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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Identification of a cast iron alloy containing nonstrategic elements

A program was performed to address the mechanical and environmental needs of Stirling engine heater head and regenerator housing components, while reducing the dependence on strategic materials. An alloy was developed which contained no strategic elemental additions per se. The base is iron with additions of manganese, molybdenum, carbon, silicon, niobium, and ferro-chromium. Such an alloy should be producible on a large scale at very low cost. The resulting alloy, designated as NASAUT 4G-Al, contained 15 Mn, 15 Cr, 2 Mo, 1.5 C, 1.0 Si, 1.0 Nb (in weight percent) with a balance of Fe. This alloy was optimized for chemistry, based upon tensile strength, creep-rupture strength, fracture behavior, and fatigue resistance up to 800 C. Alloys were also tested for environmental compatibility. The microstructure and mechanic properties (including hardness) were assessed in the as-cast condition and following several heat treatments, including one designed to simulate a required braze cycle. The alloy was fabricated and characterized in the form of both equiaxed and columnar-grained castings. The columnar grains were produced by directional solidification, and the properties were characterized in both the longitudinal and transverse orientations. The NASAUT 4G-Al alloy was found to be good in cyclic-oxidation resistance and excellent in both hydrogen and hot-corrosion resistance, especially in comparison to the baseline XF-818 alloy. The mechanical properties of yield strength, stress-rupture life, high-cycle-fatigue resistance, and low-cycle-fatigue resistance were good to excellent in comparison to the current alloy for this application, HS-31 (X-40), with precise results depending in a complex manner on grain orientation and temperature. If required, the ductility could be improved by lowering the carbon content.

Cooper, C. V.↗
DOE OSTI2018

Thermo-structural design of the European DEMO water-cooled blanket with a multiscale-multiphysics framework

The Water-Cooled Lithium-Lead (WCLL) blanket concept is one of four possible embodiments under consideration for the European Demonstration Power Plant DEMO, beyond ITER. It is based on a water-cooled first wall and blanket structure with the RAFMS (Reduced Activation Ferritic/Martensitic Steel, Eurofer 97) as structural material and PbLi as neutron multiplier and tritium breeder. We first develop a multiphysics modeling framework in order to optimize the design and achieve long blanket lifetime, maintainability, and high reliability. The approach is demonstrated by coupling Computational Fluid Dynamics (CFD), heat transfer and solid mechanics. The multiphysics framework is then utilized to provide the loading conditions for a multiscale design approach particularly focused on modeling the effects of both steady-state and operational transients on the structural integrity of the First Wall (FW). The methodology builds on the ITER Structural Design Criteria for In-Vessel Components (ISDC-IC), then extending the criteria to progressively incorporate continuum plasticity models and microstructure-based representation of deformation and fracture. We finally introduce advanced fracture mechanics concepts based on a Materials-Specific Failure Assessment Diagram (MS-FAD), in which precise calculations of the J-integral of an elasto-plastic material is required. This is especially important for the water-cooled design because of the limited fracture toughness of Eurofer 97 below 300 °C. The methodology has been applied to screen the FW/Blanket performance of a range of steady state heat flux assumed to be applied during the plasma pulse flat top, and up to 0.8 MW/m 2 . It has become clear that the radiation steady state load will be lower than the values screened here, while the local heat flux due to particle loads will lead to global higher values than the values investigated here. The methodology will be further fine-tuned to specific loading conditions in order to assess actual performance limits of the DEMO WCLL BB.

European DEMO↗
DOE OSTI2017

Design of Novel Precipitate-Strengthened Al-Co-Cr-Fe-Nb-Ni High-Entropy Superalloys

Here, a series of non-equiatomic Al-Co-Cr-Fe-Nb-Ni high-entropy alloys, with varying levels of Co, Nb and Fe, were investigated in an effort to obtain microstructures similar to conventional Ni-based superalloys. Elevated levels of Co were observed to significantly decrease the solvus temperature of the γ' precipitates. Both Nb and Co in excessive concentrations promoted the formation of Laves and NiAl phases that formed either during solidification and remained undissolved during homogenization or upon high-temperature aging. Lowering the content of Nb, Co, or Fe prevented the formation of the eutectic type Laves. In addition, lowering the Co content resulted in a higher number density and volume fraction of the γ' precipitates, while increasing the Fe content led to the destabilization of the γ' precipitates. Various aging treatments were performed which led to different size distributions of the strengthening phase. Results from the microstructural characterization and hardness property assessments of these high-entropy alloys were compared to a commercial, high-strength Ni-based superalloy RR1000. Potentially, precipitation-strengthened high-entropy alloys could find applications replacing Ni-based superalloys as structural materials in power generation applications.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Effect of processing conditions on microstructural features in Mn–Si sintered steels

Sintering of steels containing oxidation sensitive elements is possible if such elements are alloyed with others which present lower affinity for oxygen. In this work, a master alloy powder containing Fe–Mn–Si–C, specifically designed to create a liquid phase during sintering, has been used for such purpose. The effect of processing conditions such as sintering temperature and atmosphere was studied with the aim of describing the microstructural evolution as well as the morphology and distribution of oxides in the sintered material, evaluating the potential detrimental effect of such oxides on mechanical properties. Chemical analyses, metallography and fractography studies combined with X-ray photoelectron spectroscopy analyses on the fracture surfaces were used to reveal the main mechanism of fracture and their correlation with the chemical composition of the different fracture surfaces. The results indicate that the main mechanism of failure in these steels is brittle fracture in the surrounding of the original master alloy particles due to degradation of grain boundaries by the presence of oxide inclusions. Mn–Si oxide inclusions were observed on intergranular decohesive facets. The use of reducing atmospheres and high sintering temperatures reduces the amount and size of such oxide inclusions. Besides, high heating and cooling rates reduce significantly the final oxygen content in the sintered material. A model for microstructure development and oxide evolution during different stages of sintering is proposed, considering the fact that when the master alloy melts, the liquid formed can dissolve some of the oxides as well as the surface of the surrounding iron base particles. - Highlights: • Oxide distribution in steels containing oxidation-sensitive elements • Mn, Si introduced in a master alloy powder, mixed with a base iron powder • Selective oxidation of Mn and Si on iron grain boundaries • Decohesive fracture caused by degradation of grain boundaries by oxide inclusions • Reducing agents efficient at low temperatures critical for avoiding oxide inclusions.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Fine grained fully lamellar structure acquisition and microstructure characteristics of Ti-44Al-4Nb-4V-0.3Mo-Y alloy

Highlights: • Cellular structure is the component of the microstructure of hot forging in α + β two-phase-field. • Inhomogeneous lamellar structure could be eliminated by hot forging in β+γ binary phase field. • After hot forging and annealing at β+γ two-phase-region, fine grained fully-lamellar microstructure is obtained. - Abstract: In this paper, the microstructure characteristic of a β solidifying TiAl alloy Ti-44Al-4Nb-4V-0.3Mo-Y (at. %) was investigated systematically. Cylindrical blanks were isothermal forged at 1250 °C within (α + β) two-phase-field and 1200 °C within (β + γ) two-phase-field under the strain rate of 0.02 s{sup −1} and 0.03 s{sup −1}, with a total reduction of 75%. The microstructure of the alloy forged in α + β two-phase-field consists of lamellar colonies (only represents α{sub 2}/γ lamellar colonies), mixture structure of β/B2 phase and γ phase as well as β/γ lamellae resulted from cellular reaction. However, a large amount of equiaxed γ grains appear with no β/γ lamellae available under forging in β + γ two-phase-field, and the average size of γ grain is about 10 μm. By further annealed at 900 °C for about 0.5 h, the structure of hot forging at 1250 °C is composed of β/B2 phase and equiaxed γ grains with the mean size about 5 μm. After heat treated at 1200 °C for 2 h, the microstructure of this annealed samples is characterized by fine grained fully lamellar (FFL) structure with size of 20 μm. A specially designed hot forging process is proposed, which prevents the existence of inhomogeneous lamellar structure.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Rapid Design and Manufacturing of High-Performance Materials for Turbine Blades

This research demonstrated the concept of carbide precipitation-strengthened refractory high entropy alloys (RHEA). The advantage of a precipitation strengthened alloy is all phases are in thermodynamic equilibrium promoting microstructural stability, and consequently retention of properties at elevated temperatures. Additionally, as with any precipitation strengthened – or age hardened - alloy, components can be heat-treated after manufacturing to manipulate the microstructure and optimize properties for performance. This is an advantage of the precipitation strengthened alloys over composites and ceramics materials, where the microstructure and properties are essentially fixed upon the initial materials manufacturing stage. High throughput (HT), multi-scale computer modeling was used to identifying novel RHEA compositions with desired characteristics needed for precipitation strengthening. Designs were validated by producing small ingots via are melting. The results showed that carbides precipitated and consequently, the strength of the alloys (measured in compression) increased after heat-treatment, which is the desired effect. The project also demonstrated the feasibility of producing articles from RHEA by additive manufacturing (AM). Electron beam melting (EBM) and laser direct energy deposition (L-DED) additive manufacturing methods, were explored with various processing parameters were interrogated for both methods. Sound (crack-free and dense) precipitation strengthened RHEA samples were produced via EDM AM, demonstrating the feasibility of the concept.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Effects of Constituent Properties on Performance Improvement of a Quenching and Partitioning Steel

In this paper, a two-dimensional microstructure-based finite element modeling method is adopted to investigate the effects of material parameters of the constituent phases on the macroscopic tensile behavior of Q&P steel and then to do a computational materials design approach for its performance improvement. For this purpose, a model Q&P steel is first produced and various experiments are then performed to characterize the steel. Actual microstructure-based model is generated based on the information from EBSD, SEM and nano-indentation test, and the material properties for the constituent phases are determined based on the initial constituents’ properties from HEXRD test and the subsequent calibration of model prediction to tensile test results. Influence of various material parameters of the constituents on the macroscopic behaviors is then investigated by separately adjusting them by small amount. Based on the observation on the respective influence of constituents’ material parameters, a new set of material parameters are devised, which results in better performance in ductility. The results indicate that various material parameters may need to be concurrently adjusted in a cohesive way in order to improve the performance of Q&P steel. In summary, higher austenite stability, less strength difference between the phases, higher hardening exponents of the phases are generally beneficial for the performance improvement. The information from this study can be used to devise new Q&P heat-treating parameters to produce the Q&P steels with better performance.

Advanced high strength steel↗
DOE OSTI2014

Hydrogen Embrittlement of Structural Steels

Carbon-manganese steels are candidates for the structural materials in hydrogen gas pipelines; however, it is well known that these steels are susceptible to hydrogen embrittlement. Decades of research and industrial experience have established that hydrogen embrittlement compromises the structural integrity of steel components. This experience has also helped identify the failure modes that can operate in hydrogen containment structures. As a result, there are tangible ideas for managing hydrogen embrittlement in steels and quantifying safety margins for steel hydrogen containment structures. For example, fatigue crack growth aided by hydrogen embrittlement is a well-established failure mode for steel hydrogen containment structures subjected to pressure cycling. This pressure cycling represents one of the key differences in operating conditions between current hydrogen pipelines and those anticipated in a hydrogen delivery infrastructure. Applying structural integrity models in design codes coupled with measurement of relevant material properties allows quantification of the reliability/integrity of steel hydrogen pipelines subjected to pressure cycling. Furthermore, application of these structural integrity models is aided by the development of physics-based predictive models, which provide important insights such as the effects of microstructure on hydrogen-assisted fatigue crack growth. Successful implementation of these structural integrity and physics-based models enhances confidence in the design codes and enables decisions about materials selection and operating conditions for reliable and efficient steel hydrogen pipelines.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Bulk nanocrystalline Al alloys with hierarchical reinforcement structures via grain boundary segregation and complexion formation

Grain size engineering, particularly reducing grain size into the nanocrystalline regime, offers a promising pathway to further improve the strength-to-weight ratio of Al alloys. Unfortunately, the fabrication of nanocrystalline metals often requires non-equilibrium processing routes, which typically limit the specimen size and require large energy budgets. In this study, multiple dopant elements in ternary Al alloys are deliberately selected to enable segregation to the grain boundary region and promote the formation of amorphous complexions. Three different fully dense bulk nanocrystalline Al alloys (Al-Mg-Y, Al-Fe-Y, and Al-Ni-Y) with small grain sizes were successfully fabricated using a simple powder metallurgy approach, with full densification connected directly to the onset of amorphous complexion formation. All the compositions demonstrate densities above 99% with grain sizes <60 nm following consolidation via hot pressing at 585 °C. The very fine grain structure results in excellent mechanical properties, as evidenced by nanoindentation hardness values in the range of 2.2-2.8 GPa. Detailed microstructural characterization verifies the segregation of all dopant species to grain boundaries as well as the formation of amorphous complexions, which suggests their influential role in aiding effective consolidation and endowing thermal stability in the alloys. Moreover, nanorods with a core-shell structure are also observed at the grain boundaries, which likely contribute to the stabilization of the grain structure while also strengthening the materials. Lastly, intermetallic particles with sizes of hundreds of nanometers form in all systems. As a whole, the results presented here demonstrate a general alloy design strategy of segregation and boundary evolution pathway that enables the fabrication of multiple nanocrystalline Al alloys with hierarchical microstructures and improved performance.

36 MATERIALS SCIENCE↗
DOE OSTI2019

T cell activation and immune synapse organization respond to the microscale mechanics of structured surfaces

Cells have the remarkable ability to sense the mechanical stiffness of their surroundings. This has been studied extensively in the context of cells interacting with planar surfaces, a conceptually elegant model that also has application in biomaterial design. However, physiological interfaces are spatially complex, exhibiting topographical features that are described over multiple scales. This report explores mechanosensing of microstructured elastomer surfaces by CD4 + T cells, key mediators of the adaptive immune response. We show that T cells form complex interactions with elastomer micropillar arrays, extending processes into spaces between structures and forming local areas of contraction and expansion dictated by the layout of microtubules within this interface. Conversely, cytoskeletal reorganization and intracellular signaling are sensitive to the pillar dimensions and flexibility. Unexpectedly, these measures show different responses to substrate rigidity, suggesting competing processes in overall T cell mechanosensing. The results of this study demonstrate that T cells sense the local rigidity of their environment, leading to strategies for biomaterial design.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2015

Uncertainty Quantification and Management for Multi-scale Nuclear Materials Modeling

Understanding and improving microstructural mechanical stability in metals and alloys is central to the development of high strength and high ductility materials for cladding and cores structures in advanced fast reactors. Design and enhancement of radiation-induced damage tolerant alloys are facilitated by better understanding the connection of various unit processes to collective responses in a multiscale model chain, including: dislocation nucleation, absorption and desorption at interfaces; vacancy production, radiation-induced segregation of Cr and Ni at defect clusters (point defect sinks) in BCC Fe-Cr ferritic/martensitic steels; investigation of interaction of interstitials and vacancies with impurities (V, Nb, Ta, Mo, W, Al, Si, P, S); time evolution of swelling (cluster growth) phenomena of irradiated materials; and energetics and kinetics of dislocation bypass of defects formed by interstitial clustering and formation of prismatic loops, informing statistical models of continuum character with regard to processes of dislocation glide, vacancy agglomeration and swelling, climb and cross slip.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2023

Elucidating Design Rules toward Enhanced Solid-State Charge Transport in Oligoether-Functionalized Dioxythiophene-Based Alternating Copolymers

This study investigates the solid-state charge transport properties of the oxidized forms of dioxythiophene-based alternating copolymers consisting of an oligoether-functionalized 3,4-propylenedioxythiophene (ProDOT) copolymerized with different aryl groups, dimethyl ProDOT (DMP), 3,4-ethylenedioxythiophene (EDOT), and 3,4-phenylenedioxythiophene (PheDOT), respectively, to yield copolymers P(OE3)-D, P(OE3)-E, and P(OE3)-Ph. At a dopant concentration of 5 mM FeTos 3 , the electrical conductivities of these copolymers vary significantly (ranging between 9 and 195 S cm –1 ) with the EDOT copolymer, P(OE3)-E, achieving the highest electrical conductivity. UV–vis–NIR and X-ray spectroscopies show differences in both susceptibility to oxidative doping and extent of oxidation for the P(OE3) series, with P(OE3)-E being the most doped. Wide-angle X-ray scattering measurements indicate that P(OE3)-E generally demonstrates the lowest paracrystallinity values in the series, as well as relatively small π–π stacking distances. The significant (i.e., order of magnitude) increase in electrical conductivity of doped P(OE3)-E films versus doped P(OE3)-D or P(OE3)-Ph films can therefore be attributed to P(OE3)-E exhibiting both the highest carrier ratios in the P(OE3) series, along with good π–π overlap and local ordering (low paracrystallinity values). Furthermore, these trends in the extent of doping and paracrystallinity are consistent with the reduced Fermi energy level and transport function prefactor parameters calculated using the semilocalized transport (SLoT) model. Observed differences in carrier ratios at the transport edge (c t ) and reduced Fermi energies [η(c)] suggest a broader electronic band (better overlap and more delocalization) for the EDOT-incorporating P(OE3)-E polymer relative to P(OE3)-D and P(OE3)-Ph. Ultimately, we rationalize improvements in electrical conductivity due to microstructural and doping enhancements caused by EDOT incorporation, a structure–property relationship worth considering in the future design of highly electrically conductive systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Near-Net-Shape Hot Isostatic Press Manufacturing Modality for sCO2 CSP Capital Cost Reduction

Through this DOE funded 3.5-year research project, feasibility of fabricating supercritical carbon dioxide (sCO2) turbine components by powder metallurgy (PM) based near-net-shape (NNS) hot isostatic pressing (HIP) was demonstrated in a turbine nozzle ring, a turbine casing with Haynes 282 powder, and a bimetallic pipe with Haynes 282 and SS415 powder. As-HIP microstructure of various powders and HIP processing conditions was studied to downselect a condition for the prototype components. Tensile strength and low cycle fatigue (LCF) capability of PM HIP 282 was found to be superior to cast 282, despite a debit in creep stress capability that could be mitigated by component design modification. Near-Net-shape with minimal post machining was achieved by modeling the non-uniform shrinkage during HIP cycle and designing the HIP tooling to meet dimensional targets. The prototypes of turbine nozzle ring and bimetallic pipe were successful in achieving overall dimension, microstructure, and properties, despite dimensional tolerance affected by chemical milling rate. The prototype of a 1700lbs turbine casing was partially successful in achieving dimension, microstructure in as-HIP state, and providing consistent mechanical properties, however, cracking issue during post heat treatment required further investigation. The estimated manufacturing cost using NNS HIP was a ~50% reduction compared to forging with extensive machining, which translated into ~$100/kWe CAPEX cost reduction for concentrated solar power (CSP) power block.

14 SOLAR ENERGY↗
DOE OSTI2024

Design of a first-of-A-kind instrumented advanced test reactor irradiation Capsule experiment for In situ thermal conductivity measurements of metallic fuel

Metallic fuel undergoes dramatic microstructural changes early in life due to fission gas swelling until ~2–3 at% burnup which affects the conductivity of the material, however the evolution of metallic fuel thermal conductivity during this early phase burnup has never been successfully measured in situ. The Irradiated Material Properties Accelerated Characterization Test (IMPACT) experiment will be the first in a series of experiments to irradiate advanced nuclear metallic fuel specimens with novel embedded thermal conductivity probes in ATR. In the current work the IMPACT experiment final design and supporting analysis is reported in detail. Results are evaluated for various reactor operational conditions to meet the functional requirements of the experiment. Finally, the first iteration of this IMPACT experiment will provide data regarding thermal properties evolution in uranium-zirconium (U10Zr) fuel, but this experiment vehicle is envisioned for future advanced fuels and structural materials irradiations in ATR.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2022

Mechanical response and microstructure evolution from multiaxial stress relaxation in textured zircaloy nuclear cladding

Modern energy markets provide motivation for nuclear reactors to increase operational flexibility and load following capacity of existing reactor designs. The operational power changes result in fuel pellet expansion and contraction resulting in pellet-cladding mechanical interaction (PCMI) and high cladding stresses that are strongly related to stressed corrosion cracking (SCC) which can lead to fuel rod failure. This work aims to quantify the stress fields in cladding with a focus on multiaxial stress relaxation response from an imposed strain and the resulting microstructure changes in textured zircaloy claddings. Stress relaxation tests resulting in multiaxial stress fields are performed to measure the material response of Zircaloy-4 nuclear cladding. Multiple experiments using samples from the same piece of cladding are performed so samples with the same processing history may be removed at strategic points throughout mechanical testing for microstructure characterization. The microstructure evolution is analyzed with mechanical response to evaluate the static recovery impact on crystallographic texture and grain morphology. Experiments are performed at Idaho National Laboratory using an experimental device capable of applying internal pressure and independent axial load to commercial nuclear cladding at elevated temperatures with stress- or strain-controlled experimental capability. X-ray diffraction and electron backscatter diffraction are used for microstructure analysis. Rheological models are used to visualize the multiaxial stress-strain relationships and isolate elastic, plastic, and viscoplastic material properties for analysis.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2019

Concentration dependence of hydrogen diffusion in α-iron from atomistic perspectives

Evaluation of hydrogen diffusion in structural materials is essential to predict the leakage and embrittlement of hydrogen storage applications. Here, we investigate the atomic-scale diffusion of interstitial hydrogen (H) in α-iron (Fe) over a temperature range from 350 to 900 K with different H concentrations (0.01–5%), employing classical molecular dynamics (MD) simulations. The self-diffusivity of H atoms increases with increasing temperature and decreasing concentration. With low concentrations, the calculated diffusion properties agree well with prior experiments. However, with a higher concentration (≥1%), the H diffusivity at low temperatures deviates from a high-temperature Arrhenius behavior. Through the energetic and structural analysis, we suggest that this deviation is attributed to a reduced mobility due to increased energy barrier by other H interstitials. This work contributes to the effective design of H storage applications by identifying temperature and concentration effects on permeability and addressing possible microstructural transformation.

08 HYDROGEN↗
DOE OSTI2021

Constructing high-performance radiation-resistant ternary YSZ-MgO-CNT nanocomposites via tailored nanostructures

Developing long-lifetime bulk-form ceramic-based materials with high irradiation resistance is crucial for advanced nuclear systems. Here, we incorporated carbon nanotubes (CNTs) into yttria-stabilized zirconia (YSZ) and magnesia (MgO) nanocrystals to fabricate bulk YSZ-MgO-CNT nanocomposites with abundant ternary nanostructures by spark plasma sintering. To understand the role of tailored ternary nanostructure on irradiation, we investigated the microstructure and mechanical properties evolutions of the YSZ-MgO-CNT nanocomposites irradiated by multi-energy He + ions at high temperature to different fluences. Compared with the single-phase YSZ and ultrafine-grained YSZ-MgO composites, the YSZ-MgO-CNT nanocomposites possessed higher ability to manage irradiation-induced He bubbles/defects via the defect-interface interactions of proposed “loading-unloading” and “loading-transporting-unloading” mechanisms for controlling the dynamical behaviors of He atoms/defects in the CNT-doped ternary nanostructures, thereby presenting more stable microstructure and better performance in resisting irradiation hardening. In conclusion, this work provides insight into the design of advanced inert matrix nuclear fuel and new nuclear waste management materials.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Microstructure evolution of 7050 Al alloy during age-forming

The microstructure evolution of the 7050 Al alloy treated by age-forming was studied using a designed device which can simulate the age-forming process. The grain shape, grain boundary misorientation and grain orientation evolution of 7050 Al alloy during age-forming have been quantitatively characterized by electron backscattering diffraction technique. The results show that age-forming produced abundant low-angle boundaries and elongated grains, which attributed to stress induced dislocation movement and grain boundary migration during the age-forming process. On the other side, the stress along rolling direction caused some unstable orientation grains to rotate towards the Brass and S orientations during the age-forming process. Hence, the intensity of the rolling texture orientation in age-formed samples is enhanced. But this effect decays gradually with increasing aging time, since stress decreases and precipitation hardening occurs during the age-forming process. - Highlights: • Quantitative analysis of grain evolution of 7050 Al alloys during age-forming • Stress induces some grain rotation of 7050 Al alloys during age-forming. • Creep leads to elongate grain of 7050 Al alloys during age-forming. • Obtains a trend on texture evolution during age-forming applied stress.

36 MATERIALS SCIENCE↗