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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 1,567 records · Page 87
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Effect of cold deformation on the recrystallization behavior of FePd alloy at the ordering temperature using electron backscatter diffraction

In this study, the evolution of the recrystallization texture and microstructure was investigated after annealing of 50% and 90% cold-rolled FePd alloy at 530 °C. The FePd alloy was produced by vacuum arc melting in an atmosphere of 97% Ar and 3% H{sub 2}. The specimens were cold rolled to achieve 50% and 90% reduction in thickness. Electron backscatter diffraction measurements were performed on the rolling direction–normal direction section. With increased deformation from 50% to 90%, recrystallized texture transition occurs. For the 50% cold-rolled alloy, the preferred orientation is (0 1 0) [11 0 1], which is close to the cubic orientation after 400 h of annealing. For the 90% cold-rolled alloy, the orientation changes to (0 5 4) [22–4 5] after 16 h of annealing. - Highlights: • Texture and microstructure in cold-rolled FePd alloy was investigated during annealing using EBSD. • The recrystallized texture of 50% cold-rolled FePd is (0 1 0) [11 0 1] at 530 °C for 400 hours. • The recrystallized texture of 90% cold-rolled FePd is changed to (0 5 4) [22–4 5] at 530 °C after 16 hours.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Effect of pre-annealing deformation on the recrystallized texture and grain boundary misorientation in commercial pure titanium

Highlights: • Tailoring the misorientation angle distribution by pre-annealing rolling in CP-Titanium. • Enhancing the inheritance of basal scatter texture by medium pre-annealing rolling. • Moderate pre-annealing rolling produces refined recrystallized grains. - Abstract: The effects of rolling reduction followed by annealing (at 650 °C) on commercial pure titanium sheet are investigated. The microstructure, texture and misorientation angle distributions after rolling and annealing are observed by electron back scatter diffraction (EBSD). It is found that, when the rolling deformation was low (20%) or medium (40%), a fraction of non-TD-split basal texture is inherited from the deformed state and remains even after long time (60 min) annealing. However, heavy rolling deformation (85%) causes a strong and typical TD-split basal texture in the deformed and annealed states. In addition, the misorentation angle distributions are relatively homogeneous for the recrystallized samples with a low or medium pre-annealing deformation. But with heavy pre-annealing deformation, the misorientation angle distributions exhibits two peaks, around 15–30° and 70–80°. The texture and misorientation angle evolution mechanisms are discussed in this work. The study shows the possibility to tailor the texture and the misorientation angle distribution of commercial pure titanium sheet by ordinary rolling process.

36 MATERIALS SCIENCE↗
DOE OSTI2018

A high-performance β-solidifying TiAl alloy sheet: Multi-type lamellar microstructure and phase transformation

Highlights: • A high-performance β-solidifying TiAl alloy sheet is fabricated via hot rolling. • Fine multi-type β/γ and α{sub 2}/γ lamellar structures are formed during hot-rolling. • These lamellar structures are induced by the β → γ and α + γ → α{sub 2} + γ/γ{sub T} transformations. • The nano-scaled antiphase domain is induced by α → α{sub 2} disorder-order transformation. • The fine multi-type lamellar structures contribute to the strength enhancement. - Abstract: TiAl alloys are widely used in the aerospace industry and, hence, a thorough understanding of the corresponding microstructural evolution is crucial for providing insight into the fabrication of high-performance TiAl alloy sheets. In this study, a high-performance β-solidifying Ti-43Al-9V-0.2Y alloy sheet with multi-type lamellar structures was obtained via hot-rolling at an initial rolling temperature of 1260 °C. Owing to the temperature drop and reheat associated with multi-pass rolling, relatively fine irregular β/γ and regular α{sub 2}/γ lamellar microstructures (average size: ~25 μm) with nano-scaled antiphase domains (APDs) were generated by the β → γ and α + γ → α{sub 2} + γ/γ{sub T} phase transformations. These two lamellar structures have different formation mechanisms. The results of electron backscatter diffraction and transmission electron microscopy revealed that the nucleation and growth of (i) β/γ and (ii) α{sub 2}/γ lamellar structures are induced mainly by (i) stress and (ii) a combination of the stress and temperature drop during hot-rolling, respectively. Thin γ{sub T} precipitates from the α/α{sub 2} or γ phases. This precipitation is induced by the higher stress and lower temperature associated with the later stage (compared with those occurring in the initial stages) of hot-rolling. Moreover, compared with the corresponding as-forged alloy, the as-rolled TiAl alloy sheet exhibits better performance at both room and elevated temperatures. The improvement in the tensile properties is attributed to the duplex microstructure consisting of fine multi-type lamellar structures with nano-scaled APDs. The interface boundaries of β/γ, α{sub 2}/γ and APDs, which are effective in retarding dislocation motion, contribute mainly to strengthening of the alloy sheet.

36 MATERIALS SCIENCE↗
DOE OSTI2018

The significant impact of cold deformation on structure-property relationship in phase reversion-induced stainless steels

Highlights: • Parts of metastable austenite transformed into strain-induced martensite in 18Cr-8Ni stainless steel during cold-rolled process. • The kinetics of reversion transformation from martensite to austenite was fastest in 90% cold-rolled sample during annealing treatment. • The austenite grain size for the 90% cold-rolled sample after annealing was smallest and most uniform, which induced highest yield strength and elongation combination. - Abstract: The present study aims to investigate the impact of cold deformation on structure-property relationship in phase reversion-induced stainless steels. The commercial 18Cr-8Ni stainless steel was cold rolled at room temperature to 30%, 60% and 90% thickness reduction, respectively and subsequently annealed at 900 °C for 1–100 min. Evolution of phases in selected samples was identified and quantified by X-ray diffraction together with the corresponding microstructural characterization through optical, scanning and transmission electron microscopy, and electron backscatter diffraction. Mechanical properties of selected samples were determined by the tensile test. The results indicated that parts of metastable austenite transformed into strain-induced martensite during cold rolling process, and the volume fraction of martensite increased with increase in cold rolling reduction. The kinetics of reversion transformation from martensite to austenite was fastest in 90% cold-rolled sample during annealing treatment. The austenite grain size for the 90% cold-rolled sample after annealing was smallest and most uniform, which induced highest yield strength and elongation combination.

36 MATERIALS SCIENCE↗
DOE OSTI2023

The influence of thermomechanical treatment pathways on texture and mechanical properties in ARB Cu/Nb nanolaminates

Accumulative roll-bonded Cu/Nb nanolaminates (ARB Cu/Nb) possess high strength, thermal stability, and radiation tolerance arising from a high content of heterophase interfaces at fine layer thicknesses. These properties can be tailored by processing parameters used in the ARB Cu/Nb fabrication process, in which layer thickness, thermal history, and strain pathway determine the interface types and resultant properties found in the material. In this work, we subject ARB Cu/Nb to annealing, and then two different rolling pathways – one where rolling direction is held constant (longitudinal rolling, or LR), and one where rolling direction is rotated by 90º and held constant thereafter (cross rolling, or CR). Rolling is performed on ARB Cu/Nb over a targeted range of layer thicknesses from 193 to 25 nm and resultant bulk textures measured by neutron diffraction are correlated with mechanical properties measured by miniaturized tensile tests. The annealing procedure sharpens texture in both phases. We find that Cu mostly develops the same texture in LR and CR. In contrast, Nb develops a distinct texture along the CR pathway that is distinct from the LR texture. The composite texture of Cu/Nb is thus distinct between LR and CR pathways. This difference in texture development between Cu and Nb as a function of strain after change in rolling direction demonstrates the viability for deliberate pairing of Cu LR and Nb CR textures at a desired layer thickness. For mechanical properties, we find that differences in texture do not result in yield or flow stress differences above a layer thickness of 25 nm. Below a layer thickness of 25 nm, despite similar Taylor factors, yield and flow stress and are significantly different. In conclusion, this indicates texture only influences mechanical behavior at low layer thickness, where interface structure dominates mechanical properties.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Imaging Complex Subsurface Structures for Geothermal Exploration at Pirouette Mountain and Eleven-Mile Canyon in Nevada

Accurate imaging of subsurface complex structures with faults is crucial for geothermal exploration because faults are generally the primary conduit of hydrothermal flow. It is very challenging to image geothermal exploration areas because of complex geologic structures with various faults and noisy surface seismic data with strong and coherent ground-roll noise. In addition, fracture zones and most geologic formations behave as anisotropic media for seismic-wave propagation. Properly suppressing ground-roll noise and accounting for subsurface anisotropic properties are essential for high-resolution imaging of subsurface structures and faults for geothermal exploration. We develop a novel wavenumber-adaptive bandpass filter to suppress the ground-roll noise without affecting useful seismic signals. This filter adaptively exploits both characteristics of the lower frequency and the smaller velocity of the ground-roll noise than those of the signals. Consequently, this filter can effectively differentiate the ground-roll noise from the signal. We use our novel filter to attenuate the ground-roll noise in seismic data along five survey lines acquired by the U.S. Navy Geothermal Program Office at Pirouette Mountain and Eleven-Mile Canyon in Nevada, United States. We then apply our novel anisotropic least-squares reverse-time migration algorithm to the resulting data for imaging subsurface structures at the Pirouette Mountain and Eleven-Mile Canyon geothermal exploration areas. The migration method employs an efficient implicit wavefield-separation scheme to reduce image artifacts and improve the image quality. Our results demonstrate that our wavenumber-adaptive bandpass filtering method successfully suppresses the strong and coherent ground-roll noise in the land seismic data, and our anisotropic least-squares reverse-time migration produces high-resolution subsurface images of Pirouette Mountain and Eleven-Mile Canyon, facilitating accurate fault interpretation for geothermal exploration.

15 GEOTHERMAL ENERGY↗
DOE OSTI2015

Radioguided localisation of impalpable breast lesions using 99m-Technetium macroaggregated albumin: Lessons learnt during introduction of a new technique to guide preoperative localisation

Preoperative wire-guided localisation (WGL) of impalpable breast lesions is widely used but can be technically difficult. Risks include wire migration, inaccurate placement, and inadequate surgical margins. Research shows that radioguided occult lesion localisation (ROLL) is quicker, easier, and can improve surgical and cosmetic outcomes. An audited introduction of ROLL was conducted to validate the technique as a feasible alternative to WGL. Fifty patients with single impalpable lesions and biopsy proven malignancy or indeterminate histology underwent WGL followed by intralesional radiopharmaceutical injection of 99m-Technetium macroaggregated albumin. Postprocedural mammography was performed to demonstrate wire position, and scintigraphy to evaluate radiopharmaceutical migration. Lymphoscintigraphy and intraoperative sentinel node biopsy were performed if indicated, followed by lesion localisation and excision using a gamma probe. Specimen imaging was performed, with immediate reexcision for visibly inadequate margins. Accurate localisation was achieved in 86% of patients with ROLL compared to 72% with WGL. All lesions were successfully removed, with clear margins in 71.8% of malignant lesions. Reexcision and intraoperative sentinel node localisation rates were equivalent to preaudit figures for WGL. ROLL was easy to perform and problems were infrequent. Inaccurate radiopharmaceutical placement necessitating WGL occurred in four patients. Minor radiopharmaceutical migration was common, but precluded using ROLL in only two cases. ROLL is effective, simple, inexpensive, and easily learnt; however, preoperative confirmation of correct radiopharmaceutical placement using mammography and the gamma probe is important to help ensure successful lesion removal. Insertion of a backup hookwire is recommended during the initial introduction of ROLL.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Complete Status Report Documenting the Development of Friction Stir Welding for Producing a Butt Joint in Thin Wall Tubing of ODS Alloys

A challenging attempt using friction stir welding to produce a butt joint between two 1.0 mm thick plates of 14YWT was nearly successful. The modified tool pin mostly penetrated the thickness of the adjoined thin plate samples resulting in a small blunt notch on the bottom surface of the butt joint. A bend occurred in the thin plate sample due to formation of stresses from clamping the thin plate sample during FSW. The peak displacement of the bend occurred along the center line of the butt joint. The weld zone showed good microstructure mixing with some flashing mostly on the retreating side that suggested excess heat input by friction between the traveling and spinning tool pin and thin plates of 14YWT. Neutron diffraction experiments were performed on the bent sample of 14YWT to measure the residual stresses in the butt joint on the HB-2B beam line at the Neutron Residual Stress Facility at HFIR. However, the neutron scattering to background noise ratio was very low during data acquisition. Measurements of lattice strains were obtained in the rolling (RD) and normal (ND) directions but not in the extrusion direction (ED) of the thin plate sample. Unfortunately, the quality of the data was not sufficient for determining the residual stresses in the butt joint. From the previous neutron scattering experiments conducted on four hot rolled plates (R1, R2, R3 and R4) of 14YWT, the residual stresses were calculated from lattice strain data and plotted in 2-D color contour maps for ED, RD and ND. The results showed variations in the magnitude and spatial position of residual stresses in the microstructure of the four plates. The magnitude in residual stresses in ED and RD increased gradually with increasing rolling deformation for R1 (50%) to R2 (76%), followed by larger increases in R3 (89%) and R4 (95%). The maximum peaks in residual stresses for R4 was ~710-730 MPa in ED and RD. The residual stresses in ND were below ~300 MPa for each of the 4 rolled plates, with a maximum residual stress in R4 (95%) of ~400 MPa. These results indicated that significant residual stresses representing ~57% of the yield stress of 14YWT (SM13) had accumulated in the 14YWT plate after hot rolling to the 1 mm thickness, which was used in the FSW experiments. The microstructure analysis of the 1.0 mm thick plate of 14YWT containing the butt joint produced by FSW revealed significant changes in the grain structure and texture between the unaffected zone (UZ) of the rolled plate and the butt joint weld. In the UZ, the grains were severely elongated after 95% deformation and mainly possessed the {101} texture component in the ED. Two predominant grain misorientation angles were observed: one consisting of small misorientations of <5º between highly elongated grains and the other consisting of large misorientations of >15º in pockets of small grains that might have formed by dynamic recrystallization processes during rolling of the plate at 1000ºC. The morphology and texture of grains in the heat affected zone (HAZ) were similar to those in UZ, except the grains had coarsened due to excess heat input during FSZ. A population of pores formed and the grains both coarsened and changed to isotropic morphology in the microstructure of the butt joint on both the advancing and retreating sides. The texture of grains in both regions were randomly orientated between the 3 poles {001}, {101} and {111}. The main difference in texture of grains between the advancing side and retreating side was with the misorientation angles of neighboring grains. Most of the grains in the advancing side had misorientation angles of >5º indicating that these grains experienced recrystallization. On the retreating side, areas containing larger grains showed high misorientation angles of >15º compared to areas appearing as bands of grains with misorientation angles of <5º and between 5º-15º. Numerous small pockets of grains with low misorientation angles of <5º were distributed in the microstructure among the grains showing high misorientation angles of >15º. It was determined that the grains associated with low misorientation angles contained sub-grain structures, which was consistent with both recrystallization and recovery mechanisms for grains located on the retreating side of the butt joint. These results demonstrate the complex microstructure that evolves in the microstructure of 14YWT resulting from the input of high temperatures and severe deformations during FSW.

36 MATERIALS SCIENCE↗
NASA NTRS1984

A preliminary look at the effects of coupled lateral modes on aircraft handling qualities

Analytic and six-degree-of-freedom motion base simulator studies have been conducted to better understand how the coupled roll-spiral and coupled roll-aileron actuator modes affect aircraft handling qualities. The results reported herein are preliminary and are subject to change until other aircraft and several more data points can be examined. The results obtained thus far indicate that when the roll-spiral coupled mode is brought about by unusual values of an aircraft's stability and control derivatives, the lateral-directional handling qualities will invariably be degraded. However, when the roll spiral coupling is brought about by a roll-rate command/roll-attitude hold stability and control augmentation system (SCAS), the requirements for satisfactory handling qualities can be correlated to the natural frequency and the damping of the coupled mode. Satisfactory handling qualities were also achieved when the lateral SCAS brought about a coupling of the roll mode with the aileron actuator mode. In this case, the pilot ratings indicate that the handling qualities may be correlated to the natural frequency of the coupled roll-aileron mode.

Ruflin, S. J.↗
NASA NTRS1991

Unsteady surface pressure measurements on a slender delta wing undergoing limit cycle wing rock

An experimental investigation of slender wing limit cycle motion known as wing rock was investigated using two unique experimental systems. Dynamic roll moment measurements and visualization data on the leading edge vortices were obtained using a free to roll apparatus that incorporates an airbearing spindle. In addition, both static and unsteady surface pressure data was measured on the top and bottom surfaces of the model. To obtain the unsteady surface pressure data a new computer controller drive system was developed to accurately reproduce the free to roll time history motions. The data from these experiments include, roll angle time histories, vortex trajectory data on the position of the vortices relative to the model's surface, and surface pressure measurements as a function of roll angle when the model is stationary or undergoing a wing rock motion. The roll time history data was numerically differentiated to determine the dynamic roll moment coefficient. An analysis of these data revealed that the primary mechanism for the limit cycle behavior was a time lag in the position of the vortices normal to the wing surface.

Arena, Andrew S., Jr.↗
NASA NTRS1993

Aerodynamic control of NASP-type vehicles through vortex manipulation. Volume 3: Wing rock experiments

Free-to-roll tests were conducted in water and wind tunnels in an effort to investigate the mechanisms of wing rock on a NASP-type vehicle. The configuration tested consisted of a highly-slender forebody and a 78 deg swept delta wing. In the water tunnel test, extensive flow visualization was performed and roll angle histories were obtained. In the wind tunnel test, the roll angle, forces and moments, and limited forebody and wing surface pressures were measured during the wing rock motion. A limit cycle oscillation was observed for angles of attack between 22 deg and 30 deg. In general, the experiments confirmed that the main flow phenomena responsible for the wing-body-tail wing rock are the interactions between the forebody and the wing vortices. The variation of roll acceleration (determined from the second derivative of the roll angle time history) with roll angle clearly slowed the energy balance necessary to sustain the limit cycle oscillation. Different means of suppressing wing rock by controlling the forebody vortices using small blowing jets were also explored. Steady blowing was found to be capable of suppressing wing rock, but significant vortex asymmetrices are created, causing the model to stop at a non-zero roll angle. On the other hand, alternating pulsed blowing on the left and right sides of the fore body was demonstrated to be a potentially effective means of suppressing wing rock and eliminating large asymmetric moments at high angles of attack.

Suarez, Carlos J.↗
NASA NTRS1960

Supersonic Aerodynamic Characteristics of a Low-Drag Aircraft Configuration having an Arrow Wing of Aspect Ratio 1.86 and a Body of Fineness Ratio 20

A free-flight rocket-propelled-model investigation was conducted at Mach numbers of 1.2 to 1.9 to determine the longitudinal and lateral aero-dynamic characteristics of a low-drag aircraft configuration. The model consisted of an aspect-ratio -1.86 arrow wing with 67.5 deg. leading-edge sweep and NACA 65A004 airfoil section and a triangular vertical tail with 60 deg. sweep and NACA 65A003 section in combination with a body of fineness ratio 20. Aerodynamic data in pitch, yaw, and roll were obtained from transient motions induced by small pulse rockets firing at intervals in the pitch and yaw directions. From the results of this brief aerodynamic investigation, it is observed that very slender body shapes can provide increased volumetric capacity with little or no increase in zero-lift drag and that body fineness ratios of the order of 20 should be considered in the design of long-range supersonic aircraft. The zero-lift drag and the drag-due-to-lift parameter of the test configuration varied linearly with Mach number. The maximum lift-drag ratio was 7.0 at a Mach number of 1.25 and decreased slightly to a value of 6.6 at a Mach number of 1.81. The optimum lift coefficient, normal-force-curve slope, lateral-force-curve slope, static stability in pitch and yaw, time to damp to one-half amplitude in pitch and yaw, the sum of the rotary damping derivatives in pitch and also in yaw, and the static rolling derivatives all decreased with an increase in Mach number. Values of certain rolling derivatives were obtained by application of the least-squares method to the differential equation of rolling motion. A comparison of the experimental and calculated total rolling-moment-coefficient variation during transient oscillations of the model indicated good agreement when the damping-in-roll contribution was included with the static rolling-moment terms.

Gillespie, Warren, Jr.↗
NASA NTRS2022

Analysis of Base Metal Microstructures and Mechanical Properties of a Single-Piece, Spin-Formed Forward Pressure Vessel Bulkhead

In 2012, a pathfinder forward pressure vessel bulkhead (FPVBH) for the Orion Multi-Purpose Crew Vehicle (MPCV) was fabricated using aluminum (Al) alloy 2219. The demonstration article was offered as a replacement for the baseline configuration, which at that time was a multi-piece welded construction using aluminum-lithium (Al-Li) alloy 2195. In 2014, the NASA Engineering and Safety Center (NESC) funded a Phase I effort to explore spin-forming as a manufacturing method to produce a complex-shaped, single-piece FPVBH for the crew module (CM) [1]. The primary focus of the NESC effort was to expand spin-forming technology to the fabrication of an Al-Li 2195 FPVBH. As a result, limited testing and analysis was performed on the original Al 2219 article. In this study, a sufficiently large plate of Al 2219 was not available for the fabrication of a FPVBH. Therefore, the forming blank comprised two plates (from different lots) butt welded together using a single friction stir weld. The welded forming blank was then spin formed into the FPVBH configuration and heat treated to the T62 temper. Mechanical property testing of the spin-formed 2219-T62 FPVBH revealed that the tensile properties were comparable to the Metallic Material Properties Development and Standardization (MMPDS) A-basis allowable for Al 2219-T6 wrought products. However, post-spin forming application of the standard heat treatment produced large, recrystallized grains in the material. The response varied within the two plates; one plate lot exhibited nearly complete recrystallization, while the other lot contained bands of recrystallization. Although no reduction in tensile properties was observed due to these microstructural variations, a more detailed investigation was recommended to better understand the effect of spin forming on the recrystallization mechanism and the impact on other material properties. The current study examined the microstructure and mechanical properties of the fully processed Al 2219-T62 FPVBH with emphasis on comparing differences between the two plates. Testing was limited to the cone region of the FPVBH. The two specific tasks in this study were: a) Characterization of the microstructure and mechanical properties in the two plates used in the FPVBH. b) Isolation of the impact of each step in the thermo-mechanical processing (TMP) sequence of the FPVBH on recrystallization and grain growth. Mechanical property testing sampled regions containing both large, recrystallized and small, unrecrystallized grains. Tensile strengths and elongations were equivalent in both regions and exceeded MMPDS A-basis allowables. Fracture toughness was equivalent in both regions and fracture morphology was typical of aluminum alloys. The fatigue precrack region of the fracture toughness specimens appeared more faceted in the recrystallized plate. This suggests that property testing that is more sensitive to grain size, such as fatigue crack growth rate and stress corrosion cracking, may be warranted. Alcoa reviewed the production records for the two plate lots and confirmed that composition of both plates was within the allowable range for Al 2219 and that plate processing steps were all performed within production limits. However, the Fe content was notably higher in the fully recrystallized plate, resulting in a greater volume fraction of large Fe-bearing inclusions and Al-Cu constituent particles. Alcoa did not provide details regarding plate processing variables for the two plate lots. It was surmised that deformation by hot rolling was the most accurate TMP simulation of commercial spin forming within a laboratory setting. Both hot rolling and spin forming comprise combinations of shear and compressive deformation. The through-thickness strain caused by hot rolling is symmetrical about the mid-plane, as the rollers contact both sides of the material. Shear strains are maximum at the inner and outer surfaces and trend toward zero at the mid-thickness. In contrast, spin forming utilizes a single roller on the outer surface, producing a gradient in shear stress through the thickness. Shear strains in spin-formed material are highest at the outer surface due to direct contact with the roller, and trend toward zero at the inner surface. Consequently, there will undoubtedly be some discrepancies in the mechanical response of hot-rolled and spin-formed products in the through-thickness direction. Interrupted TMP simulations were performed on remnant plate from the FPVBH forming blank in order to isolate the effects of a post-weld anneal, spin-forming deformation/thermal cycling, and solution heat treatment (SHT) on development of the recrystallized microstructures. Analysis confirmed that large, recrystallized grains formed exclusively during SHT and only after a certain deformation level was exceeded. Remnant plate from both lots that received thermal processing only did not exhibit recrystallization but exhibited fully recrystallized microstructures when processed by hot rolling. This indicates that (1) the level of deformation exceeded the critical level for recrystallization in both plates and (2) that the level of deformation during hot rolling was greater than that which accumulated during spin forming of the FPVBH. Comparison of the hot-rolled plate with the spin-formed material showed that the recrystallized grain size was larger in the FPVBH, providing further evidence that deformation levels were lower in the FPVBH. The most plausible explanation for the differing degrees of recrystallization in the two plates is particle stimulated nucleation (PSN) at the Fe-bearing inclusions and large Al-Cu constituent particles. In the plate with higher solute content, the greater volume fraction of these particles reduces the deformation level required to promote recrystallization. During spin forming the critical deformation level was likely exceeded for the higher Fe content plate resulting in a fully recrystallized microstructure. The lower Fe content plate developed a microstructure that exhibited bands of recrystallization due to the combination of a non-uniform distribution of particles and deformation. The critical deformation required for recrystallization was likely only exceeded during spin forming in regions of higher particle content. While there were differences in Fe content between these lots of Al 2219 plate, the composition of both was within defined alloy limits and Alcoa reported no anomalies during plate production. The observed differences in recrystallization after spin forming may reflect the inherent variability between these two lots of plate. The spin-forming vendor, Spincraft, reported that similar variations in recrystallized microstructures have been observed during examination of multiple spin-forming trials of a different 2xxx series aluminum alloy. Hence, tighter chemical specification limits on impurity levels in Al 2219 plate may help ensure uniform, predictable microstructures. Finally, the tensile and fracture toughness properties were not affected by the microstructural variations noted.

single-piece↗
DOE OSTI2021

System and method for large-scale PCB production including continuous selective adhesion

A method for the large-scale production of PCBs including a continuous selective adhesion process for creating printed circuit traces providing input to a production line. A roll of printed circuit traces is produced using rolls of flexible substrate, conductive layer, and conductive layer support by applying adhesive between the rolls of flexible substrate and conductive layer, bringing the rolls together, transferring a circuit pattern onto the flexible substrate, curing the adhesive through non-opaque areas of the circuit pattern, and separating the non-bonded areas. The resulting printed circuit traces are applied from the roll to mounts, and circuit components are applied from a roll to the traces as the mounts move along the line. Additional rolls of printed circuit traces and circuit components may be incorporated, and multi-layer PCBs may be produced. As part of the production line, the finished PCBs may be applied to flat or contoured products.

Hatch, Jonathan Douglas↗
DOE OSTI2013

Low Cost Electrochromic Film on Plastic for Net-Zero Energy Buildings

Over 4 Quads of energy are lost through windows annually. Passive coatings reduce wasted energy, but energy lost through windows would remain over 2 Quads with complete replacement of Low-E glass. Active control of transmitted light and solar heating with electrochromic (EC) windows can transform the efficiency of energy use within buildings, thereby reducing energy footprints and corresponding greenhouse emissions. High production, integration, and distribution cost limits adoption of current EC products. ITN aimed to utilize its proven heritage of efficiently transitioning technologies from rigid to flexible substrates employing roll-to-roll manufacturing to capture the emerging EC window market opportunity. The project focused on three main efforts (1) Transition Small Scale Prototypes To Limited 0.5 Meter Wide, Web Coater Production, (2) Satisfy Market Driven EC Performance Metrics on Plastic Substrates, and (3) Product Development and Commercialization. The overall goal was to substantially reduce investor risk to motivate private investment in a production facility to further transition and scale this promising technology. A 0.5 meter roll-to-roll web coater was designed, constructed, and commissioned at ITN to support EC development effort. With this tool, we were able to establish the feasibility of roll-to-roll production of EC devices. Individually layers were continuously produced at lengths up to 3 meters with good uniformity, both down web and cross web. Solid state devices were produced, and device performance was being enhanced through hardware modifications underway at the close of the project. When deployed in composite device structures, we were able to verify that individual layers were able to achieve a transmission range of 3-70% transmission average over the visible portion of the spectrum. Initial development of intelligent process controls led to verification of a 2-state controller employed during deposition of the electrochromic layer. The project also successfully increased device performance in line with market needs. Improved device materials provided increased transmission range to a 5-65% transmission over the visible spectrum and faster switching times for both small area batch parts and large area composite materials. We were able to demonstrate durable cycling over 10,000-20,000 cycles in a variety of architectures including suspended films in an IGU and films laminated to glass tested in open air representative of retrofit applications. Robust packaging techniques were identified and samples proved durable even in 40C and 100% relative humidity outside the IGU environment.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2024

In-line, High-Throughput Quality Monitoring for Fuel Cell and Electrolyzer Components Based on Transmission and Reflection Imaging

During the manufacturing of fuel cell and electrolyzer membranes and membrane electrode assemblies (MEAs), real-time, in-line, high-throughput optical-based quality monitoring methods are essential for detecting defects and monitoring thickness variations, thus improving the performance and increasing the durability of fuel cell and electrolyzer in the hydrogen industry. For the MEAs with very opaque coatings, optical transmission-based imaging has been developed and applied in the Roll-to-Roll system using a flashlight and a high-sensitivity CCD camera. We observed high signal-to-noise ratio images while the Roll-to-Roll system ran at 5 ft/min. The entire sample image could quickly be recovered from the discrete frames using customized Python codes for automatic frame cropping and stitching. We detected significant non-uniformities in our experimental MEAs specimen. For fuel cell and low-temperature electrolysis (LTE) transparent membranes, we used optical reflectance hyperspectral imaging with interference fringe-based thickness mapping. We set up a hyperspectral camera to measure various rolls of commercial membranes. The measurement results are analyzed to find the thickness distribution of each roll and to check for defects. Transmission and reflection imaging-based quality monitoring techniques demonstrated in this project can be widely used in the mass production environment to improve the production yield and performance of hydrogen devices.

DIRECT ENERGY CONVERSION,ENGINEERING↗
DOE OSTI2015

Evolution of microstructure, texture and inhibitor along the processing route for grain-oriented electrical steels using strip casting

In the present work, a regular grade GO sheet was produced successively by strip casting, hot rolling, normalizing annealing, two-stage cold rolling with intermediate annealing, primary recrystallization annealing, secondary recrystallization annealing and purification. The aim of this paper was to characterize the evolution of microstructure, texture and inhibitor along the new processing route by comprehensive utilization of optical microscopy, X-ray diffraction and transmission electron microscopy. It was found that a fine microstructure with the ferrite grain size range of 7–12 μm could be obtained in the primary recrystallization annealed sheet though a very coarse microstructure was produced in the initial as-cast strip. The main finding was that the “texture memory” effect on Goss texture started on the through-thickness intermediate annealed strip after first cold rolling, which was not similar to the “texture memory” effect on Goss texture starting on the surface layers of the hot rolled strip in the conventional production route. As a result, the origin of Goss nuclei capable of secondary recrystallization lied in the grains already presented in Goss orientation in the intermediate annealed strip after first cold rolling. Another finding was that fine and dispersive inhibitors (mainly AlN) were easy to be produced in the primary recrystallization microstructure due to the initial rapid solidification during strip casting and the subsequent rapid cooling, and the very high temperature reheating usually used before hot rolling in the conventional production route could be avoided. - Highlights: • A regular grade grain-oriented electrical steel was produced. • Evolution of microstructure, texture and inhibitor was characterized. • Origin of Goss nuclei lied in the intermediate annealed strip. • A fine primary recrystallization microstructure could be produced. • Effective inhibitors were easy to be obtained in the new processing route.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Production of High-Resistivity Electrical Steel Alloys by Substitution of Si with Al and Cr

Fe-3Si-3Al and Fe-4Si-4Cr (wt%) experimental alloys were processed to assess the electrical resistivity and workability effects of substituting Al and Cr for Si in high-Si electrical steel alloys. The experimental alloys were made by arc melting, and processed by hot rolling and cold rolling to produce strips. Samples were characterized by means of metallography, hardness, workability and resistivity. Results showed that the two alloys could be rolled down to 200 μm thickness (90% hot rolled reduction and 80% cold rolled reduction) without crack formation in the strips. Hardness in the annealed condition and electrical resistivity were 228 HV/74 μΩ·cm and 243 HV/85 μΩ·cm, respectively, for the Fe-3Si-3Al and for Fe-4Si-4Cr alloys. The resistivity measured for Fe-4Si-4Cr was higher than the resistivity reported for the benchmark high-Si alloy, Fe-6.5Si. Both experimental alloys showed improvement on the workability compared to Fe-6.5Si since there was no edge cracking on the cold-rolled strips up to 80% percent reduction, and the hardness was approximately 35% lower.

Electrical steels↗