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Additive manufacturing (AM), applied to metal industry, is a family of processes that allows complex shape components to be realized from raw materials in the form of powders. Electron beam melting (EBM) is a relatively new additive manufacturing (AM) technology. Similar to electron-beam welding, EBM utilizes a high-energy electron beam as a moving heat source to melt metal powder, and 3D parts are produced in a layer-building fashion by rapid self-cooling. By EBM, it is possible to realize metallic complex shape components, e.g. fine network structures, internal cavities and channels, which are difficult to make by conventional manufacturing means. This feature is of particular interest in titanium industry in which numerous efforts are done to develop near net shape processes. In the field of mechanical engineering and, in particular, in the aerospace industry, it is crucial for quality certification purpose that components are produced through qualified and robust manufacturing processes ensuring high product repeatability. The contribution of the present work is to experimentally identify the EBM job parameters (sample orientation, location of the sample in the layer and height in the build chamber) that influence the dimensional accuracy and the surface roughness of the manufactured parts in Ti6Al4V. The repeatability of EBM is investigated too.

Electron Beam Melting (EBM) is an emerging additive manufacturing technique for the fabrication of titanium alloy Ti-6Al-4V for orthopedic applications. Here, a hybrid manufacturing technique viz. EBM with Friction Stir Processing (FSP) has been proposed to enhance implant surface properties. The surface modification using FSP reduces the roughness generated by the EBM technique from ~44.77 μm to ~15.82 μm. Simultaneously, FSP improves the biological and mechanical properties of the Ti-6Al-4V substrates. The roughness, wettability, amounts of ions released, and surface microhardness were measured to analyze the stability of the substrates. The effect of the hybrid processing strategy on cell viability was tested against mouse fibroblast cells NIH3T3 through MTT assay, and we found that the friction stir processed substrate (EBM-F) showed the highest cell viability. The EBM-F surface displays a two-fold increase in the cell-viability as compared to the unprocessed EBM surface after 24 h of cell-seeding. The FSP substrate allows human cervical cells HeLa to adhere onto its surface while selectively preventing the attachment of E.coli bacterial cells. These observations towards cells signify biocompatible surface characteristics of the FSP EBM substrate.

Electron Beam Melting is an Additive Manufacturing technology that allows the production of items using metal powder as raw material. The main advantage of Additive Manufacturing (AM) is realizing complex shape components; however one of the main defects is the poor quality of the surface. To this aim, different post processing treatments have been proposed such as machining, surface laser melting, sand blasting, etc. The main drawback of these technologies is the necessity to use tools that makes complex shape item difficult to handle. This inconvenient does not occur in chemical machining, since a chemical solution can operate in an undifferentiated way on the whole surface of a component. In this work some components in Ti6Al4V obtained through AM have been treated in acidic solutions containing HF and HNO3 with different HF/HNO3 molar ratio. All the solutions employed have proven to be effective in smoothing the metal surface, but the best results have been obtained with solutions with high content of HNO3. It should be noted that the process causes changes in the surface composition with respect to the received samples with an impoverishment of Al. This effect is partially mitigated by the passivating action of HNO3.

The Electron Beam Melting (EBM) is an Additive Layer Manufacturing (ALM) technique used to directly manufacture 3D functional parts from metal powder, selectively melted, layer by layer, by an electron beam according to a geometry defined by a CAD model. The EBM technology allows benefitting from countless advantages: material waste reduction, easy manufacturing of complex shapes, lead time reduction, etc; on the other hand the EBM process is typically associated with lower resolutions and higher surface roughness (Ra = 25–30 μm) compared to similar laser based powder bed metal processes. Therefore the surface morphology may be a critical issue for the structural integrity of components made in EBM and used in-service in their “as built” condition, i.e. with the characteristic surface released by the process. This study evaluates surface morphology and tensile properties of Ti6Al4V specimens of varying nominal thickness (1–5.0 mm), made by using EBM process with a layer thickness of 50 μm. The aim is therefore to investigate how the surface morphology and the tensile properties are affected by the nominal thickness of the component.

Additive manufacturing of titanium alloy Ti-6Al-4?V has significantly increased over the past few years, primarily due to its broad application over the conventional manufacturing process for complex and near net shape production. However, difficulties arise while printing complex and huge structures and therefore, the components need a suitable joining process. We study the feasibility of friction stir welding of Ti-6Al-4?V plates made by electron beam melting, performing both microstructural and mechanical analysis. Microstructures for all the welds reveal lamellar (??+??) phase and very fine equiaxed ? grain with the prior ? phase at grain boundaries in the stirred zone. Microhardness at different depths of the joint is measured and the strength of the joint is determined using a tensile test. The results obtained prove the feasibility of the process and provide the necessary processing conditions., by Amit Kumar Singha, Bhoopendra Kumara, Kaushal Jha, Astarita Antonello, Squillace Antonino, Stefania Franchitti and Amit Arora

Additive Layer Manufacturing is one of the most promising and investigated manufacturing system due to its advantages to produces near net shape components, also with a very complex shape, in a single shot. Among the different techniques now available, the Electron Beam Melting (EBM) is of particular interest in the production of metal components. Particularly the application of this technique to titanium alloys allows to produces components with a very low buy to fly ratio. In the present paper the microstructure attained is accurately described and mini tensile tests performed allowed to understand the fracture behavior of specimen with the specific microstructure realized under static load. © 2016 Author(s).