Download or read book Tailoring Mechanical Properties and Porosity in Laser Powder Bed Fusion by Spatial Manipulation of Feedstock Composition written by Bethany Rose Lettiere and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Additive manufacturing (AM) is capable of forming complex geometries, can build custom products, and offers greater versatility than many conventional manufacturing processes. Metal AM has revolutionized the design and production of rocket engines, enabled lightweight robotics and drones, and created heat exchangers that improve the efficiency of energy conversion systems. Typically, the feedstock for metal AM is a single alloy powder, metal powder, or a stochastic mixture of alloys. The design space of AM can be expanded by techniques for local manipulation of the powder feedstock, thereby enabling the tailoring of composition or microstructure gradients to improve mechanical or thermal properties. Current methods for local manipulation of the feedstock incorporate hopper- or vacuum-based methods with spatial deposition resolution on the order of 500 [mu]m and typically require a secondary recoating step after depositing the material, further limiting the resolution and fidelity of property. In this thesis, a new hybrid AM technique combining inkjet deposition followed by laser powder bed fusion (LPBF) is studied, and the technique is demonstrated in exemplary contexts. To begin, a rapid experimental workflow is developed, whereby etched metal substrates are used as templates for spreading a thin layer of metal powder; spreading is preceded by inkjet deposition onto the wells and is followed by laser scanning to form a solid material with tailored characteristics. This workflow facilitates an understanding of the influence of additive concentration, laser power, and scan speed on the process. Using this workflow, the thesis: (1) assesses the resolution (~ 200 [mu]m) and limitations of the hybrid inkjet-LPBF process; (2) demonstrates the fabrication of porous stainless steel using a polymer-based ink as the deposited additive, achieving spatially controlled porosity upwards of 8% locally with pore sizes of 250-800 [mu]m2 and a spatial resolution of ~ 400 [mu]m; (3) demonstrates spatial tailoring of the hardness of stainless steel using an ink with carbon black as the additive, achieving a local increase in the microhardness from a control of 178 HV to 196.6 HV with a spatial resolution of 250 [mu]m. In the case of porosity control, a scaling model of thermal effects, combined with an understanding of the melt pool's flow and stability, rationalizes the experimental outcomes and the process parameter space. This thesis validates the multi-material inkjet-laser process for high-resolution, spatially graded metal AM. These findings lay the foundation for a hybrid inkjet-LPBF fusion system to develop high-precision components and its use for rapid alloy development in metal AM.
Download or read book Relationship Between Porosity and Mechanical Properties in Laser Powder Bed Fusion Fabricated Ti6Al4V Alloy written by Flavio Weinstein Silva and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Laser Powder Bed Fusion (LPBF) is an Additive Manufacturing (AM) process that offers superior versatility and direct part manufacturing from Computer Aided Design (CAD) model. It provides nearly unrestricted freedom to design in order to optimize part functionality producing shapes that would be impossible with conventional manufacturing such as moulding or machining. Moreover, it has a very low buy-to-fly ratio offering savings in material usage and lower waste from machining.Despite all the ground-breaking benefits mentioned, porosity is currently an inevitable process-induced defect commonly found in as-fabricated LPBF components. Porosity level as low as 0.5% contained in manufactured parts can still render them unfit for large-scale structural applications, such as in aerospace, due to its negative effects on mechanical properties. As an effective time and cost saving approach for assessing different types of pores for quality control and catastrophic failure prevention, the use of Finite Element Analysis (FEA) was proposed. By modelling the pores found in the parts' microstructure, a threshold is expected to be determined on the tolerable defect amount to be allowed while still preserving the minimum mechanical property required for a given application.The results found in this thesis presents a methodology for assessing the types of pores and pore clusters found in LPBF Ti-6Al-4V manufactured parts. The concept of stress triaxiality was used as a parameter and failure criteria for pore evaluation and damage initiation, respectively. This parameter enabled so far to obtain a trend with respect to the pore morphology and describe the dominant mechanism of failure pertaining this type of defect found in LPBF parts. Moreover, pore morphology and directionality simulated in FEA were found to significantly influence strain limit to fracture initiation showing a more premature failure mode for pores with smaller radius of curvature and directionally perpendicular to tensile load direction." --
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 Fundamentals of Laser Powder Bed Fusion of Metals written by Igor Yadroitsev and published by Elsevier. This book was released on 2021-05-23 with total page 678 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laser powder bed fusion of metals is a technology that makes use of a laser beam to selectively melt metal powder layer-by-layer in order to fabricate complex geometries in high performance materials. The technology is currently transforming aerospace and biomedical manufacturing and its adoption is widening into other industries as well, including automotive, energy, and traditional manufacturing. With an increase in design freedom brought to bear by additive manufacturing, new opportunities are emerging for designs not possible previously and in material systems that now provide sufficient performance to be qualified in end-use mission-critical applications. After decades of research and development, laser powder bed fusion is now enabling a new era of digitally driven manufacturing. Fundamentals of Laser Powder Bed Fusion of Metals will provide the fundamental principles in a broad range of topics relating to metal laser powder bed fusion. The target audience includes new users, focusing on graduate and undergraduate students; however, this book can also serve as a reference for experienced users as well, including senior researchers and engineers in industry. The current best practices are discussed in detail, as well as the limitations, challenges, and potential research and commercial opportunities moving forward. - Presents laser powder bed fusion fundamentals, as well as their inherent challenges - Provides an up-to-date summary of this advancing technology and its potential - Provides a comprehensive textbook for universities, as well as a reference for industry - Acts as quick-reference guide
Download or read book Laser Powder Bed Fusion of Additive Manufacturing Technology written by Di Wang and published by Springer Nature. This book was released on 2023-10-06 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book systematically introduces the powder bed laser melting technology and its application and summarizes the author's team's experience in scientific research, engineering development, and data accumulation in recent 15 years. It includes in-depth theoretical analysis and a lot of engineering experience in equipment debugging, process development, and material testing. The book takes the powder bed laser melting technology as the object and divides the content into 15 chapters. It is used as technical learning materials for researchers and engineering development personnel engaged in metal 3D printing.
Download or read book Engineering of Temperature Profiles for Location specific Control of Material Micro structure in Laser Powder Bed Fusion Additive Manufacturing written by George Lewandowski and published by . This book was released on 2020 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work explores new capabilities of recently emerged adaptive multi-beam laser power sources to optimally shape laser power spatial distribution at powder material during metallic laser powder bed fusion additive manufacturing. Conventional laser additive manufacturing (LAM) systems use a highly localized laser beam for powder material melting resulting in strong temperature gradients inside the heat affected zone (HAZ) leading to formation of columnar material grain structure having highly anisotropic mechanical properties. Beam shaping with multi-beam laser power source provides opportunities for on demand and location-specific altering grain structure from columnar to equiaxed resulting in more isotropic mechanical properties of LAM fabricated parts. In this work we perform numerical simulations of theLAM process using a reduced complexity analytical heat transfer solution in order to optimize multi-beam configurations leading to the desired transitioning from columnar to equiaxed grain morphology. The beam shaping optimization was performed using a stochastic parallel gradient descent optimization of the introduced performance metrics. The results demonstrate the possibility to significantly increase the fraction of equiaxed grains in the solidified powder material using optimal positioning and laser power control of multiple laser focal spots during LAM.
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.
Download or read book Laser Powder Bed Fusion Processed IN713 LC Efforts to Understand Cracking Mechanism Microstructure and Mechanical Properties written by and published by . This book was released on 2020 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Laser Powder Bed Fusion of beta 21S Titanium Alloy written by Maria Macias Sifuentes and published by . This book was released on 2022 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Laser powder bed fusion (LPBF), one of the most studied processes among metal additive manufacturing (AM), has raised attention due to its high degree of manufacturing freedom, its ability to produce lightweight intricate components, and its energy-efficient, and time saving route. Today, research has focused only on a limited number of alloys such as Ti-6Al-4V, Inconel 625 and 718, and stainless steel 316L. New alloys produced by this technique need to be studied to be able to maximize the advantages of AM. Metastable [beta]-titanium alloys are attractive for the aerospace industry due to their low density, high strength, excellent hardenability, and stability at high temperature. Among these alloys, [beta]-21S is known to offer improved elevated temperature strength, creep resistance, thermal stability, and oxidation resistance. Furthermore, heat treatment can be applied to this alloy for tailoring the mechanical properties according to the desired application. The manufacturability of [beta]-21S produced by LPBF, as well as the effect of heat treatment was investigated in the present thesis, to understand the relationship between the microstructure and the mechanical properties. The tensile performance of [beta]-21S in the as-built state presented comparable behavior to the wrought in solution treatment condition. Solution treatment and aging (STA) of the alloy precipitated the [alpha]-phase, increasing the microhardness, and strength, while reducing the ductility. The heat treatment applied to LPBF [beta]-21S had a similar effect compared to [beta]-21S fabricated by non-AM techniques. The properties obtained demonstrated the potential of [beta]-21S for LPBF applications"--
Download or read book Correlating In Situ Monitoring Data with Internal Defects in Laser Powder Bed Fusion Additive Manufacturing written by Andrew J. Harvey and published by . This book was released on 2020 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: The presence of defects within laser powder bed fusion (LPBF) parts can lead to reduced mechanical properties and life of components. Because of this, the ability to detect these defects within the parts is critical before the part is subject to its intended loading. Normally the parts are subjected to a quality analysis once they are completed however, this process is typically expensive and time consuming. A solution for these problems is to sense the creation of defects and pores in the parts in-situ, while the part is being fabricated. One proposed method of in-situ monitoring is visible spectroscopy to identify defects based on the light intensities during prints. In this work, in-situ spectroscopy intensities and ex-situ computed tomography defect data are compared for different processing parameters and two LPBF builds to determine correlation. Results show that changes in the signals from the spectroscopy occur for different conditions of processing parameters and geometries.
Download or read book Laser Powder Bed Fusion of 316L Stainless Steel written by and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Comparative Investigations Into Microstructural and Mechanical Properties of As cast and Laser Powder Bed Fusion LPBF Fabricated Duplex Steel 1 4517 written by Iris Raffeis and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Characterisation of Mechanically Alloyed Feedstock for Laser powder Bed Fusion written by Iain Lyall and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Surface Morphological Effects of Laser Powder Bed Fusion and Laser Micromachining in Micro scale Parts written by Abhi Ghosh and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "The heterogeneity of the as-built surface morphology of micro-scale parts produced by laser powder bed fusion (LPBF) has a significant influence over their mechanical behavior, which often leads to premature failure under tensile load. To investigate the effect of notch-like surface morphological features of as-built surface morphology on tensile strength and ductility, finite element analysis was performed on tensile plastic flow interaction with notches created by the introduction of surface features with heights ranging from 25 μm to 85 μm on 250 μm diameter struts. Results show that the uniform elongation strain decreases from ~0.52 for the plain microstrut to 0.36-0.38 for the surface-textured microstruts, primarily due to the localization of strain caused by the surface notch-like features. The progressive localization of plastic strain in the form of non-uniform thinning was confirmed via micro-tensile testing in combination with in-situ imaging. Beyond the uniform elongation strain regime, strain localization and final tensile failure dominate in the surface notches of the surface-textured and as-built microstruts.Further, the effects of as-built surface morphology on cyclic tensile properties of similar microstruts were characterized. The fatigue response of tensile-tensile cyclic stress regimes on SS316L as-built struts of 250 μm in diameter was measured. A back-tracking microtomography approach was used to characterize the location, shape, and size of a "crack-like" surface defect responsible for the fatigue crack initiation. A modified Murakami √Area parameter model was utilized to integrate the effect of surface notch-like features into the stress intensity range associated with the crack-initiating defect as well as the associated propagating crack. The crack growth rate vs. the crack's stress intensity range was compared with macroscale fatigue cracks to demonstrate the effect of the surface morphology-associated stress concentration factor on the crack growth behavior in microstruts.The influence of surface morphology on the tensile deformation of micro-scale parts was evident. Therefore, to extract mechanical properties of 500 [mu]m nominal diameter LPBF microstruts devoid of the influence of as-built surface morphology, a femtosecond laser of
Download or read book Selective Laser Melting Materials and Applications written by Prashanth Konda Gokuldoss and published by . This book was released on 2020 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 Advancement of Selective Laser Melting by Laser Beam Shaping written by Tim Marten Wischeropp and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Selective Laser Melting (SLM), also referred to as Laser Powder Bed Fusion (L-PBF), offers significant advantages for the manufacturing of complex, high-quality parts. However, its market share is still small compared to conventional manufacturing technologies. Major drawbacks hindering an industrial ramp-up are low productivity, high part costs and issues with quality and reproducibility. Comprehensive research has been done to overcome these challenges, but little attention has been paid to addressing them by optimizing the laser beam profile. Therefore, the author examines the effect of the laser beam profile on the productivity and process stability through both numerical and experimental investigations. The results show clear advantages an optimized laser beam profile offers. The content First comprehensive research on the effect of the laser beam profile on SLM process Understand the effect of the laser beam profile on the process stability and feasible productivity of the SLM process Discover the benefits in terms of manufacturing costs and time that are offered by an optimized laser beam profile The author Tim Marten Wischeropp studied mechanical engineering at the Technical University of Hamburg (TUHH), Germany. After graduating with a focus on product development, he worked as a research fellow at the Institute of Laser and System Technologies (TUHH) as well as group leader for 3D printing at the LZN Laser Zentrum Nord GmbH. Since 2018 he leads the design department at the Fraunhofer Institution for Additive Manufacturing Technologies IAPT.
Download or read book Analysis of the Laser Powder Bed Fusion Additive Manufacturing Process Through Experimental Measurement and Finite Element Modeling written by Alexander Dunbar and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective in this work is to provide rigourous experimental measurements to aid in the development of laser powder bed fusion (LPBF) additive manufacturing (AM). A specialized enclosed instrumented measurement system is designed to provide in situ experimental measurements of temperature and distortion. Experiments include comparisons of process parameters, materials and LPBF machines. In situ measurements of distortion and temperature made throughout the build process highlight inter-layer distortion effects previously undocumented for laser powder bed fusion. Results from these experiments are also be implemented in the development and validation of finite element models of the powder bed build process. Experimental analysis is extended from small-scale to larger part-scale builds where experimental post-build measurements are used in analysis of distortion profiles. Experimental results provided from this study are utilized in the validation of a finite element model capable of simulating production scale parts. The validated finite element model is then implemented in the analysis of the part to provide information regarding the distortion evolution process. A combination of experimental measurements and simulation results are used to identify the mechanism that results in the measured distortion profile for this geometry. Optimization of support structure primarily focuses on the minimization of material use and scan time, but no information regarding failure criteria for support structure is available. Tensile test samples of LPBF built support structure are designed, built, and tested to provide measurements of mechanical properties of the support structure. Experimental tests show that LPBF built support structure has only 30-40\% of the ultimate tensile strength of solid material built in the same machine. Experimental measurement of LPBF built support structure provides clear failure criteria to be utilized in the future design and implementation of support structure.
