scholarly journals Additive Manufacturing of Alloy 718 via Electron Beam Melting: Effect of Post-Treatment on the Microstructure and the Mechanical Properties

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 68 ◽  
Author(s):  
Arun Balachandramurthi ◽  
Johan Moverare ◽  
Satyapal Mahade ◽  
Robert Pederson
Keyword(s):  
Electron Beam ◽  
Additive Manufacturing ◽  
Electron Beam Melting ◽  
Elevated Temperatures ◽  
Microstructural Analysis ◽  
Solution Treatment ◽  
Post Treatment ◽  
Alloy 718 ◽  
Machined Surface ◽  
Contour Region

Alloy 718 finds application in gas turbine engine components, such as turbine disks, compressor blades and so forth, due to its excellent mechanical and corrosion properties at elevated temperatures. Electron beam melting (EBM) is a recent addition to the list of additive manufacturing processes and has shown the capability to produce components with unique microstructural features. In this work, Alloy 718 specimens were manufactured using the EBM process with a single batch of virgin plasma atomized powder. One set of as-built specimens was subjected to solution treatment and ageing (STA); another set of as-built specimens was subjected to hot isostatic pressing (HIP), followed by STA (and referred to as HIP+STA). Microstructural analysis of as-built specimens, STA specimens and HIP+STA specimens was carried out using optical microscopy and scanning electron microscopy. Typical columnar microstructure, which is a characteristic of the EBM manufactured alloy, was observed. Hardness evaluation of the as-built, STA and HIP+STA specimens showed that the post-treatments led to an increase in hardness in the range of ~50 HV1. Tensile properties of the three material conditions (as-built, STA and HIP+STA) were evaluated. Post-treatments lead to an increase in the yield strength (YS) and the ultimate tensile strength (UTS). HIP+STA led to improved elongation compared to STA due to the closure of defects but YS and UTS were comparable for the two post-treatment conditions. Fractographic analysis of the tensile tested specimens showed that the closure of shrinkage porosity and the partial healing of lack of fusion (LoF) defects were responsible for improved properties. Fatigue properties were evaluated in both STA and HIP+STA conditions. In addition, three surface conditions were also investigated, namely the ‘raw’ as-built surface, the machined surface with the contour region and the machined surface without the contour region. Machining off the contour region completely together with HIP+STA led to significant improvement in fatigue performance.

scholarly journals Characterization of Spatter and Sublimation in Alloy 718 during Electron Beam Melting

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 5953
Author(s):  
Ahmad Raza ◽  
Eduard Hryha
Keyword(s):  
Electron Beam ◽  
Electron Beam Melting ◽  
Elevated Temperatures ◽  
Ion Beam ◽  
High Vacuum ◽  
Alloying Elements ◽  
Heat Shield ◽  
Alloy 718 ◽  
Feedstock Powder ◽  
Heat Shields

Due to elevated temperatures and high vacuum levels in electron beam melting (EBM), spatter formation and accumulation in the feedstock powder, and sublimation of alloying elements from the base feedstock powder can affect the feedstock powder’s reusability and change the alloy composition of fabricated parts. This study focused on the experimental and thermodynamic analysis of spatter particles generated in EBM, and analyzed sublimating alloying elements from Alloy 718 during EBM. Heat shields obtained after processing Alloy 718 in an Arcam A2X plus machine were analyzed to evaluate the spatters and metal condensate. Comprehensive morphological, microstructural, and chemical analyses were performed using scanning electron microscopy (SEM), focused ion beam (FIB), and energy dispersive spectroscopy (EDS). The morphological analysis showed that the area coverage of heat shields by spatter increased from top (<1%) to bottom (>25%), indicating that the spatter particles had projectile trajectories. Similarly, the metal condensate had a higher thickness of ~50 μm toward the bottom of the heat shield, indicating more significant condensation of metal vapors at the bottom. Microstructural analysis of spatters highlighted that the surfaces of spatter particles sampled from the heat shields were also covered with condensate, and the thickness of the deposited condensate depended on the time of landing of spatter particles on the heat shield during the build. The chemical analysis showed that the spatter particles had 17-fold higher oxygen content than virgin powder used in the build. Analysis of the metalized layer indicated that it was formed by oxidized metal condensate and was significantly enriched with Cr due to its higher vapor pressure under EBM conditions.

scholarly journals Directionally-Dependent Mechanical Properties of Ti6Al4V Manufactured by Electron Beam Melting (EBM) and Selective Laser Melting (SLM)

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3603
Author(s):  
Tim Pasang ◽  
Benny Tavlovich ◽  
Omry Yannay ◽  
Ben Jakson ◽  
Mike Fry ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Tensile Strength ◽  
Electron Beam ◽  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
Electron Beam Melting ◽  
Rolling Direction ◽  
Laser Melting ◽  
Plate Rolling

An investigation of mechanical properties of Ti6Al4V produced by additive manufacturing (AM) in the as-printed condition have been conducted and compared with wrought alloys. The AM samples were built by Selective Laser Melting (SLM) and Electron Beam Melting (EBM) in 0°, 45° and 90°—relative to horizontal direction. Similarly, the wrought samples were also cut and tested in the same directions relative to the plate rolling direction. The microstructures of the samples were significantly different on all samples. α′ martensite was observed on the SLM, acicular α on EBM and combination of both on the wrought alloy. EBM samples had higher surface roughness (Ra) compared with both SLM and wrought alloy. SLM samples were comparatively harder than wrought alloy and EBM. Tensile strength of the wrought alloy was higher in all directions except for 45°, where SLM samples showed higher strength than both EBM and wrought alloy on that direction. The ductility of the wrought alloy was consistently higher than both SLM and EBM indicated by clear necking feature on the wrought alloy samples. Dimples were observed on all fracture surfaces.

scholarly journals Can Appropriate Thermal Post-Treatment Make Defect Content in as-Built Electron Beam Additively Manufactured Alloy 718 Irrelevant?

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 536 ◽  
Author(s):  
Sneha Goel ◽  
Kévin Bourreau ◽  
Jonas Olsson ◽  
Uta Klement ◽  
Shrikant Joshi
Keyword(s):  
Electron Beam ◽  
Process Optimization ◽  
Electron Beam Melting ◽  
Phase Distribution ◽  
Hot Isostatic Pressing ◽  
Alloy 718 ◽  
Proof Of Concept ◽  
Defect Content ◽  
Enhancing Production ◽  
Hardness Values

Electron beam melting (EBM) is gaining rapid popularity for production of complex customized parts. For strategic applications involving materials like superalloys (e.g., Alloy 718), post-treatments including hot isostatic pressing (HIPing) to eliminate defects, and solutionizing and aging to achieve the desired phase constitution are often practiced. The present study specifically explores the ability of the combination of the above post-treatments to render the as-built defect content in EBM Alloy 718 irrelevant. Results show that HIPing can reduce defect content from as high as 17% in as-built samples (intentionally generated employing increased processing speeds in this illustrative proof-of-concept study) to <0.3%, with the small amount of remnant defects being mainly associated with oxide inclusions. The subsequent solution and aging treatments are also found to yield virtually identical phase distribution and hardness values in samples with vastly varying as-built defect contents. This can have considerable implications in contributing to minimizing elaborate process optimization efforts as well as slightly enhancing production speeds to promote industrialization of EBM for applications that demand the above post-treatments.

scholarly journals The Effect of Hydrogen-Charging on Mechanical Properties of Austenitic CrNi Steel Fabricated by Wire-Feed Electron Beam Additive Manufacturing

2021 ◽  
Vol 225 ◽  
pp. 01011
Author(s):  
Marina Panchenko ◽  
Eugeny Melnikov ◽  
Valentina Moskvina ◽  
Sergey Astafurov ◽  
Galina Maier ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electron Beam ◽  
Additive Manufacturing ◽  
Hydrogen Embrittlement ◽  
Yield Strength ◽  
Cast Steel ◽  
Solution Treatment ◽  
Fracture Mechanisms ◽  
Hydrogen Charging ◽  
Wire Feed

A comparative study of the mechanical properties, fracture mechanisms and hydrogen embrittlement peculiarities was carried out using the specimens of austenitic CrNi steel produced by two different methods: wire-feed electron beam additive manufacturing and conventional casting followed by solid-solution treatment. Hydrogen-induced reduction of ductility and the increase in the yield strength are observed in steel specimens produced by both methods. Despite hydrogen embrittlement index is comparable in them, the increase in the yield strength after hydrogen-charging is different: 25 MPa for cast steel and 175 MPa for additively manufactured steel. This difference is associated with the peculiarities of phase composition and phase distribution in steels produced by different methods.

Microgeometry of the surface of electron beam additive manufacturing products. Selective electron beam melting

2021 ◽  
pp. 408-418
Author(s):  
E.V. Krasnova ◽  
Yu.A. Morgunov ◽  
B.P. Saushkin
Keyword(s):  
Electron Beam ◽  
Additive Manufacturing ◽  
Physical Model ◽  
Electron Beam Melting ◽  
Metallurgical Process ◽  
Additive Technology ◽  
Selective Electron Beam Melting ◽  
Surface Microgeometry ◽  
Microstructure Of The Material

The results of the analysis of works related to the formation of surface microgeometry in the process of selective electron-beam melting are presented, and the physical model of this process is refined. The developing additive technology of selective electron-beam alloying and the directions in which its research is carried out, in particular, the analysis of the metallurgical process, the formation of the microstructure of the material, the formation of microstructure defects, are described. The roughness of the surface of products obtained by the SEBM technology, as well as the microgeometry of surfaces and the mechanisms of its formation, depending on various parameters of the process, are considered.

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