Download or read book Microstructural Analysis of Critical Geometries and Heat Treated Laser Powder Bed Fusion Produced Aluminum Alloy A356 written by Melissa Trask and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Additive Manufacturing (AM) has garnered much attention due to the considerable advantages it offers over traditional manufacturing. Laser Powder Bed Fusion (LPBF) is a common AM method for metals, particularly in aerospace, due to the complex components that traditional manufacturing methods are able to produce, albeit with difficulty. Aluminum alloys are among those that are being examined for use in the aerospace industry, as the trend for lightweight components continues. Therefore, an advantage emerges in combining the benefits of aluminum alloys such as A356 (Al-7Si-Mg) with those of LPBF. However, the combination has to be studied in detail before it can be put into practice. The objective of this work is to study the microstructure and mechanical properties that result from the manufacture of A356 through LPBF. In this work, the effect of the component geometry on the microstructure was studied. In order to better reflect the microstructure that could occur in real components, common geometries were selected to be studied. It was found that the geometry had a minimal effect on the microstructure. The build temperature was found to have a greater effect on the microstructure. The effect that heat treatment has on the microstructure and mechanical properties of LPBF A356 was also studied, as heat treatment is commonly applied to components used in aerospace. It was found that the build temperature also has an effect in the heat treatment, as the samples processed at 200°C were in an already overaged condition in the as-fabricated state. It was found that the heat treatment that resulted in the highest hardness was a T5 heat treatment, rather than the more typical T6 heat treatment. " --

Download or read book Pulse Laser Powder Bed Fusion of High Strength Aluminum Alloys written by Andrew Walker and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "This work presents the foundation and results of a study of the pulse laser powder bed fusion process (P-LPBF). It focuses on the unique opportunity offered for the additive manufacturing (AM) industry to control the microstructure and mechanical properties of high strength aluminum alloys.A literature review has been presented covering the topics; additive manufacturing, high strength aluminum alloys, solidification physics, and evaporation phenomena. The work goes on to present results of a P-LPBF processing study of Al-Zn-Mg-Cu and Al-Mg-Si alloys. It was found that as built specimens of 98.0±0.5 Vol% density were achievable for the Al-Zn-Mg-Cu alloy, whereas samples with 99.3±0.4 Vol% density were produced from the Al-Mg-Si alloy.Solidification microstructures were examined and found to present highly refined second phases with coarse melt pool regions for both alloys. Quantitative analysis of the solidification behaviour of the Al-Zn-Mg-Cu alloy was conducted with the CGM and KGT microstructure development models. It was concluded that neither alloy exhibited significant departure from equilibrium solidification behaviour. The bulk chemical analyses of P-LPBF specimens of each alloy indicated that significant solute loss had occurred. Standard T6 heat treatment procedures were applied to the samples, yielding the expected microstructure and hardness results. The observed hardness of the Al-Zn-Mg-Cu alloy samples were found to fall below the wrought material while Al-Mg-Si alloy samples were able to slightly exceed the wrought properties. Solute loss was identified as the main variable driving this phenomenon. The AA7175 composition was more sensitive to solute loss as it depended more heavily on precipitation strengthening, while AA6061 made significant use of the Hall-Petch hardening mechanism, allowing it to tolerate substantial solute loss while maintaining the desired mechanical properties.In summary, this work has investigated the microstructural, mechanical, and chemical properties of two solidification crack susceptible aluminum alloys. The findings clearly demonstrate promising results for the feasibility of P-LPBF AM processing of high strength aluminium alloys." --

Download or read book Elements of Metallurgy and Engineering Alloys written by Flake C. Campbell and published by ASM International. This book was released on 2008-01-01 with total page 671 pages. Available in PDF, EPUB and Kindle. Book excerpt: This practical reference provides thorough and systematic coverage on both basic metallurgy and the practical engineering aspects of metallic material selection and application.

Download or read book Selective Laser Melting written by Prashanth Konda Gokuldoss and published by MDPI. This book was released on 2020-04-03 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: Additive manufacturing (AM) is one of the manufacturing processes that warrants the attention of industrialists, researchers, and scientists. AM has the ability to fabricate materials to produce parts with complex shapes without any theoretical restrictions combined with added functionalities. Selective laser melting (SLM), also known as laser-based powder bed processing (LPBF), is one of the main AM process that can be used to fabricate wide variety of materials that are Al-, Ti-, Fe-, Ni-, Co-, W-, Ag-, and Au-based, etc. However, several challenges need to be addressed systematically, such as development of new materials that suit the SLM process conditions so the process capabilities can be fully used to produce new properties in these materials. Other issues in the field are the lack of microstructure–property correlations, premature failure, etc. Accordingly, this Special Issue (book) focuses mainly on the microstructure-correlation in three different alloys: AlSi10Mg, Ti6Al4V, and 304L stainless steel, where six articles are presented. Hence, this Special Issue outlines microstructure–property correlations in the SLM processed materials and provides a value addition to the field of AM.

Download or read book Microstructural and Mechanical Property Characterization of Shear Formed Aerospace Aluminum Alloys written by Lillianne P. Troeger and published by . This book was released on 2000 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced manufacturing processes such as near-net-shape forming can reduce production costs and increase the reliability of launch vehicle and airframe structural components through the reduction of material scrap and part count and the minimization of joints. The current research is an investigation of the processing-microstruture-property relationships for shear formed cylinders of the Al-Cu-Li-Mg-Ag alloy 2195 for space applications and the Al-Cu-Mg-Ag alloy C415 for airframe applications. Cylinders which had undergone various amounts of shear-forming strain were studied to correlate the grain structure, texture, and mechanical properties developed during and after shear forming.

Download or read book Evaluation of Laser Power Bed Fusion LPBF Fabricated A356 A17SiMg Components Through Finite Element Analysis written by Shih-Cheng Chou and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Laser powder bed fusion (LPBF) is a type of additive manufacturing (AM) process that is primarily used to fabricate metallic components. In this study, two LBPF systems, a custom built LPBF system and a commercial LPBF system (EOS 290M), were used to fabricate a series of aluminum-silicon alloy specimens for material characterizations and mechanical property evaluations. A356 (Al7SiMg) alloy was selected to be the focus material in which the microstructure morphology, and grain morphology obtained by rapid solidification was investigated. Directionality of the LPBF fabricated components was further addressed in this work.The initial phase of the research aims to evaluate the effects of rapid solidification on microstructure morphology and grain morphology of A356 specimens fabricated using the LPBF based AM system. In this study, A356 specimens were fabricated through a custom built pulsed laser powder bed fusion (P-LPBF) system that provided greater control over process parameters. The part density of P-LPBF fabricated A356 specimens were measured to achieve 98% ± 0.4%. The results revealed a fine cellular microstructure with the intercellular network consisting of Al cells and defined by a network of Si arms. The Al cells at the center of the melt pools and within the melt pool boundary bands were measured to be 423±49 nm and 664±76 nm, respectively. The presence of a fine columnar grain structure and epitaxial growth on partially melted grains was observed and explained by the KGT model and Hunt's criterion.Further studies are done using a commercialized LPBF system, EOS M290, to fabricate A356 tensile specimens for mechanical property evaluations. Tensile testing is performed on A356 tensile specimens fabricated in three different directions: vertical direction, 45-degree direction, and horizontal direction. Tensile results show that the LPBF fabricated A356 specimens exhibit directional mechanical properties. Combined with the results from the initial study, it is concluded that the anisotropic yield behavior of the A356 specimens is attributed to microstructure inhomogeneity and directional grain growth. Finite element analyses (FEAs) are performed to evaluate the impacts of different fabrication orientations, different pre-heat temperatures on LPBF fabricated A356 components, and simulate mechanical responses of the A356 components under in-service conditions." --

Download or read book Reliability of Selective Laser Melted AlSi12 Alloy for Quasistatic and Fatigue Applications written by Shafaqat Siddique and published by Springer. This book was released on 2018-09-18 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: Selective laser melting (SLM) has established itself as the most prominent additive manufacturing (AM) process for metallic structures in aerospace, automotive and medical industries. For a reliable employment of this process, it has to conform to the demanding requirements of these industries in terms of quasistatic and, especially, fatigue performance. Shafaqat Siddique identifies the influence of SLM processing conditions on the microstructural features, and their corresponding influence on the mechanical behavior of the processed AlSi12 alloy structures. The author also gives insight into integrated manufacturing by combining conventional and SLM processes to get the synergic benefits. Requirements for fatigue-resistant designs in additive manufacturing are highlighted, and a novel method is developed for agile fatigue life prediction. About the Author Shafaqat Siddique worked as Scientific Assistant at TU Dortmund University, Department of Materials Test Engineering (WPT), headed by Prof. Dr.-Ing. Frank Walther, and completed his Ph.D. research in cooperation with Laser Zentrum Nord (LZN) in Hamburg. He continues his post-doctoral research at TU Dortmund University, Germany.

Download or read book Anisotropic mechanical behaviors and microstructural evolution of thin walled additively manufactured metals written by Cheng-Han Yu and published by Linköping University Electronic Press. This book was released on 2020-09-07 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt: Additive manufacturing (AM), also known as 3D printing, is a concept and method of a manufacturing process that builds a three-dimensional object layer-by-layer. Opposite to the conventional subtractive manufacturing, it conquers various limitations on component design freedom and raises interest in various fields, including aerospace, automotive and medical applications. This thesis studies the mechanical behavior of thin-walled component manufactured by a common AM technique, laser powder bed fusion (LPBF). The studied material is Hastelloy X, which is a Ni-based superalloy, and it is in connection to a component repair application in gas turbines. The influence of microstructure on the deformation mechanisms at elevated temperatures is systematically investigated. This study aims for a fundamental and universal study that can apply to different material grades with FCC crystallographic structure. It is common to find elongated grain and subgrain structure caused by the directional laser energy input in the LPBF process, which is related to the different printing parameters and brands of equipment. This thesis will start with the study of scan rotation effect on stainless steel 316L in an EOS M290 equipment. The statistic texture analysis by using neutron diffraction reveals a clear transition when different level of scan rotation is applied. Scan rotation of 67° is a standard printing parameter with intention to lower anisotropy, yet, the elongated grain and cell structure is still found in the as-built microstructure. Therefore, the anisotropic mechanical behavior study is carried out on the sample printed with scan rotation of 67° in this thesis. Thin-walled effects in LPBF are investigated by studying a group of plate-like HX specimens, with different nominal thicknesses from 4mm down to 1mm, and a reference group of rod-like sample with a diameter of 18mm. A texture similar to Goss texture is found in rod-like sample, and it becomes <011>//BD fiber texture in the 4mm specimen, then it turns to be <001> fiber texture along the transverse direction (TD) in the 1mm specimen. Tensile tests with the strain rate of 10?3 s?1 have been applied to the plate-like specimens from room temperature up to 700 ?. A degradation of strength is shown when the sample becomes thinner, which is assumed to be due to the overestimated load bearing cross-section since the as-built surface is rough. A cross-section calibration method is proposed by reducing the surface roughness, and a selection of proper roughness parameters is demonstrated with the consideration of the calculated Taylor’s factor and the residual stress. The large thermal gradient during the LPBF process induces high dislocation density and strengthens the material, hence, the LPBF HX exhibits better yield strength than conventionally manufactured, wrought HX, but the work hardening capacity and ductility are sacrificed at the same time. Two types of loading condition reveal the anisotropic mechanical behavior, where the vertical and horizontal tests refer to the loading direction being on the BD and TD respectively. The vertical tests exhibit lower strength but better ductility that is related to the larger lattice rotation observed from the samples with different deformation level. Meanwhile, the elongated grain structure and grain boundary embrittlement are responsible for the low horizontal ductility. A ductile to brittle transition is traced at 700 ?, so a further study with two different slow strain rates, 10?5 s?1 and 10?6 s?1, are carried out at 700 ?. Creep damage is shown in the slow strain rates testing. Deformation twinning is found only in the vertical tests where it forms mostly in the twin favorable <111> oriented grain along the LD. The large lattice rotation and the deformation twinning make the vertical ductility remain high level under the slow strain rates. The slow strain rate tensile testing lightens the understanding of creep behavior in LPBF Ni-based superalloys. In summary, this thesis uncovers the tensile behavior of LPBF HX with different variations, including geometry-dependence, temperature-dependence, crystallographic texture-dependence and strain rate-dependence. The generated knowledge will be beneficial to the future study of different mechanical behavior such as fatigue and creep, and it will also enable a more robust design for LPBF applications. Additiv tillverkning, eller 3D-utskrifter, är tillverkningsmetoder där man skapar ett tredimensionellt objekt genom att tillföra material lager for lager. Till skillnad från konventionella avverkande tillverkningsmetoder elimineras många geometriska begränsningar vilket ger större designfrihet och metoderna har därför väckt stort intresse inom en rad olika områden, inklusive flyg-, fordons- och medicinska tillämpningar. I denna avhandling studeras mekaniska egenskaper hos tunnväggiga komponenter tillverkade med en vanligt förekommande laserbaserad pulverbädds-teknik, laser powder bed fusion (LPBF). Det studerade materialet är Hastelloy X, en Ni-baserad superlegering som är vanligt förekommande for både nytillverkning och reparation av komponenter för gasturbiner. Inverkan av mikrostruktur på deformationsmekanismerna vid förhöjda temperaturer undersöks systematiskt. Detta arbete syftar till att ge grundläggande och generisk kunskap som kan tillämpas på olika materialtyper med en kubiskt tätpackad (FCC) kristallstruktur. Det är vanligt att man hittar en utdragen kornstruktur orsakad av den riktade tillförseln av laserenergi i LPBF-processen, vilket kan relateras till olika processparametrar och kan variera mellan utrustningar frän olika leverantörer. Denna avhandling inleds med studien av effekten av scanningsstrategi vid tillverkning av rostfritt stål 316L i en EOS M290-utrustning. En statistisk texturanalys med hjälp av neutrondiffraktion påvisar en tydlig övergång mellan olika mikrostrukturer när olika scanningsstrategier tillämpas. En scanningsrotation på 67 mellan varje lager är en typisk standardinställning med avsikt att sanka anisotropin i materialet, dock finns den utdragna kornstrukturen oftast kvar. I denna avhandling studeras därför de anisotropa egenskaperna hos material tillverkade med 67 scanningsrotation. Effekten av tunnväggiga strukturer i LPBF undersöks genom att studera en uppsättning platta HX-prover, med olika nominella tjocklekar från 4 mm ner till 1 mm, samt en referensgrupp med cylindriska prov med en diameter på 18 mm. Kristallografisk textur som liknar den av Goss-typ återfinns i de cylindriska proverna vilket gradvis övergår från en fibertextur med <011> i byggriktningen for 4mm-proven till en fibertextur med <001> i tvärriktningen for 1mm-proven. Dragprovning med en töjningshastighet på 10?3 s?1 har utförts på de platta provstavarna från rumstemperatur upp till 700 ?. En sänkning av styrkan uppvisas när proven blir tunnare, vilket kan antas bero på att det lastbarande tvärsnittet överskattas på grund av den grova ytan. En metod för tvärsnittskalibrering föreslås genom att kompensera for ytråheten, och valet av lämplig ytfinhetsparameter motiveras med hänsyn till den beräknade Taylor-faktorn och förekomsten av restspänningar. Den stora termiska gradienten som uppstår for LPBF-processen inducerar en hög dislokationstäthet vilket höjer materialets styrka och följaktligen uppvisar LPBF HX högre sträckgräns an konventionellt tillverkad, smidda HX, men förmågan till deformationshårdnande samt duktiliteten i materialet sänks samtidigt. Tester utförda i två olika belastningsriktningar, vertikalt respektive horisontellt mot byggriktningen, demonstrerar det anisotropiska mekaniska beteendet. De vertikala testerna uppvisar lägre hållfasthet men bättre duktilitet vilket kan relateras till en större benägenhet for kristallstukturen att rotera när deformationsgraden ökar. Samtidigt är den utdragna kronstukturen ansvarig for den lägre duktiliteten for de horisontella proverna. En övergång från ett duktilt till ett mer sprött beteende noterades vid 700 ?, och därför initierades ytterligare en studie där tester med två lägre töjningshastigheter, 10?5 s?1 och 10?6 s?1, utfördes vid 700 ?. Det kan noteras att krypskador återfinns i tester med en långsam deformationshastighet och deformationstvillingar uppstår endast i de vertikala provstavarna där det främst bildas tvillingar i korn orienterade med <111> riktningen längs belastningsriktningen. Den stora förmågan till rotation i kristallstrukturen och deformationstvillingarna bidrar till att den vertikala duktiliteten förblir hög även i testerna med en låg deformationshastighet. Testerna med en långsam draghastighet bidrar därför till en bättre förståelse av krypbeteendet i LPBF Nibaserade superlegeringar. Sammanfattningsvis så bidrar denna avhandling till bättre förståelse av de mekaniska egenskaperna hos LPBF HX i olika utföranden och förhållanden, inklusive geometriberoende, temperaturberoende, deformationshastighetsberoende samt inverkan av kristallografisk textur. Den genererade kunskapen kommer att vara till stor nytta vid fortsatta studier av olika mekaniska egenskaper som utmattning och kryp, samt bidrar till att möjliggöra en mer robust design for LPBF-tillämpningar.

Download or read book Influence of Powder Layer Thickness on Microstructure and T5 Heat Treatability of AlSi7Mg Alloy Fabricated by Laser Powder Bed Fusion written by Chin Chieh Cheng and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Laser powder bed fusion (LPBF) is one of the frequently used manufacturing methods to fabricate complex metal components. Lightweight Al alloy has a promising potential in aerospace and automobile industry applications. Even though LPBF is approaching mainstream manufacturing, the knowledge gap regarding heat treatment of LPBF fabricated AlSi7Mg alloy remains to be studied. This thesis aims to study the influence of layer thickness during T5 heat treatment through several approaches. Two different layer thicknesses, i.e. 30 μm and 50 μm, were employed to fabricate AlSi7Mg bar samples. T5 aging curves, of 150 °C, 160 °C, and 170 °C, show the positive strengthen response for both 30 μm and 50 μm layer thickness. Scanning electron microscopy (SEM) micrographs display the comparable eutectic Si microstructure after T5 heat treatment. Transmission electron microscopy (TEM) micrographs exhibit the identical cluster precipitation developed during T5. Finally, Johnson-Mehl-Avrami model was used to obtain the apparent activation energy of around 140 kJ/mol for both layer thicknesses"--

Download or read book Microstructure property Models for Heat Treatment of A356 Aluminum Alloy written by Leo John Colley and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Manufacturing and Application of Stainless Steels written by Andrea Di Schino and published by MDPI. This book was released on 2020-04-15 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stainless steels represent a quite interesting material family, both from a scientific and commercial point of view, following to their excellent combination in terms of strength and ductility together with corrosion resistance. Thanks to such properties, stainless steels have been indispensable for the technological progress during the last century and their annual consumption increased faster than other materials. They find application in all these fields requiring good corrosion resistance together with ability to be worked into complex geometries. Despite to their diffusion as a consolidated materials, many research fields are active regarding the possibility to increase stainless steels mechanical properties and corrosion resistance by grain refinement or by alloying by interstitial elements. At the same time innovations are coming from the manufacturing process of such a family of materials, also including the possibility to manufacture them starting from metals powder for 3D printing. The Special Issue scope embraces interdisciplinary work covering physical metallurgy and processes, reporting about experimental and theoretical progress concerning microstructural evolution during processing, microstructure-properties relations, applications including automotive, energy and structural.

Download or read book Microstructure and Properties of Materials written by James Chen-Min Li and published by World Scientific. This book was released on 1996 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the second volume of an advanced textbook on microstructure and properties of materials. (The first volume is on aluminum alloys, nickel-based superalloys, metal matrix composites, polymer matrix composites, ceramics matrix composites, inorganic glasses, superconducting materials and magnetic materials). It covers titanium alloys, titanium aluminides, iron aluminides, iron and steels, iron-based bulk amorphous alloys and nanocrystalline materials.There are many elementary materials science textbooks, but one can find very few advanced texts suitable for graduate school courses. The contributors to this volume are experts in the subject, and hence, together with the first volume, it is a good text for graduate microstructure courses. It is a rich source of design ideas and applications, and will provide a good understanding of how microstructure affects the properties of materials.Chapter 1, on titanium alloys, covers production, thermomechanical processing, microstructure, mechanical properties and applications. Chapter 2, on titanium aluminides, discusses phase stability, bulk and defect properties, deformation mechanisms of single phase materials and polysynthetically twinned crystals, and interfacial structures and energies between phases of different compositions. Chapter 3, on iron aluminides, reviews the physical and mechanical metallurgy of Fe3Al and FeAl, the two important structural intermetallics. Chapter 4, on iron and steels, presents methodology, microstructure at various levels, strength, ductility and strengthening, toughness and toughening, environmental cracking and design against fracture for many different kinds of steels. Chapter 5, on bulk amorphous alloys, covers the critical cooling rate and the effect of composition on glass formation and the accompanying mechanical and magnetic properties of the glasses. Chapter 6, on nanocrystalline materials, describes the preparation from vapor, liquid and solid states, microstructure including grain boundaries and their junctions, stability with respect to grain growth, particulate consolidation while maintaining the nanoscale microstructure, physical, chemical, mechanical, electric, magnetic and optical properties and applications in cutting tools, superplasticity, coatings, transformers, magnetic recordings, catalysis and hydrogen storage.

Download or read book Investigating and Modeling the Microstructure and Mechanical Properties of Additively Manufactured High Strength Alloys written by Ala'aldin Alafaghani and published by . This book was released on 2021 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laser-based powder bed fusion (LPBF) is an additive manufacturing method that fabricates parts layer by layer by fusing the raw material powder using laser as the energy source. Originally, LPBF was used for rapid prototyping due to its capability to fabricate prototypes whenever changes are introduced to the concept CAD model without lead-time or the need to modify the fabrication line. Due to the inferior mechanical properties such as strength and stiffness of the fabricated parts compared to conventionally manufactured parts, and the limited options of materials, additive manufacturing was not used to fabricate end user functional parts. However, the recent developments in the last decade such as the introduction of high-power lasers with more compatible wavelengths, and higher quality raw materials, provide the opportunity to produce functional parts with high mechanical properties. Currently, LPBF is capable of producing parts with near full relative density. However, these parts still suffer from high anisotropy, defects, residual stresses, and inferior tensile strength, and fatigue life. This dissertation investigates different approaches to render the manufacturing of load-bearing metallic parts using LPBF more effective and reliable. The work presented focuses on two alloys, 15-5PH stainless steel and Inconel 718, due to their comparability with LPBF and their use in aerospace and automotive industries where additive manufacturing can be used cost-effectively. The microstructure and mechanical properties of LPBF parts are highly sensitive to the processing parameters during fabrication and post-processing. Metallic parts are sensitive to the laser power, laser scanning speed, hatch spacing, powder layer thickness, and the orientation of the part during fabrication. Several studies investigated the effect of the processing parameters on the relative density and mechanical properties of LPBF parts. It was found that the set of processing parameters required to obtain high relative density is usually different than the set of processing parameters required to optimize the mechanical properties. To achieve the full potential of LPBF parts this work aims at optimizing the microstructure and mechanical properties of parts fabricated with the set of processing parameters that maximizes the relative density of the part. Therefore, the first objective of this dissertation is to characterize the microstructure and mechanical properties of as-fabricated LPBF parts at room and elevated temperatures. The second objective is to develop and investigate different post-processing heat treatments that aim to homogenize the microstructure, improve the reliability of the parts, and identify the treatments that have the potential to improve fatigue strength and life. Finally, the last objective of this dissertation is to develop predictive models that assist in estimating the effect of different heat treatments on the mechanical properties of LPBF produce parts. A hybrid approach of physical and data-based derived models was used to evaluate the influence of post-processing heat treatment on the tensile strength of additively manufactured Inconel 718.

Download or read book Effect of Build Geometry and Build Parameters on Microstructure Fatigue Life and Tensile Properties of Additively Manufactured Alloy 718 written by Anna Dunn and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Additive Manufacturing (AM), particularly laser powder bed fusion, is being studied for use in critical component applications. Tensile and fatigue testing shows differences when built using different laser powers. However, when fabricated in an as-printed geometry, the gauge sections of the two specimens are different and experience different thermal behavior. This work explores microhardness, microstructure size, Niobium segregation, and porosity from samples made with varying laser power and different build geometry sizes representative of the gauge sections in the tensile and fatigue bars. Results show that microhardness varies spatially across the sample. Smaller diameter metallographic coupons (fatigue diameter) have a coarser microstructure and lower microhardness than the larger diameter (tensile diameter) when built using the same parameters. Therefore, the fatigue and tensile properties are not comparing the same material structure. Understanding the effect of build geometry on microstructure provides insight towards consistency in AM mechanical properties testing strategies.

Download or read book Investigation on Microstructure and Mechanical Properties of Porous Structures Processed by Laser Powder Bed Fusion written by Samarth Ramachandra and published by . This book was released on 2021 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt: Inconel 718 (i.e., IN718) is a prominent nickel-based, precipitation-hardening superalloy which exhibits exceptionally stable mechanical and corrosion resistant properties, even at temperature range of 650oC to 700oC, making it suitable for a wide range of applications such as aerospace, nuclear reactors, tooling, turbines, oil and gas applications. The high toughness and work hardening offered by this superalloy, however, greatly limits the choice of machinability. The presence of low levels of aluminum permits good weldability which further allows the use of laser-based additive manufacturing (AM) to efficiently fabricate IN718 parts without the limitations associated with conventional manufacturing methods. Thanks to AM techniques, it is possible to even fabricate parts with complex geometries, such as porous structures, thin walls, and curved surfaces. Implementation of engineered porosity in an IN718 part successively promotes further advantages such as reduced weight and material use, making them great candidates for lightweight applications such as aerospace, space, automobile, biomedicine, and defense industries.The porous structures commonly used in AM have been greatly inspired by the biological patterns and other naturally occurring structures such as honeycomb, molecular lattice cubic structures (e.g., FCC,FCC-Z, BCC, BCC-Z) and triply periodic minimal surface structures (e.g., Schwarz, gyroid and diamond).Different porous structures tend to have varied effects on the mechanical properties of the part based on the material used. While low density parts with enhanced local surface area can be fabricated for most of the materials along with other desired qualities, the key to obtain a part with optimized mechanical attributes is the right combination of the porous type and porosity level corresponding to the material involved. In this study, IN718 structures with different porosity type and level are studies in terms of their microstructure and mechanical properties. To this aim, compression and hardness tests are conducted onall the test samples to obtain the mechanical properties. Also, compositional analysis using X-ray powder diffraction (XRD), and microstructural analysis using scanning electron microscope (SEM), are carried out on the specimens to study the defects and causes of failure. Through these tests and analyses, the process structure-property relationship for porous IN718 are also identified, which could be used as a basis for optimization of process parameters to achieve better mechanical properties and part quality.

Download or read book LASER POWDER BED FUSION OF Ti 6Al 2Sn 4Zr 2Mo 0 08Si Ti 6242 ALLOY PROCESS MICROSTRUCTURE PROPERTIES RELATIONSHIP written by Harish Chandra Kaushik and published by . This book was released on 2024 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The current work is focused on Laser-powder bed fusion (L-PBF) of Ti-6Al-2Sn-4Zr-2Mo-0.08Si (Ti-6242) which is a near-Îł titanium alloy used for high-temperature applications. The fabrication of Ti-6242 is common using conventional techniques such as casting, forging, and powder metallurgy whereas the L-PBF of Ti-6242 is comparatively new. This offers the opportunity to develop the process-microstructure-property relationship of Ti-6242 fabricated through L-PBF. This includes tasks like 3D printing of Ti-6242 followed by the study of mechanical properties and the governing microstructures of as-built (AB) and after post-processing (heat treatment in this case). In the current study, the 3D printing of Ti-6242 was done by varying the volumetric energy density (E_v) from 41.67 to 66.67 J/mm3 by changing the scanning speeds. The variation in E_v results in variation in mechanical properties. Both the microstructure and defect analysis are performed. The defect characteristics are changed from keyhole to lack of fusion by varying the E_v from high to low whereas the microstructural characteristics are almost consistent. This concluded that the changes in mechanical properties of laser-powder bed fused Ti-6242 (L-PBF-Ti-6242) are defect-driven rather than microstructure-driven in the AB condition. The sample fabricated with process parameters offering the best combination of strength and ductility is selected for further studies. The systematic study of L-PBF-Ti-6242 is further proceeded by investigating the kinetics of Îł to Îø phase transformation using differential scanning calorimetry (DSC). Both non-isothermal and isothermal kinetics models are developed using the DSC results and employing the Johnson-Mehl-Avrami-Kolmogorov equation. As the AB microstructure of L-PBF-Ti-6242 consists of Îł0́9 martensite which is a brittle constituent it shows high strength and low ductility. To achieve the strength-ductility synergy, the modeled Îł to Îø phase transformation kinetics is used to design and develop two-step (solutionizing and aging) post-process heat treatment with an emphasis on preserving the unique, ultrafine, and hierarchical microstructure. The solutionized microstructure, 900℗ʻC for 10 minutes (S), has Îł/Îł0́9 and Îø phases with different dislocation densities. This condition results in the lowest strength and highest ductility, governed by the presence of the bcc phase (Îø), and high mean effective slip length in the Îł/Îł0́9 phase. The aging process, 300℗ʻC for 48 hours following the solutionizing step (STA) results in changes in dislocation substructure in the Îł/Îł0́9 phase which leads to an increase in strength, controlled by a reduction in mean effective slip length. The formulated two-step heat treatment leads to the best strength-ductility synergy in this study. The high-temperature mechanical property of L-PBF-Ti-6242 was investigated for AB, S, and STA conditions. In the AB condition, the LPBF-Ti-6242 shows superior strength at high temperatures in comparison with Ti-6Al-4V. In the case of L-PBF-Ti-6242, although the STA shows superior strength at room temperature, both S and STA exhibit almost similar strength at high temperatures. It is proposed that the developed heat treatment recipe attained a better combination of strength and ductility at room as well as high temperature. This justified the importance of the study of phase transformation kinetics to develop the heat treatment recipe for titanium alloys newly fabricated through L-PBF.

Download or read book Laser Additive Manufacturing of High Performance Materials written by Dongdong Gu and published by Springer. This book was released on 2015-04-21 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book entitled “Laser Additive Manufacturing of High-Performance Materials” covers the specific aspects of laser additive manufacturing of high-performance new materials components based on an unconventional materials incremental manufacturing philosophy, in terms of materials design and preparation, process control and optimization and theories of physical and chemical metallurgy. This book describes the capabilities and characteristics of the development of new metallic materials components by laser additive manufacturing process, including nanostructured materials, in situ composite materials, particle reinforced metal matrix composites, etc. The topics presented in this book, similar as laser additive manufacturing technology itself, show a significant interdisciplinary feature, integrating laser technology, materials science, metallurgical engineering and mechanical engineering. This is a book for researchers, students, practicing engineers and manufacturing industry professionals interested in laser additive manufacturing and laser materials processing. Dongdong Gu is a Professor at College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics (NUAA), PR China.