HEA. Our new findings address the quantitative discrepancy found in our earlier work.

Correlation of Microstructure with Anisotropy of Low‐Temperature Toughness in Two API X70 Pipeline Steels

This study aims to investigate the correlation between the microstructures and the anisotropy of low‐temperature toughness for two high‐strength API X70 pipeline steels fabricated at different coiling temperatures. The microstructures are characterized using an optical microscope, a scanning electron microscope, and an electron backscattered diffraction analysis, with tensile and Charpy V‐notch impact tests also conducted on the steel specimens in various directions relative to the rolling direction. Some pearlites formed by a higher coiling temperature increase the ductile‐to‐brittle transition temperature (DBTT) by 38 °C in the T–L (transverse‐longitudinal) direction. On the other hand, the DBTT of the specimens with the T–L and L–T (longitudinal–transverse) directions (−106.6 and −109.3 °C, respectively) exhibits excellent low‐temperature toughness, but the specimen with the D–D (diagonal–diagonal) direction shows the highest DBTT (−65.2 °C). The resulting anisotropy in the low‐temperature toughness of the API X70 pipeline steel is discussed from the standpoint of an orientation distribution function analysis in this study. It is suggested the anisotropy of the low‐temperature toughness is mainly attributed to the texture components of RD (rolling direction) fibers originating from deformed austenite.

The effect of temper rolling and final annealing on microstructure, texture and magnetic properties of non-oriented electrical steels

In this paper, the effect of temper rolling and final annealing on microstructure, texture and magnetic properties of a 0.6 wt% Si non-oriented electrical steel, with 5.7% temper rolling reduction, were investigated via EBSD and XRD three-dimensional orientation distribution function (ODF) analysis. The results indicate that final annealing plays an essential role in improving the magnetic properties of non-oriented electrical steels. The core loss decreases with the increasing annealing time, reaches the lowest value at 10 min, and then tends to be stable. The magnetic induction quickly increased with prolonged annealing time, reached the highest value, then decreased slightly to a lower value after 15 min. The peak permeability increased rapidly with the increasing annealing time, reached the highest value after 3 min, and became stable after 10 min. The grains abnormally develop from the sample surface to the inner layer derived from gradient strain. Before and after temper rolling, the texture of the material is mainly dominated by {111}<112>. As annealing time increases, the intensity of {111}<112> decreases, emerging the weak Goss ({110}<001>) and other orientations. Finally, there are without preferred orientations when time exceeds 10 min.

Textural development, martensite lath formation and mechanical properties variation of a super strength AISI4340 steel due to austenitization and tempering temperature changes

In this investigation, the textural development, as well as martensite lath formation on the microstructural changes and mechanical properties variation of a super strength AISI 4340 was studied under different austenitization and tempering conditions. To study the influence of tempering temperature, austenitization temperature of 900 °C was followed by tempering in the range of 200–425 °C on the sheet samples. As well, to investigate the effect of austenitization temperature, austenitization temperature of 850–1200 °C was followed by rapid quenching and tempering at 200 °C. Microstructural investigations were conducted using optical microscopy (OM), field emission scanning electron microscopy (FE-SEM) that was equipped with the electron backscattered (EBSD) as well as energy dispersive spectroscopy (EDS) detectors, X-Ray diffraction (XRD), and transmission electron microscopy (TEM). In addition, mechanical properties were evaluated using tensile testing, macro-hardness testing, and Charpy impact testing. Results showed that increasing austenitization temperature up to 950 °C increased ductility which was followed by a sharp drop as the austenitization temperature increased thereafter. Also, it was found that increasing the austenitization temperature from 850 to 1200 °C decreased yield strength (Y.S), and ultimate tensile strength (U.T.S) for about 24%, 26%, respectively. It reduced impact energy by about 35%. Such reductions were related to the increased mean diameter of the prior austenite grain size from 2 μm for the former temperature to 110 μm in the latest temperature. EBSD analysis showed that the steel texture was mostly randomized at high austenitization temperature. (100) pole figure analysis showed that Cube ({100} 〈001〉) and Copper ({112} 〈111〉) components were developed during the optimized heat treatment of 900 °C followed by tempering at 200 °C. PF analysis also indicated that the texture intensity was weakened at lower austenitization temperatures. The presence of the Copper component at the very low austenitization temperature could explain the low ductility of this scenario. Orientation distribution function (ODF) analysis showed that the Cube component was dominant, and the Copper component severely weakened, during the optimum austenitization temperature, which would explain the optimum mechanical properties combinations, particularly ductility. Finally, the mentioned optimized route provided Y.S of 1720 MPa, U.T.S of 1900 MPa, El% of 11%, and Impact energy of 44 J, which confirmed the development of super-strength steel.

Texture development in Al alloys during tensile testing

Abstract Tensile tests were made on commercially pure Al (A1050), Al-4.4 wt.% Mg (A5182) and Al-4 wt.% Cu (A2017) alloys by varying the test temperature and the strain rate. Textures developed at various stages of the tensile deformation were investigated with the orientation distribution function analysis. During the tensile test of pure Al with a strain rate of 3 × 10–4 s –1 at 20 °C, the tensile axis readily rotated toward the &lt;111&gt; stable end orientation. However, such a rotation occurred only at the later stage of the tensile deformation near the tensile stress, where the stress– strain curve became flat, and where work hardening was almost saturated. It is suggested that the size and the morphology of the dislocation cell, which had developed up to this stage, played a significant role in the subsequent texture development. In fact, the addition of Mg and Cu, which inhibited the development of the well-defined cell structure due to the Portevin –Le Chatelier effect, strongly suppressed the rotation of the tensile axis toward &lt;111&gt;. In all the materials investigated, textures were not affected by the strain rate and also by the temperature of the tensile test.

Contribution of dislocation substructures developed during cold rolling to the formation of rolling textures in Al–Mg alloys

Abstract In order to investigate the mechanism of the development of rolling textures in Al –Mg alloys, hot bands of high-purity Al, Al-3 wt. %Mg and Al-5 wt. %Mg alloys were solution-treated at 450 °C and cold-rolled by varying rolling reductions up to 97%. Rolling textures of these specimens were investigated with the orientation distribution function analysis. Comparisons of the results of the texture analysis with those of the hardness measurement and transmission electron microscopy observations revealed that, in all specimens, the texture development occurred mainly at the later half of work hardening, i. e., at rolling reductions above 80 %, where dislocation substructures were well developed. In pure Al, in which well defined, elongated cell structures were developed, {112}&lt;111&gt; and {123}&lt;634&gt; components developed remarkably, whereas in the Al-5% Mg alloys, in which only dense dislocation tangles and ill defined small cells were developed, the development of {112}&lt;111&gt; and {123}&lt;634&gt; components was strongly suppressed. All these observations thus suggested that the development of rolling textures was strongly affected by the development of dislocation substructures, which occurred concurrently during rolling, and that the formation of elongated cell structures was more favorable for the development of rolling textures. In cold rolling, elongated cell structures may be the final form of dislocation substructures, providing both mechanical stability and orientation stability.

Development of cube recrystallization textures in high-purity Al

Abstract High-purity (99.99 wt.%) Al containing 50 wt. ppm Cu was cold rolled to 98% reduction in thickness and annealed by varying the heating rate of annealing and annealing cycles. Textures developed at various stages of annealing were investigated with the orientation distribution function analysis. The observed results were compared with those obtained on standard high purity (99.99 wt.%) Al without Cu addition. In slow heating rate annealing, it was found that in high purity Al the addition of 50 wt.ppm Cu significantly enhanced the development of {100}&lt;001&gt; recrystallization textures. Intensities of {100}&lt;001&gt; developed in high purity Al with 50 wt. ppm Cu were about twice as high as those observed in high purity Al without Cu addition. {123}&lt;634&gt; R orientations were completely eliminated by the addition of 50 wt. ppm Cu. In rapid heating annealing, on the other hand, annealing at temperatures above 325 °C resulted in the formation of very coarse recrystallized grains with weak {100}&lt;001&gt; recrystallization textures irrespective of Cu content. Such grain coarsening could be suppressed by pre-annealing at temperatures between 225 and 300 °C. In the specimens subjected to this pre-annealing, strong {100}&lt;001&gt; recrystallization textures could be obtained, even if they were annealed with a rapid heating rate in final annealing.

Effects of post heat treatment on the microstructure evolution of Inconel 718 manufactured by selective laser melting

In this work, the microstructure, precipitations, crystal orientation and texture of an Inconel 718 superalloy manufactured by selective laser melting (SLM) are investigated by performing post heat treatment. Horizontal and vertical reference faces are examined in the as-built condition, solution conditions for 0.5 and 1 h, and aging condition, respectively. In the as-built condition, Inconel 718 superalloy exhibited cellular and columnar dendrites, a large amount of the fine Laves phase, and several γ′ phases. During post treatment, the grain size on the horizontal face is changed, which is ranged from 502.23 to 523.55 μm2 per grain. Meanwhile, grains coarsened distinctly on the vertical face. The average area of the grain is 739.48 μm2 in the as-built condition and increases to 898.19 μm2 in the aging condition. Additionally, the amount of MC carbides, γ′, and γ″ strengthening phases increased as well during the post heat treatment process, while that of the Laves phase decreased after solution treatment. The preferred orientation on the horizontal face was 〈111〉//X, 〈001〉//Y in the as-built condition, and 〈101〉//Z in the solution and aging conditions. The preferred orientation on the vertical face was 〈001〉//X, 〈101〉//Y in the as-built condition, 〈101〉//Y in the solution condition, and 〈001〉//X in the aging condition. The orientation distribution function (ODF) analysis showed that the main textures in the as-built and solution conditions were {110}〈110〉 and {110}〈112〉, respectively, which transformed to {001}〈100〉 and {001}〈110〉 during aging. The values of multiples of uniform density (mud) in both horizontal and vertical reference faces the aforementioned preferred orientation and texture increased during post heat treatment. Application of post heat treatment can lead to an ideal microstructure Inconel 718 superalloy manufactured by SLM.

Texture Characterization of Duplex Stainless Steel 2205 Using Neutron Diffraction Method

Duplex stainless steel (DSS) is widely used in chemical processes, petrochemical, oil &amp; gas industries, and nuclear technology due to its excellent mechanical properties and exceptional generalized and localized corrosion resistance. In this study, the crystal structure, material phases, and texture characterization of DSS were carried out using the neutron diffraction method. The characterization results show that the duplex has two phases: α (ferrite) and g (austenite), each with a lattice parameter 2.8736 Angstrom and 3.6076 Angstrom, respectively. The sample symmetrization method from triclinic to orthorhombic are used to analyze pole figures. The crystallite orientation in the α and g phases have the opposite direction. The α phase has a crystallite orientation towards {110} &lt;001&gt; or Goss orientation, and the g phase, crystal orientation towards {100} &lt;001&gt; or the cube orientation. The orientation distribution function shows that the orientation strength of ferrite is much stronger than austenite. The crystallite orientation (texture) obtained by the orientation distribution function analysis follows the crystal structure analysis.

Fracture toughness of Si3N4 ceramic composites: Effect of texture

Silicon nitride (Si3N4) ceramics with Al2O3, MgO and Y2O3 as sintering additives were fabricated via hot-pressing sintering and gas pressure sintering, respectively, focusing on the texture and fracture toughness. The hardness and fracture toughness on the plane perpendicular and parallel to the hot-pressing direction were different in the hot-pressing sintered samples, and similar values were obtained in the gas pressure sintering. The orientation distribution function (ODF) analyses via X-ray diffraction measurements revealed the presence of 112¯0〈0001〉 type texture in the hot-pressing sintered samples. This suggested that the 0001 planes of most rod-shaped β-Si3N4 grains were oriented in the hot-pressing direction or their c-axes were oriented towards the radial directions of the sintered cylinder-shaped samples. The presence of such a β-Si3N4 grain texture led to the anisotropy in fracture toughness, with its values changing from 9.3–11.3 MPa m1/2 with increasing indentation angles on the plane parallel to the hot-pressing direction.

Symmetry Breakdown Related Fracture in 42CrMo4 Steel

Austenite grains that underwent the f.c.c. to b.c.c. (or b.c.t.) transformation are typically composed of 24 Kurdjumov–Sachs variants that can be categorized by three axes of Bain transformations; thus, a complete transformation generally displays 3-fold symmetry in (001) pole figures. In the present work, crystallographic symmetry in 42CrMo4 steel austempered below martensite start temperature was investigated with the help of the orientation distribution function (ODF) analysis based on the FEG-SEM/EBSD technique. It is shown that, upon phase transformations, the specimens contained 6-fold symmetry in all (001), (011), and (111) pole figures of an ODF. The ODF analysis, verified by theoretical modeling, showed that under plane-strain conditions cracks prefer to propagate through areas strongly offset by the high symmetry. The origin of high symmetry was investigated, and the mechanism of the symmetry breakdown was explained.

The correlation of microstructure, recrystallization texture and mechanical properties with second–phase content in Al/WO3/SiC hybrid nanocomposite during ARB process

In the present work, the evaluation of microstructure, recrystallization texture with second–phase content in Al/WO3/SiC hybrid nanocomposite during accumulative roll bonding process was investigated by electron back scatter diffraction (EBSD) and analysis of orientation distribution function (ODF). The results showed that the density of nanoparticles played a critical role in the microstructural changes, recrystallization texture and mechanical properties. When the volume fraction of nanoparticles increases, the recrystallized grains are elongated in the rolling direction (RD) due to the Zener-pinning of nanoparticles at high angle grain boundaries and consequently the HAGBs spacing in the normal direction (ND) are constantly reduced. The texture intensity increased sharply with increasing the volume fraction of nanoparticles and eventually reached Fg = 27.23 for S3 nanocomposite. In addition, with development of recrystallization, the random texture in S1and S2 nanocomposites increased significantly. Also, the low intensity of the texture components in S1 and S2 specimen is clearly evident for all fibers. Furthermore, mechanical properties were measured for all specimens and results of the tensile strengths and elongation showed that with decreasing the volume fraction of reinforcing nanoparticles and increasing the volume fraction of recrystallized grains, the tensile strength and elongation were decreased and increased, respectively.

Visualization of texture components using MTEX.

Knowledge of the appearance of texture components and fibres in pole figures, in inverse pole figures and in Euler space is fundamental for texture analysis. For cubic crystal systems, such as steels, an extensive literature exists and, for example, the book by Matthies, Vinel & Helming [Standard Distributions in Texture Analysis: Maps for the Case of Cubic Orthorhomic Symmetry, (1987), Akademie-Verlag Berlin] provides an atlas to identify texture components. For lower crystal symmetries, however, equivalent comprehensive overviews that can serve as guidance for the interpretation of experimental textures do not exist. This paper closes this gap by providing a set of scripts for the MTEX package [Bachmann, Hielscher & Schaeben (2010). Solid State Phenom. 160, 63-68] that allow the texture practitioner to compile such an atlas for a given material system, thus aiding orientation distribution function analysis also for non-cubic systems.

Electrospray Deposition of {200} Oriented Regular-Assembly BaTiO3 Nanocrystal Films under an Electric Field.

Highly oriented, regularly assembled nanocrystalline films have recently emerged as attractive new functional materials. In this study, we deposited a BaTiO3 (BT) nanocube dispersion on a Si substrate by electrospraying, resulting in a dense, regularly assembled BT nanocrystalline film. X-ray diffraction analysis revealed that applying a voltage between the electrospray nozzle and the Si substrate during electrospraying caused the BT nanocubes to form a regular array in the 200 plane aligned perpendicularly to the substrate. The volume fraction of BT nanocubes in the 200 plane in the assembly was estimated by the orientation distribution function analysis to be about 50%. The formation of this regularly assembled layer was determined to be linked to the interaction between the vaporized solvent and the substrate, enabled by the enhanced wettability under the electric field. Electrospray deposition has potential applications in the manufacture of nanocrystalline assembled films for nanofunctional devices.

Texture variations and mechanical properties of aluminum during severe plastic deformation and friction stir processing with SiC nanoparticles

Annealed 1050-aluminum sheets were severely deformed at the strain magnitude of 2.32 through constrained groove pressing (CGP) process. Texture variations and mechanical properties were investigated during CGP and subsequent friction stir processing (FSP) with different volume fractions of SiC nanoparticles. The results revealed that the predominant texture component in the annealed aluminum was {001}〈100〉 cube texture. After CGP, deformed and shear texture components developed while the cube texture was partially remained. In the specimen undergone FSP without nanoparticles, {001}〈110〉 rotated cube and nearly {001}〈110〉 shear texture component C were mainly pronounced, which was indicative of shear deformation of material in the stir zone. Orientation distribution function analysis from the stir zone demonstrated variations in the texture development with the incorporation of SiC nanoparticles. An increase in the fraction of nanoparticles changed the grain orientation in such a way that the {001}〈110〉 shear texture component C gradually developed from the rotated cube texture. However, the overall texture intensity became weaker by increasing the fraction of SiC nanoparticles due to the activation of particle stimulated nucleation mechanism forming randomly oriented grains. The incorporation of SiC nanoparticles in the stir zone also enhanced the yield strength, Young's modulus, and hardness of the stir zone without considerable reduction in the elongation. In such situation, Orowan strengthening was suggested as a dominant mechanism involved.

Texture development in the interfacial zone of Al/Cu bimetal cold roll-bonded for E-mobility

Cold roll-bonded Al/Cu bimetal has been widely used in heat sinks for main converters in E-mobility. The development of textures in the interfacial zone of cold roll-bonded Al/Cu bimetal was investigated with the help of orientation distribution function (ODF) analysis based on the FEG-SEM/EBSD technique. The present results show that the texture development of the cold-rolled Al strips can be represented by an α-fibre shift approaching the bonding interface. Cold rolling of Cu strips in the bonding zone splits Goss {1 1 0}<0 1 0> and increases the intensities of metastable T {1 1 2}<1 3 1> texture components. By approximating the bonding interface, T components dissolve and both α- and γ-fibre sharpen. The intensities of the approx. 40° <1 1 1> pair, Cu {1 1 2}<1 1 1> and RC {1 0 0}<0 1 1>, increase significantly. The strong bonding of the bimetal can be attributed to the strain-induced formation of ultrafine grains during severe plastic deformation at the bonding interface without recourse to concepts such as ‘diffusion’ or ‘intermetallics’.

Assessing texture development and mechanical response in microscale reverse extrusion of copper

Abstract

Microstructural investigation after vacuum electrical breakdown of the W-30wt.%Cu contact material

In the present work, characteristics regarding the sub-micron scale microstructure of the W-30 wt%Cu contact material after vacuum electrical breakdown have been investigated by SEM and EDS. EBSD was also utilized to reveal the change of grain size, misorientation and micro-texture for both Cu and W phases after arc erosion. The results revealed that the arc erosion led to distinct grain refinement and intensified local misorientation strain. Besides, with the help of orientation distribution function analysis, strong peak type {112}<4–61> component was identified to be an important arc erosion texture for the first breakdown phase of Cu, which would complicate the following breakdown process during service due to the work function anisotropies.