Modeling anisotropic and rate-dependent plasticity in short-fiber reinforced thermoplastics

In this study, an anisotropic viscoelastic-viscoplastic macro-mechanical model is presented for short-fiber reinforced thermoplastics (SFRT). In injection molding of SFRT, the fiber orientation is influenced by the flow velocity profile which varies throughout the mold. The flow-induced orientation in the microstructure leads to anisotropy in the mechanical response. In addition to the mechanical anisotropy, SFRTs show time dependent behavior because of the thermoplastic matrix. The developed model captures the effects of both material orientation and loading rate on the yield behavior. In this study, uniaxial tests are performed at different strain rates and material orientations with samplescutfrominjectionmoldedplaques. Theexperimentalresultsshowthattheeffects of loading rate and material orientation on the yield are decoupled. The presented model takes advantage of this observation to simplify material characterization. An implicit integration scheme is used for the numerical implementation of the model as a UMAT in ABAQUS. Multiple relaxation times are used in order to capture the nonlinear pre-yield regime. An efficient method for obtaining the model parameters for different modes is proposed. Experimental results are used for validation of the model and a good agreement is observed for the prediction of viscoelastic and viscoplastic behavior

Features of shear transformation texture in seamless pipes

Microstructure and texture in seamless 0.08C-Cr-Mo-V, 0.25C-Cr-Mo-V-Nb, 0.08-13Cr-3Ni-Mo-V-Nb, and 18Cr-9Ni steel pipes are studied in the as-rolled and heat-treated states using orientation EBSD microscopy. It has been found that all types of microstructure (ferrite, martensite, and bainite) in products, both after hot rolling and after heat treatment, have well-defined axial crystallographic texture, where the direction is predominately perpendicular to the pipe surface. It is demonstrated that texture formation in heat-treated states is inherited due to the following factors important for the rules of orientation selection during the γ→α phase transformation: 1) occurrence of stable orientation of austenite grains resulted from straining; 2) special misorientation (boundaries) of austenite grains where transformation starts; 3) orientation relationships known for phase transformation; 4) thermal stresses in a product, formed during cooling. The latter can be considered as factor determining special texture in seamless steel pipes. © 2018 Author(s)

Structure and properties study of V-based membrane alloys for ultra-high purity hydrogen production

The reported study was funded by RFBR according to the research project No.16-38-00759 мол_а, the equipment of Shared Research Center Ural-M was used to make this study

ПРИНЦИПИАЛЬНОЕ РАЗЛИЧИЕ МЕТОДОВ НИЗКОЧАСТОТНОГО И УЛЬТРАЗВУКОВОГО ВОЗДЕЙСТВИЙ НА РАСПЛАВЫ

There were considered factors that determine difference of low and ultrasonic frequency treatment methods with regard to composite melts: cavitation events, dissipation losses, capability to turbulent mixing of melt. There was proven independence of every of these methods.Рассматриваются факторы, определяющие различие низкочастотного и ультразвукового методов обработки композиционных расплавов: кавитационные явления, диссипативные потери, способность к турбулентному перемешиванию расплава. Доказывается самостоятельность каждого из методов

ОСОБЕННОСТИ СТРУКТУРЫ ЛИГАТУРНЫХ СПЛАВОВ Al–Hf–Sc

The microstructure peculiarities of the new Al–Hf–Sc master alloys were studied using the methods of optical and scanning electronic (SEM) microscopy in combination with EDX analysis. The alloys studied included the meta-stable intermetallic compounds (aluminides) having cubic lattices identical to those in the matrix of aluminum alloys. Binary and ternary alloys were melted in graphite crucibles at a carbon-resistance furnace under an argon atmosphere. Al–0,96at.%Hf (5,98 wt.% Hf) and Al–0,59at.%Hf (3,77 wt.% Hf) alloys were prepared by superheating above the melting point up to about 200 and 400 degrees respectively. Melts were poured into a bronze casting form where crystallization rate was ~103 degrees/sec. Besides stable aluminides with tetragonal lattices, Al3Hf metastable aluminides with cubic lattices were formed only in the melt superheated by 400 degrees above the melting point. The degree of superheat for ternary alloys where Aln(Hf1–xScx) meta-stable aluminides were formed was 240, 270 and 370 degrees. The hafnium fraction in the Aln(Hf1–xScx) aluminides changed from 0,46 to 0,71 depending on the Hf : Sc ratio in the alloy. The master alloys produced (at.%): Al–0,26Hf–0,29Sc and Al–0,11Hf–0,25Sc (wt.%: Al–1,70Hf–0,47Sc and Al–0,75Hf–0,42Sc) demonstrate fine grain structures with meta-stable aluminides of Aln(Hf0,58Sc0,42) and Aln(Hf0,46Sc0,54) compositions respectively. Aluminide sizes are less than 12 and 7 μm. Their crystal lattice mismatch with the aluminum alloy matrix lattice is less than for Al3Sc. This fact allows us to expect high modifying effects of the experimental Al–Hf–Sc master alloys in their further application. In addition, replacement of expensive scandium with hafnium in the master alloys can reduce scandium consumption considerably.С использованием методов оптической и электронной сканирующей микроскопии, рентгеноспектрального микроанализа изучены особенности микроструктуры новых лигатурных сплавов системы Al–Hf–Sc с метастабильными алюминидами, имеющими кубическую решетку, идентичную решетке матрицы алюминиевых сплавов. Выплавку бинарных и тройных сплавов проводили в печи угольного сопротивления в графитовых тиглях в атмосфере аргона. Сплавы Al–0,96ат.%Hf (5,98 мас.% Hf) и Al–0,59ат.%Hf (3,77 мас.% Hf) готовили при перегреве над температурой ликвидуса около 200 и 400 град соответственно. Расплавы заливали в бронзовую изложницу, скорость кристаллизации в которой составляла ~103 град/с. Только в сплаве, перегретом над температурой ликвидуса на 400 град, наряду со стабильными алюминидами с тетрагональной решеткой образовались метастабильные алюминиды Al3Hf с кубической решеткой. Перегрев тройных расплавов, в которых сформировались метастабильные алюминиды Aln(Hf1–xScx), составил 240, 270 и 370 град. В зависимости от соотношения Hf и Sc в сплаве доля гафния в алюминидах Aln(Hf1–xScx) изменяется от 0,46 до 0,71. Лигатурные сплавы (ат.%) Al–0,26Hf–0,29Sc и Al–0,11Hf–0,25Sc (мас.%: Al–1,70Hf–0,47Sc и Al–0,75Hf–0,42Sc) характеризуются тонкой структурой зерна и метастабильными алюминидами состава Aln(Hf0,58Sc0,42) и Aln(Hf0,46Sc0,54) соответственно. Размеры алюминидов не превышают 12 и 7 мкм. Несоответствие их решеток с решеткой матрицы алюминиевых сплавов меньше, чем таковое для Al3Sc. Это позволяет предположить проявление опытными лигатурами Al–Hf–Sc высокого модифицирующего эффекта при их дальнейшем использовании. Кроме того, замещение гафнием дорогостоящего скандия в лигатурных сплавах может значительно сократить расход последнего

Research Grain Structure of Zr–2,5 % Nb Alloy Tubes by SEM Methods

The research was performed on thin sections of the transverse and longitudinal sections of tubes with a diameter of 88 mm from an alloy of Zr–2,5 %Nb, which have a fine-grained structure. Using scanning electron microscopy (SEM), the average grain size and structural components of the alloy after manufacture are determined. EBSD analysis compiled maps of preferred crystallographic orientations.Проведено исследование на шлифах поперечного и продольного разреза трубного изделия диаметром 88 мм из сплава Zr–2,5 %Nb, обладающих мелкозернистой структурой (~ 1–2 мкм). Методами сканирующей электронной микроскопии (СЭМ) определены структурные составляющие сплава (твердый раствор α-Zr и частицы β-Nb), а также средний размер зерен α-Zr. Ориентационным анализом (EBSD) составлены карты преимущественных кристаллографических ориентировок

SHEAR BANDS IN STABLE ORIENTATIONS OF BCC-METALS AT DEFORMATION

Методом ориентационной микроскопии (EBSD) были исследованы кристаллографические особенности формирования полос сдвига (ПС) в стабильных при холодной прокатке ориентировках ОЦК-решетки (на примере Fe–3%Si и Mo). В кристаллах {111} формируются ПС с ориентировкой близкой к {110}, находящиеся с матрицей в специальной разориентации близкой к Σ9. В кристаллах {112}…{111} формируются ПС с ориентировками близкими к {110}, находящиеся с матрицей в специальной разориентации, близкой к Σ5. В кристаллах {110} формируются ПС с ориентировками близкими к {100}, находящиеся с матрицей в специальной разориентации, близкой к Σ5. В кристаллах {001} ПС не образуются. Показано, что во всех ориентировках образуются ПС двух типов, отличающиеся углами наклона к плоскости прокатки и степенью рассеяния ориентировки внутри полос.The method of orientation microscopy (EBSD) was investigated by the crystallographic characteristics of shear bands (SBs) formation in the stable by cold rolling orientations of the BCC lattice (Fe–3% Si and Mo). In crystals {111} are formed of SB with the orientation approximate to {110}, which is a matrix in a special orientation near to Σ9. In crystals {112}...{111} SB are generated with orientations approximate to {110}, which is a matrix in a special orientation near to Σ5. In crystals {110} are formed of SB with orientations approximate to {100}, which is a matrix in a special orientation near to Σ5. In crystals {001} SBs are not formed. It is shown that in all orientations of SB are formed of two types with different angles of inclination to the plane of rolling and the degree of scattering orientation within the bands.Работа выполнена в рамках проектной темы МОиН РФ (задание № 11.1465.2014/K). Авторы выражают признательность за содействие Программе поддержки ведущих университетов РФ в целях повышения их конкурентоспособности № 211 Правительства РФ № 02.А03.21.0006

MICROSTRUCTURE AND PROPERTIES OF V-Ti-Ni MEMBARANE ALLOYS

Alloys based on vanadium having bcc structure are considered as an alternative to palladium membrane alloys for hydrogen filtering. The advantages of vanadium alloys are relatively high hydrogen permeability and low prime cost. Both bulk and surface characteristics of the membrane alloys influence on filtering efficiency. The alloys of V-Ti-Ni system were investigated by means of XRD, SEM, XPS and hydrogen permeability techniques.Работа выполнена в рамках Государственного задания ИМЕТ УрО РАН по теме № 0396-2015-0079. Работа выполнена с использованием оборудования ЦКП “Урал-М”

Interaction of perceptual grouping and crossmodal temporal capture in tactile apparent-motion

Previous studies have shown that in tasks requiring participants to report the direction of apparent motion, task-irrelevant mono-beeps can "capture'' visual motion perception when the beeps occur temporally close to the visual stimuli. However, the contributions of the relative timing of multimodal events and the event structure, modulating uni- and/or crossmodal perceptual grouping, remain unclear. To examine this question and extend the investigation to the tactile modality, the current experiments presented tactile two-tap apparent-motion streams, with an SOA of 400 ms between successive, left-/right-hand middle-finger taps, accompanied by task-irrelevant, non-spatial auditory stimuli. The streams were shown for 90 seconds, and participants' task was to continuously report the perceived (left-or rightward) direction of tactile motion. In Experiment 1, each tactile stimulus was paired with an auditory beep, though odd-numbered taps were paired with an asynchronous beep, with audiotactile SOAs ranging from -75 ms to 75 ms. Perceived direction of tactile motion varied systematically with audiotactile SOA, indicative of a temporal-capture effect. In Experiment 2, two audiotactile SOAs-one short (75 ms), one long (325 ms)-were compared. The long-SOA condition preserved the crossmodal event structure (so the temporal-capture dynamics should have been similar to that in Experiment 1), but both beeps now occurred temporally close to the taps on one side (even-numbered taps). The two SOAs were found to produce opposite modulations of apparent motion, indicative of an influence of crossmodal grouping. In Experiment 3, only odd-numbered, but not even-numbered, taps were paired with auditory beeps. This abolished the temporal-capture effect and, instead, a dominant percept of apparent motion from the audiotactile side to the tactile-only side was observed independently of the SOA variation. These findings suggest that asymmetric crossmodal grouping leads to an attentional modulation of apparent motion, which inhibits crossmodal temporal-capture effects