Papers by Keyword: Deformation Texture

Abstract: Evolution Texture and microstructure has been investigated in a Fe-14Mn-6Si-9Cr-5Ni shape memory alloy during cold rolling and annealing. The starting solution-annealed material show a nearly random texture with microstructure composed of equi-axed austenite grains with some e martensite plates inside. Cold rolling induces a strong alloy type texture with Brass {011}<211> and Goss {011}<100> as major components. Annealing of the cold deformed material produces a nearly random texture. The microstructural investigation reveals that with increasing cold deformation the amount of stress induced e and a’ martensite volume fraction increases. The electron back scattered diffraction (EBSD) phase mapping shows that reversion of the e martensite starts only after commencement of recrystallization.

Abstract: Texutre evolution of 1235 aluminum alloy deformed at different strain rates was studied by dynamic thermal-simulated technology with the aid of some modern analytical and testing technique called election backscatter diffraction (EBSD). The results showed that the effect of strain rate on grain boundary and deformation texture of 1235 aluminum alloy was obvious. At deformation temperature for 400°C and distortion for 50%, the value of the maximum density level came to the minimum by 11.489 at the strain rate for 0.01s^-1. The texture was weaker for the grains were less likely to rotate. The relative volume of textures increased as the strain rate increasing. The relative volume of textures was merely 1.95% at strain rate for 0.01s^-1 but ascended to 5.4% at strain rate for 50s^-1.

Abstract: With the entrance temperature at 300°C, cold mill rolling produced deformation texture transition from brass type to copper type in worked 85/15 α-brass. From the texture and TEM scale microstructure evidence, it is suggested that, rather than deformation twinning, recovery and easy cross slip favor in the deformation process, as the interior working temperature falls into the texture transition range proposed by Tranchant.

Abstract: It is well known that the deformation and recrystallisation of metals and alloys are accompanied by changes in texture and microstructure. These changes can lead to anisotropy in metal flow and affect the formability of sheet metals. Therefore, a significant amount of research on the development of textures and the principles governing them has been conducted in recent years. One of the most important factors contributing to the texture development of materials is the initial grain size. Unlike other factors such as stacking fault energy, strain and deformation temperature, relatively little work has been carried out on the effect of grain size on texture development, even though a considerable understanding exists regarding the effect of grain size on work hardening and recrystallisation kinetics upon annealing. Hence, this research describes the effect of the initial hot band grain size on the development of texture during cold rolling and subsequent annealing.

Abstract: The drawing textures of aluminum, copper, gold, silver, and Cu-7.3% Al bronze wires are approximated by major <111>+minor <100>, except silver wire, which can have the <100> texture at extremely high reductions. The <111> component in the drawing textures of aluminum, copper, gold, and silver transform to the <100> component after recrystallization. On the other hand, the <111> deformation texture of the Cu-7.3% Al bronze wire, which has very low stackingfault- energy, remains unchanged after recrystallization. The <100> + <111> recrystallization textures change to the <111> texture after abnormal grain growth. The Brass component {110}<112> in rolling textures of high stacking-fault-energy metals such as aluminum, copper, Cu- 16% Mn, and Cu-1% P changes to the Goss orientation {110}<001> after recrystallization. However, the Brass orientation in rolling textures of low stacking-fault-energy fcc metals such as brass and silver appears to change to an orientation approximated by the {236}<385> orientation after annealing. The texture changes are discussed based on the strain-energy-release-maximization model for medium to high stacking-fault-energy metals and on grain growth for low stacking-fault energy metals.

Abstract: Nucleation and normal or abnormal grain growth of new grains have been observed in several metals and alloys during annealing after various levels of strain (from few percents for abnormal grain growth in steel and aluminium to 90 % strain for static recrystallization of highly deformed copper, zirconium and steel). For each of these cases, the links between the initial deformation state of the polycristalline samples and their final textures after annealing are analyzed in some details, by taking into acount the distribution of orientations and misorientations within the samples, as well as the repartition of stored energy . With the help of polycristalline models for the simulation of deformation and recrystallization processes, some general conclusions regarding the nucleation and growth processes are finally drawn.

Abstract: Finite element models for metal forming and models for the prediction of forming limit strains should be as accurate as possible, and hence should take effects due to texture, microstructure and substructure (dislocation patterns) into account. To achieve this, a hierarchical type of modelling is proposed in order to maintain the balance between calculation speed (required for engineering applications) and accuracy. This means that the FE models work with an analytical constitutive model, the parameters of which are identified using results of multilevel models. The analytical constitutive model will be discussed, as well as the identification procedure. The multilevel models usually connect the macro-scale with a meso-scale (grain level) via a homogenisation procedure. They can also be used to make predictions of deformation textures. These will be quantitatively compared with experimentally obtained rolling textures of steel and aluminium alloys. It was found that only models which to some extent take both stress and strain interactions between adjacent grains into account perform well. Finally an example of a three level model, also including the micro-scale (i.e. the dislocation substructure), will be given.

Abstract: Thermoelectric oxide Bi1.5Pb0.5Sr1.7Y0.5Co2O9- δ is produced by sintering method. Uniaxial compression deformation is performed on the oxide under various strain rates at 1113K, close to the melting temperature. After deformation, density, microstructure, texture and thermoelectric characteristics such as specific electric resistance and Seebeck coefficient, are experimentally studied. Deformation mechanism is examined by stress change test. It is found that the oxide plastically deforms mainly by the motion of dislocations at the present temperature, resulting in an increase in density as well as the development of texture. It is concluded that the specific electric resistance extensively decreases by the high temperature compression deformation through densification and texture development.

Abstract: Theories of the pencil glide theory for bcc metal and MPG(modified pencil glide) theory for fcc metal are reviewed. Interest is focused to both analogy and difference in derivation of the theories. Some visualization figures using them are introduced. At last, it is informed that the authors have opened both the bcc pencil glide theory and MPG(fcc) theory on website publication which calls everybody to look and download the fundamentals, applications, visualization , procedure of calculation and C program for calculation for the both pencil glide theories.

Abstract: Texture evolution and microstructure development of hot extruded pure magnesium and the magnesium alloy AZ31 deformed by plane strain deformation at select temperatures and strain rates were investigated using X-ray techniques, electron back scattered diffraction (EBSD) and optical microscopy. At a deformation temperature of 200 °C both materials showed a heterogeneous microstructure consisting of highly deformed zones appearing as huge grains or bands and of very small (~ 3 μm) grains. High temperature deformation (400 °C) gave rise to completely different microstructures. Changing of deformation conditions, i.e. the temperature and strain rate resulted in different final textures. At high deformation temperature and low strain rate the formation of a basal texture was suppressed.