Metal Additive Manufacturing: A Review
08 Apr 2014-Journal of Materials Engineering and Performance (Springer US)-Vol. 23, Iss: 6, pp 1917-1928
TL;DR: The state-of-the-art of additive manufacturing (AM) can be classified into three categories: direct digital manufacturing, free-form fabrication, or 3D printing as discussed by the authors.
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.
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TL;DR: A review of the emerging research on additive manufacturing of metallic materials is provided in this article, which provides a comprehensive overview of the physical processes and the underlying science of metallurgical structure and properties of the deposited parts.
4,192 citations
Cites background from "Metal Additive Manufacturing: A Rev..."
...Wire and metallic sheet based AM processes are fast but lack dimensional accuracy and result in defects and poor surface finish especially for parts with complex shapes [13,14]....
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TL;DR: In this paper, the authors describe the complex relationship between additive manufacturing processes, microstructure and resulting properties for metals, and typical microstructures for additively manufactured steel, aluminium and titanium are presented.
2,837 citations
Cites background from "Metal Additive Manufacturing: A Rev..."
...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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TL;DR: In this article, a review of additive manufacturing (AM) techniques for producing metal parts are explored, with a focus on the science of metal AM: processing defects, heat transfer, solidification, solid-state precipitation, mechanical properties and post-processing metallurgy.
Abstract: Additive manufacturing (AM), widely known as 3D printing, is a method of manufacturing that forms parts from powder, wire or sheets in a process that proceeds layer by layer. Many techniques (using many different names) have been developed to accomplish this via melting or solid-state joining. In this review, these techniques for producing metal parts are explored, with a focus on the science of metal AM: processing defects, heat transfer, solidification, solid-state precipitation, mechanical properties and post-processing metallurgy. The various metal AM techniques are compared, with analysis of the strengths and limitations of each. Only a few alloys have been developed for commercial production, but recent efforts are presented as a path for the ongoing development of new materials for AM processes.
1,713 citations
TL;DR: The approach to metal-based additive manufacturing is applicable to a wide range of alloys and can be implemented using a range of additive machines, and provides a foundation for broad industrial applicability, including where electron-beam melting or directed-energy-deposition techniques are used instead of selective laser melting.
Abstract: Metal-based additive manufacturing, or three-dimensional (3D) printing, is a potentially disruptive technology across multiple industries, including the aerospace, biomedical and automotive industries. Building up metal components layer by layer increases design freedom and manufacturing flexibility, thereby enabling complex geometries, increased product customization and shorter time to market, while eliminating traditional economy-of-scale constraints. However, currently only a few alloys, the most relevant being AlSi10Mg, TiAl6V4, CoCr and Inconel 718, can be reliably printed; the vast majority of the more than 5,500 alloys in use today cannot be additively manufactured because the melting and solidification dynamics during the printing process lead to intolerable microstructures with large columnar grains and periodic cracks. Here we demonstrate that these issues can be resolved by introducing nanoparticles of nucleants that control solidification during additive manufacturing. We selected the nucleants on the basis of crystallographic information and assembled them onto 7075 and 6061 series aluminium alloy powders. After functionalization with the nucleants, we found that these high-strength aluminium alloys, which were previously incompatible with additive manufacturing, could be processed successfully using selective laser melting. Crack-free, equiaxed (that is, with grains roughly equal in length, width and height), fine-grained microstructures were achieved, resulting in material strengths comparable to that of wrought material. Our approach to metal-based additive manufacturing is applicable to a wide range of alloys and can be implemented using a range of additive machines. It thus provides a foundation for broad industrial applicability, including where electron-beam melting or directed-energy-deposition techniques are used instead of selective laser melting, and will enable additive manufacturing of other alloy systems, such as non-weldable nickel superalloys and intermetallics. Furthermore, this technology could be used in conventional processing such as in joining, casting and injection moulding, in which solidification cracking and hot tearing are also common issues.
1,670 citations
TL;DR: The state-of-the-art of topological design and manufacturing processes of various types of porous metals, in particular for titanium alloys, biodegradable metals and shape memory alloys are reviewed.
1,393 citations
References
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TL;DR: Amid this growing use of additive manufacturing, the government has several opportunities to act as an early adopter to accelerate market adoption, especially in aerospace, defense, and medical applications.
Abstract: Additive manufacturing (AM), also referred to as 3D printing, is a layer-by-layer technique of producing three-dimensional (3D) objects directly from a digital model. With markets including prototyping, tooling, direct part manufacturing, and maintenance and repair, the industry has grown significantly to $1.3B of materials, equipment, and services in 2010. Despite significant progress in the field, a number of technical challenges remain. Issues such as material characterization and availability, among many others, have been identified by various groups as areas for improvement. Though many issues are being examined by groups in academia, industry, and government, some challenges would likely benefit from increased coordination and funding opportunities. While some topics, such as achieving better material properties, have been around since the early days of additive manufacturing, new ideas have emerged in recent years. These topics involve basic science including materials, lightweight and exotic structures, bioprinting, and conformal electronics. They also include more applied areas, such as the environmental impact of additive manufacturing and 3D scanning. Many areas of AM R&D and associated technical challenges could benefit from incentive competitions that aim to spur and accelerate innovation. Some competitions involving additive manufacturing have already taken place but more could potentially benefit, especially in areas such as design software and web-based design tools. There is interest at several Federal organizations in advancing research and procurement of additive manufacturing for many types of components. Amid this growing use of additive manufacturing, the government has several opportunities to act as an early adopter to accelerate market adoption, especially in aerospace, defense, and medical applications. Over the years, the number of regular conferences aimed at advancing AM technologies has grown, with events that now take place annually throughout the globe. In addition to conferences, a number of workshops and roadmapping events have also taken place, covering topics spanning from R&D areas to educational needs. Standards play an important role in the adoption of many technologies and, as of 2009, there has been significant activity in developing AM standards through the ASTM International F42 committee. There are currently four technical subcommittees working towards standards in materials and processes, terminology, design and data formats, and test methods. They have produced four standards to date and also charted new territory in iv a partnership with the ISO, signing a cooperation agreement that governs ongoing collaborative efforts between the two groups. Additive manufacturing holds great potential to engage a broad population—not …
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TL;DR: In this article, the authors provide a comprehensive state-of-the-art review of environmental impact assessment of existing rapid prototyping and rapid tooling, and identify prospective research needs.
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125 citations
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TL;DR: In this article, a study of laser energy transfer efficiency, melting efficiency, and deposition efficiency has been conducted for the laser-engineered net-shaping process (LENS) for H-13 tool steel and copper powder deposits.
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120 citations
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