Review on powder-based electron beam additive manufacturing technology

Manufacturing Review, Apr 2014

This paper presents a thorough literature review of the powder-based electron beam additive manufacturing (EBAM) technology. EBAM, a relatively new additive manufacturing (AM) process, can produce full-density metallic parts directly from the electronic data of the designed part geometry. EBAM has gained broad attentions from different industries such as aerospace and biomedical, with great potential in a variety of applications. The paper first introduces the general aspects of EBAM. The unique characteristics, advantages and challenges of EBAM are then presented. Moreover, the hub of this paper includes extensive discussions of microstructures, mechanical properties, geometric attributes, which impact the application ranges of EBAM parts, with focus on commonly used titanium alloys (in particular, Ti-6Al-4V). In the end, modeling efforts and process metrology of the EBAM process are discussed as well.

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Review on powder-based electron beam additive manufacturing technology

Manufacturing Rev. Review on powder-based electron beam additive manufacturing technology Xibing Gong 1 Ted Anderson 0 Kevin Chou 1 0 Advanced Manufacturing Team, Marshall Space Flight Center , Huntsville, AL 35811 , USA 1 Mechanical Engineering Department, The University of Alabama , Tuscaloosa, AL 35487 , USA - This paper presents a thorough literature review of the powder-based electron beam additive manufacturing (EBAM) technology. EBAM, a relatively new additive manufacturing (AM) process, can produce full-density metallic parts directly from the electronic data of the designed part geometry. EBAM has gained broad attentions from different industries such as aerospace and biomedical, with great potential in a variety of applications. The paper first introduces the general aspects of EBAM. The unique characteristics, advantages and challenges of EBAM are then presented. Moreover, the hub of this paper includes extensive discussions of microstructures, mechanical properties, geometric attributes, which impact the application ranges of EBAM parts, with focus on commonly used titanium alloys (in particular, Ti-6Al-4V). In the end, modeling efforts and process metrology of the EBAM process are discussed as well. Electron beam additive manufacturing (EBAM); Geometric attributes; Mechanical properties; Microstructures; Metallic powder; Process modeling; Process metrology Introduction Additive manufacturing (AM), also known by various terms, e.g., direct digital manufacturing, based on ‘‘layer-bylayer’’ fabrications is an emerging technology, by which physical solid parts are made directly from electronic data, generally files from computer-aided design (CAD) software. This group of technologies offers many design and manufacturing advantages such as short lead time, complex geometry capability, and tooling free. Electron beam additive manufacturing (EBAM) is a relatively new AM technology [ 1 ]. Similar to electron-beam welding, EBAM utilizes a high-energy electron beam, as a moving heat source, to melt and fuse, by rapid self-cooling, metal powder and produce parts in a layer-building fashion. Moreover, EBAM is one of a few AM technologies capable of making full-density functional metallic parts, drastically extending AM applications. In particular, the ability of direct fabrications of metallic parts can significantly accelerate product designs and developments in a wide variety of metallic-part applications, especially for complex components, e.g., fine network structures, internal cavities and channels, which are difficult to make by conventional manufacturing means [ 1, 2 ]. EBAM machines were first commercialized, around 1997, by Arcam AB Corporation in Sweden. Because EBAM has many unique characteristics such as high energy efficiency, high scan speed, and moderate operation cost, the technology has attracted, in recent years, increased interests from different industries. The use of an electron beam offers extensive features such as higher build rates due to increased penetration depths and rapid scanning speeds. Since then, many research groups have been studying the EBAM technology from different aspects and for various applications. Despite the potential benefits over conventional manufacturing technologies, EBAM still has a few process deficiencies, such as process stability, part defects and quality variations [ 3 ], etc. As EBAM technology is relatively new, there have not been detailed reviews. The objective of this paper is to offer a survey of various investigations into EBAM, especially for the study of the titanium (Ti) alloy parts, along with the EBAM part microstructures and associated mechanical properties. In addition, modeling and simulation of the EBAM process, though rare, for process understanding and advancements are also discussed. EBAM details Process principle A conceptual schematic of an EBAM machine is shown in Figure 1 [ 2 ]. The principle is very similar to that of a scanning electron microscope. A heated tungsten filament, in the upper column, emits electrons which are collimated and accelerated to a kinetic energy of about 60 keV. The electron beam is controlled by two magnetic coils, which are housed in the lower column. The first one is a magnetic lens which focuses the beam to the desired diameter, and the second one deflects the focused beam to the desired point on a build platform. The electron-beam gun itself is fixed, no moving mechanical parts involved in beam deflections. The beam current is controlled in the range 1–50 mA and the beam diameter can be focused down to about 0.1 mm. In the chamber of the middle part of the machine, fine metal powder, on the order of 10–100 lm, is supplied from two hoppers and forms a thin layer by a raking mechanism before each layer build. The typical layer thickness is in the range 0.05–0.2 mm. The computer-controlled electron beam scans over the powder layer in a predefined pattern and consolidates the desired a (...truncated)


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Xibing Gong, Ted Anderson, Kevin Chou. Review on powder-based electron beam additive manufacturing technology, Manufacturing Review, 2014, pp. 2, 1, DOI: 10.1051/mfreview/2014001