Article
Engineering, Manufacturing
Minsoo Jin, Ehsan Hosseini, Stuart R. Holdsworth, Minh-Son Pham
Summary: The CrMnFeCoNi high-entropy alloy shows great potential for applications at different temperatures and is highly printable for complex structures through additive manufacturing. This study provides a comprehensive understanding of the relationship between the as-built cellular microstructures and fatigue behavior of the alloy. It reveals the stability of dislocation cells and the thermo-mechanical dependence of fatigue behavior, shedding light on the factors influencing the cyclic hardening and softening phenomena.
ADDITIVE MANUFACTURING
(2022)
Article
Engineering, Mechanical
D. Martinez de Luca, A. R. Hamilton, P. A. S. Reed
Summary: In this study, Inconel 718 manufactured by Laser Powder Bed Fusion was characterized in terms of microstructure, post-processing heat treatment, and the dependence of fatigue crack growth (FCG) on build orientation. Long crack fatigue tests were conducted at different temperatures and frequencies. It was found that at 350 degrees C, build orientation had no effect on FCG rates, but at higher temperatures, build orientation significantly affected FCG rates due to microstructural differences caused by the printing strategy.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Article
Chemistry, Physical
Tomer Ron, Avi Leon, Vladimir Popov, Evgeny Strokin, Dan Eliezer, Amnon Shirizly, Eli Aghion
Summary: The interest in refractory high-entropy alloys (HEAs) has grown in the last decade due to their thermal stability, mechanical properties, and corrosion resistance. However, their drawbacks in processing and machining operations hinder their use as common structural materials. The recent progress in additive manufacturing (AM) technologies has provided the option to produce complex components made of HEAs with minimal machining processes.
Article
Engineering, Mechanical
M. Tarik Hasib, Halsey E. Ostergaard, Xiaopeng Li, Jamie J. Kruzic
Summary: The study found that the fatigue crack growth rates of Ti-6Al-4V material are influenced by build orientation and post heat treatments, while texture and build orientation have minimal impact on slow crack growth rates and fatigue thresholds. The definition of fatigue thresholds lies in the ability to transfer slip from one α' / α laths to another, with some effect of crack closure induced by roughness. The transition away from microstructure sensitive fatigue crack growth occurred when the packet/colony size equaled the cyclic plastic zone size.
INTERNATIONAL JOURNAL OF FATIGUE
(2021)
Article
Engineering, Manufacturing
M. Tarik Hasib, Halsey E. Ostergaard, Qian Liu, Xiaopeng Li, Jamie J. Kruzic
Summary: The study compared the effects of build orientation and post heat treatments on the tensile and fatigue crack growth behavior of titanium alloys, revealing that heat treatments altered grain structure, affecting tensile strength and fatigue crack growth threshold; titanium alloys manufactured using laser powder bed fusion were generally stronger and more fatigue resistant than wrought materials.
ADDITIVE MANUFACTURING
(2021)
Article
Nanoscience & Nanotechnology
Shahriar Afkhami, Vahid Javaheri, Kalle Lipiainen, Mohsen Amraei, Edris Dabiri, Timo Bjork
Summary: This study investigates the fatigue performance of additively manufactured steel CX under uniaxial high cycle loading. The results show that surface quality is the most influential parameter that affects the fatigue behavior of the material, while heat treatment has little influence on the fatigue performance.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Engineering, Industrial
Wessel W. Wits, Emiel Amsterdam
Summary: This paper adapts an industry-accepted fatigue model based on generalized stress-life (S-N) curves for metal parts fabricated by laser powder bed fusion (LPBF). The model relates initial defects, such as part porosity, inherent to the fabrication process to fatigue life performance. Fatigue tests on additively manufactured test specimens are conducted to formulate a function that predicts fatigue life based on the size of initial defects. The predictions show good correlation with experimental results and provide a quality measure to eliminate outliers. The method enables the prediction of life expectancy for LPBF parts based on a priori detected defect sizes.
CIRP ANNALS-MANUFACTURING TECHNOLOGY
(2023)
Article
Engineering, Industrial
Wessel W. Wits, Enrico Scolaro, Emiel Amsterdam, Adam T. Clare
Summary: The integrity of additively manufactured components is limited by internal defects, and current manufacturing strategies have not achieved fatigue-resistant performance.
CIRP ANNALS-MANUFACTURING TECHNOLOGY
(2022)
Article
Materials Science, Multidisciplinary
Chen Zhang, Junkai Zhu, Chaoyue Ji, Yuzheng Guo, Rui Fang, Shuwen Mei, Sheng Liu
Summary: Through the use of high-entropy alloy as a strengthening phase, stainless-steel composites processed via laser powder bed fusion achieved simultaneous improvements in strength, ductility, and corrosion resistance. The high strength was achieved through high-entropy alloy nanoparticles and high-density dislocations, while the improved ductility was attributed to the semi-obstructive effect of the interface on dislocations.
MATERIALS & DESIGN
(2021)
Article
Engineering, Mechanical
Dehua Li, Zhiqian Zhang, Shengci Li, Jiamin Yang, Siyu Zhang, Xinli Bian, Yuqin Zhang, Liang Qi, Olanrewaju A. Ojo
Summary: An Al-Zn-Mg-Cu alloy modified by Si-Zr-Er was fabricated using laser powder bed fusion (LPBF), exhibiting a tensile strength of 445 MPa. Precipitates including Al2CuMg, MgZn2, Mg2Si, and Al3(Zr,Er) were observed in the alloy. The presence of accumulated dislocations near the crack tip, combined with the second phases, hindered the propagation of fatigue crack. The alloy showed both transgranular and intergranular fatigue crack growth modes, with deflection occurring when encountering high misorientation grains. The highest fatigue life (N = 1.02 x 106 cycles) was achieved under r = 0.5 and Pmax = 0.3kN conditions.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Review
Materials Science, Multidisciplinary
A. Raja, Srinivasa Rakesh Cheethirala, Pallavi Gupta, Nilesh J. Vasa, R. Jayaganthan
Summary: This article reviews the interrelationship between LPBF process parameters, microstructure, crack initiation, and crack growth mechanisms under fatigue loading conditions. It highlights the importance of standardizing mechanical testing techniques, specimen design guidelines, and post-manufacturing treatments for improving the fatigue resistance of AlSi10Mg alloy. The influence of microstructural features and post-processing conditions on fatigue properties is discussed, along with the crack growth mechanism observed in LPBF processed material.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2022)
Article
Nanoscience & Nanotechnology
Esmaeil Sadeghi, Gbenga Asala, Paria Karimi, Dunyong Deng, Johan Moverare, Thomas Hansson
Summary: A unique melting strategy was implemented in EB-PBF of Alloy 718, resulting in the formation of a bimodal grain morphology consisting of fine equiaxed and columnar grains. The microstructure was preserved following various thermal post-treatments. Clustered inclusions acted as the crack initiation site, reducing the specimens' total fatigue life. Intergranular fracture mode was favored in the plastic zone ahead of the crack tip.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Engineering, Manufacturing
Ying Chen, Chuangwei Xiao, Shang Zhu, Zhiwen Li, Wenxin Yang, Feng Zhao, Shengfu Yu, Yusheng Shi
Summary: This study successfully developed a crack-free and high-strength Al-Cu-Mg-Y alloy using rare earth yttrium (Y) modified alloy powders. The addition of Y effectively eliminated solidification cracks by reducing susceptibility and refining grains. Through a specific heat treatment, the alloy exhibited higher compressive yield strength and homogeneously distributed precipitates.
ADDITIVE MANUFACTURING
(2022)
Article
Nanoscience & Nanotechnology
Marius S. Knieps, William J. Reynolds, Juliette Dejaune, Adam T. Clare, Alper Evirgen
Summary: In-situ alloying is a cost-effective method for laser powder bed fusion, allowing for development of novel alloys like high entropy alloys. However, the role of powder characteristics in mixed feedstocks and their impact on the process and resulting properties have not been explored in literature. This study demonstrates that using spherical, bi-modally distributed powder with specific particle size distribution can create a highly homogeneous alloy and optimize the powder bed density in LPBF.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Review
Materials Science, Multidisciplinary
Esmaeil Sadeghi, Paria Karimi, Reza Esmaeilizadeh, Filippo Berto, Shuai Shao, Johan Moverare, Ehsan Toyserkani, Nima Shamsaei
Summary: This paper comprehensively reviews the fundamentals and recent advances in the PBF-built Alloy 718 parts with improved fatigue life, including the influence of thermal and mechanical post-treatment, mechanisms of fatigue crack initiation and growth, thermo-mechanical fatigue, dwell-time fatigue, as well as fracture behavior in different loading conditions and environments considering anisotropic characteristics of the material. An unbiased review of the literature provides an understanding of the advanced and outstanding achievements in the field that assure further research. An evaluation of the status of the field, the gaps in the theoretical understanding, and the fundamental needs for the sustainable development of PBF-built Alloy 718 with enhanced fatigue life in specific applications are also provided.
PROGRESS IN MATERIALS SCIENCE
(2023)
Article
Nanoscience & Nanotechnology
J. Lertthanasarn, C. Liu, M. S. Pham
Summary: The study investigates the mechanical behavior of polycrystal-like meta-crystals fabricated from Ti6Al4V alloy by laser powder bed fusion (LPBF), revealing the impact of hierarchical lattice structures across length-scales on the material's mechanical properties.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Materials Science, Multidisciplinary
Bogdan Dovgyy, Marco Simonelli, Minh-Son Pham
Summary: This study developed a design methodology against liquid-state cracking by combining solidification simulations and Machine Learning analysis, resulting in a Fe-20Cr-7Al-4Mo-3Ni alloy with high relative densities. The printed material was characterized to be single-phase with low texture and negligible chemical segregation, without solidification or liquation cracks detected. However, the alloy suffered from solid-state cracking, hindering ductility.
MATERIALS RESEARCH LETTERS
(2021)
Article
Multidisciplinary Sciences
Chen Liu, Jedsada Lertthanasarn, Minh-Son Pham
Summary: The crystal-inspired approach has been successful in designing damage-tolerant architected materials, such as meta-crystals, leading to the need for fundamental studies to understand the underlying mechanisms responsible for strength and deformation control. Boundary strengthening in polycrystal-like meta-crystals is influenced by the interaction between shear bands and polygrain-like boundaries, with boundary type and coherency playing a key role in governing shear band transmission across meta-grain boundaries. Insights gained from this study are crucial for developing high-strength architected materials with the ability to control and program mechanical strength and damage path.
NATURE COMMUNICATIONS
(2021)
Article
Engineering, Manufacturing
Vitor Vieira Rielli, Alessandro Piglione, Minh-Son Pham, Sophie Primig
Summary: IN718 is a commonly used nickel-based superalloy for manufacturing aircraft engine parts, with optimized strength, fatigue, and creep properties. Recent studies have shown its potential for additive manufacturing of aerospace parts using laser powder bed fusion. However, there is still limited understanding of the microstructure-property relationships during the LPBF process.
ADDITIVE MANUFACTURING
(2022)
Article
Engineering, Manufacturing
Minsoo Jin, Ehsan Hosseini, Stuart R. Holdsworth, Minh-Son Pham
Summary: The CrMnFeCoNi high-entropy alloy shows great potential for applications at different temperatures and is highly printable for complex structures through additive manufacturing. This study provides a comprehensive understanding of the relationship between the as-built cellular microstructures and fatigue behavior of the alloy. It reveals the stability of dislocation cells and the thermo-mechanical dependence of fatigue behavior, shedding light on the factors influencing the cyclic hardening and softening phenomena.
ADDITIVE MANUFACTURING
(2022)
Article
Materials Science, Multidisciplinary
Ehsan Hosseini, Serjosha Robmann, Thomas Luthi, Christian Affolter, Edoardo Mazza
Summary: This study analyzes the mechanical response of additive manufacturing Ti6Al4V struts in orthopedic implants and discusses the relationship between their geometry and stress-strain response. It suggests that considering the true mechanical response of struts is not feasible in the design stage, and proposes using representative apparent constitutive models in finite-element simulations as a viable alternative.
ADVANCED ENGINEERING MATERIALS
(2023)
Article
Engineering, Multidisciplinary
E. Hosseini, P. Gh Ghanbari, R. Molinaro, S. Mishra
Summary: This study explores the application of physics informed neural networks (PINNs) as a low-cost physics-based simulation approach for the thermal analysis of the laser powder bed fusion (LPBF) process. PINNs solve the heat transfer equation parametrically and provide reliable transient and steady-state temperature profiles for single-track LPBF depositions. The trained PINNs can calculate temperature profiles and melt-pool dimensions during the LPBF process with practically zero computational cost. The reliability of PINNs outcomes is verified through ground-truth data based on benchmark finite element simulations.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2023)
Article
Materials Science, Multidisciplinary
I. Ferretto, D. Kim, W. J. Lee, E. Hosseini, N. M. della Ventura, A. Sharma, C. Sofras, J. Capek, E. Polatidis, C. Leinenbach
Summary: The fcc-c-, hcp-e-, and bcc-a' martensitic transformation of a Fe-Mn-Si-based shape memory alloy fabricated by laser powder bed fusion (LPBF) is studied for the first time. Comparison between horizontal and vertical specimens shows that sample orientation considerably influences the alloy's shape memory and mechanical properties. The reason for this variation is found in the distinct crystallographic texture generated during the LPBF process.
MATERIALS & DESIGN
(2023)
Article
Materials Science, Multidisciplinary
Alessandro Piglione, Tom Bellamy, Jian Yu, Jinqian Zhao, Chengbo Xiao, Fionn P. E. Dunne, Minh-Son Pham
Summary: This study investigates the local plasticity near stress concentrations in a cyclically loaded Ni-based single-crystal superalloy. By combining transmission electron microscopy (TEM) observations and microstructure-based crystal plasticity modeling, the study provides new insights into the deformation micromechanisms leading to fatigue crack initiation in single-crystal superalloys. It shows that increasing local stresses play a role in high dislocation density and extensive gamma' shearing, but cannot solely explain the distinctive arrangements of dislocations in the crack initiation region.
ADVANCED ENGINEERING MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Chen Liu, Minh-Son Pham
Summary: This study proposes a new approach inspired by physical metallurgical principles to create a new class of intelligent mechanical metamaterials that can precisely tune mechanical properties and enhance adaptivity. These programmable materials have high strength and plastic deformation stability, as well as the ability to regulate local deformation states and control the internal propagation of deformation.
ADVANCED MATERIALS
(2023)
Article
Engineering, Multidisciplinary
Jian Tang, Siddhant Kumar, Laura De Lorenzis, Ehsan Hosseini
Summary: We propose Neural Cellular Automata (NCA) for simulating microstructure development in the solidification process of metals. NCA, based on convolutional neural networks, can learn essential features of solidification and are much faster than conventional Cellular Automata (CA). Notably, NCA can make reliable predictions beyond their training range, indicating their understanding of the physics of solidification. While CA data is used for training in this study, NCA can be trained on any microstructural simulation data, such as phase-field models.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2023)
Article
Engineering, Manufacturing
X. Li, R. Esmaeilizadeh, H. Jahed, E. Toysarkani, M. S. Pham, S. R. Holdsworth, E. Hosseini
Summary: This study compares the tensile response of laser powder bed fusion (LPBF) fabricated Hastelloy X (HX) coupons with those of conventionally manufactured HX. The LPBF HX showed comparable ultimate tensile strength and higher yield strengths. The stress strain response of LPBF HX exhibited pronounced evidence of dynamic strain aging (DSA) at certain temperatures, which occurred at lower temperatures than that for conventionally manufactured HX. The differences in tensile and DSA responses were attributed to the differences in dislocation microstructure observed through scanning transmission electron microscopy.
ADDITIVE MANUFACTURING LETTERS
(2023)
Article
Engineering, Manufacturing
Pooriya Gh Ghanbari, Patrik Markovic, Steven Van Petegem, Malgorzata Grazyna Makowska, Rafal Wrobel, Thomas Mayer, Christian Leinenbach, Edoardo Mazza, Ehsan Hosseini
Summary: In laser powder bed fusion (LPBF), complex components are manufactured layer-by-layer using a high intensity laser. The unique temperature profiles in LPBF result in an inhomogeneous microstructure and high residual stresses. This study used operando X-ray diffraction (XRD) to measure and compare temperature histories on the laser path for Hastelloy X. Finite element thermal simulations were used to discuss the cooling behavior and thermal heterogeneities.
ADDITIVE MANUFACTURING LETTERS
(2023)
Article
Engineering, Manufacturing
V. Kalyanasundarama, A. De Lucaa, R. Wrobel, J. Tanga, S. R. Holdswortha, C. Leinenbacha, E. Hosseini
Summary: The tensile and creep rupture properties of crack-free CM247LC alloy processed via laser powder bed fusion were characterized in this study at temperatures up to 1000℃. The alloy exhibits comparable or even higher tensile performance than its directionally solidified counterpart up to 700℃, but both strength and ductility decline rapidly at higher temperatures. Agglomeration of discrete carbides facilitates the nucleation, linking, and propagation of micro-cracks along adjacent grain boundaries at elevated temperatures. Short-term creep-rupture tests conducted at 800℃ highlight the need for significant improvement in the microstructure of this alloy to compete with its directionally solidified or conventionally cast counterparts in turbomachinery components operating up to approximately 950℃. Increasing grain size, incorporating grain boundary engineering concepts, and better understanding of carbide/precipitate evolutionary characteristics can greatly enhance the material's suboptimal creep response.
ADDITIVE MANUFACTURING LETTERS
(2023)
Article
Engineering, Manufacturing
Caterina Iantaffi, Chu Lun Alex Leung, Yunhui Chen, Shaoliang Guan, Robert C. Atwood, Jedsada Lertthanasarn, Minh-Son Pham, Martina Meisnar, Thomas Rohr, Peter D. Lee
Summary: This study reveals that oxygen contamination in additively manufactured titanium alloys can lead to changes in molten pool geometry, defect formation, and microstructure. It also shows that oxygen levels can suppress the commonly formed martensitic microstructure, forming a different tetra-modal microstructure in the presence of high oxygen levels.
ADDITIVE MANUFACTURING LETTERS
(2021)
Article
Engineering, Manufacturing
Przemyslaw Golebiewski, Pawel Wienclaw, Jaroslaw Cimek, Pawel Socha, Dariusz Pysz, Adam Filipkowski, Grzegorz Stepniewski, Olga Czerwinska, Ireneusz Kujawa, Ryszard Stepien, Rafal Kasztelanic, Andrzej Burgs, Ryszard Buczynski
Summary: We report the development of a 3D printing process for producing soft glass optical fibers. The process involves direct printing using a miniaturized crucible and depositing straight horizontally-oriented lines to replace traditional assembly techniques. Experimental results demonstrate good performance of the printed photonic crystal fiber preform.
ADDITIVE MANUFACTURING
(2024)
