Article
Engineering, Manufacturing
Chaochao Wu, Muhammad Qasim Zafar, Haiyan Zhao, You Wang, Christoph Schoeler, Christian Heinigk, Markus Niessen, Wolfgang Schulz
Summary: The research analyzes the formation process of side surfaces in electron beam PBF through 3-D mesoscale multi-physics simulation, providing insights into side roughness mechanisms from the perspective of heat and mass transfer. The study reveals that cases with lower heat input result in greater fluctuations in melted traces, leading to higher side roughness. The investigation also identifies melt pool flow driven by surface tension as the main cause of track shape fluctuation.
ADDITIVE MANUFACTURING
(2021)
Review
Engineering, Manufacturing
Lucas C. B. Carolo, Robert E. Cooper
Summary: This review examines the mechanisms and process variables that contribute to surface roughness in EB-PBF, focusing on the performance and quality of Ti-6Al-4V parts. The challenges in surface metrology and new perspectives for future research are also discussed.
ADDITIVE MANUFACTURING
(2022)
Article
Engineering, Manufacturing
A. Plotkowski, J. Ferguson, B. Stump, W. Halsey, V Paquit, C. Joslin, S. S. Babu, A. Marquez Rossy, M. M. Kirka, R. R. Dehoff
Summary: By developing a new geometry agnostic scan path algorithm, the ability to control grain structure and crystallographic texture during metal additive manufacturing has been demonstrated, with profound implications for the design and optimization of next-generation products.
ADDITIVE MANUFACTURING
(2021)
Article
Chemistry, Physical
Spencer Jeffs, Robert Lancaster, Gareth Davies, William Hole, Brenna Roberts, David Stapleton, Meurig Thomas, Iain Todd, Gavin Baxter
Summary: The study found relationships between process parameters, microstructural characteristics, and impact energy results in AM materials, with vertically built specimens exhibiting higher impact energy and beam velocity displaying the most significant influence on impact energy results.
Review
Engineering, Manufacturing
Paria Karimi, Mohsen K. Keshavarz, Esmaeil Sadeghi, Mahdi Habibnejad, Mihaela Vlasea
Summary: The electron beam-powder bed fusion (EB-PBF) process is a potential alternative for manufacturing gamma-TiAl structures with superior properties. Compared to other additive manufacturing processes, EB-PBF offers advantages such as high vacuum processing, faster and more efficient processing, and a high-temperature environment with reduced residual stress. The review discusses the microstructure evolution, correlation between microstructural characteristics and processing conditions, thermal post-treatment, mechanical properties, fracture toughness behavior, creep, and fatigue performance of gamma-TiAl structures.
ADDITIVE MANUFACTURING
(2023)
Article
Engineering, Manufacturing
B. Gao, H. Peng, H. Yue, H. Guo, C. Wang, B. Chen
Summary: This paper presents the utilization of multi-spot melt strategy combined with smaller layer thickness to produce Y2O3/γ-TiAl nanocomposite through additive manufacturing. Compared with the hatch melt, the multi-spot melt strategy leads to a lower proportion of γ and B2-phases, a smaller lamellar spacing with straight α2/γ interfaces, and a more uniform distribution of nanoparticles with a finer size. The formation of twins within the γ grains and γ lamellae is observed in both multi-spot and hatch melt samples. The as-built condition achieves a good combination of tensile strength, ductility, and fracture toughness. Quantitative microscopy confirms a homogeneous microstructure in the x-y plane for the multi-spot sample, and the smaller layer thickness helps reduce microstructure degradation during thermal cycling. TEM analysis identifies rod-like Y2O3 with a monoclinic crystal system and near-spherical Y2O3 with a cubic crystal system. The Y2O3/TiAl interface is found to be clean and free of interfacial reactions, suggesting strong bonding.
ADDITIVE MANUFACTURING
(2023)
Article
Chemistry, Physical
Alexander Kirchner, Burghardt Kloeden, Marie Franke-Jurisch, Gunnar Walther, Thomas Weissgaerber
Summary: In the current state of the art, spherical alloy powders are used in powder bed fusion processes, but they are expensive. This study examines the use of water atomized material in electron beam powder bed fusion and investigates the addition of alloying elements through powder blending. The results show that this method can reduce costs while maintaining desired density.
Article
Materials Science, Multidisciplinary
Yufan Zhao, Kenta Aoyagi, Kenta Yamanaka, Akihiko Chiba
Summary: This study investigated the effect of powder layer thickness on the electron beam powder bed fusion process. The results showed that a relatively larger powder layer thickness can expand the processing window but also decrease the melting efficiency and result in surface height differences. Numerical simulation further confirmed the dependency of the layer thickness effect on the processing conditions.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2023)
Article
Engineering, Manufacturing
Yaron Itay Ganor, Andrey Garkun, Roni Z. Shneck, Ori Yeheskel
Summary: This study investigates the anelastic phenomena in Ti6Al4V alloy at room temperature, and suggests that it is related to dislocation bowing-out and the formation and motion of twin walls. The presence of residual stresses in the as-built samples contributes to the largest loop area, while heating above 700℃ reduces the tension-compression anisotropy.
ADDITIVE MANUFACTURING
(2022)
Article
Engineering, Manufacturing
Christopher Arnold, Carolin Koerner
Summary: The study demonstrates the potential of in-situ acquisition of electron optical images for measuring thermal expansion, monitoring thermal shrinkage, and quantifying thermal strain with remarkable accuracy. This opens up new applications for in-situ electron-optical observation in temperature management and validation of numerical frameworks.
ADDITIVE MANUFACTURING
(2021)
Article
Nanoscience & Nanotechnology
Dmitriy Khrapov, Aleksandra Paveleva, Maria Kozadayeva, Sergei Evsevleev, Tatiana Mishurova, Giovanni Bruno, Roman Surmenev, Andrey Koptyug, Maria Surmeneva
Summary: Electron Beam Powder Bed Fusion-manufactured porous components may contain trapped powder, requiring proper powder removal procedures. This study investigated different post-processing methods for sheet-based porous structures, including a powder recovery system, chemical etching, and ultrasound vibration-assisted powder removal. The results showed that the powder recovery system was insufficient for removing all residual powder, while chemical etching affected the structure's mechanical properties. Ultrasound vibration proved to be effective for powder removal without significant degradation of mechanical properties, and it also caused grain refinement.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Chemistry, Physical
Haoyang Li, Taomei Zhang, Dan Li, Yiyou Wu, Zhaowen Geng, Chao Chen, Xiaoyong Zhang, Kechao Zhou
Summary: In this study, a eutectoid Ti-7Ni alloy was additively manufactured using E-PBF. The effects of electron beam current and preheating time on the microstructure and mechanical properties of the alloy were investigated. It was found that the microstructure of the alloy can be controlled through in-situ heat treatment, leading to good mechanical properties.
Article
Engineering, Manufacturing
Jakob Renner, Christoph Breuning, Matthias Markl, Carolin Koerner
Summary: Electron optical imaging is a monitoring method in electron beam powder bed fusion that allows in situ detection of porosity in each layer of a part. This study introduces the ability to quantitatively and in situ measure surface topographies using electron optical imaging. By recording electron optical images and employing a computation chain based on a developed imaging process model, it becomes possible to correct image distortions and calculate the gradient information of the surfaces. This enables the reconstruction of height maps of melt surfaces and the comparison with laser scanning microscope measurements validates the computation chain. Electron optical imaging can measure porosity and bulging simultaneously, providing important process information for process control and the implementation of feedback control loops.
ADDITIVE MANUFACTURING
(2022)
Article
Nanoscience & Nanotechnology
Paria Karimi, Esmaeil Sadeghi, Joakim Algardh, Jonas Olsson, Magnus Hornqvist Colliander, Peter Harlin, Ehsan Toyserkani, Joel Andersson
Summary: This study introduces a unique melting strategy in electron beam-powder bed fusion to tailor the grain morphology of Alloy 718 from columnar to equiaxed. By controlling the local solidification conditions and motions within the melt pools, the transition in grain morphology was achieved. Four different microstructures were identified, with the typical texture being <001>, and shrinkage defects and cracks were reduced with a decrease in areal energy input. Hardness was increased due to the growth of gamma precipitates and high grain boundary density in the fully-equiaxed grain morphology.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Materials Science, Multidisciplinary
Hamid Reza Ghorbani, Mohammad Hossein Mosallanejad, Masoud Atapour, Manuela Galati, Abdollah Saboori
Summary: Hybrid Additive Manufacturing (HAM) enhances the flexibility of Additive Manufacturing (AM) techniques. This study reports the HAM of Ti6Al4V using Transient Liquid Phase (TLP) bonding of an Electron Beam Powder Bed Fused (EB-PBF) sample to a conventional one. Shear strength tests show that TLP bonding at 970 degrees C achieves higher shear strengths and better microstructural integrity.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2022)