Download or read book Microstructural Evolution in the 2219 Aluminum Alloy During Severe Plastic Deformation written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerous investigations have demonstrated that intense plastic deformation is an attractive procedure for producing an ultrafine grain size in metallic materials. Torsional deformation under high pressure and equal-channel angular extrusion are two techniques that can produce microstructures with grain sizes in the submicrometer and nanometer range. Materials with these microstructures have many attractive properties. The microstructures formed by these two processing techniques are essentially the same and thus the processes occurring during deformation should be the same. Most previous studies have examined the final microstructures produced as a result of severe plastic deformation and the resulting properties. Only a limited number of studies have examined the evolution of microstructure. As a result, some important aspects of ultra-fine grain formation during severe plastic deformation remain unknown. There is also limited data on the influence of the initial state of the material on the microstructural evolution and mechanisms of ultra-fine grain formation. This limited knowledge base makes optimization of processing routes difficult and retards commercial application of these techniques. The objective of the present work is to examine the microstructure evolution during severe plastic deformation of a 2219 aluminum alloy. Specific attention is given to the mechanism of ultrafine grain formation as a result of severe plastic deformation.

Download or read book Microstructural Evolution of Aluminum Alloy 2219 T87 with Hot Torsion and Bobbin Tool Friction Stir Welding written by Andrew Gilmore and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study comprehensively analyzed the mechanical behavior and microstructural evolution of aluminum alloy AA2219-T87 undergoing high deformation and strain rates at elevated temperature via hot torsion tests. An integrated experimental and modeling approach has been employed, where a finite element model is developed with ABAQUS to address local deformation and non-uniform temperature distribution along the specimen gauge section. A Johnson-Cook constitutive material model is calibrated based on the calculated and measured torque curves at different conditions. Combined with the ABAQUS calculated local thermo-mechanical conditions, microstructure modeling using established literature-based equations are established to provide insights into grain size distribution and recrystallization mechanisms. The calibrated material constitutive model, recrystallization model, and grain size model can be utilized to model various manufacturing processes which involves hot deformation of aluminum alloys in the intermediate strain rate range of 14/s-78/s. These findings were applied to further works with Bobbin Tool Friction Stir Welding of thick plate AA2219. Analysis of cross sections and welding parameter effects on microstructural and phenomenological outcomes were performed to maximize understanding of the specific material behavior in elevated temperature, high strain rate processes as seen in hot torsion as well as friction based solid state welding.

Download or read book Microstructural Evolution of AA6061 Subjected to Severe Plastic Deformation written by Yogesh Bhambri and published by . This book was released on 2003 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Early Microstructural Evolution and Deformation Behavior in Solution Heat Treated Aluminum lithium Alloys written by Shelly Midori Miyasato and published by . This book was released on 1991 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Microstructural and Strain Rate Effects on Plastic Deformation in Aluminum Alloy 2219 T87 written by Carlos D. Rincon and published by . This book was released on 1998 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Production of Ultra Fine Grains and Evolution of Grain Boundaries During Severe Plastic Deformation of Aluminum and Its Alloys written by Douglas L. Swisher and published by . This book was released on 2000-12-01 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: Equal channel-angular pressing (ECAP) is a recently developed method for deformation processing of material that can produce an ultra-fine grain structure in bulk material through severe plastic deformation. This study will present results on micro structural evolution during repetitive ECAP of pure aluminum. The principal method of data collection was Orientation Imaging Microscopy (OIM). The results of the study indicate that, after one ECAP pass, the structure is inhomogeneous and anisotropic, and consists mostly of deformation-induced features. After repetitive ECAP, the aluminum material exhibited a homogeneous grain size but retained an anisotropic character to the microstructure. After twelve ECAP passes the microstructure consisted mainly of fine grains surrounded by high-angle boundaries but an appreciable fraction of low-angle boundaries remained. This microstructure thus comprises a mixture of deformation-induced and recrystallization features. Further results were also obtained documenting the existence of deformation banding in this material as well as in a rolled aluminum alloy. This phenomenon may be general in nature and associated with severe plastic deformation in aluminum and its alloys.

Download or read book Molecular Dynamics Study of Microstructural Evolution in Alloys Subjected to Severe Plastic Deformation written by Samson Olusikunanu Odunuga and published by ProQuest. This book was released on 2007 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: The atomic transport resulting from plastic deformation has been analyzed in new depths by tracking the evolution of pair of marker atoms. This analysis has proved to be a powerful tool in identifying the deformation mechanisms, including the glide of leading and trailing partial dislocations, and vacancy assisted atomic jumps during deformation, as well as quantifying the relative contributions of these mechanisms. It is found that the glide of dislocations plays a more important role than previously thought in accommodating plastic deformation in nanocrystalline alloys. A new property of the atomic mixing by plastic deformation that has been uncovered is that the effective diffusion coefficient increases, nearly linearly, with the separation distance of pairs of atoms. This superdiffusive mixing is revealed by monitoring the relative displacement of atoms as a function of the separation distance. This result can be tested experimentally by measuring the rate of dissolution of precipitates during deformation. This finding also provides a direct rationalization for the stabilization of compositional patterns when thermal diffusion and forced mixing compete.

Download or read book Ultrafine Grained Materials II written by Yuntian Theodore Zhu and published by John Wiley & Sons. This book was released on 2013-09-25 with total page 886 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of a symposium sponsored by the Shaping and Forming Committee of the Materials Processing and Manufacturing Division (MPMD) and the Mechanical Behavior Committee (Jt. SMD/ASM-MSCTS) of the Structural Materials Division (SMD) of TMS (The Minerals, Metals & Materials Society) and held during the 2002 TMS Annual Meeting in Seattle, Washington February 17-21,2002.

Download or read book Simulating Microstructure Evolution of Realistic 3D Aluminum Alloy Polycrystal During Large Plastic Deformation at Elevated Temperature written by Jing Lu and published by . This book was released on 2006 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Microstructure Evolution and Mechanical Properties of Severely Plastically Deformed SPD Aluminum Alloys written by and published by . This book was released on 2007 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: A combined experimental and modeling study has been carried out to characterize the structure and mechanical properties of severely plastically deformed (SPD) aluminum and its alloys as well as the effect of strengthening mechanism on fracture toughness and failure mode. This investigation is focused specifically on Equal Channel Angular Pressing (ECAP) and heavy cold rolling of high solute Al alloys. A particular reason for studying the high strength potentially achievable by these routes is the expectation that since the fracture toughness of precipitation hardened aluminum alloys is known to be degraded by grain boundary precipitates, the high strengths achievable by strain hardening without precipitation has a reasonable prospect of yielding a higher combination of yield strength and toughness than by conventional precipitation hardening. In this study it has been shown that SPD processing of high solute Al alloys can be carried out to higher strains before strain localization occurs if mechanical stress relieving is done prior to processing and that strengths unobtainable through precipitation hardening can readily be achieved by strain hardening. The effect of natural aging on strain hardening has been investigated and found to be a significant factor in the rate at which the flow stress increases with increasing plastic strain. It has been shown that strain hardened Al alloys are more ductile and exhibit higher strain hardening rates then precipitation hardened alloys at equivalent strengths and that strain hardening is a viable processing route for improving toughness. On the modeling side, we have developed new micromechanical finite element models that employ crystal plasticity constitutive framework and are able to successfully simulate texture evolution in the sample during complex routes of ECAP.

Download or read book Recrystallization and Grain Growth III written by and published by . This book was released on 2007 with total page 884 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Flow Behavior and Microstructural Evolution During Superplastic Deformation of AA8090 Aluminum lithium Alloy written by and published by . This book was released on 1906 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Superplasticity in AA8090 Al-Li alloy has been a subject of extensive studies, due to its potential for commercial applications since last decade. However, the anisotropy and microstructural gradient existing in this material introduce additional complication in understanding the mechanisms for superplastic deformation and has resulted in a debate about the role of dislocation activity. This has necessitated a more detailed microstructural study, especially texture, than that is commonly required to understand the deformation mechanism in other superplastic materials. Attempt has been made in this investigation to achieve this by means of microstructural characterization of specimens deformed in ten ion by using optical microscopy, TEM, SEM and orientation imaging microscopy (OIM). The microstructural characterization of the as-received material showed that there were three distinct layers in the cross-section of the sheet. Pancake grains in the center layer of about 1/3 thickness with brass-type texture, and nearly equiaxed grains on either side of it of about 1/3 thickness with copper texture. Tensile tests were conducted over a temperature range of $25{-}570\sp\circ$C and a strain rate range of $\rm 1 \times 10\sp{-4}{-}1 \times 10\sp{-2}/s.$ Optimum superplastic conditions were found in a temperature range of 500-530$\sp\circ$C and in a strain rate range of $\rm 1 \times 10\sp{-4}{-}1 \times 10\sp{-3}/s.$ These deformation conditions yielded the maximum value of strain rate sensitivity index $\rm(m \approx 0.5)$ and the minimum value of instability parameter (I). During superplastic deformation, there occurred grain growth, texture weakening and change in grain shape. The disappearance of initial microstructural gradient occurred at a strain of about 1.0. The relationship between grain size (d) and strain $(\varepsilon)$ could be expressed as $\rm d\propto\varepsilon\sp{q}, $ with the value of exponent q ranging from 0.21-0.44 depending on the test temperature. T.

Download or read book Evolution and Control of 2219 Aluminum Microstructural Features Through Electron Beam Freeform Fabrication written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-24 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: The layer-additive nature of the electron beam freeform fabrication (EBF3) process results in a tortuous thermal path producing complex microstructures including: small homogeneous equiaxed grains; dendritic growth contained within larger grains; and/or pervasive dendritic formation in the interpass regions of the deposits. Several process control variables contribute to the formation of these different microstructures, including translation speed, wire feed rate, beam current and accelerating voltage. In electron beam processing, higher accelerating voltages embed the energy deeper below the surface of the substrate. Two EBF3 systems have been established at NASA Langley, one with a low-voltage (10-30kV) and the other a high-voltage (30-60 kV) electron beam gun. Aluminum alloy 2219 was processed over a range of different variables to explore the design space and correlate the resultant microstructures with the processing parameters. This report is specifically exploring the impact of accelerating voltage. Of particular interest is correlating energy to the resultant material characteristics to determine the potential of achieving microstructural control through precise management of the heat flux and cooling rates during deposition. Taminger, Karen M. and Hafley, Robert A. and Domack, Marcia S. Langley Research Center NASA/TM-2006-214297, L-19246

Download or read book Flow Behavior and Microstructural Evolution During Superplastic Deformation of AA8090 Aluminum lithium Alloy written by Wenjie Fan and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Metallurgical Mechanisms Controlling Mechanical Properties of Aluminum Alloy 2219 Produced by Electron Beam Freeform Fabrication written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-27 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: The electron beam freeform fabrication (EBF3) layer-additive manufacturing process has been developed to directly fabricate complex geometry components. EBF3 introduces metal wire into a molten pool created on the surface of a substrate by a focused electron beam. Part geometry is achieved by translating the substrate with respect to the beam to build the part one layer at a time. Tensile properties demonstrated for electron beam deposited aluminum and titanium alloys are comparable to wrought products, although the microstructures of the deposits exhibit cast features. Understanding the metallurgical mechanisms controlling mechanical properties is essential to maximizing application of the EBF3 process. Tensile mechanical properties and microstructures were examined for aluminum alloy 2219 fabricated over a range of EBF3 process variables. Unique microstructures were observed within the deposited layers and at interlayer boundaries, which varied within the deposit height due to microstructural evolution associated with the complex thermal history experienced during subsequent layer deposition. Microstructures exhibited irregularly shaped grains with interior dendritic structures, described based on overall grain size, morphology, distribution, and dendrite spacing, and were correlated with deposition parameters. Fracture features were compared with microstructural elements to define fracture paths and aid in definition of basic processing-microstructure-property correlations. Domack, Marcia S. and Tainger, Karen M. Langley Research Center NASA/TM-2006-214316, L-19265

Download or read book Effect of Plastic Deformation on Subsequent Decomposition in Aluminum Alloys Al Si and Al Mg Si written by Nikolaĭ Nikolaevich Buĭnov and published by . This book was released on 1953 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of plastic deformation on subsequent decomposition in the alloys Al-Si (1.2 percent Si) and Al-Mg-Si (1.4 percent Mg2Si) was studied with an electron microscope. These alloys were chosen because the first is easily quenched and does not age at room temperature and because in the second no decomposition after quenching and natural aging is detected with the electron microscope (although the properties change). These alloys were chosen also because they could be studied by the oxide-film method. This method was used to study the surface of the samples, which was etched before deformation and aging. It is then possible to observe simultaneously, on the electron photographs, precipitation, the block structure, and those alterations (slip lines, bending of blocks, cracks, etc.) in the submicroscopic structure of the alloys which are caused by deformation.

Download or read book Recrystallization and Grain Growth SF2M written by and published by . This book was released on 2004 with total page 772 pages. Available in PDF, EPUB and Kindle. Book excerpt: