Journal articles: 'Strain-deformed state'

1

Wang, Hao, and Mo Li. "Nonlinear stress-strain relations for crystalline solids in initially deformed state." Journal of Applied Physics 112, no. 9 (November 2012): 093501. http://dx.doi.org/10.1063/1.4762000.

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Gasanov, B. G., A. A. Aganov, and P. V. Sirotin. "Features of determining the deformed state of a particle material during hot stamping of porous moldings." Izvestiya vuzov Poroshkovaya metallurgiya i funktsional’nye pokrytiya, no. 1 (March 17, 2021): 21–30. http://dx.doi.org/10.17073/1997-308x-2021-1-21-30.

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The paper describes main methods for assessing the deformed state of porous body metal frames developed by different authors based on the analysis of yield conditions and governing equations, using the principle of equivalent strains and stresses, and studying the kinetics of metal strain during pressing. Formulas were derived to determine the components of the powder particle material strain tensor through dyads, as scalar products of the basis vectors of the convected coordinate system at each moment of porous molding strain. The expediency of using the analytical expressions developed to determine the deformed state of the particle material was experimentally substantiated subject to the known displacement vector parameters of representative elements (macrostrains) of porous billets. The applications of well-known analytical expressions were established, and the proposed formulas proved applicable for the deformed state assessment of particle metal during the pressure processing of powder products of different configurations and designing billets with a defined porosity and geometric parameters as a basis for compiling software algorithms for the computer simulation of porous molding hot stamping.

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Belikova, A. F., S. N. Buravova, and Yu A. Gordopolov. "Strain localization and its connection with the deformed state of the material." Technical Physics 58, no. 2 (February 2013): 302–4. http://dx.doi.org/10.1134/s1063784213020035.

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Vaquero-Aguilar, Cristina, and Manuel Jiménez Melendo. "Creep Behavior of Yb-Doped Barium Cerate Perovskite." Advances in Science and Technology 65 (October 2010): 238–43. http://dx.doi.org/10.4028/www.scientific.net/ast.65.238.

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Polycrystalline ytterbium-doped barium cerate with composition BaCe0.95Yb0.05O3- has been fabricated by solid state reaction. The compound has an orthorhombic perovskite structure and a fine and homogeneous grain size distribution, with a mean value of 0.4 m. The creep behavior was studied by means of constant crosshead-speed compression tests in air at temperatures of up to 1300 °C. At the lower strain rates and higher temperatures, the material deformed by grain boundary sliding; the corresponding true stress-true strain curves displayed an initial strength drop followed by an extended steady state stage. A continuous transition towards a brittle regime was observed with increasing initial strain rate and/or decreasing temperature.

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Kellermann Slotemaker, A., J. H. P. de Bresser, C. J. Spiers, and M. R. Drury. "Microstructural Evolution of Synthetic Forsterite Aggregates Deformed to High Strain." Materials Science Forum 467-470 (October 2004): 579–84. http://dx.doi.org/10.4028/www.scientific.net/msf.467-470.579.

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Microstructures provide the crucial link between solid state flow of rock materials in the laboratory and large-scale tectonic processes in nature. In this context, microstructural evolution of olivine aggregates is of particular importance, since this material controls the flow of the Earth’s upper mantle and affects the dynamics of the outer Earth. From previous work it has become apparent that if olivine rocks are plastically deformed to high strain, substantial weakening may occur before steady state mechanical behaviour is approached. This weakening appears directly related to progressive modification of the grain size distribution through competing effects of dynamic recrystallization and syn-deformational grain growth. However, most of our understanding of these processes in olivine comes from tests on coarse-grained materials that show grain size reduction through dynamic recrystallization. In the present study we focused on fine-grained (~1 µm) olivine aggregates (i.e., forsterite/Mg2SiO4), containing ~0.5 wt% water and 10 vol% enstatite (MgSiO3), Samples were axially compressed to varying strains up to a maximum of ~45%, at 600 MPa confining pressure and a temperature of 950°C. Microstructures were characterized by analyzing full grain size distributions and textures using SEM/EBSD. We observed syndeformational grain growth rather than grain size reduction, and relate this to strain hardening seen in the stress-strain curves.

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Daniūnas, Alfonsas. "ANALYSIS OF COMPLICATED FORM SECTIONS OF STEEL MEMBERS." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 3, no. 9 (March 31, 1997): 34–38. http://dx.doi.org/10.3846/13921525.1997.10531669.

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Strain-deformed state analysis of free form sections of steel members is defined in an elastic-plastic state while using the extremum energy principles of elastic-plastic systems [1], The solution is obtained by using finite elements with the constant distribution of stresses.

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Liu, Bai Xiong, and Bao Jun Han. "Microstructure Characterization of Large Strain Deformed Fe-32%Ni Alloy." Advanced Materials Research 146-147 (October 2010): 248–51. http://dx.doi.org/10.4028/www.scientific.net/amr.146-147.248.

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High-resolution electron backscatter diffraction (EBSD) in scanning electron microscope and transmission electron microscope (TEM) were used to investigate the microstructure of Fe-32%Ni alloy processed by large strain multi-axial forging. The samples were compressed with loading direction changed through 90º from pass to pass at temperature of 500°C and a strain rate of 10-2/s. The results show the microstructure evolution is characterized by full development of almost equi-axed fine grains, not well-developed grain boundaries accompanied by high dislocation density and the existence of extensive extinction contours in the vicinity of grain boundaries, and the structure characteristics indicate that the grain boundaries are in a non-equilibrium state with high internal stresses.

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Renzetti, Reny Angela, M. J. R. Sandim, Hugo Ricardo Zschommler Sandim, K. T. Hartwig, Heide H. Bernardi, and Dierk Raabe. "EBSD Characterization of Pure Iron Deformed by ECAE." Materials Science Forum 638-642 (January 2010): 1995–2000. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.1995.

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Polycrystalline iron was deformed by eight ECAE passes using the route Bc to a total strain of 9.2. After deformation the material was annealed at temperatures up to 800oC. Scanning electron microscopy (SEM) and high-resolution electron backscatter diffraction (EBSD) were used to characterize both deformed and annealed structures. In the as-deformed state, the mean grain size is 650 nm and the volume fraction of high angle boundaries (VHAB) is 56%. Upon annealing there is a pronounced softening above 300oC. At the beginning of recrystallization, at about 400oC, the VHAB increases to 71%. The results indicate that discontinuous recrystallization is the main softening mechanism in severely deformed iron.

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Lomakin, E. V., and P. V. Tishin. "Constitutive relations for materials with strain state dependent properties." PNRPU Mechanics Bulletin, no. 1 (December 15, 2021): 52–62. http://dx.doi.org/10.15593/perm.mech/2021.1.06.

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Many materials demonstrate a dependence of mechanical properties on the type of stressed or deformed states. This is most noticeable in the dependence of the processes of shear and bulk deformation. Such materials include rocks, structural graphite, concrete, some grades of steel, cast iron, and aluminum. The main properties of these materials are an absence of a "single curve" relationship between the intensity of stresses and the intensity of deformations. Under shear conditions, bulk deformations can occur. Such materials can be described by constitutive equations that depend on the parameter of the type of a stress state, which is the ratio of the first invariant of the stress tensor to the stress intensity. Thus, these defining relations give the dependence of the strain tensor components on the stress tensor components. Such defining relations can be quite cumbersome, and therefore do not allow an analytical treatment to obtain defining relations that give the dependence of the components of the stress tensor on the components of the strain tensor. The paper proposes the constitutive relations obtained from the analysis of test results of various materials, which properties depend on the type of deformed state. Conditions are derived for material constants that ensure the uniqueness of the solution of boundary value problems. Based on experimental data obtained under the conditions of the proportional loading of various rocks: limestone and talcochlorite, as well as the results of mechanical tests of several grades of concrete, the constants of the mathematical model are determined. The results of the experimental studies are compared with theoretical dependencies predicted by the model. The limited applicability of the proposed constitutive relations is established.

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Miszczyk, Magdalena M., and Henryk Paul. "Cube{100}<001> Grains Nucleation during Annealing of S-Oriented Aluminum Single Crystal." Materials Science Forum 941 (December 2018): 1511–16. http://dx.doi.org/10.4028/www.scientific.net/msf.941.1511.

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The crystallographic aspects of nucleation of cube grains during annealing have been analyzed in (234)[20-28 11] - oriented aluminum single crystal. The samples were plane strain compressed in a channel-die up to logarithmic strains of 0.5 (40%) and then annealed to develop initial and final stages of primary recrystallization. The deformed and annealed samples were analyzed using scanning electron microscopy equipped with EBSD facility. Local orientation measurements reveled that significant part of the sample deforms homogeneously with only small deviation from the initial crystal orientation. The heterogeneities were thin bands of localized strain in which the crystal lattice rotate towards another variant of S orientation. After annealing the orientations identified inside deformed/recovered areas were similar to that observed in the sample just after deformation. The crystal lattice of recrystallized grains exhibit a well-defined clockwise and anticlockwise rotations around the axes grouped near all normals of the {111} planes of the deformed/recovered state. The cube grains were observed in both homogeneously and heterogeneously deformed areas despite the cube-oriented nuclei surrounded by high angle boundary were not present in the as-deformed structure.

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Kurachev, Radjab M., Dmitriy A. Vysokovsky, Anton Chepurnenko, and Pavel A. Shvetsov. "Modeling of Reactor Dry Protection Stressed-Strain State Taking into Account Temperature and Radiation Exposure." Materials Science Forum 931 (September 2018): 107–12. http://dx.doi.org/10.4028/www.scientific.net/msf.931.107.

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The paper proposes the method of stress calculation in three-layer protecting structures of nuclear reactors under thermal and radiation effects. We consider the case of a plane deformed state. One-dimensional axisymmetric finite elements are used. The effect of indirect material heterogeneity on the stress-strain state of the structure is investigated.

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Liu, Hong Yan, Kee Sam Shin, Jung Hoon Yoo, Ji Ling Dong, Quoc Bao Huynh, Hui Yu, Chan Gyu Lee, Young Sang Na, Kyung Shik Cho, and Jong Hoon Lee. "Microstructural Analysis of Compressive Zr₆₂Cu₁₇Ni₁₃Al₈ Bulk Amorphous Alloy." Defect and Diffusion Forum 273-276 (February 2008): 367–74. http://dx.doi.org/10.4028/www.scientific.net/ddf.273-276.367.

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Zr62Cu17Ni13Al8 in the supercooled liquid state is expected to be micro-formable at a relatively low stress. We used X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and quantitative high-resolution TEM (HRTEM) to investigate the microstructures of Zr62Cu17Ni13Al8 amorphous alloy after compression test. The alloy exhibited the homogeneous amorphous microstructure with some crystalline phases dispersed in the matrix. According to the XRD results, under the certain strain rate in the supercooled liquid state, the alloy showed higher crystallization at the higher heat treatment temperature. However, at the same heat treatment temperature, the alloy deformed under low strain rate showed higher crystallization. The β crystalline phase particles with spherical shape were detected by SEM and TEM. The sample with higher strain rate and temperature showed longer shear bands. Nano-voids formed by the coalescence of excess free volume in shear bands were investigated by quantitative HRTEM. Compared with the undeformed area, in the shear band, nanovoids were identified in the deformed area through quantitative HRTEM simulation.

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PROTOSENYA, A. G., and G. A. IOVLEV. "STRESS-STRAIN STATE PREDICTION SURROUNDING UNDERGROUND STRUCTURE, CONSTRUCTED IN NONLINEAR DEFORMED MEDIUM-SOFT SOILS." News of the Tula state university. Sciences of Earth 2, no. 1 (2020): 215–28. http://dx.doi.org/10.46689/2218-5194-2020-2-1-215-228.

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Article proposes an approach for constructing a computational model for calculating the stress-strain state around tunnel, in medium soft soils. Set of deformations and strengths properties of which a given by elastic, elastic perfectly-plastic, and non-linear models. It founded, that with the input parameters used in model for elastic perfectly-plastic, and nonlinear models around tunnel formed yield surfaces. Analysis of the distinctions between elastic perfectly-plastic, and non-linear models was made. Was showed, that maximum deviatoric stress q is over-estimated in Mohr-Coulomb model. For hardening soil model was determined boundary of the plastic deformations.

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Hagemann, Philipp, Rudolf Kawalla, Grzegorz Korpala, and Matthias Schmidtchen. "The Influence of the Initial State on the Softening and Precipitation Kinetics in Hot Metal Forming." Materials Science Forum 706-709 (January 2012): 1397–402. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.1397.

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Energy-efficient production in today’s metal industry includes the usage of casting heat to allow hot deformation directly after solidification for saving time and cost of expensive reheating processes. Due to the different initial state this processing route also leads to differences in deformation behavior (strain, flow stress) and softening and precipitation kinetics compared to a reheated material. This is caused by the different microstructures in the material directly after solidification, showing a much more coarsed grain structure and a higher amount of dissolved microalloying elements. Therefore, a material directly deformed after solidification usually shows a retarded softening behavior accompanied by precipitation processes. The different behaviour of a reheated material and a material directly deformed after solidification is shown in this work. The different modes of action for micro-alloying elements in different initial states are compared at the example of steels with different chemical compositions. Differences in deformation behaviour were simulated with semi-empirical models including specific coefficients to consider the processing parameters strain, strain rate, temperature, and chemical composition. The models are capable of describing the retarded softening caused by a superimposed precipitation kinetic leading to a typical plateau. The results of these models are compared with established physical models.

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Ariskin, M. V., D. O. Martyshkin, and I. V. Vanin. "Mathematical modeling of stress-strain state of elements of joints of wooden structures on glued fiberglass washers." Journal of Physics: Conference Series 2131, no. 3 (December 1, 2021): 032095. http://dx.doi.org/10.1088/1742-6596/2131/3/032095.

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Abstract Design models of single-component and three-component samples were developed on glued fiberglass washers in order to investigate the stress-strain state (SF) of the elements of joints of wooden structures. The picture and the nature of the actual stressed-deformed state of the wooden element with glued washers are obtained. Quite high bearing capacity of wooden structures connection is shown.

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Bernardi, Heide Heloise, Karine Andrea Käfer, Leonardo K. F. Naito, and Jorge Otubo. "Shape Recovery in Stainless FeMnSiCrNi(-Co) SMA Processed by ECAE." Materials Science Forum 738-739 (January 2013): 252–56. http://dx.doi.org/10.4028/www.scientific.net/msf.738-739.252.

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Stainless shape memory steel presents reasonable shape recovery but lower than the traditional NiTi shape memory alloys (SMA). However, recent results have shown that the shape recovery could be improved by decreasing the austenitic grain size. The present work describes the influence of the austenitic grain size on the shape recovery in stainless shape memory steel deformed by equal channel angular extrusion (ECAE) using a die intersection angle of 120o. Two alloys, FeMnSiCrNi and FeMnSiCrNiCo, were deformed by 1 ECAE pass and then they were compared in the deformed state; deformed and annealed in different temperatures for 1 h, resulting different grain sizes. Both alloys were evaluated by compression tests and the results shows an increase in total shape recovery related to grain size decrease. The best total shape recovery was 73% after a pre-strain of 4% for FeMnSiCrNi alloy.

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Zhao, Yonghao, Yanglin Gu, and Yazhou Guo. "Plasticity and Deformation Mechanisms of Ultrafine-Grained Ti in Necking Region Revealed by Digital Image Correlation Technique." Nanomaterials 11, no. 3 (February 25, 2021): 574. http://dx.doi.org/10.3390/nano11030574.

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The conventional engineering stress-strain curve could not accurately describe the true stress-strain and local deformability of the necking part of tensile specimens, as it calculates the strain by using the whole gauge length, assuming the tensile specimen was deformed uniformly. In this study, we employed 3D optical measuring digital image correlation (DIC) to systematically measure the full strain field and local strain during the whole tensile process, and calculate the real-time strain and actual flow stress in the necking region of ultrafine-grained (UFG) Ti. The post-necking elongation and strain hardening exponent of the UFG Ti necking part were then measured as 36% and 0.101, slightly smaller than those of the coarse grained Ti (52% and 0.167), suggesting the high plastic deformability in the necking part of the UFG Ti. Finite elemental modeling (FEM) indicates that when necking occurs, strain is concentrated in the necking region. The stress state of the necking part was transformed from uniaxial in the uniform elongation stage to a triaxial stress state. A scanning electron microscopic (SEM) study revealed the shear and ductile fracture, as well as numerous micro shear bands in the UFG Ti, which are controlled by cooperative grain boundary sliding. Our work revealed the large plastic deformability of UFG metals in the necking region under a complex stress state.

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Tobisch, O. T., and Q. Williams. "Use of microgranitoid enclaves as solid state strain markers in deformed granitic rock: an evaluation." Journal of Structural Geology 20, no. 6 (June 1998): 727–43. http://dx.doi.org/10.1016/s0191-8141(98)00009-1.

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Scheriau, Stephan, A. Vorhauer, and Reinhard Pippan. "In Situ Annealing of Severe Plastic Deformed OFHC Copper." Materials Science Forum 558-559 (October 2007): 1345–51. http://dx.doi.org/10.4028/www.scientific.net/msf.558-559.1345.

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A pure OFHC copper is subjected to severe plastic deformation (SPD) by a well defined high pressure torsion process at ambient temperature. The change in microstructure of samples deformed to different strains, up to ε=64, is investigated in-situ, during annealing at 170°C, within a scanning electron microscope. The spatial distribution of nucleation sites changes significantly with increasing strain from nucleation at triple junctions and grain boundaries to a random distribution of sites for von Mises equivalent strains beyond ε=4. The resulting mean size of recrystallized grains is about 6.75 times larger than the mean microstructural size of the corresponding as-deformed state. For strains larger than ε=16 the recrystallized microstructure appears to be independent of preceding strain. A detailed investigation of the nucleation of recrystallized grains following very large strains shows that certain microstructural elements are favoured as nuclei and were particularly taken into account.

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Yablokov, Alexander S., Sergey A. Borunov, Alexander D. Devin, and Vladislav V. Shutov. "EVALUATION OF STRESSED-DEFORMED CONDITIONS OF ELEMENTS TRAVERSE WITH LOAD CAPACITY OF 160 TONS." Russian Journal of Water Transport, no. 64 (August 29, 2020): 215–32. http://dx.doi.org/10.37890/jwt.vi64.113.

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The article calculates the analysis of the stress-strain state of the traverse, taking into account additional loads acting in full-scale operating conditions. The presented calculation methodology is based on determining the permissible stresses and modeling the structure using the finite element method. A design scheme, a solid-deformed model have been developed, and a finite element method has been calculated in the CAD / CAE system. To determine the operating values in the steel structure of the lower service, we will construct a model in natural values with observance of the given characteristics and geometrical dimensions. The stress-strain state of the traverse elements is quite complex, since both compressive stresses and tensile stresses arise in one element in different planes, which are interchanged during the operation of the lifting structure. The above calculation and analysis of the strength of the metal structure of the lifting structure showed that this approach is suitable for the development on its basis of expert systems for assessing the lifespan of lifting structures, both at the stage of design and at the stage of operation

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Matvijchuk, Viktor, Andrii Shtuts, Mykola Kolisnyk, Ihor Kupchuk, and Iryna Derevenko. "Investigation of the Tubular and Cylindrical Billets Stamping by Rolling Process with the Use of Computer Simulation." Periodica Polytechnica Mechanical Engineering 66, no. 1 (December 22, 2021): 51–58. http://dx.doi.org/10.3311/ppme.18659.

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Forming of blanks during stamping by rolling (RS) is possible according to technological schemes of deposition, landing, direct and reverse extrusion, distribution and compression, etc. Controlling the relative position and shape of the deformed tool allows you to control the direction of flow of the workpiece material and the nature of its formation, as well as the stress-strain state of the material. The complexity and versatility of RS processes necessitate computer modeling for sound management of basic technological parameters.Physical experimental as well as computer modeling of the RS process in the DEFORM-3D software package was performed in the work.According to the results of computer simulation, the distribution of deformation components, stresses and temperatures in the deformed workpiece area was obtained, and using the Cockroft-Latham criterion, the destruction of metals during cold deformation was also predicted.Physical modeling of the SR process on lead blanks confirmed the nature of their deformation, obtained by computer simulation. And the analysis of the stress-strain state of the material based on the results of measurements of the deformed grid confirmed the validity of the appointment of boundary conditions in computer simulation.This approach is suitable for modeling by the method of SR of any metal models, for which it is necessary to know their mechanical characteristics, including boundary deformation curves.

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Khadeev, Grigorii, Dmitrii Ringinen, and Leonid Efron. "Effect of Multistage Deformation during the Pipe Processing on Mechanical Properties of Steels Strength Grade X70-X80." Key Engineering Materials 716 (October 2016): 957–62. http://dx.doi.org/10.4028/www.scientific.net/kem.716.957.

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In this research effect of the pipe forming on strength properties of rolled metal was investigated. Deformed state of metal during pipe processing was analyzed and tests with specimens from plate were performed. Analysis of the experimental data was exploited to evaluate effect of the strain on yield stress in each stage of the pipe forming and specimen flattening. The model for estimation of mechanical properties of the rolling mill product based on the required mechanical properties of the pipe was created.

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You, Jing, Yingjie Huang, Chuming Liu, Hongyi Zhan, Lixin Huang, and Guang Zeng. "Microstructural Study of a Mg–Zn–Zr Alloy Hot Compressed at a High Strain Rate." Materials 13, no. 10 (May 20, 2020): 2348. http://dx.doi.org/10.3390/ma13102348.

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Understanding the correlation of plasticity with deformation and dynamic recrystallization (DRX) behaviors, in magnesium (Mg) alloys deformed under high-strain-rate conditions, is increasingly important for wrought Mg processing. In the present study, a ZK30 (Mg-2.61%Zn-0.66%Zr by weight percent (wt.%)) alloy in the as-forged state was hot compressed to various strain levels at a temperature of 350 °C and a strain rate of 10 s−1. Heterogeneous deformation and dynamic recrystallization (DRX) behaviors of the complicated microstructures in the deformed samples were analyzed via a grain-partitioning approach based on intra-grain misorientation analysis from electron back-scattered diffraction (EBSD). The ZK30 alloy showed excellent formability, remaining intact at a true strain of −1.11. Continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) via grain boundary corrugation/bulging are the dominant mechanisms for the relaxation of strain energy during hot compression. Initial Zr-rich coarse grains undertook a significant portion of the plastic strain as the compression progressed, reflected by the increased misorientations within their interior and marked change in their aspect ratios. The results indicate that the excellent plasticity of the as-forged ZK30 alloy can be attributed to the operative CDRX mechanisms and the reduced deformation anisotropy of Zr-rich coarse grains containing Zn–Zr nano–precipitates.

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Zhao, Yonghao, and Yanglin Gu. "Deformation mechanisms and plasticity of ultrafine-grained Al under complex stress state revealed by digital image correlation technique." Nanotechnology Reviews 10, no. 1 (January 1, 2021): 73–86. http://dx.doi.org/10.1515/ntrev-2021-0007.

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Abstract Conventional engineering stress–strain curve could not accurately describe the local deformability of the tensile necking part because the strain is calculated by assuming that the tensile specimen was deformed uniformly. In this study, we used 3D optical measuring digital image correlation to systematically measure the full strain field and actual flow stress in the necking region of ultrafine-grained (UFG) Al. The post-necking elongation and strain hardening exponent of the UFG Al were measured as 80% and 0.10, slightly smaller than those of the coarse-grained Al (117% and 0.28), suggesting the high plastic deformability of the UFG Al under complex stress state. Microstructural studies revealed the shear and ductile fracture, numerous micro-shear bands, and elongated UFG grains in the UFG Al, which are controlled by cooperative grain boundary sliding and multiple dislocation slips.

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Yuan, Sen, Wu Xiao Wang, and Bai Ling Jiang. "Microstructure Evolution of Deformed Magnesium Alloy in Semi-Solid State." Materials Science Forum 488-489 (July 2005): 313–16. http://dx.doi.org/10.4028/www.scientific.net/msf.488-489.313.

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Magnesium alloy slurry was prepared using Strain-Induced Melt Activation(SIMA) technique. The samples were quenched into water so as to fix the high temperature instantaneous microstructures. The microstructure evolution of compressed deformation Mg alloy is studied in the process of continuous heating and iso-temperature of semi-solid state. The results indicate that deformed Mg alloy (AZ91) has first occurred to have the conversion of dendrite crystal-oriented isometric crystals in the continuous heating process. When the temperature rises to the range of semisolid state, the region with high energy at the pressed stripes begins to melt, showing that the cellular structures emerge in the crystal boundary and melting micro-pool phenomena appear within the crystals. With the iso-temperature time in semisolid state prolongs, the isometric crystals can be gradually converted into spherical crystal grains.

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Roeder, Blayne A., Klod Kokini, J. Paul Robinson, and Sherry L. Voytik-Harbin. "Local, Three-Dimensional Strain Measurements Within Largely Deformed Extracellular Matrix Constructs." Journal of Biomechanical Engineering 126, no. 6 (December 1, 2004): 699–708. http://dx.doi.org/10.1115/1.1824127.

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The ability to create extracellular matrix (ECM) constructs that are mechanically and biochemically similar to those found in vivo and to understand how their properties affect cellular responses will drive the next generation of tissue engineering strategies. To date, many mechanisms by which cells biochemically communicate with the ECM are known. However, the mechanisms by which mechanical information is transmitted between cells and their ECM remain to be elucidated. “Self-assembled” collagen matrices provide an in vitro-model system to study the mechanical behavior of ECM. To begin to understand how the ECM and the cells interact mechanically, the three-dimensional (3D) mechanical properties of the ECM must be quantified at the micro-(local) level in addition to information measured at the macro-(global) level. Here we describe an incremental digital volume correlation (IDVC) algorithm to quantify large (>0.05) 3D mechanical strains in the microstructure of 3D collagen matrices in response to applied mechanical loads. Strain measurements from the IDVC algorithm rely on 3D confocal images acquired from collagen matrices under applied mechanical loads. The accuracy and the precision of the IDVC algorithm was verified by comparing both image volumes collected in succession when no deformation was applied to the ECM (zero strain) and image volumes to which simulated deformations were applied in both 1D and 3D (simulated strains). Results indicate that the IDVC algorithm can accurately and precisely determine the 3D strain state inside largely deformed collagen ECMs. Finally, the usefulness of the algorithm was demonstrated by measuring the microlevel 3D strain response of a collagen ECM loaded in tension.

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Koyankin, A. A., and V. M. Mitasov. "Stressstrain state of cast-in-place and precast structure with loaded cast-in-place element." Vestnik Tomskogo gosudarstvennogo arkhitekturno-stroitel'nogo universiteta. JOURNAL of Construction and Architecture 23, no. 3 (June 28, 2021): 129–42. http://dx.doi.org/10.31675/1607-1859-2021-23-3-129-142.

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The paper presents the strength analysis of cast-in-place and precast structures in accordance with regulatory documents, which require clarifications, since the properties of such structures distinguish them from conventional reinforced concrete structures. These properties include the beginning of the deformation process, ultimate strain, physical properties, and others. The strength analysis of cast-in-place and precast structure is conducted with regard to these properties.The proposed analysis is based on the load-bearing capacity exhaustion of deformed concrete or reinforcement and allows considering the different time of involvement in the deformation process of cast-in-place and precast structures as well different stress and strain properties of concrete. The experimental data are in good agreement with theoretical calculations.

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Rekov, A. M. "The Density of Deformations Distribution on the Side Edges during Strip Rolling." Solid State Phenomena 316 (April 2021): 340–45. http://dx.doi.org/10.4028/www.scientific.net/ssp.316.340.

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Experimental densities of intensity distribution for main deformations, as well as the stress strain state of a metal on the side edges of an aluminum strip during its flat rolling, have been determined. Strain, spread and extrusion ratio have been evaluated. The dimensions of the strip cross-section have been chosen in a way that minimizes spreading. Therefore, the deformed state under rolling is close to a flat one. The correlation between the deformation intensity and the stress-strain state of macro-volumes occurred on strip edges has been estimated. The parameters of two-dimensional probability-density function for the joint distribution of deformation intensity and the Nadai-Lode stress-strain parameter have been determined. Distribution densities for longitudinal, transverse deformations and the intensity of main deformations in the zone of strip rolling are bimodal, which corresponds to both forward and backward slip zones under rolling. The results of the work can be used to predict the depletion of plasticity resources during strip rolling.

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Poleshchuk, V. M., and V. L. Brovkin. "Scheme of stressed-deformed condition of continuous-casted slab in technological casting lines." Fundamental and applied problems of ferrous metallurgy, no. 32 (2018): 290–99. http://dx.doi.org/10.52150/2522-9117-2018-32-290-299.

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The aim of the work is to develop a model of the deformation-stressed state of a continuous-cast billet, taking into account its behavior in the continuous casting machine line. A new physical model of the ingot crust bending process in the inter-roller gap has been proposed. The model is based on the regularities of the change in the deformed state of the surface of the crust under the action of ferrostatic pressure. It is established that the crust undergoes a cyclic alternating deformation in the process of moving it across the inter-roller gap. It is shown that the surface of the crust comes into contact with the surface of the roller before approaching the inter-roller gap. This causes the appearance of an anomalous area with a constant curvature of the crust at the final stage of its buckling. The second anomalous deformation zone of the ingot crust is the junction zone of the previous crust and the subsequent inter-roller gap, where the crust instantly changes its curvature. In combination with the flat scheme of the stress-strain state, a physical model is presented, which makes it possible to identify in each of the inter-roller gaps the zone of maximum values of the tensile strain rate. Identifying the zone of maximum values of the tensile strain indicator and comparing it with the maximum allowable one allows determining and correcting the length of the inter-roller gaps of the continuous casting machine.

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30

Leenders, A., M. Ullrich, L. O. Kautschor, and H. C. Freyhardt. "High temperature deformation of vertical gradient freeze method melt-textured Y1Ba2Cu3O7−x." Journal of Materials Research 14, no. 2 (February 1999): 354–58. http://dx.doi.org/10.1557/jmr.1999.0052.

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The deformation behavior of melt-textured Y1Ba2Cu3O7-x (YBCO) prepared by the vertical gradient freeze (VGF) method was investigated by high temperature deformation experiments at temperatures ranging from 850 to 950 °C. The experiments were performed in an atmosphere of pure oxygen under uniaxial pressure with constant strain rates in the range from 1 × 10−5 to 5 − 10−4 s−1. An analysis of the dependence of the steady state flow stress on the strain rate and the deformation temperature reveals that the predominant deformation mechanism is dislocation glide and climb controlled by climb at Y-211 particles and that no significant grain boundary sliding occurs. Furthermore, transmission electron microscopy observations of deformed and undeformed samples support a deformation mechanism based on dislocation movement. The total fracture strain, however, does not depend on the temperature or strain rate. Scanning electron microscopy investigations of the fracture faces of samples deformed until fracture reveal that fracture does not occur within the Y-123 matrix but along platelet boundaries. An improvement of the fracture behavior is expected by introducing large Y-211 particles interconnecting neighboring platelets.

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Sherbakov, S. S., L. A. Shemet, and A. A. Nasan. "Computer modeling of volumetric damageability in the mine roadway neighbourhood." Doklady BGUIR 18, no. 7 (November 25, 2020): 47–54. http://dx.doi.org/10.35596/1729-7648-2020-18-7-47-54.

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The object of research is a rock massif with various cross-sectional shapes of roadway. The purpose of work: computer modeling of stress-strain state and volumetric damageability in the neighbourhood of a mine roadway. The undisturbed rock massif has an initial stress-strain state (under its own weight) before a mine roadway is formed. Therefore, to determine the stress-strain state of the rock massif with the mine roadway, we must first calculate the stress state of the rock massif without the roadway and then take it into account as a pre-stressed state for the rock massif therewith. Damageability assessment of the rock massif with a mine roadway was carried out based on the obtained distributions of stresses and strains. We calculated volumetric damageability through the model of a deformed solid body with dangerous volume. Dangerous volume is a limited area where stresses or strains exceed the predetermined threshold. Calculation of dangerous volumes and integral damageability was carried out in the finite element package ANSYS. The program was written in APDL. The ratios between the existing and limiting stresses was calculated for each finite element. The elements for which this ratio exceeds unity will form a dangerous volume for the whole model. As a result, we have an array of finite elements constituting the dangerous volume and its value. The developed method for assessing damageability in the mine roadway neighbourhood takes into account various cross-sectional shapes of the mine roadway and its depth. The relevance of studying possible destruction regions using the model of a deformed solid body with dangerous volume was substantiated.

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32

Owen, J. Victor. "Determination of the finite-strain ellipsoid from deformed porphyroblastic mineral aggregates and preferentially oriented feldspars in a mylonitized metamafic dyke." Canadian Journal of Earth Sciences 26, no. 11 (November 1, 1989): 2333–40. http://dx.doi.org/10.1139/e89-199.

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Strain in a narrow mylonite zone has been estimated from deformed garnetiferous porphyroblastic aggregates and from preferentially oriented plagioclase porphyroclasts with high aspect ratios. In the undeformed metamafic dyke hosting the mylonite, the mineral aggregates have spheroidal to slightly oblate shapes, and plagioclase is nearly randomly oriented. In the mylonite, the mineral aggregates are prolate ellipsoids, and plagioclase in the aggregates and matrix is symmetrically oriented about the mylonitic planar fabric. Comparison with the radii of spheres of equal volume shows that the ellipsoidal mineral aggregates underwent triaxial strain, with maximum extension of 50–140% parallel to X and with shortening of up to −30 and −45% parallel to Y and Z, respectively. The maximum strain ratio varies between 1.9 and 4.2 (mean of 10 measurements = 3.1). The orientation and aspect ratios of elongate plagioclase grains measured in the X–Z plane indicate an intermediate value (2.7) for the strain ratio. Plagioclase deformation was apparently accommodated by dislocation glide on (010), recovery processes (subgrain rotation), and microcracking. The effects of mechanical anisotropy in plagioclase, however, were subordinate to the strain regime, strain ratio, and initial aspect ratio of grains in determining the final aspect ratio and rest position of these porphyroclasts.Both the deformed garnetiferous aggregates and the plagioclase porphyroclasts record state of strain in the mylonite. This suggests that the preferred orientation of densely packed feldspars of high aspect ratio potentially may be used to estimate strain in tectonites.

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Glowacki, Miroslaw, and Marcin Hojny. "Inverse analysis applied for determination of strain–stress curves for steel deformed in semi-solid state." Inverse Problems in Science and Engineering 17, no. 2 (March 2009): 159–74. http://dx.doi.org/10.1080/17415970802082757.

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34

Jun, Li, T. H. Jacka, and W. F. Budd. "Strong single-maximum crystal fabrics developed in ice undergoing shear with unconstrained normal deformation." Annals of Glaciology 30 (2000): 88–92. http://dx.doi.org/10.3189/172756400781820615.

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AbstractLaboratory-ice deformation experiments are described that use an apparatus designed to apply a simple-shear stress configuration. Ice samples are deformed by applying horizontal parallel forces, with no vertical forces imposed, and with no attempt made to restrain sample dimension in the vertical direction. The vertical dimensions of the samples however are measured and, for a sample initially of rectangular vertical cross section, it is found that there is an apparent strain (compression) in this direction that increases with the shear strain. For samples initially with a 30° "back-cut" shape, a vertical (extension) strain is evident during approximately the first 20% horizontal strain until the sample has deformed to near the rectangular section shape. For a sample with length-to-height ratio of 10 the maximum vertical strain was about 1%. At this maximum vertical strain, the strain rate in the vertical direction is zero and the sample is undergoing a close approximation to plane laminar (simple shear) flow. It is then followed by a vertical (compression) strain until termination of the experiment. The greater the ratio of length-to-height for the test samples, the less the vertical stain and the greater the strain period over which approximate plane laminar flow persists. This 20% horizontal strain is sufficient to ensure, for a sample of initially isotropic ice, that tertiary steady state has been attained, and the resulting crystal fabrics indicate a strong single-maximum pattern similar to those found deep in polar ice sheets. The single-maximum pattern is however lightly elongated perpendicular to the shear direction.

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35

Andreev, Vladimir, and Vladislav Nosyrin. "Stress-strain state of a soil array with a cylindrical cavity supported by a reinforcing ring." E3S Web of Conferences 97 (2019): 04060. http://dx.doi.org/10.1051/e3sconf/20199704060.

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The article deals with the problem of calculating a stress-strain soil massif with a horizontal cylindrical cavity created by an explosion (for example, drilling and blasting method of penetration), in the presence of a reinforcing ring. The calculation takes into account the radial local inhomogeneity of the array near the cavity, due to the explosive effects. The problem is solved in a two-dimensional formulation (flat deformed state). The solution uses a numerical-analytical method that reduces the solution to a system of ordinary differential equations with variable coefficients.

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36

Zhang, Hong Wen, Xiao Xu Huang, Richard Pippan, and Niels Hansen. "Thermal Behavior of Nickel Deformed to Ultra-High Strain by High Pressure Torsion." Materials Science Forum 715-716 (April 2012): 387–92. http://dx.doi.org/10.4028/www.scientific.net/msf.715-716.387.

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Polycrystalline Ni (99.5 %) has been deformed to an ultra-high strain ofεvM=100 (εvM, von Mises strain) by high pressure torsion (HPT) at room temperature. The deformed sample is nanostructured with an average boundary spacing of 90 nm, a high density of dislocations of >1015m-2and a large fraction of high angle boundaries (>15o) 68% as determined by transmission electron microscopy and 80% as determined by electron backscatter diffraction. The thermal behavior of this nanostructued sample has been investigated by isochronal annealing for 1h at temperatures from 100 to 600°C, and the evolution of the structural parameters (boundary spacing, average boundary misorientation angle and the fraction of high angle boundaries), crystallographic texture and hardness have been determined. Based on microstructural parameters the stored energy in the deformed state has been estimated to be 24 MPa. The isochronal annealing leads to a hardness drop in three stages: a relatively small decrease at low temperatures (recovery) followed by a rapid decrease at intermediate temperatures (discontinuous recrystallization) and a slow decrease at high temperatures (grain growth). Due to the presence of a small amount of impurity elements, the recovery and recrystallization are strongly retarded in comparison with Ni of high purity (99.967%). This finding emphasizes the importance of alloying in delaying the process of recovery and recrystallization, which enables a tailoring of the microstructure and properties through an optimized annealing treatment.

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37

Smirnov, Oleg M., and M. A. Tsepin. "Rheological Models as the Basic Element of Metal Forming Processes Simulation." Materials Science Forum 575-578 (April 2008): 545–48. http://dx.doi.org/10.4028/www.scientific.net/msf.575-578.545.

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The variety of metal forming processes can be arranged according to some essential features such as structure, properties and structure evolution of the metal being deformed, deformation temperature and dynamics of its changing during deformation, interrelation between flow stress, strain and strain rate, temperature and structural parameters etc. These features in the aggregate compose rheological behavior of the metal being deformed and the rheological equation’s database for simulation of metal forming processes in cold, warm, hot and superplastic state. Taking these ideas into account, the authors would like to present some basic elements of these rheological models database i.e. classification of metallic materials as objects of deformation, classification of deformation modes in dependence on temperature regimes, thermal-kinetic map of metal processing and, as a result of this analysis, a set of rheological models related to certain modes of metal forming processes, which can be used as basic elements of computer software systems for simulation of these processes.

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38

Leszczyńska-Madej, B., M. W. Richert, I. Nejman, and P. Zawadzka. "Processing of Copper by Hydrostatic Extrusion – Studies of Microstructure and Properties." Archives of Metallurgy and Materials 61, no. 3 (September 1, 2016): 1575–80. http://dx.doi.org/10.1515/amm-2016-0257.

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AbstractThe present study attempts to apply HE to 99.99% pure copper. The microstructure of the samples was investigated by both light microscopy and scanning transmission electron microscopy (STEM). Additionally, the microhardness was measured, the tensile test was made, and statistical analysis of the grains and subgrains was performed. Based on Kikuchi diffraction patterns, misorientation was determined. The obtained results show that microstructure of copper deformed by hydrostatic extrusion (HE) is rather inhomogeneous. The regions strongly deformed with high dislocation density exist near cells and grains/subgrains free of dislocations. The measurements of the grain size have revealed that the sample with an initial in annealed-state grain size of about 250 μm had this grain size reduced to below 0.35μm when it was deformed by HE to the strain ε=2.91. The microhardness and UTS are stable within the whole investigated range of deformation.

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39

Shin, Da Woon, Hong Min, and Jin Kyu Lee. "Microstructure and Mechanical Properties of Cu-Ni-Zr-Ti Bulk Metallic Glass Composites by Spark Plasma Sintering." Korean Journal of Metals and Materials 59, no. 5 (May 5, 2021): 281–88. http://dx.doi.org/10.3365/kjmm.2021.59.5.281.

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In the present study, Cu54Ni6Zr22Ti18 bulk metallic glass composites were developed by spark plasma sintering(SPS) using gas atomized Cu54Ni6Zr22Ti18 metallic glass powders and Ta powders. Metallic glass composites with Ta phase were fabricated by SPS. The successful consolidation of Cu54Ni6Zr22Ti18 metallic glass matrix composites with the Ta phase was achieved through the strong bonding due to the plastic deformation of the Ta powder and the super-plastic behavior of the metallic glass powder in the supercooled liquid state during SPS. The deformed Ta phases were well distributed in the Cu54Ni6Zr22Ti18 metallic glass matrix. The compressive fracture strength and total strain were 1770 Mpa and 10.2%, respectively, for the Cu54Ni6Zr22Ti18 bulk metallic glass composite with 40 wt% Ta phases. The uniformly dispersed deformed Ta phase in the Cu54Ni6Zr22Ti18 metallic glass matrix effectively impedes the propagation of the first shear band and generates a second shear band, causing a crossing of the shear bands, resulting in an improvement in plastic strain. This increase in plastic deformation is related to the fact that the deformed Ta phase, uniformly distributed in the Cu54Ni6Zr22Ti18 metallic glass matrix, acts as a source of shear bands and at the same time effectively suppresses the movement of the shear bands, dispersing the stress and causing wide plastic deformation.

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40

Perunov, Aleksandr, and Aleksey Baulin. "Systematic monitoring of the deformed state of long-length reinforced concrete structures with an assessment of their reliability." E3S Web of Conferences 263 (2021): 02003. http://dx.doi.org/10.1051/e3sconf/202126302003.

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The article shows the method of systematic monitoring of the stress-strain state of reinforced concrete structures covering one of the operated public railway stations. The description of large-span structures of the building, their defects and damages acquired during the operation of the building is given. The article describes the methodology and methods used for long-term, more than 2 years, continuous monitoring of the deformed state of coating structures in operation. The most damaged structures are examined in detail with the help of installed devices to obtain accurate data. The features of measurements in different periods of time and time of year are described. Based on the results of the obtained measurements of the stress-strain state of the building coating structures, the possibility of their further operation is predicted, taking into account the defects and damages found during the survey.

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41

Shareef, Shaik Nagul, Ch Harikrishna, M. J. Davidson, and Cherukuri Nagaraju. "Analysis of Bi-Axial and Tri-Axial State of Stresses in Plastically Deformed Solid Cylindrical Specimens under Dry Lubrication." Advanced Materials Research 585 (November 2012): 407–11. http://dx.doi.org/10.4028/www.scientific.net/amr.585.407.

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This paper explains the type of stresses induced in the AA2014 solid cylindrical specimens when deformed plastically between a set of rigid dies. The solid cylindrical specimens machined to different height(h) to the diameter(d) ratios namely h/d=1, h/d=0.75 and h/d=0.5 were compressed between the dies using a 100 ton capacity UTM. These billets were deformed to different strains. At each and every stage of the incremental strain, the various elements of the geometry such as contact diameter at the die/billet interface, bulged diameter at the equatorial region and the height after deformation were noted down. The significance of measuring the various elements of the geometry is to predict the value of stresses namely axial stress, hoop stress, hydrostatic stress and effective stress which influence the ductility or formability of the material. The stresses induced in the billets were predicted using the empirical equations and a comparison has been made for uni-axial, bi-axial and tri-axial state of stresses for different aspect ratios. A notified behavior in the value of stresses has been observed for all the aspect ratios and for different state of stresses

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42

Takahashi, Y., T. Koguchi, and K. Nishiguchi. "Effect of Bulk Deformation on Viscoplastic Adhering Process—A Numerical Study of Solid State Pressure Welding." Journal of Engineering Materials and Technology 115, no. 2 (April 1, 1993): 171–78. http://dx.doi.org/10.1115/1.2904203.

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Viscoplastic intimate contact process of uneven surfaces is numerically studied by using the finite element model proposed in our previous paper. The model treats only the case that the interfacial contact is the rate determining step of the solid state bonding process. The distribution of the equivalent strain rate around the void surface is strongly influenced by the bulk constraint conditions, i.e., the interfacial deformation is greatly affected by the bulk deformation. The strain rate at the void tip is strikingly increased by the bulk deformation, which accelerates the void shrinkage on the bond interface. If the bulk is deformed, the contacting process is also affected by the asperity angle α0 due to surface waviness. When α0 < 30 deg, the bonded area growth is mainly produced by the folding phenomena of the faying surfaces.

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43

Nath, Parswa, Saswati Ganguly, Jürgen Horbach, Peter Sollich, Smarajit Karmakar, and Surajit Sengupta. "On the existence of thermodynamically stable rigid solids." Proceedings of the National Academy of Sciences 115, no. 19 (April 19, 2018): E4322—E4329. http://dx.doi.org/10.1073/pnas.1800837115.

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Customarily, crystalline solids are defined to be rigid since they resist changes of shape determined by their boundaries. However, rigid solids cannot exist in the thermodynamic limit where boundaries become irrelevant. Particles in the solid may rearrange to adjust to shape changes eliminating stress without destroying crystalline order. Rigidity is therefore valid only in the metastable state that emerges because these particle rearrangements in response to a deformation, or strain, are associated with slow collective processes. Here, we show that a thermodynamic collective variable may be used to quantify particle rearrangements that occur as a solid is deformed at zero strain rate. Advanced Monte Carlo simulation techniques are then used to obtain the equilibrium free energy as a function of this variable. Our results lead to a unique view on rigidity: While at zero strain a rigid crystal coexists with one that responds to infinitesimal strain by rearranging particles and expelling stress, at finite strain the rigid crystal is metastable, associated with a free energy barrier that decreases with increasing strain. The rigid phase becomes thermodynamically stable when an external field, which penalizes particle rearrangements, is switched on. This produces a line of first-order phase transitions in the field–strain plane that intersects the origin. Failure of a solid once strained beyond its elastic limit is associated with kinetic decay processes of the metastable rigid crystal deformed with a finite strain rate. These processes can be understood in quantitative detail using our computed phase diagram as reference.

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44

GAL, E., M. ZELKHA, and R. LEVY. "A SIMPLE CO-ROTATIONAL GEOMETRICALLY NON LINEAR MEMBRANE FINITE ELEMENT WRINKLING ANALYSIS." International Journal of Structural Stability and Dynamics 11, no. 01 (February 2011): 181–95. http://dx.doi.org/10.1142/s0219455411004038.

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Thin pre-tensioned membranes are often used in civil architecture as well as in marine and space technologies. Lacking in-plane compression stiffness, membranes will wrinkle at certain states of stress. This paper presents a geometrically nonlinear analysis of membranes in the presence of wrinkling using a unique incremental formulation that accounts for equilibrium in the deformed state and the current wrinkling state by iterations. The membranes with wrinkling are simulated by a geometrically nonlinear upgraded version of the constant strain triangular (CST) membrane finite element. Each load step is comprised of two iteration cycles: the geometrically nonlinear cycle that ensures equilibrium in the deformed sate using the Newton–Raphson iterations and the wrinkling cycle that identifies the location and direction of the wrinkles and redistributes stresses accordingly. Finally, validation and verification of the proposed analysis is made by comparing the present results with those existing for the benchmark examples.

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45

An, Jae-Young, Suk Min Han, Young Jae Kwon, and Yeon Chul Yoo. "Continuous Dynamic Recrystallization of AISI 430 Ferritic Stainless Steel by Hot Torsion Deformation." Materials Science Forum 475-479 (January 2005): 145–48. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.145.

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The high temperature deformation behavior of AISI 430 ferritic stainless steel has been studied over a temperature range of 800 to 1000°C and strain rate of 0.05-5.0/sec. The evolution of flow stress and microstructures showed the characteristics of continuous dynamic recrystallization (CDRX). The flow stress curves gradually decreased with increasing strain over the peak stress until 500% of strain without any steady state shown in typical austenitic stainless steel. Sub-grains of low angle firstly formed along the original high angle grain boundary were propagated into the inside of original grain and transformed to high angle. The CDRX grain sizes of AISI 430 deformed at 1000 °C and 0.5/sec was about 30-35㎛.

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46

Martinkovič, Maroš, and Stanislav Minarik. "Evaluation of Grain Deformation in Polycrystals." Materials Science Forum 782 (April 2014): 41–44. http://dx.doi.org/10.4028/www.scientific.net/msf.782.41.

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Method of local strain estimation based on evaluation of relative surface area of grain boundaries in deformed and undeformed state is used very often [. Unfortunately, this method requires information about the parameter of structure in case of zero value of initial deformation. Mentioned parameter is unknown in most cases. In addition, value of parameter of structure depends on grain size and it can change in volume of material.

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47

Humphreys, John F. "Nucleation in Recrystallization." Materials Science Forum 467-470 (October 2004): 107–16. http://dx.doi.org/10.4028/www.scientific.net/msf.467-470.107.

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The nucleation of recrystallization in deformed and annealed metals is reviewed. The main mechanisms are thought to involve the growth of subgrains by low angle boundary (LAGB) migration in an orientation gradient or the strain induced boundary migration (SIBM) of existing boundaries. Although these mechanisms are reasonably well understood, the details of the dislocation recovery mechanisms which are often required before migration can occur, particularly in metals in which recovery is slow, are poorly understood. Complete experimental investigation of the nucleation event requires a 3-d in-situ technique which will resolve dislocations, and this is not currently available. Although recrystallized grains of orientations not in the deformed structure have been reported, there is as yet no substantial evidence or theory to suggest the creation of new orientations by mechanisms other than annealing twinning. It is concluded that further understanding of the deformed state is required before adequate models of nucleation can be formulated and verified.

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48

Berman, Tracy D., and John E. Allison. "Coupling Thermomechanical Processing and Alloy Design to Improve Textures in Mg-Zn-Ca Sheet Alloys." JOM 73, no. 5 (March 29, 2021): 1450–59. http://dx.doi.org/10.1007/s11837-021-04630-0.

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AbstractThe effect of Ca and Zn additions on the microstructure and texture evolution during thermomechanical processing of Mg-Zn-Ca sheet alloys was systematically investigated and quantified. Plane strain compression testing in a Gleeble thermomechanical simulator was used to physically simulate a 10-pass rolling schedule, while allowing for careful control and monitoring of the processing parameters. Textures in the as-deformed ternary alloy samples demonstrate a weak maximum basal intensity and spreading in the transverse direction. Increasing the Zn content to 3.2 wt.% in the ternary alloys resulted in samples that exhibited weak textures in the as-deformed state. Importantly, static recrystallization (SRX) during post-deformation annealing of these alloys promoted a desirable annular texture, with the c-axis tipped from the normal direction and a lower basal texture intensity. The evolution in texture during SRX is associated with as-deformed microstructures with broad grain orientation spreads and a low degree of recrystallization.

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49

Morgenstern, R., M. Videm, Knut Marthinsen, Erik Nes, and Trond Furu. "Deformation and Recrystallization Behaviour of a Homogenised and a Heterogenised Al-Mg-Si Alloy." Materials Science Forum 519-521 (July 2006): 1611–16. http://dx.doi.org/10.4028/www.scientific.net/msf.519-521.1611.

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The starting material, the deformed state, as well as the recrystallised microstructure and texture have been analysed as a function of Zener-Hollomon parameter and strain for two differently heat-treated AlMgSi alloys, deformed in torsion. An interesting and somewhat surprising observation is that the grain size was always higher in the material heat treated to form large Mg2Si particles. Moreover, no indications of PSN effects were observed in any of the materials, even at the highest Zener-Hollomon parameters. This observation was quite unexpected as the highest Zener-Hollomon parameters were well above the typical critical level for which significant PSN effects have been observed in similar alloys. The results have been carefully analysed and possible explanations are discussed.

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Paul, Henryk. "Microstructural and Textural Aspects of Shear Banding in Plane Strain Deformed Fcc Metals." Solid State Phenomena 160 (February 2010): 257–64. http://dx.doi.org/10.4028/www.scientific.net/ssp.160.257.

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Periodic crystal lattice rotations within compact clusters of shear bands, developed in copper, have been characterized over a range of scales by optical microscopy, high resolution FEG-SEM-EBSD and TEM orientation mapping, to examine the role of local lattice re-orientation on slip propagation across pre-existing barriers to dislocation motion. Two different cases were analysed in detail. The single crystal analysis addresses the relation between the crystallographic microtexture and microstructure development due to the crystal anisotropy after a strain path change. All the changes in strain path directly lead to crystallite subdivisions and strain localization in the form of macroscopically visible bands of different morphology at the micro scale. The elongated cell substructure formed during primary straining was the source of anisotropy after changing deformation path. It is thought that the presence of this structure (here subcells) as barriers to dislocation motion is crucial for the occurrence of shear banding. The analysis of pure polycrystalline copper has been focused on the influence of local lattice re-orientations within particular grains on slip propagation across grain boundaries. The crystal lattice rotated in such a way that one of the {111} slip planes became nearly parallel to the direction of maximum shear (due to the actual state of anisotropy). A natural consequence of this rotation was the formation of a specific microtexture which facilitated slip propagation across grain boundaries.

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Journal articles on the topic 'Strain-deformed state'

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