Download or read book The Microstructural Evolution and Constitutive Analysis for a Physical Simulation of Friction Stir Processing of Ti 6Al 4V written by Jason James Livingston and published by . This book was released on 2011 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: Friction stir processing above the [beta]-transus was microstructurally evident by a stir zone composed of 10 - 40um recrystallized [beta]-grains with either a basketweave or lamellar structure and a continuous network of [alpha] at the grain boundary. Moreover, processing below the [beta]-transus provided a dimensionless heat input of Q = 37.5, while processing above the [beta]-transus was Q less than 50, suggesting this dimensionless heat input does not correlate well with the resulting microstructures.

Download or read book Microstructural Evolution of Friction Stir Processed Ti 6Al 4V written by Paul Andrew Pavka and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Friction stir welding has been developed over the past ten years to permit joining of high strength alloys that cannot be fusion welded. More recently friction stir processing (FSP) has been shown to alter the surface microstructure of a material by essentially in situ thermo mechanical processing. In this study we have used FSP to alter the surface microstructure of Ti-6Al-4V. In all trials, the friction stir processing (FSP) applied to the surface of cast +H.I.P. slabs has resulted in changing the coarse lamellae to small equiaxed [alpha] grains that are about 1 in diameter. This process leaves the coarse lamellar microstructure in the bulk of the material. These findings are believed to produce a microstructure that will have better fatigue strength than what was previously available from the cast + H.I.P. coarse microstructure. Orientation imaging microscopy (OIM) of the fine-grained, equiaxed process zone has shown that there is no preferred grain orientation. A new technique for locally measuring yield strength using small, in-situ compressive cylinders (pillars) has been used to determine the strength change between the fine grain and as-cast structure. Pillars made from focused ion beam milling (FIB) have demonstrated that the fine-grained stirred material is about 30% stronger than the as-cast material. Definition of the mechanism that controls the conversion from the lamellar structure to the equiaxed structure is still being developed, but several observations suggest that the -transus has not been exceeded. More work is being done to verify the fatigue strength of the new microstructure, and to develop a better understanding of the mechanism that controls the conversion process. This work is ongoing but the microstructure changes associated with FSP are described in here.

Download or read book The Use of Modeling Based Physical Simulation to Reveal the Relationship Between Process Parameters and Microstructural Evolution in Thermal Stir Processed TSP TI6A1 4V written by and published by . This book was released on 2009 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: The initial work statement targeted quantifying the hot working conditions experienced by titanium during friction stir welding/processing (FSW/P). Of particular interest was the identification of the hot working conditions (i.e. strain rate, strain, and temperature) required to refine the grains in the weld zone or nugget. Using a kinematic approach toward modeling of the FSW/P, the instantaneous shear strain rate encountered by the material entering the rotation plug around the weld tool is estimated to be in the range of 103 to 106 s-l at strains levels in excess of 50. A similar level of grain refinement has been reported in metal chips formed during cutting operations where the shear strain rate is estimated to be in the range of 103 to 106 s-l, but at strain levels less than 5. Both these processes are predicted to instantaneously impart strain rates on the order of ballistic impact on the metal. In contrast grain refinement has also been reported in equal channel angular extrusion (ECAE) where the grain size reduction has been correlated with the increasing amount of strain achieved by multi passes at quasi-static strain rates. The motivation for this study is furthering our understanding of the mechanics responsible for grain refinement as influenced by ballistic level sheer strain rate and/or shear strain.

Download or read book Microstructural Evolution during Forging of Ti 6Al 4V Alloy written by and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modeling and Simulation of Microstructure Evolution in Solidifying Alloys written by Laurentiu Nastac and published by Springer Science & Business Media. This book was released on 2007-05-08 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of Modeling and Simulation of Microstructure Evolution in Solidifying Alloys is to describe in a clear mathematical language the physics of the solidification structure evolution of cast alloys. The concepts and methodologies presented here for the net-shaped casting and the ingot remelt processes can be applied, with some modifications, to model other solidification processes such as welding and deposition processes. Another aim of the book is to provide simulation examples of the solidification structure modeling in some crucial commercial casting technologies as well as to provide practical techniques for controlling the structure formation during the solidification processes.

Download or read book Microstructural Evolution of Commercial Purity Ti and Superplasticity of Ti 6Al 4V Alloy Processed by Equal Channel Angular Extrusion written by and published by . This book was released on 2006 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: This project focused on deformation processing, microstructural development, and mechanical properties of Ti and Ti-6Al-4V alloys. Specific tasks included: (1) Study superplastic deformation of a Ti-6Al-4V alloy that have been processed by equal channel angular extrusion and relate the deformation mechanism to the enhancement of superplasticity, and (2) Examine the effect of strain path for Ti fabricated by equal channel angular extrusion and uniaxial compression, with a special focus on the improved mechanical properties of the deformed Ti. As a part of the report, two papers were published in Materials Science and Engineering A (vol. A410-411, 2005, 156-159) and Metallurgical and Materials Transactions A (vol.37, 2006, 381-391). The work was begun under AOARD 034023, "Microstructure development of ultrafine grained Ti and superplasticity of Ti-6Al-4V alloy." Most of that effort was devoted to Ti-6Al-4V alloy. Much progress has been made over the more than two years of effort. We propose to complete our studies by studying, in detail, deformation mechanisms for the enhanced superplasticity in the ultrafine grained Ti-6Al-4V alloy with a special focus on the role of non-equilibrium grain boundaries.

Download or read book Investigating the Process Microstructure Mechanical Property Development in Ti 6AL 4V Friction Stir Welds written by Sarah Baker and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Friction Stir Welding written by Daniela Lohwasser and published by Elsevier. This book was released on 2009-12-18 with total page 437 pages. Available in PDF, EPUB and Kindle. Book excerpt: Friction stir welding (FSW) is a highly important and recently developed joining technology that produces a solid phase bond. It uses a rotating tool to generate frictional heat that causes material of the components to be welded to soften without reaching the melting point and allows the tool to move along the weld line. Plasticized material is transferred from the leading edge to trailing edge of the tool probe, leaving a solid phase bond between the two parts. Friction stir welding: from basics to applications reviews the fundamentals of the process and how it is used in industrial applications.Part one discusses general issues with chapters on topics such as basic process overview, material deformation and joint formation in friction stir welding, inspection and quality control and friction stir welding equipment requirements and machinery descriptions as well as industrial applications of friction stir welding. A chapter giving an outlook on the future of friction stir welding is included in Part one. Part two reviews the variables in friction stir welding including residual stresses in friction stir welding, effects and defects of friction stir welds, modelling thermal properties in friction stir welding and metallurgy and weld performance.With its distinguished editors and international team of contributors, Friction stir welding: from basics to applications is a standard reference for mechanical, welding and materials engineers in the aerospace, automotive, railway, shipbuilding, nuclear and other metal fabrication industries, particularly those that use aluminium alloys. - Provides essential information on topics such as basic process overview, materials deformation and joint formation in friction stir welding - Inspection and quality control and friction stir welding equipment requirements are discussed as well as industrial applications of friction stir welding - Reviews the variables involved in friction stir welding including residual stresses, effects and defects of friction stir welds, modelling thermal properties, metallurgy and weld performance

Download or read book Friction Stir Superplasticity for Unitized Structures written by Zongyi Ma and published by Butterworth-Heinemann. This book was released on 2014-05-27 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes the fundamentals and potential applications of 'friction stir superplasticity for unitized structures'. Conventional superplastic forming of sheets is limited to the thickness of 3 mm because the fine grained starting material is produced by rolling. Friction stir superplasticity has grown rapidly in the last decade because of the effectiveness of microstructural refinement. The thickness of the material remains almost constant, and that allows for forming of thick sheets/plates, which was not possible before. The field has reached a point where designers have opportunities to expand the extent of unitized structures, which are structures in which the traditional primary part and any supporting structures are fabricated as a single unit. With advanced optimization and material considerations, this class of structures can be lighter weight and more efficient, making them less costly, as well as mechanically less complex, reducing areas of possible failure. - Discusses how friction stir processing allows selective microstructural refinement without thickness change - Demonstrates how higher thickness sheets and plates can be superplastically formed - Examples are presented for aluminum, magnesium and titanium alloys - Covers the production of low-cost unitized structures by selectively processing cast sheets/plates

Download or read book Large Scale Phase Field Simulations of Microstructure Evolution During Thermal Cycling of TI 6AL 4V written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dependence of Microstructure Evolution Texture and Mechanical Behavior of a Magnesium Alloy on Thermo mechanical Input During Friction Stir Processing written by Zhenzhen Yu and published by . This book was released on 2010 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, the relationship among friction stir processing (FSP) parameters, microstructure evolution, texture development, and mechanical hehavior[sic] of AZ31B Mg alloy was investigated. First of all, in order to reveal the correlation among the deformation conditions, dynamic recrystallization (DRX) mechanisms, and microstructure evolution in the Mg alloy, hot compression tests at a wide range of Zener-Hollomon parameter (Z) values were conducted. Through optical microscopic examination, it was found out that above a critical Z value, twinning influences the DRX process resulting in a more effective grain refinement, which is manifested in a significant change in the slope of the Z-d[subscript rec] relationship, where d[subscript rec] is the recrystallized grain size. Moreover, EBSD examination revealed that the twinning also contributed to a distinct change in the recrystallization texture. Compression tests were performed along both through-thickness and in-rolling-plane directions of the plate to study the orientation dependency of twinning activities and its influence on the DRX process. X-ray line profile analysis (XLPA) provides further insights by highlighting the differences in the dislocation density/types, subgrain sizes, and twin densities during the DRX processes operating with or without the twinning. Secondly, the constitutive behaviour study was applied to the investigation of microstructure evolution during FSP. By varying the key FSP parameters systematically, i.e. rotation and travel rates of the tool, a series of FSP specimens were prepared with a wide range of thermo-mechanical inputs in terms of Z. The resulting tensile behavior in the stir zone (SZ) showed a dramatic change as a function of Z, caused by a systematic change in the texture within SZ measured by neutron diffraction. A three-dimensional transient model was developed to investigate the detailed deformation history including the temperature and strain rate profiles and material flow pattern during FSP of the Mg alloy. Such deformation history can be combined with the constitutive study from the compression tests in order to analyze the developments of micro-texture and DRX grains during FSP, which will, in turn, dominate the mechanical properties. Based on the studies above, new fundamental understandings were gained on the governing mechanisms for the deformation and recrystallization processes during FSP and the influence of thermo-mechanical input during FSP on ductility enhancement in the Mg alloy.

Download or read book Modeling Characterizing and Reconstructing Mesoscale Microstructural Evolution in Particulate Processing and Solid state Sintering written by Shaohua Chen and published by . This book was released on 2018 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: In material science, microstructure plays a key role in determining properties, which further determine utility of the material. However, effectively measuring microstructure evolution in real time remains an challenge. To date, a wide range of advanced experimental techniques have been developed and applied to characterize material microstructure and structural evolution on different length and time scales. Most of these methods can only resolve 2D structural features within a narrow range of length scale and for a single or a series of snapshots. The currently available 3D microstructure characterization techniques are usually destructive and require slicing and polishing the samples each time a picture is taken. Simulation methods, on the other hand, are cheap, sample-free and versatile without the special necessity of taking care of the physical limitations, such as extreme temperature or pressure, which are prominent issues for experimental methods. Yet the majority of simulation methods are limited to specific circumstances, for example, first principle computation can only handle several thousands of atoms, molecular dynamics can only efficiently simulate a few seconds of evolution of a system with several millions particles, and finite element method can only be used in continuous medium, etc. Such limitations make these individual methods far from satisfaction to simulate macroscopic processes that a material sample undergoes up to experimental level accuracy. Therefore, it is highly desirable to develop a framework that integrate different simulation schemes from various scales to model complicated microstructure evolution and corresponding properties. Guided by such an objective, we have made our efforts towards incorporating a collection of simulation methods, including finite element method (FEM), cellular automata (CA), kinetic Monte Carlo (kMC), stochastic reconstruction method, Discrete Element Method (DEM), etc, to generate an integrated computational material engineering platform (ICMEP), which could enable us to effectively model microstructure evolution and use the simulated microstructure to do subsequent performance analysis. In this thesis, we will introduce some cases of building coupled modeling schemes and present the preliminary results in solid-state sintering. For example, we use coupled DEM and kinetic Monte Carlo method to simulate solid state sintering, and use coupled FEM and cellular automata method to model microstrucutre evolution during selective laser sintering of titanium alloy. Current results indicate that joining models from different length and time scales is fruitful in terms of understanding and describing microstructure evolution of a macroscopic physical process from various perspectives.

Download or read book Physical Simulation of Friction Stir Processed TI 5AI 1Sn 1Zr 1V 0 8Mo written by Melissa Joanne Rubal and published by . This book was released on 2009 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: A continuous cooling transformation (CCT) diagram was constructed for Ti-5111 to separate the effects of deformation and non-equilibrium temperature profiles on the depression of the alpha-beta transformation observed during processing. Similar transformation temperatures were observed during testing, indicating the significant reduction in transformation temperature is independent of the extreme deformation.

Download or read book Structure evolution in tribological interfaces studied by multilayer model alloys written by Cihan, Ebru and published by KIT Scientific Publishing. This book was released on 2020-10-21 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent studies of deformation mechanisms of metals and alloys pioneer the better investigation of the friction and wear behavior of materials with well-defined initial microstructures. Within this scope, in this work, the effect of sub-surface deformations on the resulting friction and wear behavior has been searched by means of a systematic experimental study on Au-Ni metallic multilayer model alloy system.

Download or read book Solidification Microstructure Simulation of Ti6Al4V in Laser Wire Deposition Additive Manufacturing written by Jinghao Li and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Metal additive manufacturing (MAM) technology is now changing the pattern of the high-end manufacturing industry, among which microstructure simulation gradually shows its importance and attracts many research interests. Until today, the simulation of solidification microstructure in MAM remains challenging because of the complex solidification conditions. This research develops a data-driven model to investigate the competitive grain growth behaviour and a novel method to quantitively simulate the topology structures of the columnar grains in laser wire directed energy deposition (DED) fabricated Ti6Al4V. With a thorough review of the literature, the development of existing solidification microstructure simulation methods as well as their capacity and applicability on MAM are discussed. Traditional solidification microstructure simulation methods all have their merits as well as drawbacks when applied in MAM processes. To fill the gaps in the rapid solidification theory, a data-driven approach is developed to analyze the anisotropic grain growth effect under a rapid directional solidification condition in laser wire DED fabricated Ti6Al4V. A series of laser wire DED, optical microscope, and electron backscatter diffraction (EBSD) experiments were carried out under the experimental design to gather the training and testing data for the artificial neural network (ANN), which is used as an engine to predict the transient grain boundary angles. After parameter tuning and model testing, the strategy and ANN model developed in this work is demonstrated to be an efficient way to describe the competitive grain growth behaviour in laser wire DED fabricated Ti6Al4V. In conjunction with the regression relation found by the ANN, a deterministic solidification microstructure simulation model named the "invasion model", is established to avoid the essential defects of traditional methods, such as the high computational cost and the handling of rapid solidification phenomena. This model focuses on the interaction between the neighbouring bi-crystals instead of simulating the growth kinetics of each columnar grain or deriving the field form of variables. Within a bi-crystal system, the grain boundary tilt from the vertical direction of solidification front is understood as a transient invasion behaviour of one grain to another, and the competitive grain growth behaviour along the buildup process of MAM is an accumulation of all the invasions in bi-crystal systems. Laser wire DED fabricated Ti6Al4V thin wall samples with full dendritic columnar grains (prior beta) are used as a benchmark to test the validation of the novel simulation model. The grain structure of reconstructed prior beta grains along the build-up direction has a good agreement with the simulation result which shows the unique capabilities of the invasion model compared to the traditional ones. In the end, the crystal (prior beta grain) introducing mechanism in laser wire DED fabricated Ti6Al4V is investigated. Recrystallization is found to be the main reason that introduces new crystals into the printing domain and influences the resultant solidification microstructure. The formation tendency of the early-stage recrystallized grain indicates its strong dependency on the grain boundary alpha phase. Some of the recrystallized grains are able to participate in the following competitive grain growth, thus influencing the solidification microstructure in the fabricated part dramatically"--

Download or read book Theory and Modeling of Microstructural Evolution in Polycrystalline Materials written by Ning Ma and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: To accurately predict microstructure evolution and, hence, to synthesis metal and ceramic alloys with desirable properties involves many fundamental as well as practical issues. In the present study, novel theoretical and phase field approaches have been developed to address some of these issues including solute drag and segregation transition at grain boundaries and dislocations, grain growth in systems of anisotropic boundary properties, and precipitate microstructure development in polycrystalline materials. The segregation model has allowed for the prediction of a first-order segregation transition, which could be related to the sharp transition of solute concentration of grain boundary as a function of temperature. The incorporating of interfacial energy and mobility as functions of misorientation and inclination in the phase field model has allowed for the study of concurrent grain growth and texture evolution. The simulation results were analyzed using the concept of local grain boundary energy density, which simplified significantly the development of governing equations for texture controlled grain growth in Ti-6Al-4V. Quantitative phase field modeling techniques have been developed by incorporating thermodynamic and diffusivity databases. The models have been validated against DICTRA simulations in simple 1D problems and applied to simulate realistic microstructural evolutions in Ti-6Al-4V, including grain boundary a and globular a growth and sideplate development under both isothermal aging and continuous cooling conditions. The simulation predictions agree well with experimental observations.

Download or read book High Speed Machining written by Kapil Gupta and published by Academic Press. This book was released on 2020-01-31 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: High-Speed Machining covers every aspect of this important subject, from the basic mechanisms of the technology, right through to possible avenues for future research. This book will help readers choose the best method for their particular task, how to set up their equipment to reduce chatter and wear, and how to use simulation tools to model high-speed machining processes. The different applications of each technology are discussed throughout, as are the latest findings by leading researchers in this field. For any researcher looking to understand this topic, any manufacturer looking to improve performance, or any manager looking to upgrade their plant, this is the most comprehensive and authoritative guide available. - Summarizes important R&D from around the world, focusing on emerging topics like intelligent machining - Explains the latest best practice for the optimization of high-speed machining processes for greater energy efficiency and machining precision - Provides practical advice on the testing and monitoring of HSM machines, drawing on practices from leading companies