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Modeling Of Texture Evolution During Hot Forging Of Alpha Beta Titanium Alloys Preprint
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Book Synopsis Modeling of Texture Evolution During Hot Forging of Alpha/Beta Titanium Alloys (Preprint). by :
Download or read book Modeling of Texture Evolution During Hot Forging of Alpha/Beta Titanium Alloys (Preprint). written by and published by . This book was released on 2007 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Texture development during the subtransus hot forging of alpha/beta titanium alloys with an equiaxed-alpha microstructure was modeled using the Los Alamos Polycrystalline Plasticity (LApp) code and 111 pencil-glide polycrystalline plasticity code coupled with the finite-element-method (FEM) program DEFORM. The methodology treated the partitioning of the imposed strain between the alpha and beta phases, and thus enabled the prediction of the distinct deformation textures developed in the primary alpha and beta matrix during hot working. Two variant selection rules in conjunction with the beta deformation texture were also examined to establish a method for predicting the transformation texture of secondary alpha developed as a result of beta decomposition during cool-down following forging or heat treatment. The approach was validated via an industrial-scale trail comprising hot pancake forging of Ti-6Al-4V.
Book Synopsis Modeling and Simulation of Texture Evolution During the Thermomechanical Processing of Titanium Alloys (PREPRINT). by :
Download or read book Modeling and Simulation of Texture Evolution During the Thermomechanical Processing of Titanium Alloys (PREPRINT). written by and published by . This book was released on 2008 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of crystallographic texture, the preferred orientation of grains in a polycrystalline aggregate, during thermomechanical processing (TMP) can play an important role with regard to the secondary-forming response (e.g., deep drawing of sheet) and service performance (e.g., strength, elastic modulus, ductility, fracture toughness) of metallic materials. Crystallographic texture, or simply texture for succinctness, may arise as a result of large-strain deformation, dynamic/static recrystallization, grain growth, or phase transformation. A second form of anisotropy, mechanical texturing or mechanical fibering, refers to the alignment of microstructure, inclusions, etc., during deformation processes and may also affect mechanical properties such as ductility and fracture toughness. This latter form of texture is not discussed in the present article.
Book Synopsis Modeling of Microstructure Evolution During the Thermomechanical Processing of Titanium Alloys (Preprint). by :
Download or read book Modeling of Microstructure Evolution During the Thermomechanical Processing of Titanium Alloys (Preprint). written by and published by . This book was released on 2008 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt: Titanium and titanium alloys are widely used for a variety of aerospace, chemical, marine, and other specialty applications because of their high strength, low density, good ductility, fatigue and corrosion resistance, as well as other properties. Depending on the application, a specific property (or combination of properties) can be obtained through microstructural modification. Microstructure evolution and control in titanium alloys is heavily dependent on the allotropic transformation from a hexagonal-close-packed crystal structure (denoted as alpha phase) found at low temperatures to a body-centered-cubic crystal structure (denoted as beta phase) at high temperatures. For pure titanium, this occurs at 882 deg C. In many titanium alloys, the beta phase is partially stabilized at lower temperatures, and the equilibrium volume fractions of alpha and beta vary with temperature. The temperature at which a specific alloy becomes entirely beta is called the beta transus. The conditions used for hot working and heating/heat treatment are often selected relative to the beta-transus temperature.
Book Synopsis The Deformation and Texture Evolution of Ti-10V-2Fe-3Al by : Juan Zhao
Download or read book The Deformation and Texture Evolution of Ti-10V-2Fe-3Al written by Juan Zhao and published by . This book was released on 2015 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt: Beta titanium alloys form one of the most versatile classes of materials with respect to processing, microstructure, and mechanical properties. Owing to their body centered cubic structure, [beta] titanium alloys offer an attractive alternative to the [alpha]+[beta] and [alpha] alloys as they usually possess higher specific strengths, better heat treat ability, deep hardening properties, and lower processing temperatures. However, beta titanium alloys are very sensitive to deformation parameters and may produce quite different microstructures and further various mechanical properties. It is necessary to explore the effect of deformation parameters on the microstructure evolution, including testing temperature, strain rate and strain.Texture introduced by deformation may produce a strong anisotropy of mechanical and other properties, and can also lead to the localization of these properties. Therefore, in order to make use of the advantages of [beta] titanium alloys, we must also understand the evolution of texture.The aim of this project is to reveal the deformation mechanisms and the evolution of texture during hot deformation in [beta] titanium based on compression tests, optical microscopy (OM), scanning electron microscopy (SEM) and texture evolution by Electron backscattered diffraction (EBSD) and x-ray texture observation.The microstructure, texture and mechanical response of forged Ti-10V-2Fe-3Al plates were investigated. Forged plates of as-received Ti-10V-2Fe-3Al alloy features fine [alpha] phase in large [beta] grains. Yield locus tests were performed which confirmed that [beta] phase {001} 110 texture resulted in lower mechanical anisotropy in the forged plate. The relationship between [alpha] phase and [beta] matrix texture was characterized by EBSD. The Burgers relationship is observed between these two phases in the as-received state, and this is preserved from the forging process and following 760 °C heat treatment. After further heat treatment at 820 °C, both [beta] phase and [alpha] phase form recrystallization textures and the Burgers relationship is no longer obvious. Furthermore, through thickness texture inhomogeneity was studied in the as-received plate. A rotated cube texture is widely spread at the surface, and more intense at quarter thickness and center. At the surface there is a tendency to form the {111} 112 recrystallization texture while in the quarter thickness and center, the restoration mode is mainly recovery.Following solution treatment in single [beta] phase field, deformation in [alpha]+[beta] phase field was performed, which presented a considerable effect on [alpha] phase morphologies. The microstructure of [alpha] phase is basically an evolution of lamellar [alpha] breaking up into shorter lamellar and coarsening into globular morphologies. Dynamic recovery is the main restoration mechanism for [beta] phase. The dominant orientations of beta phase include a strong rotated cube texture and weak 111 orientations parallel to compression direction. The orientation relationship between [alpha] phase and [beta] matrix follows the Burgers relationship and deformation in [alpha]+[beta] phase field does not destroy this orientation relationship.Deformation at above [beta] transus temperature leads to strong 001 and weak 111 textures. With increasing temperature and decreasing strain rate, the 001 texture gets strengthened gradually and 111 orientations show weakening tendency. The volume fractions of dynamic recrystallization are lower than 10% under all the deformation conditions in the single [beta] phase field, showing the main dynamic restoration mechanism is also dynamic recovery at above [beta] transus temperature tested in this thesis. Moreover, deformation parameters show significant effects on microstructure evolution. At low strain rate, dislocation annihilation and dynamic recovery are very effective, resulting in significantly larger subgrain size and less pancaked original grains. Besides dynamic recovery, continuous dynamic recrystallization by progressive lattice rotation is also observed, which occurs at high strain rate and low temperature. Geometric dynamic recrystallization hardly occurs, as HAGB spacing is much larger than the subgrain size at the highest strain of 0.9. Discontinuous dynamic recrystallization is rarely observed in the sing [beta] phase field in Ti-10V-2Fe-3Al.
Book Synopsis Modeling of Mechanical Properties in Alpha/beta-Titanium Alloys by : Sujoy Kumar Kar
Download or read book Modeling of Mechanical Properties in Alpha/beta-Titanium Alloys written by Sujoy Kumar Kar and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The accelerated insertion of titanium alloys in component application requires the development of predictive capabilities for various aspects of their behavior, for example, phase stability, microstructural evolution and property-microstructure relationships over a wide range of length and time scales. In this presentation some novel aspects of property-microstructure relationships and microstructural evolution in alpha/beta Ti alloys will be discussed. Neural Network (NN) Models based on a Bayesian framework have been developed to predict the mechanical properties of alpha/beta Ti alloys. The development of such rules-based model requires the population of extensive databases, which in the present case are microstructurally-based. The steps involved in database development include producing controlled variations of the microstructure using novel approaches to heat-treatments, the use of standardized stereology protocols to characterize and quantify microstructural features rapidly, and mechanical testing of the heat-treated specimens. These databases have been used to train and test NN Models for prediction of mechanical properties. In addition, these models have been used to identify the influence of individual microstructural features on the mechanical properties, consequently guiding the efforts towards development of more robust mechanistically based models. In order to understand the property-microstructure relationships, a detailed understanding of microstructure evolution is imperative. The crystallography of the microstructure developing as a result of the solid-state beta to beta + alpha transformation has been studied in detail by employing Scanning Electron Microscopy (SEM), Orientation Imaging Microscopy (in a high resolution SEM), site-specific TEM sample preparation using focused ion beam, and TEM based techniques. The influence of variant selection on the evolution of microstructure will be specifically addressed.
Book Synopsis COLLABORATIVE RESEARCH AND DEVELOPMENT (CR & D) Delivery Order 0043: Deformation and Texture Development During Hot Working of Titanium by :
Download or read book COLLABORATIVE RESEARCH AND DEVELOPMENT (CR & D) Delivery Order 0043: Deformation and Texture Development During Hot Working of Titanium written by and published by . This book was released on 2008 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research in support of the Air Force Research Laboratory Materials and Manufacturing Directorate was conducted at Wright-Patterson AFB, Ohio from 3 November 2005 through 31 January 2008. This task developed constitutive models for alpha/beta titanium alloys with colony-alpha microstructure and validated texture prediction models for plate rolling. A method for separating the textures of primary alpha [alpha(sub p] and secondary alpha [alpha(sub s)] in alpha/beta titanium alloys with a duplex microstructure was developed. Utilizing electron backscatter diffraction (EBSD) and energy-dispersive spectroscopy (EDS), the approach relies on the non-uniform partitioning of alloying elements between primary alpha and regions containing secondary-alpha lamellae and residual beta matrix phase. The method was evaluated using samples of Ti-6Al-4V for which vanadium partitions strongly to secondary alpha + beta regions. The technique thus provides a useful tool for quantifying the evolution of deformation texture in the primary alpha and transformation texture in secondary alpha formed via decomposition of the beta matrix following hot working or final heat treatment.
Book Synopsis Beta Forging of Titanium Alloys by : H. J. Henning
Download or read book Beta Forging of Titanium Alloys written by H. J. Henning and published by . This book was released on 1968 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report discusses the current situation in beta forging of titanium alloys, based on a literature search plus the author's personal interviews with both using and forging industries. Manufacturers and users of beta forgings are listed in the report. Strength and fatigue properties of beta forgings are described and compared with the properties in structures forged by conventional means. Control of properties by microstructural control is discussed and illustrated by several photographs. Forging designs and practices are discussed. (Author).
Book Synopsis Texture Strengthening of Heat-treated Alpha-beta Titanium Alloys by : J. M. Fitzpatrick
Download or read book Texture Strengthening of Heat-treated Alpha-beta Titanium Alloys written by J. M. Fitzpatrick and published by . This book was released on 1969 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Effect of Thermo-Mechanical Treatment on Texture and Microstructure Evolution of Polycrystalline Alpha Titanium by :
Download or read book Effect of Thermo-Mechanical Treatment on Texture and Microstructure Evolution of Polycrystalline Alpha Titanium written by and published by . This book was released on 2005 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present work attempts to establish a unified path model for characterization as well as prediction of microstructure evolution in terms of texture and micro-texture, in commercially pure titanium that has undergone thermo-mechanical processing. Two deformation temperatures, room temperature (cold rolling) and 260C (warm rolling), and five different deformation levels of 20%, 40%, 60%, 80% and 95% were used in the present investigation. In this report only the experimental results of texture analysis is presented. The modeling of processing path model, texture evolution and the experimental results for other temperature ranges will be presented elsewhere.
Book Synopsis Texture Evolution During Laser Direct Metal Deposition of Ti-6Al-4V. by :
Download or read book Texture Evolution During Laser Direct Metal Deposition of Ti-6Al-4V. written by and published by . This book was released on 2016 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Titanium alloys are used in a wide variety of high performance applications and hence the processing of the titanium and the resulting microstructures after additive manufacturing has received significant attention. During additive manufacturing the processing route involves the transition from a liquid to solid state. The addition of successive layers results in a complex microstructure due to solid-state transformations. The current study focuses on understanding the phase transformations and relate it to the transformation texture in Ti-6Al-4V to identify conditions leading to a strong alpha transformation texture. The as deposited builds were characterized using optical microscopy and electron backscattered diffraction. The results showed columnar prior [beta] grains with a martensitic structure after the deposition of a single layer. On subsequent depositions the martensitic microstructure decomposes to a colony and basketweave microstructure with a stronger transformation texture. The alpha texture with a colony and basketweave microstructure shows a stronger transformation texture as a result of variant selection. Thus by controlling the cooling rate of the build from the [beta] transus it is possible to control the alpha transformation texture.
Book Synopsis The Development of Textures and Microstructures in Alpha/beta Titanium Alloys by : Dhriti Bhattacharyya
Download or read book The Development of Textures and Microstructures in Alpha/beta Titanium Alloys written by Dhriti Bhattacharyya and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The relationship between the texture and the microstructure of both beta processed and alpha/beta processed Ti alloys has been examined in this study. In the beta-processed microstructures, it has been shown that two sets of alpha colonies sharing a common 0001 plane and rotated by 10.5° from each other may have growth directions which have very large angles of about 80.7° between them. Moreover, it was observed that alpha laths growing from certain prior beta grain boundaries sometimes shared common basal planes. In some special cases, the alpha laths growing into two different prior beta grains from the grain boundary between them had almost exactly the same orientation, although they had vastly different growth directions. Additionally, there were some cases in which alpha laths growing into different prior beta grains not only had the same crystallographic orientation, but also had the same growth direction. Scanning Electron Microscopy (SEM), Orientation Imaging Microscopy (OIM) and Transmission Electron Microscopy (TEM) have been used to investigate these phenomena and the existing theories of growth directions have been used in conjunction with the results obtained to explain them. In alpha/beta-processed alloys, the phenomenon of globularization of alpha laths breaks down the beta-processed microstructure and modifies the texture of these alloys. Samples of Ti-6Al-4V having colony and basketweave microstructures were hot deformed in the high alpha/beta temperature range and their microstructure and microtexture were examined by the use of SEM and OIM. It is shown that the samples which had a colony microstructure had greater "clustering" of grains with similar orientations than those having a basketweave microstructure. The mode of transformation on heating from the alpha to the beta phase was investigated by measuring the texture of both phases at different temperatures, in situ, using the HIPPO instrument at the Los Alamos Neutron Science Center. A comparison of the pole figures for both phases has allowed an insight into the mode of transformation of the alpha to the beta phase, and it appears that the beta phase forms by the growth of the preexisting beta, and not by fresh nucleation of beta in the alpha phase.
Book Synopsis Defect Occurrence and Modeling for the Thermomechanical Processing of Aerospace Alloys (Preprint). by :
Download or read book Defect Occurrence and Modeling for the Thermomechanical Processing of Aerospace Alloys (Preprint). written by and published by . This book was released on 2007 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mechanism-based models for the evolution of defects during the thermomechanical processing of aerospace titanium- and nickel-base alloys are described. These defects include those comprising microstructural/metal-flow irregularities and those that are damage-related (i.e., cracks and cavities.). The development of undesirable/non-uniform microstructures and cavities during the mill processing of alpha/beta titanium alloys is addressed first. Relatively simple, diffusion-based models of spheroidization and coarsening are applied to quantify the propensity for microstructure non-uniformities. Similarly, first order micromechanical models have been formulated to estimate the effect of local crystallographic texture on non-uniform flow, the generation of triaxial stresses, and cavity growth/closure in alpha/beta titanium alloys with a colony-alpha microstructure. The occurrence of non-uniform grain structures (and so-called ALA, or 'as large as, ' grains) in cast, wrought, and powder-metallurgy superalloys are also discussed. A physics-based model to treat the topology of recrystallization and the evolution of ALA grains in such materials is proposed.
Book Synopsis Alpha/Beta Heat Treatment of a Titanium Alloy with a Non-Uniform Microstructure (Preprint). by :
Download or read book Alpha/Beta Heat Treatment of a Titanium Alloy with a Non-Uniform Microstructure (Preprint). written by and published by . This book was released on 2006 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of alpha/beta solution temperature and cooling rate on the evolution of microstructure during the heat treatment of Ti-6Al-2Sn-4Zr-2Mo-0.1Si (Ti6242Si) with a partially-spheroidized starting microstructure of equiaxed + remnant lamellar alpha was established. Experiments comprising induction heating to a peak temperature of 971 or 982 degrees C followed by cooling at a rate of 11 or 42 degrees C/min revealed that the volume fraction of the equiaxed alpha grew much more rapidly than the lamellar constituent. These results were explained semi-quantitatively using simple diffusion analyses of the growth of either spherical or elliptical particles, taking into account the soft-impingement of the concentration fields. Despite the much lower diffusivity of molybdenum, which appears to control the growth of primary alpha in Ti6242Si, the similarity of the overall kinetics compared to those measured previously for Ti-6Al-4V was explained on the basis of the higher supersaturations developed during cooldown in the present alloy.
Book Synopsis Microstructure and Texture Evolution During Thermo-mechanical Processing of Two Phase Titanium Alloy Ti-6Al-4V. by : Bama Perumal
Download or read book Microstructure and Texture Evolution During Thermo-mechanical Processing of Two Phase Titanium Alloy Ti-6Al-4V. written by Bama Perumal and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Coupled EBSD/EDS Method to Determine the Primary- and Secondary-Alpha Textures in Titanium Alloys With Duplex Microstructures (Preprint). by :
Download or read book A Coupled EBSD/EDS Method to Determine the Primary- and Secondary-Alpha Textures in Titanium Alloys With Duplex Microstructures (Preprint). written by and published by . This book was released on 2007 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: A method for separating the textures of primary alpha and secondary alpha in alpha/beta titanium alloys with a duplex microstructure was developed. Utilizing electron backscatter diffraction (EBSD) and energy-dispersive spectroscopy (EDS), the approach relies on the non-uniform partitioning of alloying elements between primary alpha and regions containing secondary-alpha lamellae and residual beta matrix phase. The method was evaluated using samples of Ti-6Al-4V for which vanadium partitions strongly to secondary alpha + beta regions. The technique thus provides a useful tool for quantifying the evolution of deformation texture in the primary alpha and transformation texture in secondary alpha formed via decomposition of the beta matrix following hot working or final heat treatment.
Book Synopsis Dynamic Transformation of [alpha] - [beta] at Temperatures Below the [beta]-transus in Commercially Pure Titanium by : Anes Foul
Download or read book Dynamic Transformation of [alpha] - [beta] at Temperatures Below the [beta]-transus in Commercially Pure Titanium written by Anes Foul and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "The concept of dynamic transformation was first discovered in steels in the late 1980s. Yada and co-workers showed that austenite can be transformed into ferrite by deformation at temperatures above the Ae3 (transformation temperature). Recently, various researchers around the world have proposed explanations of this unusual phenomenon. This is important in controlling and modelling the microstructure generated after deformation. The deformation behavior of commercially pure titanium grade 2 during hot working was previously studied by many researchers. For different titanium and titanium alloys, an increase in the [beta] volume fraction by deforming at temperatures below the [beta]-transus is observed. Here the driving force for transformation is taken as the flow stress difference between the work hardened alpha and the yield stress of the fresh beta that takes its place. Koike et al. (2000) showed an increase in [beta] volume fraction after hot deformation below the [beta]-transus on a Ti-5.5 wt%Al-1.5 wt%Fe alloy. This was also observed in the work of Xu et al. (2010) where high sub-tranus softening was observed in CP Ti grade 2. Jonas et al. (2017) also showed that this phenomenon was observed on three titanium alloys including a near [alpha] titanium (IMI834) alloy. Finally, Aranas and the current author (2017) explained the thermodynamic behavior behind this unusual phenomenon in CP Ti grade 2. In the present work, compression tests at temperatures between 750 and 970 oC were performed to determine the experimental driving force, dependence of the [beta] volume fraction produced on deformation temperature, and the minimum temperature to induce dynamic transformation in CP Ti grade 2." --
Book Synopsis Mechanism of Beta-Grain Growth in Alpha/Beta Titanium Alloys During Continuous, Rapid Heating by :
Download or read book Mechanism of Beta-Grain Growth in Alpha/Beta Titanium Alloys During Continuous, Rapid Heating written by and published by . This book was released on 2001 with total page 57 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rapid Heat Treatment (RHT) of commercial titanium alloys is a promising novel technology ensuring a high level of mechanical properties as well as high cost efficiency of processing. One of the significant advantages of RHT is related to the possibility of employing heating to temperatures in the single-phase beta field. By this means, the technique can be used to obtain fully lamellar intragrain microstructures favorable for high creep resistance and fracture toughness with relatively small or moderate size beta-grains. Such microstructures give rise to good tensile ductility and fatigue properties, comparable to those of equiaxed or bimodal microstructures. Therefore, fully lamellar microstructures with a controlled beta grain size of around 100 micrometers are a feasible way to balance the tensile, fatigue, and creep properties of titanium alloys. With direct resistance heating, these microstructures and the corresponding properties can be produced throughout the part uniformly. With induction heating, gradient type microstructures can be produced in which the properties of surface and core volumes of the heat-treated part are selectively controlled depending on the intended service application. In either case, an understanding of beta grain growth behavior during continuous, rapid heating is the key point. Thus, the goal of this investigation was to establish the temperature dependence of beta-grain size and its dependence on crystallographic texture for the alpha/beta alloy Ti-6A1-4V. The principal variables to be investigated include processing history, heating rate, and method of rapid heating (direct resistance or induction) in order to provide an explanation of beta-grain growth mechanism during continuous rapid heating. As a final output of this effort, practical recommendations for choosing RHT parameters to ensure optimized balance of mechanical properties will be developed.
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