Dependence of Microstructure Evolution, Texture, and Mechanical Behavior of a Magnesium Alloy on Thermo-mechanical Input During Friction Stir Processing PDF Download
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Author: Zhenzhen Yu
Publisher:
ISBN:
Category :
Languages : en
Pages : 148
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Book Description
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.
Author: Zhenzhen Yu
Publisher:
ISBN:
Category :
Languages : en
Pages : 148
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Book Description
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.
Author: Hang Z. Yu
Publisher: Elsevier
ISBN: 0128243953
Category : Technology & Engineering
Languages : en
Pages : 351
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Book Description
Additive Friction Stir Deposition is a comprehensive summary of the state-of-the-art understanding on this emerging solid-state additive manufacturing technology. Sections cover additive friction stir deposition, encompassing advances in processing science, metallurgical science and innovative applications. The book presents a clear description of underlying physical phenomena, shows how the process determines the printing quality, covers resultant microstructure and properties in the as-printed state, highlights its key capabilities and limitations, and explores niche applications in repair, cladding and multi-material 3D printing. Serving as an educational and research guide, this book aims to provide a holistic picture of additive friction stir deposition-based solid-state additive manufacturing as well as a thorough comparison to conventional beam-based metal additive manufacturing, such as powder bed fusion and directed energy deposition. - Provides a clear process description of additive friction stir deposition and highlights key capabilities - Summarizes the current research and application of additive friction stir deposition, including material flow, microstructure evolution, repair and dissimilar material cladding - Discusses future applications and areas of research for this technology
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 7
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Book Description
Texture evolution is strongly dependent on the deformation mode during thermo-mechanical treatments. In this paper, we report the texture evolution in a duplex Mg-Li alloy. The results provide an evidence of deformation mode transition in the hexagonal-close-packed (hcp) alpha phase with various thickness reductions. The activation sequence of deformation modes is basal slip first, and then pyramidal slip during hot-rolling to a thickness reduction of 40%. The relative activity of c+a slip decreases with further thickness reduction. After annealing, basal texture is strengthened and pyramidal component disappears due to static recrystallization and grain growth. The microstructure, specifically texture evolution in both hcp alpha and body-centered cubic (bcc) beta phase and their effects on mechanical properties are quantitatively analyzed and assessed. (C) 2016 Elsevier B.V. All rights reserved.
Author: Qiang Yu
Publisher:
ISBN:
Category : Metals
Languages : en
Pages : 0
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Book Description
Author: Lucas F. M. da Silva
Publisher: Springer Nature
ISBN: 9811529574
Category : Science
Languages : en
Pages : 178
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Book Description
This book presents recent material science-based and mechanical analysis-based advances in joining processes. It includes all related processes, e.g. friction stir welding, joining by plastic deformation, laser welding, clinch joining, and adhesive bonding, as well as hybrid joints. It gathers selected full-length papers from the 1st Conference on Advanced Joining Processes.
Author: Sivanesh Palanivel
Publisher:
ISBN:
Category : Friction stir welding
Languages : en
Pages : 205
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Book Description
The recent emphasis on magnesium alloys can be appreciated by following the research push from several agencies, universities and editorial efforts. With a density equal to two-thirds of Al and one-thirds of steel, Mg provides the best opportunity for lightweighting of metallic components. However, one key bottleneck restricting its insertion into industrial applications is low strength values. In this respect, Mg-Y-Nd alloys have been promising due to their ability to form strengthening precipitates on the prismatic plane. However, if the strength is compared to Al alloys, these alloys are not attractive. The primary reason for low structural performance in Mg is related to low alloying and microstructural efficiency. In this dissertation, these terminologies are discussed in detail. A simple calculation showed that the microstructural efficiency in Mg-4Y-3Nd alloy is 30% of its maximum potential. Guided by the definitions of alloying and microstructural efficiency, the two prime objectives of this thesis were to: (i) to use thermomechanical processing routes to tailor the microstructure and achieve high strength in an Mg-4Y-3Nd alloy, and (ii) optimize the alloy chemistry of the Mg-rare earth alloy and design a novel rare--earth free Mg alloy by Calphad approach to achieve a strength of 500 MPa. Experimental, theoretical and computational approaches have been used to establish the process-structure-property relationships in an Mg-4Y-3Nd alloy. For example, increase in strength was observed after post aging of the friction stir processed/additive manufactured microstructure. This was attributed to the dissolution of Mg2Y particles which increased the alloying and microstructural efficiency. Further quantification by numerical modeling showed that the effective diffusivity during friction stir processing and friction stir welding is 60 times faster than in the absence of concurrent deformation leading to the dissolution of thermally stable particles. In addition, the investigation on the interaction between dislocations and strengthening precipitate revealed that, specific defects like the I1 fault aid in the accelerated precipitation of the strengthening precipitate in an Mg-4Y-3Nd alloy. Also, the effect of external field (ultrasonic waves) was studied in detail and showed accelerated age hardening response in Mg-4Y-3Nd alloy by a factor of 24. As the bottleneck of low strength is addressed, the answers to the following questions are discussed in this dissertation: What are the fundamental micro-mechanisms governing second phase evolution in an Mg-4Y-3Nd alloy? What is the mechanical response of different microstructural states obtained by hot rolling, friction stir processing and friction stir additive manufacturing? Is defect engineering critical to achieve high strength Mg alloys? Can application of an external field influence the age hardening response in an Mg-4Y-3Nd alloy? Can a combination of innovative processing for tailoring microstructures and computational alloy design lead to new and effective paths for application of magnesium alloys?
Author: Timothy Fagan
Publisher:
ISBN:
Category :
Languages : en
Pages : 352
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Book Description
Friction Stir Processing (FSP) is a new and exciting processing technique to locally modify the grain structure and improve mechanical properties of metals. Numerical modelling of the process will allow for improved understanding of the deeply complex thermo-mechanical processes that occur within this seemingly simple technique. An accurate numerical model will increase understanding of the process and reduce the number of experimental trials required to achieve the desired result. In FSP, a cylindrical non-consumable tool, generally consisting of a pin and shoulder, is rotated and plunged into the surface of a metal workpiece. The larger diameter shoulder prevents the surface of the metal workpiece from flowing outwards, while the specially designed pin induces a stirring action, producing a combination of frictional and adiabatic heating allowing the metal to flow around the pin from the advancing side to the retreating side. Localised severe plastic deformation occurs generally resulting in grain refinement. It is the grain refinement that has attracted the attention of many researchers and prompted development of numerical models.The typical numerical methods applied in literature rely on Eulerian or Lagrangian meshes which struggle to overcome large mesh deformation and track material history respectively. In addition, phenomenological models are generally applied which do not have a physical basis. To this end, this work will implement a particle based numerical method with a physically based constitutive law. The proposed three-dimensional fully-coupled thermo-mechanical model is able to concurrently determine the temperature field, material flow and microstructure evolution dependent on the processing conditions of FSP. The results of the complete model agree well with experimental thermocouple measurements, material flow and microstructure development.
Author: Jurij J Sidor
Publisher: Mdpi AG
ISBN: 9783036523842
Category : Technology & Engineering
Languages : en
Pages : 144
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Book Description
In the special issue related to Modelling the Deformation, Recrystallization and Microstructure-Related Properties in Metals, we presented a wide spectrum of articles dealing with modelling of microstructural aspects involved in deformation and recrystallization as well as simulation of microstructure-based and texture-based properties in various metals. The latest advances in the theoretical interpretation of mesoscopic transformations based on experimental observations were partially discussed in the current special issue. The studies dealing with the modelling of structure-property relationships are likewise analyzed in the present collection of manuscripts. The contributions in the current collection evidently demonstrate that the properties of metallic materials are microstructure dependent and therefore the thermomechanical processing (TMP) of the polycrystalline aggregates should be strictly controlled to guarantee the desired bunch of qualities. Given this, the assessment of microstructure evolution in metallic systems is of extraordinary importance. Since the trial-error approach is a time-consuming and quite expensive methodology, the materials research community tends to employ a wide spectrum of computational approaches to simulate each chain of TMP and tune the processing variables to ensure the necessary microstructural state which will provide desired performance in the final product. Although many hidden facets of various technological processes and related microstructural changes were revealed in the submitted works by employing advanced computational approaches, nevertheless, the contributions collected in this issue clearly show that further efforts are required in the field of modelling to understand the complexity of material's world. The final goal of modelling efforts might be a development of a comprehensive model, which will be capable of describing many aspects of microstructure evolution during thermomechanical processing.
Author:
Publisher:
ISBN:
Category : Magnesium alloys
Languages : en
Pages : 151
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Book Description
Author: Roger Lumley
Publisher: Elsevier
ISBN: 0857090259
Category : Technology & Engineering
Languages : en
Pages : 862
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Book Description
Aluminium is an important metal in manufacturing, due to its versatile properties and the many applications of both the processed metal and its alloys in different industries. Fundamentals of aluminium metallurgy provides a comprehensive overview of the production, properties and processing of aluminium, and its applications in manufacturing industries.Part one discusses different methods of producing and casting aluminium, covering areas such as casting of alloys, quality issues and specific production methods such as high-pressure diecasting. The metallurgical properties of aluminium and its alloys are reviewed in Part two, with chapters on such topics as hardening, precipitation processes and solute partitioning and clustering, as well as properties such as fracture resistance. Finally, Part three includes chapters on joining, laser sintering and other methods of processing aluminium, and its applications in particular areas of industry such as aerospace.With its distinguished editor and team of expert contributors, Fundamentals of aluminium metallurgy is a standard reference for researchers in metallurgy, as well as all those involved in the manufacture and use of aluminium products. - Provides a comprehensive overview of the production, properties and processing of aluminium, and its applications in manufacturing industries - Considers many issues of central importance in aluminium production and utilization considering quality issues and design for fatigue growth resistance - Metallurgical properties of aluminium and its alloys are further explored with particular reference to work hardening and applications of industrial alloys
