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Journal ArticleDOI

Additive manufacturing of metals

15 Sep 2016-Acta Materialia (Pergamon)-Vol. 117, Iss: 117, pp 371-392

Abstract: Additive Manufacturing (AM), the layer-by layer build-up of parts, has lately become an option for serial production. Today, several metallic materials including the important engineering materials steel, aluminium and titanium may be processed to full dense parts with outstanding properties. In this context, the present overview article describes the complex relationship between AM processes, microstructure and resulting properties for metals. It explains the fundamentals of Laser Beam Melting, Electron Beam Melting and Laser Metal Deposition, and introduces the commercially available materials for the different processes. Thereafter, typical microstructures for additively manufactured steel, aluminium and titanium are presented. Special attention is paid to AM specific grain structures, resulting from the complex thermal cycle and high cooling rates. The properties evolving as a consequence of the microstructure are elaborated under static and dynamic loading. According to these properties, typical applications are presented for the materials and methods for conclusion.
Topics: Aluminium (50%)
Citations
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Journal ArticleDOI
Tarasankar Debroy1, Huiliang Wei1, J.S. Zuback1, T. Mukherjee1  +6 moreInstitutions (4)
Abstract: Since its inception, significant progress has been made in understanding additive manufacturing (AM) processes and the structure and properties of the fabricated metallic components. Because the field is rapidly evolving, a periodic critical assessment of our understanding is useful and this paper seeks to address this need. It covers the emerging research on AM of metallic materials and provides a comprehensive overview of the physical processes and the underlying science of metallurgical structure and properties of the deposited parts. The uniqueness of this review includes substantive discussions on refractory alloys, precious metals and compositionally graded alloys, a succinct comparison of AM with welding and a critical examination of the printability of various engineering alloys based on experiments and theory. An assessment of the status of the field, the gaps in the scientific understanding and the research needs for the expansion of AM of metallic components are provided.

2,278 citations


Cites background from "Additive manufacturing of metals"

  • ...Nearly all of the heat treatable aluminum alloys are welded using dissimilar filler metals near the Al-Si eutectic, and these alloys have proven to be popular alloys for AM processing [4,310,384,387,440,441]....

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  • ...The metallurgy of all of these alloys can be complex, and subject to individual AM processing parameters as well as the final heat treating conditions [2,4,444], which can sometimes be incorporated into a hot isostatic press (HIP) treatment to remove residual stress and minimize porosity at the same time [2]....

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  • ...Another reason is that, in order to achieve uniform and high strength properties, the AM builds must undergo post build heat treating (PHT) to achieve the desired properties [2,4]....

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  • ...Austenitic stainless steels, AISI 304L and 316L, are very important engineering alloys that are readily weldable if the compositions are controlled to prevent solidification cracking [210,293] and have been a popular AM material [4,312,357,380]....

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  • ...The most common aluminum alloys processed by AM are the eutectic Al-Si and the hardenable Al-Si-Mg alloys [4]....

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Journal ArticleDOI
Tuan Ngo1, Alireza Kashani1, Gabriele Imbalzano1, Kate Nguyen1  +1 moreInstitutions (2)
Abstract: Freedom of design, mass customisation, waste minimisation and the ability to manufacture complex structures, as well as fast prototyping, are the main benefits of additive manufacturing (AM) or 3D printing. A comprehensive review of the main 3D printing methods, materials and their development in trending applications was carried out. In particular, the revolutionary applications of AM in biomedical, aerospace, buildings and protective structures were discussed. The current state of materials development, including metal alloys, polymer composites, ceramics and concrete, was presented. In addition, this paper discussed the main processing challenges with void formation, anisotropic behaviour, the limitation of computer design and layer-by-layer appearance. Overall, this paper gives an overview of 3D printing, including a survey on its benefits and drawbacks as a benchmark for future research and development.

2,258 citations


Journal ArticleDOI
Y. Morris Wang1, Thomas Voisin1, Joseph T. McKeown1, Jianchao Ye1  +12 moreInstitutions (4)
01 Jan 2018-Nature Materials
TL;DR: The potential of additive manufacturing to create alloys with unique microstructures and high performance for structural applications is demonstrated, with austenitic 316L stainless steels additively manufactured via a laser powder-bed-fusion technique exhibiting a combination of yield strength and tensile ductility that surpasses that of conventional 316L steels.
Abstract: Many traditional approaches for strengthening steels typically come at the expense of useful ductility, a dilemma known as strength-ductility trade-off. New metallurgical processing might offer the possibility of overcoming this. Here we report that austenitic 316L stainless steels additively manufactured via a laser powder-bed-fusion technique exhibit a combination of yield strength and tensile ductility that surpasses that of conventional 316L steels. High strength is attributed to solidification-enabled cellular structures, low-angle grain boundaries, and dislocations formed during manufacturing, while high uniform elongation correlates to a steady and progressive work-hardening mechanism regulated by a hierarchically heterogeneous microstructure, with length scales spanning nearly six orders of magnitude. In addition, solute segregation along cellular walls and low-angle grain boundaries can enhance dislocation pinning and promote twinning. This work demonstrates the potential of additive manufacturing to create alloys with unique microstructures and high performance for structural applications.

771 citations


Journal ArticleDOI
Shunyu Liu1, Yung C. Shin1Institutions (1)
15 Feb 2019-Materials & Design
Abstract: In this paper, the recent progress on Ti6Al4V fabricated by three mostly developed additive manufacturing (AM) techniques-directed energy deposition (DED), selective laser melting (SLM) and electron beam melting (EBM)-is thoroughly investigated and compared. Fundamental knowledge is provided for the creation of links between processing parameters, resultant microstructures and associated mechanical properties. Room temperature tensile and fatigue properties are also reviewed and compared to traditionally manufactured Ti6Al4V parts. The presence of defects in as-built AM Ti6Al4V components and the influences of these defects on mechanical performances are also critically discussed.

593 citations


Cites methods from "Additive manufacturing of metals"

  • ...With respect to the fabrication of dense metallic structures, powder-based AM techniques such as DED, SLM and EBM are mostly used [22,23,26]....

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Journal ArticleDOI
TL;DR: Three different alloys, covering a large range of technology readiness levels, are selected to illustrate particular microstructural features developed by AM and clarify the engineering paradigm relating process–microstructure–property.
Abstract: We present a brief review of the microstructures and mechanical properties of selected metallic alloys processed by additive manufacturing (AM). Three different alloys, covering a large range of technology readiness levels, are selected to illustrate particular microstructural features developed by AM and clarify the engineering paradigm relating process-microstructure-property. With Ti-6Al-4V the emphasis is placed on the formation of metallurgical defects and microstructures induced by AM and their role on mechanical properties. The effects of the large in-built dislocation density, surface roughness and build atmosphere on mechanical and damage properties are discussed using steels. The impact of rapid solidification inherent to AM on phase selection is highlighted for high-entropy alloys. Using property maps, published mechanical properties of additive manufactured alloys are graphically summarized and compared to conventionally processed counterparts.

366 citations


Cites background or methods from "Additive manufacturing of metals"

  • ...However, these authors also mechanically tested their samples in a 10 MPa hydrogen atmosphere to compare the hydrogen embrittlement (HE) behavior of the additively manufactured and wrought 304L....

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  • ...However, the difference in yield strength between the vertically built and horizontally built 316L is only ~50 MPa, which is a small fraction of the typical difference between the strengths of wrought or SLM 316L....

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  • ...This refinement in grain size will influence the mechanical 175 MPa for a dislocation density of 1×1015 m/m3....

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  • ...The difference is 220  MPa, of which approximately (110 to 175 MPa)/220 MPa = 50%–80% is likely due to the increased dislocation density present in the SLM 316L....

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  • ...For such samples, cycling under R=0.1 with a peak stress of 500 MPa is still not sufficient to break them after 5×106 cycles (i.e. the fatigue strength is more than 500 MPa)....

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References
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Journal ArticleDOI
William E. Frazier1Institutions (1)
Abstract: This paper reviews the state-of-the-art of an important, rapidly emerging, manufacturing technology that is alternatively called additive manufacturing (AM), direct digital manufacturing, free form fabrication, or 3D printing, etc. A broad contextual overview of metallic AM is provided. AM has the potential to revolutionize the global parts manufacturing and logistics landscape. It enables distributed manufacturing and the productions of parts-on-demand while offering the potential to reduce cost, energy consumption, and carbon footprint. This paper explores the material science, processes, and business consideration associated with achieving these performance gains. It is concluded that a paradigm shift is required in order to fully exploit AM potential.

2,960 citations


"Additive manufacturing of metals" refers background in this paper

  • ...Schematics of an LMD set-up (from Frazier [38])....

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  • ...Commonly repaired or produced parts are turbine blades, shafts and parts of gear mechanisms mostly made from steels, Ti and its alloys as well as Ni-based super alloys [38,39]....

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  • ...The melt pool which is typically protected against oxidation by supplying argon or helium is produced by the energy input of an Nd:YAG, diode or CO2 laser and the metal powder is fed by a coaxial or multi-jet nozzle [38,39], cf....

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Book
01 Dec 1994-
Abstract: Comprehensive datasheets on more than 60 titanium alloys More than 200 pages on metallurgy and fabrication procedures Input from more than 50 contributors from several countries Careful editorial review for accuracy and usefulness Materials Properties Handbook: Titanium Alloys provides a data base for information on titanium and its alloys, and the selection of specific alloys for specific applications The most comprehensive titanium data package ever assembled provides extensive information on applications, physical properties, corrosion, mechanical properties (including design allowances where available), fatigue, fracture properties, and elevated temperature properties The appropriate specifications for each alloy are included This international effort has provided a broad information base that has been compiled and reviewed by leading experts within the titanium industry, from several countries, encompassing numerous technology areas Inputs have been obtained from the titanium industry, fabricators, users, government and academia This up-to-date package covers information from almost the inception of the titanium industry, in the 1950s, to mid-1992 The information, organized by alloy, makes this exhaustive collection an easy-to-use data base at your fingertips, which generally includes all the product forms for each alloy The 60-plus data sheets supply not only extensive graphical and tabular information on properties, but the datasheets also describe or illustrate important factors which would aid in the selection of the proper alloy or heat treatment The datasheets are further supplemented with back-ground information on the metallurgy and fabrication characteristics of titanium alloys An especially extensive coverage of properties, processing and metallurgy is provided in the datasheet for the workhorse of the titanium industry, Ti-6Al-4V This compendium includes the newest alloys made public even those still under development In many cases, key references are included for further information on a given subject Comprehensive datasheets provide extensive information on: Applications, Specifications, Corrosion, Mechanical Design Properties, Fatigue and Fracture

2,208 citations


"Additive manufacturing of metals" refers background in this paper

  • ...It is also known that the distorted hexagonal lattice structure of the a0 martensite is stronger than lamellar a, mainly due to its fine lath width, though it does not necessarily reduce the ductility [143]....

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  • ...Selected microstructural features and effect on properties of titanium alloys [143]....

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Book
01 Apr 1988-
Abstract: Designed to support the need of engineering, management, and other professionals for information on titanium by providing an overview of the major topics, this book provides a concise summary of the most useful information required to understand titanium and its alloys The author provides a review of the significant features of the metallurgy and application of titanium and its alloys All technical aspects of the use of titanium are covered, with sufficient metals property data for most users Because of its unique density, corrosion resistance, and relative strength advantages over competing materials such as aluminum, steels, and superalloys, titanium has found a niche in many industries Much of this use has occurred through military research, and subsequent applications in aircraft, of gas turbine engines, although more recent use features replacement joints, golf clubs, and bicycles Contents include: A primer on titanium and its alloys, Introduction to selection of titanium alloys, Understanding titanium's metallurgy and mill products, Forging and forming, Castings, Powder metallurgy, Heat treating, Joining technology and practice, Machining, Cleaning and finishing, Structure/processing/property relationships, Corrosion resistance, Advanced alloys and future directions, Appendices: Summary table of titanium alloys, Titanium alloy datasheets, Cross-reference to titanium alloys, Listing of selected specification and standardization organizations, Selected manufacturers, suppliers, services, Corrosion data, Machining data

1,742 citations


"Additive manufacturing of metals" refers background in this paper

  • ...Donachie [140] b-ST aþ b colony 931 1055 9...

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Journal ArticleDOI
Lore Thijs1, Frederik Verhaeghe1, Tom Craeghs1, Jan Van Humbeeck1  +1 moreInstitutions (1)
01 May 2010-Acta Materialia
Abstract: Selective laser melting (SLM) is an additive manufacturing technique in which functional, complex parts can be created directly by selectively melting layers of powder. This process is characterized by highly localized high heat inputs during very short interaction times and will therefore significantly affect the microstructure. In this research, the development of the microstructure of the Ti–6Al–4V alloy processed by SLM and the influence of the scanning parameters and scanning strategy on this microstructure are studied by light optical microscopy. The martensitic phase is present, and due to the occurrence of epitaxial growth, elongated grains emerge. The direction of these grains is directly related to the process parameters. At high heat inputs it was also found that the intermetallic phase Ti3Al is precipitated during the process.

1,729 citations


Journal ArticleDOI
Barry Berman1Institutions (1)
01 Mar 2012-Business Horizons
Abstract: This article examines the characteristics and applications of 3-D printing and compares it with mass customization and other manufacturing processes. 3-D printing enables small quantities of customized goods to be produced at relatively low costs. While currently used primarily to manufacture prototypes and mockups, a number of promising applications exist in the production of replacement parts, dental crowns, and artificial limbs, as well as in bridge manufacturing. 3-D printing has been compared to such disruptive technologies as digital books and music downloads that enable consumers to order their selections online, allow firms to profitably serve small market segments, and enable companies to operate with little or no unsold finished goods inventory. Some experts have also argued that 3-D printing will significantly reduce the advantages of producing small lot sizes in low-wage countries via reduced need for factory workers.

1,525 citations


Performance
Metrics
No. of citations received by the Paper in previous years
YearCitations
202227
2021574
2020497
2019347
2018233
201795