High Taylor Factor Research Articles

How to characterise the anisotropy of laser powder bed fusion-processed parts? Towards a surrogate, non-destructive indentation-based approach

This work proposes a non-destructive indentation (NDI)-based surrogate mechanical testing framework for anisotropy and mechanical property evaluation of LPBF processed Inconel 718 superalloy. A Knoop-hardness tester was employed to develop the surrogate framework. Further post-heat treatments (PHTs) were performed at various cooling rates. The as-printed and PHT (SA, SB, SC, and SD) samples were characterized using X-ray diffraction (XRD) optical microscopy (OM), scanning electron microscopy (SEM), and electron back-scattered diffraction (EBSD) techniques. The yield locus plots show strong anisotropy for the as-printed sample. The IPF maps and pole figures for the as-printed samples showed elongated columnar grains with strong fiber texture along the (001) plane parallel to the build direction. They corroborated sufficiently with XRD, grain boundary map (GBM), and Kernel average misorientation (KAM) analysis. The yield locus shape of samples subjected to homogenization treatment becomes a nearly uniform ellipse with a reduction in the difference between σx and σy values, which can be attributed to the recrystallization of grains as observed by the transition from low-angle grain boundaries (LAGBs) to high angle grain boundaries (HAGBs). The PHT samples show a further increase in yield loci size due to the precipitation of γ’ and γ” strengthening phases due to aging treatment and corroborated with higher Taylor factor and dislocation density than the as-printed samples. The yield loci were sensitive to the PHT's cooling rates. Notably, among PHT ones, ‘SA’ samples exhibited a strong correlation (R2 ≈ 97.5 %) between the Taylor factor and yield locus. It was attributed to slower cooling rates (furnace cooled) with noticeably enhanced precipitation of strengthening phases, an increase in the volume fraction of recrystallized grains (from grain orientation spread (GOS) map), corroborating with higher dislocation density due to local strain as inferred from EBSD analysis. The proposed NDI surrogate approach was initially validated on an as-printed Inconel 718 stator blade. The yield locus showed a strong correlation between the stator blade and the as-printed sample, indicating the effectiveness of the proposed methodology.

Understanding the role of interface in deformation behavior of additively manufactured bimetallic structures of pure metals

Directed energy deposition (DED)-based additive manufacturing (AM) was employed to fabricate three distinct bimetallic compositions to understand the role interface for the deformation behavior of bimetallic structures under compressive loading. Commercially pure titanium (CP Ti) with a hexagonal closed packed (HCP) structure, nickel (Ni) with a face-centered cubic (FCC), and tantalum (Ta) with a body-centered cubic (BCC) structure were selected to understand the deformation behavior within the pure metals and damage accumulation at the bimetallic interface. By incorporating the combination of these materials, such as Ni–Ti, Ni–Ta, and Ta–Ti, we aimed to manufacture layered-base polycrystalline composite structures with FCC-HCP, FCC-BCC, and BCC-HCP crystal unit cells, respectively. In Ni–Ti and Ni–Ta bimetallic structures, it was determined that deformation is controlled by the Ni region, where the highest deflection occurs when Ni bulges out and makes lateral stress at the interface, resulting in crack initiation, propagation, and failure of the structure. Structural edges were found to experience the highest deformation, prompting grain inclination towards the <111> crystal orientation, resulting in a favorable orientation for dislocation slip and a higher Taylor factor. However, strong interfacial bonding and similar Young's modulus between Ta and Ti altered the deformation mechanisms to twinning formation in the Ti region and observed buckling of the entire structure without significant failure at the interface.

Experimental investigation of the mechanical properties and microstructures of Ti–6Al–4V solid-state diffusion bonding joint under high temperature conditions

The mechanical properties and related mechanisms of the Ti–6Al–4V alloy solid-state diffusion bonding (SSDB) joint under elevated temperature conditions have been experimentally investigated in this study. Tensile tests with temperatures (298 K–1173 K) and strain rates (0.001 s−1, 0.1 s−1) of the joint and base metal (BM) were carried out. The microstructural evolutions were characterised by optical microscope, scanning electron microscope combined with backscatter diffraction. The results show that the tensile strength and elongation of the joint are slightly lower than the BM at 298 K, which is attributed to the higher Schmid factor and unbonded areas of the joint. However, at elevated temperatures from 1023 to 1123 K, the tensile strength of the joint turns to be higher than the BM, while the elongation of the joint is much lower than the BM. Grains with relatively high Taylor factors cluster at the DB interface. The larger number fraction of high angle grain boundaries (HAGBs−88%) and a higher inclination of strain hardening at DB interface, cause a higher strength of the joint at high temperatures. No significant plasticity variation of the joint is revealed because of primitive remnant holes and new straight HAGBs at DB interface. While when the temperature further increases to 1173 K, the difference of properties between the joint and BM become negligible. Corresponding reasons are characterized as dynamic recrystallization occurs at the interface of the joint at 1173 K, which is 50 K higher than that of BM, and the interface is eliminated.

Understanding the mechanisms behind the development of cube orientation in the non-cube grains during plane strain compression of medium to high stacking-fault energy FCC metals

Medium to high stacking-fault energy FCC metals develop a pronounced cube texture during static recrystallization. Previous studies reported that the recrystallized grains can nucleate from the cube-oriented regions developed in the non-cube grains during plane strain compression. However, the mechanisms behind the development of cube orientation in the non-cube grains are still unknown. In this work, we used an elasto-viscoplastic fast Fourier transform (EVP-FFT) based crystal plasticity model to study the lattice rotation of non-cube orientations under plane strain compression. Firstly, we focus on a non-cube grain which developed the cube orientation in previous experimental work. The non-cube orientation does not rotate towards the cube orientation during single material point deformation under ideal plane strain compression. In contrast, the same non-cube orientation develops cube-oriented fragments during the polycrystalline deformation. Analysis of the micro-mechanical fields reveal that the local deviation of the RD-ND shear component leads to a remarkable change in the slip system activity which promotes the lattice rotation towards the cube orientation. Although the mechanism remains unchanged, the location and volume fraction of the cube orientation developed in the non-cube grain vary significantly in different grain neighborhoods. For the general case of a polycrystalline microstructure, deviation of the RD-ND shear component shows the highest correlation with the development of the cube orientation in the non-cube grains. The deviation is larger for the non-cube grains with higher Taylor factor. These findings have significant implications for the cube texture control during the practical rolling operation and recrystallization.

Effect of double tempering process on sulfide stress cracking susceptibility in API-5CT-C110 casing steel

The sulfide stress cracking (SSC) of the API-5CT-C110 grade casing steel in this work was evaluated by double cantilever beam (DCB) testing, two thermal treatments were used to investigate microstructures and properties. Compared to one, long-term tempering treatment, the study showed that precipitate size and dislocation density significantly decreased if two, short-term tempering treatments were used instead. DCB testing showed that SSC resistance is improved by double tempering with no degradation of strength. Specimens treated by double tempering have a lower proportion of Σ3 boundary, high-angle grain boundaries and high Taylor factor values, reduced susceptibility to crack initiation and propagation.

Enhanced strength and ductility in friction stir processed Cu–Mn alloys

In this study, the ultrafine-grained (UFG) Cu–5Mn alloys were prepared by friction stir processing (FSP) to investigate the influence of short-range ordering (SRO) on the tensile deformation behavior. Due to the dynamic recrystallization, the uniform and equiaxed UFG microstructures were obtained in FSP Cu–5Mn alloys with low density of dislocations, high fraction of high-angle grain boundaries, high Taylor factor and high degree of recrystallization. The introduction of Mn atoms into the Cu matrix cannot change the stacking fault energy apparently but increase the SRO degree. Although the dominant mechanism was still the wavy slip of dislocation, the planar slip of dislocations was motivated and many twin layers were observed in the ultrafine grains of FSP Cu–5Mn alloy. The change of SRO degree can significantly improve the dislocation storage capacity during the tensile deformation process, and promote the improvement of the strain-hardening rate, resulting in an excellent strength-ductility match in FSP UFG Cu–5Mn alloy.

Effects of microalloying with Ag, Li, and Sc on hot-deformed microstructure of Al–Mg–Si–Cu alloys

The effects of microalloying with Ag, Li, and Sc on the hot-extruded microstructures of Al–Mg–Si–Cu alloys were studied. Each microalloying element was observed to affect the hot-deformed microstructure of the alloy, with a retarding effect on its recrystallization; however, the effect of Ag-addition was relatively small. The number fraction of grains with a high Taylor factor and their kernel average misorientation significantly increased when Li and Sc were added to the Al–Mg–Si–Cu alloy, implying a strong anisotropy of slip. It was also found that Li-addition primarily weakened the C component, whereas Sc-addition significantly strengthened the rotated copper (Rt-Cu) component in the deformation texture, and strongly dissipated the recrystallization texture. Additionally, all the microalloying elements slightly increased the dislocation density and fraction of edge dislocations. Thus, a very close dislocation arrangement with a strong screening of dislocations was observed; however, this effect was relatively weak for the Sc-added alloy. The high variation in the microstructural parameters of the Sc-added alloy was understood to depend primarily on the Al3Sc dispersoid and its effect on the other precipitates. In contrast, Ag- and Li- additions did not significantly change the relatively large precipitate structure, which implies that there were changes in the nanoscale precipitates or solute clustering during the hot deformation of Ag- and Li-added alloys.

Controlling the columnar-to-equiaxed transition during Directed Energy Deposition of Inconel 625

In this work, the grain orientation and mechanical properties of Inconel 625 are tailored by varying the process parameters during directed energy deposition. Under the same deposition speed, increasing the current is effective in promoting the columnar-to-equiaxed transition due to modifications on the thermal cycle. The solidification conditions (temperature gradient and cooling rate) were characterized during the process. A comparison with an existing solidification map for Inconel 625 indicates that the temperature gradients in the melt pool of the sample fabricated with larger current decrease sufficiently to permit the nucleation and growth of equiaxed grains. Uniaxial tensile testing showed that the sample with equiaxed grain microstructure exhibits a higher yield strength (increase by 36 %) when compared to the sample with columnar grains. Contributions of various strengthening mechanisms to the yield strength are quantified in terms of grain boundary strengthening, dislocation strengthening, and solid-solution strengthening. It is found that the higher yield strength of samples that possess equiaxed grains can be attributed to the enhanced dislocation strengthening arising from the large average Taylor factor. • The temperature gradient can be tailored by adjusting the process parameters. • A transition from coarse columnar grains to fine equiaxed grains was achieved. • The sample with equiaxed grains exhibits greater yield strength. • The high Taylor factor resulted in an increase in the strength of the test sample.

Building height-related creep properties of Inconel 718 superalloy fabricated by laser powder bed fusion

The building height-dependent creep properties and microstructures of laser powder bed fusion-fabricated Inconel 718 superalloy were investigated. Creep specimens taken from the as-fabricated plate component at different building heights were tested along the building direction at 650 °C. The results show that under the same heat treatment condition, the recrystallization degree of the specimens taken from the bottom, middle and top of the Inconel 718 plate component differs widely due to the differences in the dislocation density and the texture intensity along the building direction. The bottom specimen exhibited a high recrystallization degree and thus had the longest creep life. Such excellent creep properties of the bottom specimen are mainly attributed to the lower dislocation density and the higher Taylor factor, which cause the lower creep rate, and the lower grain boundary volume fraction, thus reducing the void nucleation sites. The present findings reveal that the impact of the building height-dependent creep performance on the overall service reliability should be considered comprehensively in the subsequent geometrical design of the laser powder bed fusion-fabricated complex structural components.

On the microstructure evolution and controlling of a 2 vol% TiCp/β-Ti composite during hot deformation

In this study, microstructure and texture evolution of TiC p /β-Ti composites during hot deformation were investigated. The results indicated that high deformation temperature and low strain rate are beneficial to promote dynamic recrystallization (DRX). Besides, the DRX mechanism is dominated by continuous dynamic recrystallization and discontinuous dynamic recrystallization during hot compression. During hot compression, the 〈101〉-oriented grains will rotate to the 〈111〉 orientation with the highest Taylor factor, the <111>-oriented grains will change to the 〈001〉 orientation with the lowest Taylor factor, and the <001>-oriented grains tend to rotate to the <101> orientation with higher Taylor factor under relatively long deformation time. Moreover, the lower strain rate is conducive to the formation of θ-fiber and γ-fiber and reduces the texture strength. In addition, compared with hot compression, multi-directional forging (MDF) can significantly refine the grains without producing texture. And TiC p plays a role in particle-stimulated nucleation during hot deformation • The microstructure evolution and the dynamic recrystallization mechanism during hot compression were investigated. • The transformation of grain orientation and effect of strain rate on texture evolution during deformation were revealed. • Compared with hot compression, multi-directional forging can significantly refine the grains without producing texture. • TiC p play a role in particle-stimulated nucleation during hot deformation.

Regionalization of microstructure characteristics and mechanisms of slip transmission in oriented grains deposited by wire arc additive manufacturing

Regionalization of microstructure regulation and mechanical property adjustment during the thermal cycle of the deposition process plays a vital role in the grain morphology and orientation of aluminum alloy components manufactured using wire arc additive manufacturing (WAAM) technology. However, the microscopic mechanism of the mechanical property difference caused by uneven microstructure in different regions remains unclear for the WAAM 2319 alloy. The geometric properties of grains are described quantitatively in different regions for the WAAM 2319 alloy through EBSD data processing and analysis. The effect of grain orientation on grain boundary, including subgrain boundaries and the boundary of coincidence site lattice (CSL boundary), are explored with EBSD data. The grain boundary and dislocations are characterized by transmission electron microscopy (TEM). The distribution of geometrically necessary dislocation (GND) in the WAAM block at different regions is studied through EBSD analysis. The high Schmidt factor or Taylor factor (M) percentage was quantitatively calculated in different regions. Then the relationship between grain morphology and plastic deformation ability is established through these factors. The results indicate that the average grain size is small and located in the top and middle of the WAAM sample with a low critical Taylor factor (Mc). The Taylor factor in most grains easily exceeds Mc (Mc < M), which causes most dislocations to pass through grain boundaries quickly, and plastic deformation easily occurs in these regions. There are various CSL boundaries except Σ3 boundaries existing in the middle of the sample, which can maintain the high mobility of the grain boundaries. Therefore, more slip transmission in the middle of the WAAM sample can provide the driving force for grain boundary migration. Most grains with a high subgrain boundary density (above 2.5) and the geometrically necessary dislocation (GND) density (5 × 1014 m−2) can hinder the movement of dislocations and improve the strength of materials at the sidewall of the sample. The Schmidt factor of columnar crystals is generally low (below 0.25), and the sliding system does not start rapidly in columnar crystals, especially at the bottom of the WAAM sample.

Crystal plasticity modeling of ultrasonic softening effect considering anisotropy in the softening of slip systems

In this study, a novel approach to modeling the ultrasonic softening effect during metal plasticity is developed, where the slip systems experience differential softening depending on their orientation relative to the ultrasonic direction. The directional softening model was implemented within a Visco-Plastic Self-Consistent (VPSC) model, where the material and ultrasonic softening parameters are calibrated based on micro-tensile test data of pure copper with tension along the rolling direction of sheet. The model is then validated against the stress-strain response of the samples with tension along transverse direction. The VPSC modeling results provide new insights into ultrasonic softening, particularly that the stress reduction is not homogeneous in the whole aggregate. The degree of softening shows a strong dependence on grain orientation. A higher level of stress reduction is observed in plastically hard, high Taylor factor grains. A decrease in Taylor factor is predicted, especially in the grain subset with higher stress reduction, which agrees with experimental data. Although a traditional isotropic softening model is also capable in predicting the ultrasonically softened stress-strain response for different texture inputs, this decrease in Taylor factor cannot be captured.

Insights into the effect of different thermomechanical processing on the microstructure, phases, texture and tensile properties in Mg-0.9Al-0.6Mn-0.2Si-0.1Ca alloy

In this study, a Mg-0.9Al-0.6Mn-0.2Si-0.1Ca alloy (in as-cast form) has been subjected to homogenization treatment followed by different thermomechanical processing, namely hard plate hot forging (HPHF) and hot rolling (HR), at a fixed working temperature (723 K). The HPHF specimen has developed a bimodal grain size distribution comprising of fine recrystallized grains and coarse deformed (non-recrystallized) grains due to incomplete dynamic recrystallization. Most of these grains have basal orientations along the forging plane, leading to a strong basal fiber texture with low Schmid factor and low Taylor factor. The HR specimen, on the contrary, has developed a uniform grain size distribution consisting of mostly fine grains, with twins in some of the relatively coarser grains. Although a large number of grains in the HR specimen have basal orientations, some of the very fine newly recrystallized grains and the twinned regions attain non-basal orientations, leading to an overall weaker basal fiber texture. The Mg17Al12 phase from the as cast specimen has dissolved during both the thermomechanical treatments owing to its low melting point. Contrarily, the thermally stable Al8Mn5 precipitates are present in all the specimens. The finer grain size and higher dislocation density, along with the finer nano-sized Al8Mn5 precipitates, have resulted in greater strengthening in the HR specimen, as compared to the HPHF specimen. Furthermore, the weaker basal fiber texture, higher Schmid factor and higher Taylor factor have led to much better ductility as well as work hardening response in the HR specimen, than in the HPHF condition.

Texture Evolution by Strain-Induced Boundary Migration during Hot Deformation of Fe-3.0 wt.% Si Alloy: Experiment and Modeling

Texture and microstructure evolution during high-temperature plane-strain compression in Fe-3.0 wt.% Si alloy has been investigated by micro-texture analysis and modeling. In this study, hot deformation test is performed on the temperature range of 900 °C~1150 °C with a strain rate scope of 0.01 s−1~5 s−1, and the effect of deformation parameters is investigated by means of electron backscattered diffraction. Nucleation and growth assisted by strain-induced boundary migration result in strong {001}&lt;110&gt; and {001}&lt;210&gt; texture components with low Taylor factors, and the grain size of λ fiber increases significantly by consuming the {111}&lt;110&gt; and {111}&lt;112&gt; texture components with high Taylor factors. The critical Taylor factor above which nucleation by strain-induced boundary migration cannot occur, decreases continuously during hot deformation. With the decreasing critical Taylor factor, the increment rate of low-Taylor-factor orientation depends more sensitively on Taylor factor than the decrement rate of high-Taylor-factor orientation. The boundary separating enhanced and weakened orientations moves towards lower Taylor factor with the deformation proceeding, and medium-Taylor-factor texture components may experience a reversed change from enhancement to weakness. A quantitative model is proposed to describe texture development by incorporating the oriented nucleation probability dependent on a variable critical Taylor factor and the selective growth driven by a variable Taylor factor difference between adjacent grains. The present work can provide an efficient method for optimizing hot deformation texture by means of strain-induced boundary migration.

Effect of microstructure and texture on the mechanical properties in high strength pipeline bend

This paper focuses on the effect of microstructure and micro-texture on the mechanical properties in high strength pipeline bend. The transmission electron microscopy (TEM), and electron backscatter diffraction (EBSD) were performed on the microstructure and texture observation. Tensile tests and Charpy V-notch impact tests were used to measure the strength and impact toughness, respectively. After hot induction bending, the microstructure of both the inner arc side and the neutral axis position has some polygonal ferrite (PF) grains. High-density dislocations, M/A constituents in the bainite laths, and high frequency of high Taylor factor in the outer arc side result in the toughness lower than the other specimens. In addition, dynamic recovery and partial recrystallization occurred during hot induction bending, the recrystallized grains are small and scattered distribution in the inner arc side and the outer arc side. The results indicated that the mechanical properties of the outer arc side have anisotropy along with the longitudinal and transversal directions. Micro-texture results obtained by EBSD measurement show that the main texture components in the experimental specimens are Cube, Goss, Brass, Copper, R-cube, and {331} <1–10> possibly because of the same mother pipe. However, the Brass and {112} <110>component might be the major factor of the anisotropy for the experimental bend.

Failure analysis in API X70 pipeline steel in sour environment with an emphasis on fracture surfaces and crack propagation

The aim of this study is to investigate the fracture surfaces and crack propagation in an API X70 pipeline steel in acidic environment. To this purpose, as-received and electrochemically hydrogen-charged tensile specimens are subjected to tensile testing. Moreover, EBSD measurements were carried out on the cross section (RD-ND plane) in as-received and hydrogen-charged specimens. The results showed that hydrogen charging and strain rate of tensile testing were considered as two effective parameters in determining the type of fracture. Moreover, the fracture of the uncharged specimens was quite ductile and the strain rate had little effect on the fracture type. A direct correlation was found between type of fracture and the strain rate in hydrogen-charged specimens. With increasing strain rate, the fracture in hydrogen-charged specimens did not have enough time to initiate from inclusions and precipitates and connect to the main fracture surface. <001>∥ND oriented grains have the highest hydrogen atoms due to the largest interatomic space and the distortion energy accumulated at grain boundaries due to the lack of sufficient activated slip system. The variation of KAM distribution to higher values of hydrogen-charged specimen could be effectively associated to the formation of dislocation walls and dislocation tangles especially in the vicinity of bcc grain boundaries. The higher volume fraction of the grains with high Taylor factor data formed in the hydrogen-charged specimen were highly susceptible to plastic instability, enhancing the crack propagation.

Texture role in the mechanical property improvement contributed by grain refinement for Mg-2.6Nd-0.55Zn-0.5Zr alloy subjected to extrusion process

This work successfully fabricated the fine-grained Mg-2.6Nd-0.55Zn-0.5Zr (wt%) alloy plates with the average grain sizes of 2.39–3.49 μm via the extrusion process. The microstructure evolution during extrusion process and the associated mechanical properties were investigated. Results showed that dynamic recrystallization (DRX) significantly refined the grain size and improved the microstructure homogeneity. Extrusion fragmentation effect on the coarse Mg12Nd particles contributed to the development of fine-grained uniform microstructure, especially at the lower extrusion temperature. Additionally, extrusion process turned the fiber basal texture into the double peak basal texture owing to the sequential deformation mode activation from basal slip and tension twinning to pyramidal <c+a> slip. Subsequent continuous DRX and particle-stimulated nucleation (PSN) recrystallization played a weakening effect on the double peak basal texture. Moreover, decreasing the extrusion temperature increased the activation difficulty of pyramidal <c+a> slip and weakened the effect of PSN on texture modification, leading the basal plane distribution along the extrusion direction to be strengthened. Fine-grained strengthening significantly improved the mechanical properties, but such strengthening capability was severely dependent on the texture. During tension deformation, the weak basal texture easily activated the basal slip whereas the strong basal texture needed to activate the prismatic slip. Hall-Petch analysis indicated that the higher yield stress in the strong basal texture was ascribed to the remarkable deformation mode strengthening (activation of prismatic slip) and the geometrical strengthening (higher Taylor factor). The weak basal texture was beneficial to improve the uniform elongation owing to the higher strain hardening ability, which was more obvious when the tension twinning was activated.

Investigation of microstructure-tensile behavior relationship in Hastelloy X Ni-based superalloy processed by laser powder-bed fusion: Insights into the elevated temperature ductility loss

The microstructure-tensile response correlation in a crack-free laser powder-bed fusion (LPBF) Hastelloy X Ni-based superalloy is investigated. The LPBF process parameters in terms of volumetric energy density were optimized to obtain the maximum relative densities, as well as the lowest defect size. The microstructure and tensile behavior of samples were evaluated. Microstructural characterizations showed that the columnar grains of the austenite phase consisted of a submicron cellular microstructure with a weak texture along <100> direction. The as-built sample had an acceptable tensile behavior at the ambient temperature, as compared to the AMS 5536 N standard specification. However, at 760 °C, it was observed that the plastic deformation of the as-built sample was influenced by an intergranular brittle fracture, leading to the elevated temperature ductility loss. The results of fractography investigations, performed by means of electron backscatter diffraction analysis, indicated that grain boundaries were precipitation-free and the cracks were formed in the areas with a high Taylor factor value. The investigations also demonstrated that a high degree of grain-to-grain incompatibilities, especially in the grains having <110> parallel to the building direction orientation, resulted in the stress concentration in the grain boundaries, leading to inferior elevated temperature tensile properties.

Effects of microstructure on tensile properties of AA2050-T84 Al-Li alloy

The effect of microstructure evolution on the tensile properties of 2050 Al−Li alloy thick plate aged at 150 °C with 80 mm in thickness (t) was studied from a microstructural perspective. Scanning electron microscope, optical microscope, transmission electron microscope and X-ray diffractometer were used to explore the surface (t/6), interlayer (t/3) and center (t/2) thickness layer of this alloy. Results show that the secondary phases on grain boundaries, precipitates and textures vary depending on the thickness location. The precipitation strengthening has a stronger influence on the alloy along the rolling direction than the transverse direction from the under-aged to the peak-aging condition; however, its effect on the anisotropy is insignificant. The higher Taylor factor (M) value caused by stronger β fiber rolling textures and the intergranular phases is the main reason that leads to the highest strength at the t/2 position along the rolling direction. The M-value has a limited change at different thickness layers along the transverse direction, which causes the same tensile strength.

Continuous texture evolution during staged solid solution of Al‐Cu‐Mg and the influence on fatigue resistance

AbstractContinuous texture evolution of the Al‐Cu‐Mg alloy during the staged solid solution and corresponding influence on fatigue property has been studied by means of X‐ray diffraction, electron back scattered diffraction and scanning electron microscopy. The characteristic texture transition rate XCGB and orientation streamline approach was introduced to further investigate the behind mechanisms. The results show that the two‐step solid solution could significantly enhance the XCGB, thereby contributes to reduce the fatigue crack growth rate of Al‐Cu‐Mg T3 sheet during stage Π. The near Cube texture with high Schmid factor (SF) and low Taylor factor (TF) tends to induce significant crack deflection, crack closure and strengthened planar slip. The potential 60°&lt;1, −1, 1&gt; twin relation and mutual transformation existed between Goss and P texture would further reduce the fine random orientation grain and inter‐granular fatigue crack extension. Such above effects would be responsible for the excellent correspondence between XCGB and fatigue resistance.