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19 records found
1.
Xia, K. and G. Tausig (1998). "Liquidus casting of a wrought aluminum alloy 2618 for thixoforming." Materials Science and Engineering A 246: 1-10.
2.
Xiang-dong, H., W. Yuan-li, et al. (2004). "Microstructure and mechanical properties of low carbon steel strips produced by EAF-CSP process." Journal of Iron and Steel Research 16(3): 55-59.
Low carbon steel strips produced by EAF-CSP process were studied. It is shown that the strips with fine and uniform microstructure have higher strength. Ductile fracture was observed in tensile test. EBSD results showed that grain boundaries in ferrite are basically high angle boundaries without remarkable preferred orientation. Only small amount of micro-non-metallic inclusions was found in the strips due to high cooling rate of the slabs during and after solidification as well as the high cleanliness of molten steel. Thus greater elongation of steel strips was observed.
3.
Xiao, L. G. (1988). "On the Phenomena Related to the Dynamic Strain Aging in Alpha-Brass." Scripta Metallurgica 22(2): 179-182.
4.
Xie, C. L., S. Ghosh, et al. (2004). "Modeling Cyclic Deformation of HSLA Steels Using Crystal Plasticity." Journal of Engineering Materials and Technology 126(4): 339-352.
High strength low alloy (HSLA) steels, used in a wide variety of applications as structural components are subjected to cyclic loading during their service lives. Understanding the cyclic deformation behavior of HSLA steels is of importance, since it affects the fatigue life of components. This paper combines experiments with finite element based simulations to develop a crystal plasticity model for prediction of the cyclic deformation behavior of HSLA-50 steels. The experiments involve orientation imaging microscopy (0IM) for microstructural characterization and mechanical testing under uniaxial and stress-strain controlled cyclic loading. The computational models incorporate crystallographic orientation distributions from the OIM data. The crystal plasticity model for bcc materials uses a thermally activated energy theory for plastic flow, self and latent hardening, kinematic hardening, as well as yield point phenomena. Material parameters are calibrated from experiments using a genetic algorithm based minimization process. The computational model is validated with experiments on stress and strain controlled cyclic loading. The effect of grain orientation distributions and overall loading conditions on the evolution of microstructural stresses and strains are investigated.
5.
Xie, J.-j., F.-s. Shangguan, et al. (2005). "Method for determining crystal orientation of fracture facet using electron back-scattering diffraction." Journal - Chinese Electron Microscopy Society 24(6): 547-550.
6.
Xie, Y., H.-R. Wenk, et al. (2003). "Plagioclase preferred orientation by TOF neutron diffraction and SEM-EBSD." Tectonophysics 370: 269-286.
The lattice preferred orientation (LPO) of an anorthosite (composed of andesine) sampled from a highly deformed anorthositic mylonite (Grenville Province, Quebec) was measured by TOF neutron diffraction and SEM-EBSD. The quantitative texture analysis of neutron data was accomplished by using the Rietveld texture analysis with the WIMValgorithm, implemented in the program package Materials Analysis Using Diffraction (MAUD). The texture calculations of the EBSD data were performed by using the program BEARTEX. Analyses from neutron and electron diffraction data gave similar results if EBSD data are smoothed to account for grain statistics. The principal pole figures show (010) roughly parallel to the rock foliation, (001) poles exhibiting a low angle (~25°) to the pole to foliation, and (100) poles close to the Y-direction (perpendicular to the lineation and foliation pole). The [100] crystallographic direction shows a maximum in the lineation direction, [010] directions concentrate near the foliation pole. The geological deformation conditions and the constructed pole figure patterns indicate that the preferred orientation could be attributed to intracrystalline slip dominantly on (010) with [100] as slip direction. Elastic properties, calculated by averaging, document weak anisotropy that has implications for the seismic structure of the lower crust.
7.
Xing, Q., X. Huang, et al. (2004). Microstructural Coarsening during Annealing of Cold Rolled Aluminum. Second Joint International Conference on Recrystallization and Grain Growth, ReX & GG2, SF2M, Annecy, France, Trans Tech Publications Ltd.
8.
Xinghao, D. and W. Baolin (2005). "Continuous Dynamic Recrystallization of Extruded NiAl Polycrystals during the Superplastic Deformation Process." Metallurgical and Materials Transactions A 36A(12): 3343-3351.
The tensile deformation behavior and the associated mechanism of extruded Ni50Al50 polycrystals were systemically investigated. The superplastic deformation behavior was observed at certain conditions. The deformation microstructures consisted of subgrains, low-angle grains, and high-angle grains, meaning that a continuous dynamic recrystallization (CDRX) process was operating. This finding suggests that the relative balance between comparable work hardening (dislocation glide) and dynamic work softening (CDRX) results in the occurrence of superplastic deformation process.
9.
Xin-Ming, Z., D. Yu-Xuan, et al. (2003). "Development of cube texture in multistage annealing of high purity aluminum foils." Transactions of the Nonferrous Metals Society of China 13(6): 1389-1393.
The development of cube texture ({001}<100>) in high purity (99.99%) aluminum foils in multistage annealing was investigated by ODF and EBSD It is found that a multistage annealing process can strengthen cube texture markedly, and that each stage of the multistage annealing plays an important eigen role in nucleation and growth of the cube orientation grains. The cube orientation grain nucleates preferably at 180 degrees C because of its low activation energy of nucleation, the cube nuclei grow favorably at 400 degrees C because of the anisotropy of 40 degrees <111> growth. and the cube texture is further strengthened at 550 degrees C and becomes prodominent because of favorable bigger grain sizes.
10.
Xu, K. and A. M. Russell (2004). "Texture–strength relationships in a deformation processed Al–Sn metal–metal composite." Materials Science and Engineering A 373: 99-106.
A powder mixture of 80 vol.% face centered cubic (fcc) Al and 20 vol.% body centered tetragonal (bct) Sn was heavily deformed by extrusion and swaging to form a composite consisting of Sn filaments in an Al matrix. The fiber texture was determined by orientation imaging microscopy to be <1 0 0> for the Al and <1 0 0> for the Sn. The Sn phase deformed into a convoluted ribbon shape; a microstructure which has usually been attributed to texture of the filaments constraining their deformation to plane strain. Texture in a Sn filament deforming at room temperature is unlikely to limit Sn to a plane straining mode, which suggests that a different mechanism may be producing the ribbon-shape of these filaments. The 290MPa ultimate tensile strength of the composite was greater than the rule-of-mixtures prediction. Comparisons are made with Al–Nb, Al–Ti and Al–Mg deformation processed metal–metal composites and to various strengthening models for metal–metal composites.
11.
Xu, P., F. Yin, et al. (2004). Texture Gradient of As-Cast Low-Carbon Thin Steel Slab. Materials Science & Technology 2004, New Orleans, Louisiana, USA, The Association for Iron and Steel Technology (AIST) and TMS (The Minerals, Metals and Materials Society).
The compact strip production technology composed of thin slab casting and direct hot rolling has attracted broad attention due to its apparent cost advantage and microstructure improvement merits. In order to provide a whole evaluation to the homogeneity of microstructure and mechanical properties of the as-cast steel slab, microstructure and plastic anisotropy of the through-thickness sections in a low-carbon steel thin slab were investigated. Textures in all the through-thickness sections are mainly composed of relatively strong ã-fiber and weak {001}<uvw> components. The ã-fiber orientation components reach the maximum intensity corresponding to the largest rm value in the middle layer near S=0.4 (S is the normalized distance from the slab center to the specific layer and S of the slab surface layer is 1.0). The average grain size of the ã-fiber oriented ferrite grains exhibits a roof-shape variation with the through-thickness position. The lower carbon content in the surface layer, which shows the weakest {111}<uvw> components, is responsible for the abnormally larger rm value in that layer. In spite of the relatively strong {111}<uvw> component intensity in the center layer, the solidified shrinkage cavities and the large inclusions is considered to cause the lowest rm value.
12.
Xu, P., F. Yin, et al. (2004). "The Thickness Gradient of Microstructure and Mechanical Property in an as cast Thin Steel Slab." Materials Transactions 45(7): 2456-2462.
Steel Research Center, National Institute for Materials Science, Tsukuba 305-0047, Japan The compact strip production (CSP) technology composed of thin slab casting and direct hot rolling has attracted much attention due to its apparent cost advantage. In this paper, the microstructural and textural variations in the through-thickness direction and their effects on the plastic anisotropy gradient in a thin-slab-cast low-carbon steel are investigated by optical metallography (OM), orientation imaging microscopy (OIM), transmission electron microscopy (TEM) and quantitative X-ray texture analysis. The thin steel slab shows a relatively uniform strength-ductility balance with the exception of the surface and center layers. The textures in all the through-thickness layers are composed of relatively strong (111} (uvw) and weak (001) (uvw) components which reach their maximum intensities in the middle layer near S = 0.4 and in the center layer, respectively (S is the normalized distance from the slab center to the specific layer and S to the slab surface is 1.0). The y-fiber oriented ferrite exhibits a roof-shape tendency of the average grain size variation in the through-thickness direction. The lower carbon content in the surface layer is responsible for the better normal anisotropy (r, value) even with the weakest {111) (uvw) component. In spite of the relatively strong [Macro error: Can’t compile this script because “\” is an illegal character.]
(uvw) component intensity in the center layer, the lowest rvalue is related to the solidified shrinkage cavities and the large MnS inclusions.
13.
Xu, W.-P., L. Xing, et al. (2005). "Analysis of the grain orientation and texture of friction stir welded magnesium alloy lap joints." Cailiao Kexue Yu Gongyi (Material Science and Technology) (China) 13(3): 254-257.
The grain orientations and microtextures in a friction-stir-welded magnesium alloy lap joint, AZ80A, with a nugget zone were analyzed by Electron Back Scattered Diffraction (EBSD) and Orientation Imaging Microscopy (OIM). The results showed that there were two kinds of microcosmic processes during FSW. One was the plastic deformation, the other was the dynamic re-crystallization. In the nugget zone, texture intensities were not high and orientations were variety. From top to bottom in the nugget zone, deformation texture of {1, -1, 0, 4} < 1. 0, -1, 0 > was stronger and stronger, the number of re-crystallization orientations was more and more. Deformation texture of {1, -1, 0, 4} < 1, 0, -1, 0 > was inherited by the grains in the nugget zone from the base metal. Re-crystallized grains in the nugget zone were formed by a continuous dynamic re-crystallized mechanism.
14.
Xu, X., R. M. Ward, et al. (2002). "Tree-Ring Formation during Vacuum Arc Remelting of INCONEL 718: Part I. Experimental Investigation." Metallurgical and Materials Transactions A 33(June): 1795-1804.
15.
Xu, X., W. Zhang, et al. (2002). "Tree-Ring Formation during Vacuum Arc Remelting of INCONEL 718: Part II. Mathematical Modeling." Metallurgical and Materials Transactions A 33(June): 1805-1815.
16.
Xua, W. and M. Ferry (2005). Influence of starting microstructure on texture development in cold rolled and annealed low carbon steel strip. Textures of Materials - ICOTOM 14, Leuven, Belgium, Trans Tech Publications.
The effect of initial microstructure on the recrystallization behaviour and texture development of low carbon (LC) steel was investigated. Steel strip samples (0.05 wt.% C) of 2 mm in thickness were heat treated to produce a microstructure consisting predominantly of either polygonal ferrite or acicular ferrite. Samples were cold rolled 50, 70 and 90% reduction then annealed for various times in the temperature range 580-640°C. The microstructures and textures produced by deformation and annealing were studied by optical microscopy and electron backscatter diffraction in the SEM. The initial microstructure was found to have a substantial influence on the rate of recrystallization and final texture. It was found that polygonal ferrite recrystallizes more rapidly than acicular ferrite with the former generating the strongest <111>//ND recrystallization texture. The results are examined within the framework of improving the formability of LC steel produced by direct strip casting whereby controlled thermal and mechanical processing prior to cold rolling and annealing can generate the same types of initial microstructures, as studied in this work.
17.
Xue, Q., G. T. G. III, et al. (2005). "Influence of Shock Prestraining on the Formation of Shear Localization in 304 Stainless Steel." Metallurgical and Materials Transactions A 36A(6): 1471-1486.
Adiabatic shear localization was studied in both annealed (as-received) and shock-prestrained 304 stainless steels (304 SS). A forced shear technique was used to probe the evolution of shear localization under high-strain-rate loading using a compression split-Hopkinson pressure bar (SHPB) and hatshaped specimens. The shearing responses of the shock-prestrained steel at high strain rate indicate that they exhibit a higher initial yield strength but a lower work-hardening rates than those observed in the annealed steel. The shock-prestrained specimens, having achieved an unstable condition at a smaller plastic displacement and a lower flow stress, were seen to exhibit distinct sharp-edged bands. Corresponding comparisons between the mechanical responses and the deformed microstructures demonstrate that loading-path dependency exerts a strong influence on shear-band formation. The shock-prestrained 304 SS displayed a higher incidence of deformation twins, slip bands, and dislocation debris prior to the shear tests; this substructure suppressed further dislocation storage (work hardening) and thereby facilitated the propensity for shear localization.
18.
Xun, Y. and M. J. Tan (2004). "Microstructure evolution during high-temperature deformation of 8090 Al-Li alloy." Materials and Manufacturing Processes 19(3): 373-389.
The microstructure evolution of an as-processed 8090 Al-Li alloy during high temperature deformation has been investigated with emphasis on the dynamic grain size refinement and the formation of high-angle grain boundaries. Tensile tests were conducted at temperatures 470-560 degrees C and initial strain rates of 10-2-10-6s-1. The starting and deformed samples were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron backscattered diffraction (EBSD). The material showed a maximum elongation to failure of 660% at 530 degrees C and strain rate of 10-3s-1. A microstructural transformation from coarse grains to uniform fine microstructure through dynamic recrystallization (DRX) was observed. The DRX process was characterized by (1) a bimodal microstructure, (2) a gradual increase in average boundary misorientation angles, and (3) a gradual decrease of microtexture. The development of high angle boundaries was attributed to the absorption of dislocations into subboundaries and the grain boundary sliding (GBS)-induced subgrain rotation. The microstructural evolution was suggested to be responsible for the superplastic behavior observed in this as-processed material.
19.
Xun, Y., M. J. Tan, et al. (2005). "EBSD characterization of cavitation during superplastic deformation of Al–Li alloy." Journal of Materials Processing Technology 162-163(Special Edition): 429-434.
The cavitation microstructure of an Al–Li alloy was characterized using electron backscatter diffraction (EBSD). The results showed clear evidence of the correlation between grain boundary sliding and cavity development. It is proposed that the stress concentrations arising at boundary irregularities such as second-phase particles, boundary ledges, and triple junctions were responsible for the development of cavitation at the high angle boundary between two groups of grains and that sliding takes place as a unit.
19 records found
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