Evolution Of Crystallographic Texture Research Articles

Deformation behaviour of the silicon doped metastable Fe50-xMn30Co10Cr10Six complex concentrated alloy using experiments and crystal plasticity simulations

Deformation behaviour of transformative Fe50Mn30Co10Cr10 complex concentrated alloy doped with 0.2 wt % silicon is studied using ex-situ EBSD accompanied with mean and full field crystal plasticity simulations. On silicon doping, martensitic transformation gets suppressed rather nano twinning is observed with tensile deformation. The considerable rise in strength and tensile ductility is attributed to the solid solution strengthening and deformation twinning respectively. Furthermore, crystal plasticity simulations using mean field viscoplastic self-consistent and full field fast Fourier transform FFT approaches are performed to address the texture evolution, the effect of neighbouring grains of different orientations as well as slip and twin activity. Slip is found to be planar in nature which is verified using crystal plasticity simulations. Combination of mean and full field simulations is used to address the effect of neighbouring orientations on the rotation path of individual grains towards the stable end orientation. The critical role of deformation nano twinning in providing extended strain hardening contributing to significant ductility is established. This study highlights the importance of silicon doping in improving the mechanical properties of the Fe50Mn30Co10Cr10 CCA while offering valuable insights into the deformation mechanisms and crystallographic texture evolution.

Microstructure-crystallographic texture and substructure evolution in unpeened and laser shock peened HSLA steel upon ratcheting deformation

ABSTRACT Uniaxial ratcheting behaviours associated with microstructural development of unpeened and laser shock peened ASTM A 588 Grade D High Strength Low Alloy (HSLA) steel were studied in this investigation. The mechanism of plastic deformation and crystallographic texture evolution during ratcheting was also studied. For this, the primary experimental works involved were stress-controlled ratcheting fatigue tests (on unpeened/laser-peened specimens) at room temperature. Followed by this, microstructure and texture evolution on the surfaces and/or cross sections of the deformed specimens, using electron back scattered diffraction (EBSD) were studied in detail. Additionally, the substructural evolution of some selected samples was also studied using transmission electron microscopy (TEM). The results indicated that the average grain size of all the unpeened ratcheted specimens was marginally reduced after fatigue tests. The laser-peened specimen, however, showed a marginal increase in average grain size after ratcheting. Continuous dynamic recovery and recrystallisation (CDRR) during ratcheting was thought to be the cause of the observed reduction in average grain size in unpeened specimens, whereas continuous dynamic recrystallisation (CDRX) was believed to be the controlling factor for marginal accretion of grain size in laser-peened specimens. The plastic deformation of investigated steel was qualitatively explained by the observed dislocation patterns and their evolution.

Evolution of microstructure, microhardness, crystallographic texture, and grain size variation in dissimilar joints used in concentrated solar power plants application

High carbon stainless steel 347H (SS347H) and Inconel 625 (IN625) are high-strength alloys, commonly used in high-temperature applications. These metals are commonly used in the fabrication of concentrated solar power energy storage tanks and pipelines. Construction of such tanks involves dissimilar welding as the primary manufacturing process. The critical factor to consider when joining two different materials is the development of microstructure, as it directly impacts the mechanical characteristics of the joints. According to the available literature, an increase in the heat input (HI) promotes alloying element segregation and susceptibility to weld cracking. Traditional arc welding processes, such as metal inert gas (MIG) welding, produce a higher HI. Therefore, there is a need to develop welding techniques that result in reduced HI. In the present study, a pulse-current MIG (PC-MIG) welding method was employed, utilizing current pulsing to minimize HI during the welding process. The welding was followed by metallographic and mechanical characterization. The microstructural examination found variations in microstructure at different regions. Electron backscatter diffraction analysis shows the crystallographic orientation at different regions. Analysis shows that both SS347H and IN625 have a face-centred cubic austenite structure. The inverse pole figure discloses strong texture formation. The average tensile strength of dissimilar weldments was found to be 479 MPa, while the average hardness value of the fusion zone was measured to be 235 HV. The research indicates that the PC-MIG technique is suitable for joining dissimilar materials with reduced HI, effectively eliminating the risk of cracking and enhancing the efficiency of the joint.

Enhancement of microstructure, micro-texture, and mechanical properties of Al6061 friction stir welds using the developed static shoulder welding tool

Dissolution of strengthening precipitates and grain coarsening are the key factors that dictate the mechanical properties of heat-treatable aluminium alloys. In this study, a feasible method of static shoulder friction stir welding (SSFSW) is used to reduce these adverse effects. A novel static shoulder friction welding tool is developed here in this study by incorporating rotating and non-rotating shoulders in a single tool. The effectiveness of the tool was evaluated by welding Al6061 plates under various conditions, such as conventional friction stir welding (CFSW), underwater friction stir welding (UWFSW), and SSFSW. The evolution of crystallographic texture and microstructural changes during the process is studied using electron back scattered diffraction and transmission electron microscopy. The results showed that SSFSW reduced grain size by 37% compared to UWFSW at the centre of the stir zone and increased the yield strength by 22.8% compared to CFSW. In addition, SSFSW showed a strong presence of γ-fibre, indicating improved formability and a 7.2% improvement in joint efficiency in terms of ultimate tensile strength due to a higher fraction of precipitates and higher dislocation density.

Evolution of Microstructure and Crystallographic Texture During Welding for 1.5 GPa Ultra-high Strength Steel Toughened by an Elongated Grain Structure With Intensive Texture

Evolution of Microstructure and Crystallographic Texture During Welding for 1.5 GPa Ultra-high Strength Steel Toughened by an Elongated Grain Structure With Intensive Texture

Directed Energy Deposition With Coaxial Wire-Powder Feeding: Melt Pool Temperature and Microstructure

Abstract In this work, we developed a new additive manufacturing paradigm, coaxial wire–powder-fed directed energy deposition (CWP-DED), to enable the fabrication of metals or composites with high manufacturing flexibility and efficiency. Herein, stainless steel (SS) 316L was selected as a representative material to validate the feasibility of CWP-DED process. Effects of feed rates on the melt pool temperature during the CWP-DED process were investigated using experimental and analytical approaches. Thermal contributions of fed wire and powders to the melt pool were involved in the analytical model to predict the melt pool temperature. The experimental results from thermal imaging were also obtained for validation. Besides, we uncovered the evolution of solidification morphology and crystallographic texture with different combinations of wire and powder feed rates. Finally, the microhardness and tensile performance of different as-built parts were tested. The results showed that the powder feed rate played a more dominant role in determining the melt pool temperature than the wire feed rate. Melt pool temperature experienced an initial increase and then decrease with the powder feed rate. A fine microstructure was achieved at a low powder feed rate, producing higher microhardness and larger tensile strength. This paper revealed the relations among process, thermal variation, and microstructure of as-built metallic parts to well understand this novel DED process.

Effect of Crystallographic Orientations on Bendability in a Strongly Textured Mg-9Al Extrusion Plate and Texture Evolution during Three-Point Bending

The dependence of bendability on crystallographic orientations and texture evolution was investigated in a strongly textured Mg-9Al extrusion plate by bending along four directions. Results show that the bars have relatively small and reasonably close bendability when bent along the extrusion direction, transverse direction, and through-thickness direction. In contrast, the bendability of the 45° bar is much larger. Microstructure examination indicates that twins are prevalent in all bars. Furthermore, a detailed analysis of deformation mechanisms suggests that the initial texture transforms towards a basal texture during bending. Nevertheless, the texture transformation efficiency is drastically lower when basal slip-in contrast to tensile twinning-is the dominant deformation mechanism. The difference in texture evolution efficiency was used to rationalize the varied bendability along different directions. The findings of this provide insights into improving the bendability of magnesium alloys.

Validating texture and lattice strain evolution models via in-situ neutron diffraction and shear tests

Validating micromechanical models under different loadings is challenging due to limited availability of experimental setups that can probe complex stress states. In this work, we perform in situ neutron diffraction experiments during shear loading to study the evolution of crystallographic texture and lattice strains that develop in different grain families. The experiments are conducted on 316 stainless steel samples, having a flat shear sample geometry suitable for testing in uniaxial rigs. The complex stress state in the gauge volume is estimated using an elasto-plastic finite element (FE) simulation, which is validated via experimentally measured gauge strains. The FE simulation reveals the generation of non-negligible in-plane normal stress components together with the in-plane shear stress component. The predicted macroscopic stresses are used as boundary conditions to drive an elasto-viscoplastic fast Fourier transform (EVP-FFT) based crystal plasticity model, which predicts lattice strain evolution. In addition, the evolution of the diffraction intensity is simulated using the Taylor model. The predictions of both models match very well with the experimental results. The experiments reveal that the {220} and {311} grain families have higher lattice strains than the {200} family. This surprising result is explained with the help of simulations.

Evolution of crystallographic texture and grain boundary character in hot press sintered tungsten heavy alloy as a function of sintering temperature

Using the vacuum hot press sintering method, tungsten heavy alloys (93 W − 4.9Ni − 2.1Cu) was produced. The study explored the effect of sintering temperature on W-Ni-Cu heavy alloy. Studies in metallography reveals that an increase in sintering temperature led to the coalescence of tungsten grains and affected their mechanical, electrical properties. As a result, an alloy sintered at a high temperature (1450 °C) has the highest hardness (410 Hv0.5), electrical conductivity (19.72% of IACS), and relative density (96.6%).

Nb modified Ti-5553 alloy: Effects of heating rate on mechanical properties, corrosion behavior, and crystallographic texture

Ti–5Al–5Mo–5V–3Cr (Ti-5553) is a metastable β-type Ti alloy with excellent hardenability and high mechanical strength designed for aerospace applications. Previous studies have shown that the replacement of V with Nb, resulting in a Ti–12Nb–5Al–5Mo–3Cr (Ti-12553) alloy, can enhance the mechanical strength and hardenability. This study focuses on exploring the effects of V replacement with Nb in this alloy, aiming to evaluate the effects of the aging heating rate during aging heat treatment on the microstructure and its effect on hardness, tensile and compression strengths, corrosion resistance, and crystallographic texture development. The Ti-5553 and Nb-modified Ti-5553 (Ti-12553) alloys aged at 600 °C for 2 h resulted in a microstructure formed by α precipitates in a β matrix, with larger precipitates at a faster heating rate. This effect was more pronounced for the Ti-5553 alloy. The coarsening microstructure affected the mechanical behavior by decreasing the mechanical strength (hardness, ultimate tensile strength, and yield strength) while improving ductility and intergranular fracture mode in combination with a smaller region containing dimples. A decrease in hardness was observed at a faster heating rate, but it was still superior to that of the solution heat-treated samples. The textures formed in both alloys were similar and lacked any strong components. The replacement of V with Nb and the microstructure produced after aging heat treatment did not affect the samples’ corrosion resistance in a 3.5% NaCl solution. A stable passive protective layer with noble corrosion potential and reduced corrosion current density was observed.

Effect of ECAP die angle and route type on the experimental evolution, crystallographic texture, and mechanical properties of pure magnesium

Abstract In the current study, the effect of equal channel angular pressing parameters such as die route type and die angle were studied. Billets of pure magnesium (Mg) were processed successfully through up to 2-passes of different routes, A, Bc, and C, using equal channel angular pressing dies with different internal angles of 90° and 120° at 225°C. The crystallographic texture and microstructural evolution were investigated using electron back-scatter diffraction. The Vickers microhardness and tensile properties were investigated, analyzed, and linked to the microstructure and crystallographic texture as well. The as-annealed condition revealed relatively coarse equiaxed grains coupled with some extra-elongated grains with average grain size of 6.338 µm. Processing through 2-passes formed an ultrafine grain structure and recrystallized fine grains. This decrease in grain size was associated with hardness and tensile strength enhancement as compared with the as-annealed Mg counterpart. ECAP processing through the 90° die revealed that 2-passes of route Bc was more effective in grain refinement compared to routes A and C, and it reduced the average grain size by 76.45% compared to the as-annealed counterpart. On the other hand, for the ECAP die with 120°, route A was more effective in grain refinement compared to the other routes. Processing through 2-passes of route C resulted in a stronger texture compared to the other routes with momentous rotation for the texture components. Processing of 2-A, 2-Bc, and 2-C through the 90°-die revealed an increase in the Vickers Hardness (HV) of 76.9, 96, and 84.6%, respectively, compared to the AA counterpart. In addition, the tensile findings revealed that the 90°-die resulted in higher ultimate tensile strength coupled with a drop-in ductility compared to the 120°-die. Furthermore, ECAP processing through the 90°-die led to improvement in the ultimate tensile strength by 14.1, 38.4, and 43.75%, respectively, coupled with improving the Mg ductility by 80.9, 73.5, and 47.6% through processing via 2-A, 2-Bc, and 2-C, respectively, compared to the as-annealed counterpart.

Experimental evidence concerning the significant information depth of X-ray diffraction (XRD) in the Bragg-Brentano configuration

X-ray diffraction in the Bragg-Brentano configuration (“XRD”) is a very established method. However, experimental evidence concerning its significant information depth, i.e. microstructure components from which maximum depth can affect the information evaluated from the acquired diffraction pattern, are scarce in the scientific literature. This depth is relevant to all XRD measurements performed on compact samples, especially layered composites and samples showing a crystallographic texture evolution. This article provides experimentally determined upper and lower limits to the significant information depth: XRD patterns acquired from a compact crystal layer through a layer of compact, amorphous glass indicate that the significant information depth of XRD using Cu Kα1 and Kα2 radiation is very likely larger than 48 μm, but smaller than 118 μm, in a material of the composition Mg2Al4Si5O18 with a density of ca. ~2.6 g/cm3. The depth of 48 μm correlates to the depth larger than the layer of material from which 90% of the reflected X-rays originate at 2Θ = 25.8°.

The Defining Role of Local Shear on the Development of As-Rolled Microstructure and Crystallographic Texture in Steel

The Defining Role of Local Shear on the Development of As-Rolled Microstructure and Crystallographic Texture in Steel

Impact of gas flow direction on the crystallographic texture evolution in laser beam powder bed fusion

ABSTRACT This study demonstrated that the gas flow direction in the laser beam powder bed fusion (PBF-LB) significantly affects the crystallographic texture evolved in the products. The effect on texture is attributed to the difference in the melt pool depth, which depends on gas flow direction. The melt pool was shallower when the laser scanning and gas flow directions were parallel than when they were perpendicular. This phenomenon should be of particular concern when applying Scan Strategy_XY wherein the laser was scanned with a 90° rotation in each layer, which is often used in PBF-LB. The asymmetry in the melt pool depth generated by laser scanning in the x- and y-directions can lead to unintended variations in the crystallographic texture. The gas phase would interact with a part being manufactured immediately beneath the gas and affect the crystallographic feature of the product.

Deformation, dislocation evolution and the non-Schmid effect in body-centered-cubic single- and polycrystal tantalum

A physically-informed continuum crystal plasticity model is presented to elucidate deformation mechanisms, dislocation evolution and the non-Schmid effect in body-centered-cubic (bcc) tantalum widely used as a key structural material for mechanical and thermal extremes. We show the unified structural modeling framework informed by mesoscopic dislocation dynamics simulations is capable of capturing salient features of the large inelastic behavior of tantalum at quasi-static (10−3 s−1) to extreme strain rates (5000 s−1) and at low (77 K) to high temperatures (873 K) at both single- and polycrystal levels. We also present predictive capabilities of the model for microstructural evolution in the material. To this end, we investigate the effects of dislocation interactions on slip activities, instability and the non-Schmid behavior at the single crystal level. Furthermore, ex situ measurements on crystallographic texture evolution and dislocation density growth are carried out for polycrystal tantalum specimens at increasing strains. Numerical simulation results also support that the modeling framework is capable of capturing the main features of the polycrystal behavior over a wide range of strains, strain rates and temperatures. The theoretical, experimental and numerical results at both single- and polycrystal levels provide critical insight into the underlying physical pictures for micro- and macroscopic responses and their relations in this important class of refractory bcc materials undergoing large inelastic deformations.

Experiments and Crystal Plasticity Finite Element Simulations of Texture Development during Cold Rolling in a Ti-15V-3Cr-3Sn-3Al Alloy

The effect of deformation on the evolution of crystallographic texture in a Ti-15V-3Cr-3Sn-3Al (Ti-15333) alloy after unidirectional cold rolling was studied experimentally and numerically in the present investigation. An optical microscope (OM) and scanning electron microscope (SEM) were used to study the microstructures, while the crystallographic texture after cold rolling was studied with X-ray diffraction. The rolling process (deformation) was simulated with PRISMS-plasticity, open-source crystal plasticity software. Micro-indentations were performed on the initial solution-annealed sample with an equiaxed grain structure. The experimentally obtained load–displacement curve for a particular grain (orientation-φ1, Φ, φ2 = 325.2°, 18.0°, 66.2° (Bunge notation)) was compared with the crystal plasticity finite element method (FEM)-simulated load–displacement curve to obtain the calibration parameters. The obtained parameters, along with the experimental stress–strain curve, were used to recalibrate the PRISMS-plasticity software for the rolling simulations of the Ti-15333 alloy. It was observed that the γ-(normal direction, ND//<111>) and α-(rolling direction, RD//<110>) fibers strengthened with cold rolling, experimentally as well as numerically. The simulated orientation distribution functions (ODFs) matched reasonably well with those obtained from the experiments. The average values of von Mises stress and von Mises strain increased with an increase in deformation.

Microstructure-texture-micro-strain evolution during tensile deformation of α+β titanium alloy using in-situ Synchrotron X-ray diffraction and CPFEM simulation

The evolution of micro-strain and crystallographic texture of each phase of α+β Ti-6Al-4V titanium alloy generated during tensile deformation has been estimated numerically and then compared with the experimental results. It has been carried out based on the Crystal Plasticity Finite Element Model (CPFEM) simulation of the stress-strain curve till the uniform elongation for the equiaxed microstructure is generated synthetically. The synthetic microstructure of Ti-6Al-4V has been developed using the microstructure feature parameters (such as grain size, phase fraction, and grain orientation). The polycrystal stress-strain behaviour for the same has been simulated using the representative orientation distribution function data obtained from the electron backscatter diffraction (EBSD) scans. The present investigation discusses the mechanism of strain-partitioning during uniform elongation using CPFEM simulation in conjunction with EBSD-based experimental misorientation data to rationalize our observation.

Evolution of Crystallographic Texture, Microstructure, and Mechanical Properties during Flat Rolling of Alloys of the Cu–Zn System with Different Grain Sizes

Evolution of Crystallographic Texture, Microstructure, and Mechanical Properties during Flat Rolling of Alloys of the Cu–Zn System with Different Grain Sizes

Effect of Accumulative Roll Bonding (ARB) strain path on microstructural evolution and crystallographic texture development in aluminium

In the present study nine successive ARB cycles were applied on double-layer 1 mm aluminum sheets following three different routes; normal, reverse and cross. Severely deformed sheets were studied by XRD and EBSD to show the evolution of crystallographic textures, while mechanical properties are characterized by micro-tensile and micro-hardness tests. Results indicate that changing the route significantly affects the formation of crystallographic texture components in the structure, leading to different macro mechanical properties. As the asymmetry increases in the strain route, the intensity of the texture components reduces by 57% from as-received structure to the most asymmetric ARBed sample, i.e., cross route. The difference is attributed to different activated slip system in each route. The higher the asymmetry of the route, the lesser the necessity for the cross-slip, and the more the dynamic recrystallization in the structure. Hence, the finest grains happen to form in Normal ARBed sample. The same mechanism is responsible for higher strength (36%) and hardness (32%) observed in Normal ARBed sample. However, the change of route also lowers the bond strength in Cross and Reverse ARBed samples, weakening them by almost 12% regarding the as-received sheet.

Near-Net Shape Manufacture of Ultra-High Strength Maraging Steel Using Flow Forming and Inertia Friction Welding: Experimental and Microstructural Characterization

Abstract Flow forming and inertia friction welding (IFW) have been widely used as manufacturing processes that produce high-value engineering components. Combining these two advanced processes facilitates the fabrication of near-net shape components leading to optimized designs. This study introduces the joining of flow-formed seamless tubes of MLX®19 maraging steel using the IFW process to fabricate a near-net shape component used in landing gears and missile parts. The as-received material was initially provided ≈30% reduction in thickness from the flow forming trials and then welded at four varying weld energies while maintaining constant friction and forge pressures. The mechanical behavior of the weldments was characterized, and the optimized weld parameters were determined. The concomitant microstructural evolution of the optimized weld was also examined to comprehend the underlying deformation mechanisms. The weld strength, axial shortening, and width of dynamic recrystallization (DRX) displayed an increasing trend with an increase in the weld energy. The weld-zone (WZ) and thermomechanical affected zone (TMAZ) showed the presence of martensite, whereas in the HAZ presence of intermetallic precipitates and reverted austenite was confirmed along with tempered martensite. Based on microstructural evidence, it was concluded that the peak temperature attained in the WZ was above Ac3, whereas in the TMAZ it was in-between Ac1 and Ac3. The evolution of crystallographic texture implied that WZ was subjected to pure shear deformation during the welding whereas the TMAZ experienced a combined shear and compressive deformation.