scholarly journals Surface Roughness Characterisation and Analysis of the Electron Beam Melting (EBM) Process

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2211 ◽  
Author(s):  
Manuela Galati ◽  
Paolo Minetola ◽  
Giovanni Rizza
Keyword(s):  
Surface Roughness ◽  
Electron Beam ◽  
Cross Section ◽  
Mass Production ◽  
Electron Beam Melting ◽  
Heat Distribution ◽  
Powder Bed Fusion ◽  
Powder Bed ◽  
Key Factor ◽  
Process Factors

Electron Beam Melting (EBM) is a metal powder bed fusion (PBF) process in which the heat source is an electron beam. Differently from other metal PBF processes, today, EBM is used for mass production. As-built EBM parts are clearly recognisable by their surface roughness, which is, in some cases, one of the major limitations of the EBM process. The aim of this work is to investigate the effects of the orientation and the slope of the EBM surfaces on the surface roughness. Additionally, the machine repeatability is studied by measuring the roughness of surfaces built at different positions on the start plate. To these aims, a specific artefact was designed. Replicas of the artefact were produced using an Arcam A2X machine and Ti6Al4V powder. Descriptive and inferential statistical methods were applied to investigate whether the surface morphology was affected by process factors. The results show significant differences between the upward and downward surfaces. The upward surfaces appear less rough than the downward ones, for which a lower standard deviation was obtained in the results. The roughness of the upward surfaces is linearly influenced by the sloping angle, while the heat distribution on the cross-section was found to be a key factor in explaining the roughness of the downward surfaces.

Multi-Objective Build Orientation Optimization for Powder Bed Fusion by Laser

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Salah Eddine Brika ◽  
Yaoyao Fiona Zhao ◽  
Mathieu Brochu ◽  
Justin Mezzetta
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Integrated Approach ◽  
Powder Bed Fusion ◽  
Powder Bed ◽  
Build Orientation ◽  
Multi Objective ◽  
Build Time ◽  
Process Factors ◽  
Experimental Data Analysis

This paper proposes an integrated approach to determine optimal build orientation for powder bed fusion by laser (PBF-L), by simultaneously optimizing mechanical properties, surface roughness, the amount of support structure (SUPP), and build time and cost. Experimental data analysis has been used to establish the objective functions for different mechanical properties and surface roughness. Geometry analysis of the part has been used to estimate the needed SUPP and thus evaluate the build time and cost. Normalized weights are assigned to different objectives depending on their relative importance allowing solving the multi-objective optimization problem using a genetic optimization algorithm. A study case is presented to demonstrate the capabilities of the developed system. The major achievements of this work are the consideration of multiple objectives and the establishment of objective function considering different load direction and heat treatments. A user-friendly graphical user interface was developed allowing to control different optimization process factors and providing different visualization and evaluation tools.

scholarly journals The Effect of Post-Processing on the Mechanical Behavior of Ti6Al4V Manufactured by Electron Beam Powder Bed Fusion for General Aviation Primary Structural Applications

Aerospace ◽  
2020 ◽  
Vol 7 (6) ◽  
pp. 75
Author(s):  
Carmine Pirozzi ◽  
Stefania Franchitti ◽  
Rosario Borrelli ◽  
Antonio Chiariello ◽  
Luigi Di Palma
Keyword(s):  
Electron Beam ◽  
Mechanical Behavior ◽  
Electron Beam Melting ◽  
Melting Process ◽  
General Aviation ◽  
Powder Bed Fusion ◽  
Structural Elements ◽  
Post Processing ◽  
Powder Bed ◽  
Structural Applications

In this work a mechanical characterization of Ti6Al4V processed by electron beam powder bed fusion additive manufacturing was carried out to investigate the viability of this technology for the manufacturing of flyable parts for general aviation aircraft. Tests were performed on different manufacturing conditions in order to investigate the effect of post processing as machining on the mechanical behavior. The study provides useful information to airframe designers and manufacturing specialists that work with this technology. The investigation confirms the low process variability and provides data to be used in the design loop of general aviation primary structural elements. The test results show a high level of repeatability indicating that the process is well controlled and reliable enough to match the airworthiness requirements. In addition, the so-called “as-built specimens”, i.e., specimens produced by the electron beam melting machine without any major post-processing, have lower mechanical performances than specimens subjected to a machining phase after the electron beam melting process. Specific primary structural elements will be designed and flight cleared, resulting from the findings presented herein.

scholarly journals Smoke Suppression in Electron Beam Melting of Inconel 718 Alloy Powder Based on Insulator–Metal Transition of Surface Oxide Film by Mechanical Stimulation

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4662
Author(s):  
Akihiko Chiba ◽  
Yohei Daino ◽  
Kenta Aoyagi ◽  
Kenta Yamanaka
Keyword(s):  
Electron Beam ◽  
Oxide Film ◽  
Ball Milling ◽  
Mechanical Stimulation ◽  
Electron Beam Melting ◽  
Alloy Powder ◽  
Powder Bed Fusion ◽  
Surface Oxide Film ◽  
Inconel 718 Alloy ◽  
Powder Bed

In powder bed fusion–electron beam melting, the alloy powder can scatter under electron beam irradiation. When this phenomenon—known as smoking—occurs, it makes the PBF-EBM process almost impossible. Therefore, avoiding smoking in EBM is an important research issue. In this study, we aimed to clarify the effects of powder bed preheating and mechanical stimulation on the suppression of smoking in the powder bed fusion–electron beam melting process. Direct current electrical resistivity and alternating current impedance spectroscopy measurements were conducted on Inconel 718 alloy powder at room temperature and elevated temperatures before and after mechanical stimulation (ball milling for 10–60 min) to investigate changes in the electrical properties of the surface oxide film, alongside X-ray photoelectron spectroscopy to identify the surface chemical composition. Smoking tests confirmed that preheating and ball milling both suppressed smoking. Furthermore, smoking did not occur after ball milling, even when the powder bed was not preheated. This is because the oxide film undergoes a dielectric–metallic transition due to the lattice strain introduced by ball milling. Our results are expected to benefit the development of the powder bed fusion–electron beam melting processes from the perspective of materials technology and optimization of the process conditions and powder properties to suppress smoking.

Unsettled Topics on Surface Finishing of Metallic Powder Bed Fusion Parts in the Mobility Industry

2021 ◽  
Author(s):  
Kevin Slattery ◽  
Keyword(s):  
Surface Roughness ◽  
Electron Beam ◽  
High Surface ◽  
Metallic Powder ◽  
Surface Finishing ◽  
Powder Bed Fusion ◽  
Powder Bed ◽  
Challenges And Opportunities ◽  
The Cost ◽  
Fatigue Corrosion

Laser and electron-beam powder bed fusion (PBF) additive manufacturing (AM) technology has transitioned from prototypes and tooling to production components in demanding fields such as medicine and aerospace. Some of these components have geometries that can only be made using AM. Initial applications either take advantage of the relatively high surface roughness of metal PBF parts, or they are in fatigue, corrosion, or flow environments where surface roughness does not impose performance penalties. To move to the next levels of performance, the surfaces of laser and electron-beam PBF components will need to be smoother than the current as-printed surfaces. This will also have to be achieve on increasingly more complex geometries without significantly increasing the cost of the final component. Unsettled Topics on Surface Finishing of Metallic Powder Bed Fusion Parts in the Mobility Industry addresses the challenges and opportunities of this technology, and what remains to be agreed upon by the industry.

Multi-Objective Build Orientation Optimization for Powder Bed Fusion by Laser

2017 ◽  
Author(s):  
Salah Eddine Brika ◽  
Justin Mezzetta ◽  
Mathieu Brochu ◽  
Yaoyao Fiona Zhao
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Integrated Approach ◽  
Powder Bed Fusion ◽  
Support Structure ◽  
Powder Bed ◽  
Build Orientation ◽  
Multi Objective ◽  
Build Time ◽  
Process Factors

This paper proposes an integrated approach to determine optimal build orientation for Powder bed fusion by laser (PBF-L), by simultaneously optimizing mechanical properties, surface roughness, the amount of support structure and build time-cost. Experimental data analysis has been used to establish the objective functions for different mechanical properties and surface roughness. Geometry analysis of the part has been used to estimate the needed support structure and thus evaluate the build time and cost. Normalized weights are assigned to different objectives depending on their relative importance allowing solving the multi-objective optimization problem using a genetic optimization algorithm. A study case is presented to demonstrate the capabilities of the developed system. The major achievements of this work are the consideration of multiple objectives, the establishment of objective function considering different load direction and heat treatments. A user-friendly graphical user interface was developed allowing to control different optimization process factors and providing different visualization and evaluation tools.

Numerical Modeling of Heat Distribution in the Electron Beam Melting® of Ti-6Al-4V

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Mahdi Jamshidinia ◽  
Fanrong Kong ◽  
Radovan Kovacevic
Keyword(s):  
Numerical Modeling ◽  
Electron Beam ◽  
Process Parameters ◽  
Molten Pool ◽  
Electron Beam Melting ◽  
Flow Model ◽  
Numerical Models ◽  
Heat Distribution ◽  
Powder Bed ◽  
Thermal Fluid Flow

Electron beam melting® (EBM) is one of the fastest growing additive manufacturing processes capable of building parts with complex geometries, made predominantly of Ti-alloys. Providing an understanding of the effects of process parameters on the heat distribution in a specimen built by EBM®, could be the preliminary step toward the microstructural and consequently mechanical properties control. Numerical modeling is a useful tool for the optimization of processing parameters, because it decreases the level of required experimentation and significantly saves on time and cost. So far, a few numerical models are developed to investigate the effects of EBM® process parameters on the heat distribution and molten pool geometry. All of the numerical models have ignored the material convection inside the molten pool that affects the real presentation of the temperature distribution and the geometry of molten pool. In this study, a moving electron beam heat source and temperature dependent properties of Ti-6Al-4V were used in order to provide a 3D thermal-fluid flow model of EBM®. The influence of process parameters including electron beam scanning speed, electron beam current, and the powder bed density were studied. Also, the effects of flow convection in temperature distribution and molten pool geometry were investigated by comparing a pure-thermal with the developed thermal-fluid flow model. According to the results, the negative temperature coefficient of surface tension in Ti-6Al-4V was responsible for the formation of an outward flow in the molten pool. Also, results showed that ignoring the material convection inside the molten pool resulted in the formation of a molten pool with narrower width and shorter length, while it had a deeper penetration and higher maximum temperature in the molten pool. Increasing the powder bed density was accompanied with an increase in the thermal conductivity of the powder bed that resulted in a reduction in the molten pool width on the powder bed top surface. Experimental measurements of molten pool width and depth are performed to validate the numerical model.

scholarly journals Electron Beam Melting of Niobium Alloys from Blended Powders

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5536
Author(s):  
Jameson P. Hankwitz ◽  
Christopher Ledford ◽  
Christopher Rock ◽  
Scott O’Dell ◽  
Timothy J. Horn
Keyword(s):  
Electron Beam ◽  
Electron Beam Melting ◽  
Room Temperature ◽  
Powder Bed Fusion ◽  
Post Processing ◽  
Niobium Alloys ◽  
Powder Bed ◽  
Tungsten Alloys ◽  
Room Temperature Ductility ◽  
Structural Applications

Niobium-based tungsten alloys are desirable for high-temperature structural applications yet are restricted in practice by limited room-temperature ductility and fabricability. Powder bed fusion additive manufacturing is one technology that could be leveraged to process alloys with limited ductility, without the need for pre-alloying. A custom electron beam powder bed fusion machine was used to demonstrate the processability of blended Nb-1Zr, Nb-10W-1Zr-0.1C, and Nb-20W-1Zr-0.1C powders, with resulting solid optical densities of 99+%. Ultimately, post-processing heat treatments were required to increase tungsten diffusion in niobium, as well as to attain satisfactory mechanical properties.

Indentation-derived mechanical properties of Ti-6Al-4V: laser-powder bed fusion versus electron beam melting

2021 ◽  
pp. 130273
Author(s):  
Amir Hadadzadeh ◽  
Ebrahim Asadi ◽  
Shawkat Imam Shakil ◽  
Babak Shalchi Amirkhiz ◽  
Mohsen Mohammadi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electron Beam ◽  
Electron Beam Melting ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed
Sign in / Sign up

Export Citation Format

Share Document