Pub Date : 2025-08-25DOI: 10.1016/j.addma.2025.104995
Indrajeet Katti , Dong Qiu , Duyao Zhang , Matthias Weiss , Joy H. Forsmark , Mark Easton
The microstructures observed in Al-Si alloys are very different depending on the manufacturing technologies from coarse divorced eutectics in slowly cooled alloys to highly interconnected Si with extended solubility of Si in the α-Al in additive manufacturing. In this study, a ‘kinetic’ or effective Al-Si phase diagram is proposed by analysing the phase constituents of an Al-10Si alloy fabricated using high-pressure die casting (HPDC) and powder bed fusion-laser beam (PBF-LB) processes and comparing it with known phase equilibria. It was shown that the high cooling rates, in the order of 106 K/s in PBF-LB, resulted in approximately 400 K eutectic undercooling that in turn increased the eutectic composition from 12.6 wt% to approximately 70 wt%. Even the moderately high cooling rates in HPDC (102-103 K/s) have some effect on the effective eutectic composition and temperature. The detailed microstructure characterisation, and solidification path modelling using the Scheil-Gulliver equation, leads to a series of empirical relationships to describe the effect of cooling rate on the effective Al-Si phase diagram. The eutectic suppression with cooling rate can explain microstructure observations in additive manufacturing including increased primary α-Al, eutectic Si morphology changes and the elevated solute Si content in the eutectic α-Al. It is apparent that the elevated solute Si is due to the eutectic undercooling rather than diffusion related solute trapping phenomena. The relationships developed will benefit microstructure modelling, process design, and alloy development for processes with very high solidification rates.
{"title":"Development of a kinetic phase diagram for Al-Si alloys to enable phase constituents to be determined across a broad range of cooling rates and manufacturing technologies","authors":"Indrajeet Katti , Dong Qiu , Duyao Zhang , Matthias Weiss , Joy H. Forsmark , Mark Easton","doi":"10.1016/j.addma.2025.104995","DOIUrl":"10.1016/j.addma.2025.104995","url":null,"abstract":"<div><div>The microstructures observed in Al-Si alloys are very different depending on the manufacturing technologies from coarse divorced eutectics in slowly cooled alloys to highly interconnected Si with extended solubility of Si in the α-Al in additive manufacturing. In this study, a ‘kinetic’ or effective Al-Si phase diagram is proposed by analysing the phase constituents of an Al-10Si alloy fabricated using high-pressure die casting (HPDC) and powder bed fusion-laser beam (PBF-LB) processes and comparing it with known phase equilibria. It was shown that the high cooling rates, in the order of 10<sup>6</sup> K/s in PBF-LB, resulted in approximately 400 K eutectic undercooling that in turn increased the eutectic composition from 12.6 wt% to approximately 70 wt%. Even the moderately high cooling rates in HPDC (10<sup>2</sup>-10<sup>3</sup> K/s) have some effect on the effective eutectic composition and temperature. The detailed microstructure characterisation, and solidification path modelling using the Scheil-Gulliver equation, leads to a series of empirical relationships to describe the effect of cooling rate on the effective Al-Si phase diagram. The eutectic suppression with cooling rate can explain microstructure observations in additive manufacturing including increased primary α-Al, eutectic Si morphology changes and the elevated solute Si content in the eutectic α-Al. It is apparent that the elevated solute Si is due to the eutectic undercooling rather than diffusion related solute trapping phenomena. The relationships developed will benefit microstructure modelling, process design, and alloy development for processes with very high solidification rates.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"112 ","pages":"Article 104995"},"PeriodicalIF":11.1,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145360391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-25DOI: 10.1016/j.addma.2025.105001
Johannes Bäreis , Benjamin Wahlmann , Carolin Körner
Powder bed-based additive manufacturing allows the processing of demanding materials due to the high build space temperatures. In commercial machines up to 6 kW of power is available for the process, which is applied with a beam that can be moved almost without inertia. So far, such high beam powers have only been utilized to maintain the build chamber temperature, whereas the actual melting takes place at much lower power. This increases the time for melting as well as for heating and thus the overall process time. The aim of this study is to develop process strategies which enable a better utilization of the beam power and thus increase productivity. The resulting opportunities and challenges are exemplified with the Ni-base superalloy IN718.
{"title":"Opportunities and challenges in the use of high beam power in electron beam powder bed fusion","authors":"Johannes Bäreis , Benjamin Wahlmann , Carolin Körner","doi":"10.1016/j.addma.2025.105001","DOIUrl":"10.1016/j.addma.2025.105001","url":null,"abstract":"<div><div>Powder bed-based additive manufacturing allows the processing of demanding materials due to the high build space temperatures. In commercial machines up to 6 kW of power is available for the process, which is applied with a beam that can be moved almost without inertia. So far, such high beam powers have only been utilized to maintain the build chamber temperature, whereas the actual melting takes place at much lower power. This increases the time for melting as well as for heating and thus the overall process time. The aim of this study is to develop process strategies which enable a better utilization of the beam power and thus increase productivity. The resulting opportunities and challenges are exemplified with the Ni-base superalloy IN718.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"112 ","pages":"Article 105001"},"PeriodicalIF":11.1,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145413644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-25DOI: 10.1016/j.addma.2025.104996
Farshad Kazemi, Adam T. Clare, Xiaoliang Jin
Additive manufacturing (AM) enables the production of complex, customized parts through its layer-by-layer process. However, high surface roughness and geometrical distortions often necessitate post-processing, with machining being the most widely used method. Therefore, understanding the machinability of AM parts is essential for selecting appropriate tooling and machining parameters. This requires insight into the material’s microstructure and mechanical behavior, which are significantly influenced by AM process conditions. Rapid solidification and steep thermal gradients inherent to AM processes result in distinct crystallographic textures and columnar grain growth, which affect the material’s response during machining. Due to inconsistent experimental findings in the literature, there is a need for microstructure-informed constitutive modeling. This study presents a comprehensive constitutive model to predict flow stress and cutting forces during orthogonal cutting, incorporating key strengthening mechanisms: thermal activation, solid solution, lattice resistance, grain boundary influence, and forest dislocation interactions. AM Inconel 718 which is widely used in critical industrial applications was fabricated using laser powder bed fusion (LPBF). Microstructural features and solute atom concentrations were characterized using electron backscatter diffraction (EBSD) and energy-dispersive X-ray spectroscopy (EDS), providing input for the constitutive model. Model validation was performed through orthogonal cutting experiments under various cutting conditions. Cutting forces were measured using a dynamometer, and chips were examined via scanning electron microscopy (SEM). The model predicts flow stress and cutting forces within 10 % of experimental values. Moreover, it enables a quantitative evaluation of each strengthening mechanism’s contribution, providing insight into their individual effects on the machining behavior of AM-fabricated parts.
{"title":"Machining mechanics of additively manufactured metallic parts: Material characterization and constitutive modeling","authors":"Farshad Kazemi, Adam T. Clare, Xiaoliang Jin","doi":"10.1016/j.addma.2025.104996","DOIUrl":"10.1016/j.addma.2025.104996","url":null,"abstract":"<div><div>Additive manufacturing (AM) enables the production of complex, customized parts through its layer-by-layer process. However, high surface roughness and geometrical distortions often necessitate post-processing, with machining being the most widely used method. Therefore, understanding the machinability of AM parts is essential for selecting appropriate tooling and machining parameters. This requires insight into the material’s microstructure and mechanical behavior, which are significantly influenced by AM process conditions. Rapid solidification and steep thermal gradients inherent to AM processes result in distinct crystallographic textures and columnar grain growth, which affect the material’s response during machining. Due to inconsistent experimental findings in the literature, there is a need for microstructure-informed constitutive modeling. This study presents a comprehensive constitutive model to predict flow stress and cutting forces during orthogonal cutting, incorporating key strengthening mechanisms: thermal activation, solid solution, lattice resistance, grain boundary influence, and forest dislocation interactions. AM Inconel 718 which is widely used in critical industrial applications was fabricated using laser powder bed fusion (LPBF). Microstructural features and solute atom concentrations were characterized using electron backscatter diffraction (EBSD) and energy-dispersive X-ray spectroscopy (EDS), providing input for the constitutive model. Model validation was performed through orthogonal cutting experiments under various cutting conditions. Cutting forces were measured using a dynamometer, and chips were examined via scanning electron microscopy (SEM). The model predicts flow stress and cutting forces within 10 % of experimental values. Moreover, it enables a quantitative evaluation of each strengthening mechanism’s contribution, providing insight into their individual effects on the machining behavior of AM-fabricated parts.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"112 ","pages":"Article 104996"},"PeriodicalIF":11.1,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145323433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-25DOI: 10.1016/j.addma.2025.104991
Zixuan Li , Michel Bellet , Charles-André Gandin , Manas Vijay Upadhyay , Yancheng Zhang
In additive manufacturing, the solidification grain structure has a significant influence on the properties of as-built material. In this context, the solidification grain structure and internal stress evolution during laser scanning of polycrystalline 316L stainless steel are simulated. A strongly coupled crystal viscoplasticity model is developed and integrated with a cellular automaton–finite element (CAFE) approach to accurately capture grain structure and stress evolution, where the CAFE model is validated based on a literature experiment. The crystal viscoplasticity model is calibrated using stress–strain curves of annealed 316L from experiments considering small thermo-elasto-viscoplastic (TEVP) deformations. The resolution algorithm dynamically couples heat transfer, melting and solidification simulations while concurrently computing stress and strain evolution within the grain structure. Four scanning strategies are simulated using the coupled CAFE–crystal viscoplasticity approach, capturing stress evolution during grain growth. This enables the simultaneous thermo-viscoplastic modeling in the mushy zone and TEVP modeling in the solid, providing insights into stress evolution and grain orientation over a large domain. The melting-solidification process involves variations in compression and tension, leading to stress concentration within neighboring grains with significant orientation differences, extending along elongated grains. A framework for multiscale process-structure-mechanical investigation is established based on microscale stress evolution in additive manufacturing.
{"title":"Metallurgically-driven thermomechanical analysis of multiple side-to-side laser melting on a 316L substrate","authors":"Zixuan Li , Michel Bellet , Charles-André Gandin , Manas Vijay Upadhyay , Yancheng Zhang","doi":"10.1016/j.addma.2025.104991","DOIUrl":"10.1016/j.addma.2025.104991","url":null,"abstract":"<div><div>In additive manufacturing, the solidification grain structure has a significant influence on the properties of as-built material. In this context, the solidification grain structure and internal stress evolution during laser scanning of polycrystalline 316L stainless steel are simulated. A strongly coupled crystal viscoplasticity model is developed and integrated with a cellular automaton–finite element (CAFE) approach to accurately capture grain structure and stress evolution, where the CAFE model is validated based on a literature experiment. The crystal viscoplasticity model is calibrated using stress–strain curves of annealed 316L from experiments considering small thermo-elasto-viscoplastic (TEVP) deformations. The resolution algorithm dynamically couples heat transfer, melting and solidification simulations while concurrently computing stress and strain evolution within the grain structure. Four scanning strategies are simulated using the coupled CAFE–crystal viscoplasticity approach, capturing stress evolution during grain growth. This enables the simultaneous thermo-viscoplastic modeling in the mushy zone and TEVP modeling in the solid, providing insights into stress evolution and grain orientation over a large domain. The melting-solidification process involves variations in compression and tension, leading to stress concentration within neighboring grains with significant orientation differences, extending along elongated grains. A framework for multiscale process-structure-mechanical investigation is established based on microscale stress evolution in additive manufacturing.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"112 ","pages":"Article 104991"},"PeriodicalIF":11.1,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145413643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-25DOI: 10.1016/j.addma.2025.104998
Yi Guo , Yinghang Liu , Zhe Song , Jiafeng Ye , Gaoming Zhu , Xiaoqin Zeng , Leyun Wang
The limited ductility of laser powder bed fusion (LPBF) Ti-6Al-4V (Ti64) alloys, caused by their brittle α'-martensitic microstructure, significantly restricts their broader application. This study systematically investigates the influence of Mo additions (0, 1, 3, and 5 wt%) on the microstructure evolution, deformation mechanisms, and mechanical properties of LPBF Ti64 alloys. Incorporation of Mo notably transforms the phase composition from purely α'-martensitic (Ti64 and Ti64–1Mo) to a multi-phase structure containing metastable β and α" phases alongside α' (Ti64–3Mo and Ti64–5Mo). Ti64–3Mo exhibits an optimal balance of mechanical properties, achieving significant improvements in uniform elongation (9.5 %) and maintaining high yield strength (955 MPa). Enhanced ductility in Ti64–3Mo and Ti64–5Mo is attributed to the synergistic activation of multiple deformation mechanisms, including stress-induced martensite transformation in metastable β, and twinning coupled with multiple slip modes in the α' phase. However, early activation of twinning prior to basal slip reduces yield strength. These insights underscore the crucial role of Mo as a compositional modifier, providing a practical approach for engineering strength-ductility combinations in additively manufactured titanium alloys.
{"title":"Enhancing ductility of laser powder bed fusion Ti-6Al-4V alloys by molybdenum addition: A study on microstructure and deformation mechanisms","authors":"Yi Guo , Yinghang Liu , Zhe Song , Jiafeng Ye , Gaoming Zhu , Xiaoqin Zeng , Leyun Wang","doi":"10.1016/j.addma.2025.104998","DOIUrl":"10.1016/j.addma.2025.104998","url":null,"abstract":"<div><div>The limited ductility of laser powder bed fusion (LPBF) Ti-6Al-4V (Ti64) alloys, caused by their brittle α'-martensitic microstructure, significantly restricts their broader application. This study systematically investigates the influence of Mo additions (0, 1, 3, and 5 wt%) on the microstructure evolution, deformation mechanisms, and mechanical properties of LPBF Ti64 alloys. Incorporation of Mo notably transforms the phase composition from purely α'-martensitic (Ti64 and Ti64–1Mo) to a multi-phase structure containing metastable β and α\" phases alongside α' (Ti64–3Mo and Ti64–5Mo). Ti64–3Mo exhibits an optimal balance of mechanical properties, achieving significant improvements in uniform elongation (9.5 %) and maintaining high yield strength (955 MPa). Enhanced ductility in Ti64–3Mo and Ti64–5Mo is attributed to the synergistic activation of multiple deformation mechanisms, including stress-induced martensite transformation in metastable β, and twinning coupled with multiple slip modes in the α' phase. However, early activation of twinning prior to basal slip reduces yield strength. These insights underscore the crucial role of Mo as a compositional modifier, providing a practical approach for engineering strength-ductility combinations in additively manufactured titanium alloys.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"112 ","pages":"Article 104998"},"PeriodicalIF":11.1,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145360392","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-25DOI: 10.1016/j.addma.2025.105002
Zhennan Wang , Shilong Che , Xufei Lu , Zhiwei Hao , Tianchi Zhang , Chenghui Hu , Zhe Feng , Haiou Yang , Xinghua Wang , Fengxian Liu , Xin Lin
Achieving a favorable strength-ductility balance in heat-treated Al-Cu alloys fabricated by arc-directed energy deposition (Arc-DED) remains challenging due to the difficulty in effective microstructure control and porosity suppression. To address these issues, a synchronized liquid nitrogen cooling (LNC) strategy is introduced during Arc-DED to enhance the strength-ductility synergy of T6-treated Al-Cu components. Compared to the deposits without LNC, LNC-processed samples exhibit a 42 % increase in uniform elongation and a 7.5 % rise in ultimate tensile strength, achieving 482.1 MPa with 10.9 % elongation, outperforming the existing Arc-DED Al-Cu alloys. This improvement results from the coupled effect of 61 % porosity suppression and enhanced grain heterogeneity. Porosity reduction is attributed to a higher cooling rate that promotes hydrogen supersaturation and thereby suppresses hydrogen bubble nucleation during molten pool solidification. Grain heterogeneity arises from reduced peak temperature and the shorter melting duration at the molten-pool bottom, promoting Al3Ti particle retention, increasing nucleation sites and refining equiaxed grains. Further analysis reveals that 69 % of the ductility improvement derives from the hetero-deformation-induced (HDI) strain-hardening, while the remaining 31 % stems from the porosity suppression. Moreover, HDI stress elevates the saturation stress, contributing to the enhanced tensile strength.
{"title":"Synergistic enhancement of strength and ductility in Arc-DED Al-Cu alloys via in-situ liquid nitrogen cooling-induced grain structure heterogeneity and porosity suppression","authors":"Zhennan Wang , Shilong Che , Xufei Lu , Zhiwei Hao , Tianchi Zhang , Chenghui Hu , Zhe Feng , Haiou Yang , Xinghua Wang , Fengxian Liu , Xin Lin","doi":"10.1016/j.addma.2025.105002","DOIUrl":"10.1016/j.addma.2025.105002","url":null,"abstract":"<div><div>Achieving a favorable strength-ductility balance in heat-treated Al-Cu alloys fabricated by arc-directed energy deposition (Arc-DED) remains challenging due to the difficulty in effective microstructure control and porosity suppression. To address these issues, a synchronized liquid nitrogen cooling (LNC) strategy is introduced during Arc-DED to enhance the strength-ductility synergy of T6-treated Al-Cu components. Compared to the deposits without LNC, LNC-processed samples exhibit a 42 % increase in uniform elongation and a 7.5 % rise in ultimate tensile strength, achieving 482.1 MPa with 10.9 % elongation, outperforming the existing Arc-DED Al-Cu alloys. This improvement results from the coupled effect of 61 % porosity suppression and enhanced grain heterogeneity. Porosity reduction is attributed to a higher cooling rate that promotes hydrogen supersaturation and thereby suppresses hydrogen bubble nucleation during molten pool solidification. Grain heterogeneity arises from reduced peak temperature and the shorter melting duration at the molten-pool bottom, promoting Al<sub>3</sub>Ti particle retention, increasing nucleation sites and refining equiaxed grains. Further analysis reveals that 69 % of the ductility improvement derives from the hetero-deformation-induced (HDI) strain-hardening, while the remaining 31 % stems from the porosity suppression. Moreover, HDI stress elevates the saturation stress, contributing to the enhanced tensile strength.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"112 ","pages":"Article 105002"},"PeriodicalIF":11.1,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145413966","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-25DOI: 10.1016/j.addma.2025.104994
Michele Vanini , Samuel Searle , Lars Vanmunster , Kim Vanmeensel , Bey Vrancken
Laser powder bed fusion is a metal additive manufacturing technique, valued for its ability to produce near-net-shaped components with high precision. Its layer-by-layer approach and localized melting create complex temperature cycles, allowing for potential in-situ microstructure modifications. Recently, the productivity of laser beam-based additive manufacturing processes has been increased substantially by the introduction of multiple beams that operate in a parallel way, e.g. building at different locations on the same build platform. However, two laser beams can also be operated in tandem, i.e. using an additional laser beam as a trailing laser that follows the primary melting laser, enabling in-situ heat treatment and local microstructure control. This study investigates the application of dual laser powder bed fusion to locally tailor the microstructure of super duplex stainless steel, a material characterized by a dual-phase microstructure composed of δ-ferrite and γ-austenite. The phase ratio of ferrite and austenite is highly sensitive to the thermal trajectory experienced by the fabricated part, particularly in the critical temperature range of 800–1200 °C, where austenite nucleation and growth from the primary solidified δ-ferrite can occur. An analytical modeling approach, utilizing the thermal field solution based on a moving Goldak heat source, was employed to optimize the parameters of the second laser beam to maximize the residence time within the critical temperature range, thereby enhancing austenite formation. The modeling insights were then qualitatively compared through a dual-laser single-track campaign before being applied to bulk samples. This approach successfully produced specimens with varying austenite contents, ranging from 0 % under high-speed single-laser conditions to 48 % using optimized dual-laser settings. These results demonstrate that careful tuning of laser parameters enables exceptional local microstructure control along both the build and scan directions, i.e. in full 3D. On the other hand, achieving this optimal microstructure required a low scanning speed of 15 mm/s, which reduced the build rate to about 0.07 mm3/s, approximately an order of magnitude lower than the one achieved with higher-speed parameters. Although this demonstrates potential for precise 3D microstructure control, it also underscores a significant trade-off with productivity, presenting a practical limitation for industrial applications.
{"title":"Local microstructure engineering of super duplex stainless steel via dual laser powder bed fusion – An analytical modeling and experimental approach","authors":"Michele Vanini , Samuel Searle , Lars Vanmunster , Kim Vanmeensel , Bey Vrancken","doi":"10.1016/j.addma.2025.104994","DOIUrl":"10.1016/j.addma.2025.104994","url":null,"abstract":"<div><div>Laser powder bed fusion is a metal additive manufacturing technique, valued for its ability to produce near-net-shaped components with high precision. Its layer-by-layer approach and localized melting create complex temperature cycles, allowing for potential in-situ microstructure modifications. Recently, the productivity of laser beam-based additive manufacturing processes has been increased substantially by the introduction of multiple beams that operate in a parallel way, e.g. building at different locations on the same build platform. However, two laser beams can also be operated in tandem, i.e. using an additional laser beam as a trailing laser that follows the primary melting laser, enabling in-situ heat treatment and local microstructure control. This study investigates the application of dual laser powder bed fusion to locally tailor the microstructure of super duplex stainless steel, a material characterized by a dual-phase microstructure composed of δ-ferrite and γ-austenite. The phase ratio of ferrite and austenite is highly sensitive to the thermal trajectory experienced by the fabricated part, particularly in the critical temperature range of 800–1200 °C, where austenite nucleation and growth from the primary solidified δ-ferrite can occur. An analytical modeling approach, utilizing the thermal field solution based on a moving Goldak heat source, was employed to optimize the parameters of the second laser beam to maximize the residence time within the critical temperature range, thereby enhancing austenite formation. The modeling insights were then qualitatively compared through a dual-laser single-track campaign before being applied to bulk samples. This approach successfully produced specimens with varying austenite contents, ranging from 0 % under high-speed single-laser conditions to 48 % using optimized dual-laser settings. These results demonstrate that careful tuning of laser parameters enables exceptional local microstructure control along both the build and scan directions, i.e. in full 3D. On the other hand, achieving this optimal microstructure required a low scanning speed of 15 mm/s, which reduced the build rate to about 0.07 mm<sup>3</sup>/s, approximately an order of magnitude lower than the one achieved with higher-speed parameters. Although this demonstrates potential for precise 3D microstructure control, it also underscores a significant trade-off with productivity, presenting a practical limitation for industrial applications.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"112 ","pages":"Article 104994"},"PeriodicalIF":11.1,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145323432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-25DOI: 10.1016/j.addma.2025.104987
Matthew Ebert , Ronnie Stone , Ergun Akleman , Zhenghui Sha , Vinayak Krishnamurthy
We present Traveling Cellsman, an approach for creating a parameterization for task scheduling and collision avoidance with Cooperative 3D printing (C3DP). The parameterization is based on the distribution of work between robots (partition), which allows the robots to navigate through their printing tasks effectively while also allowing for collision avoidance with other robots. The parameterization provides straightforward optimization of makespan. Inspired by the multiple traveling salesman problem (MTSP), we schedule tasks by first clustering tasks together based on a parameterization of the partition. The clustered tasks can then be ordered for printing. Numerical results indicate that our clustering approach finds an optimal solution faster than the non-clustered approach for minimizing the pause and movement time of the robots. Physical results also show that optimization allows for faster printing time as compared to non-optimized or slicer-based methods for generating a printing schedule. While we demonstrate our method using C3DP, it is generally applicable to other multi-robot task scheduling problems where collision may occur.
{"title":"Traveling cellsman: Partition-cluster co-parameterization for multi-robot cooperative 3D printing","authors":"Matthew Ebert , Ronnie Stone , Ergun Akleman , Zhenghui Sha , Vinayak Krishnamurthy","doi":"10.1016/j.addma.2025.104987","DOIUrl":"10.1016/j.addma.2025.104987","url":null,"abstract":"<div><div>We present <em>Traveling Cellsman</em>, an approach for creating a parameterization for task scheduling and collision avoidance with Cooperative 3D printing (C3DP). The parameterization is based on the distribution of work between robots (partition), which allows the robots to navigate through their printing tasks effectively while also allowing for collision avoidance with other robots. The parameterization provides straightforward optimization of makespan. Inspired by the multiple traveling salesman problem (MTSP), we schedule tasks by first clustering tasks together based on a parameterization of the partition. The clustered tasks can then be ordered for printing. Numerical results indicate that our clustering approach finds an optimal solution faster than the non-clustered approach for minimizing the pause and movement time of the robots. Physical results also show that optimization allows for faster printing time as compared to non-optimized or slicer-based methods for generating a printing schedule. While we demonstrate our method using C3DP, it is generally applicable to other multi-robot task scheduling problems where collision may occur.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"112 ","pages":"Article 104987"},"PeriodicalIF":11.1,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145323431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-25DOI: 10.1016/j.addma.2025.104963
Charles Wade , Devon Beck , Robert MacCurdy
This paper presents a novel gradient-informed slicing method for functionally graded additive manufacturing (FGM) that overcomes the limitations of conventional toolpath planning approaches, which struggle to produce truly continuous gradients. By integrating multi-material gradients into the toolpath generation process, our method enables the fabrication of FGMs with complex gradients that vary seamlessly in any direction. We leverage OpenVCAD’s implicit representation of geometry and material fields to directly extract iso-contours, enabling accurate, controlled gradient toolpaths. Two novel strategies are introduced to integrate these gradients into the toolpath planning process. The first strategy maintains traditional perimeter, skin, and infill structures subdivided by mixture ratios, with automated ’zippering’ to mitigate stress concentrations. The second strategy fills iso-contoured regions densely, printing directly against gradients to eliminate purging and reduce waste. Both strategies accommodate gradually changing printing parameters, such as mixed filament ratios, toolhead switching, and variable nozzle temperatures for foaming materials. This capability allows for controlled variation of composition, density, and other properties within a single build, expanding the design space for functionally graded parts. Experimental results demonstrate the fabrication of high-quality FGMs with complex, multi-axis gradients, highlighting the versatility of our method. We showcase the successful implementation of both strategies on a range of geometries and material combinations, demonstrating the potential of our approach to produce intricate and functional FGMs. Although we demonstrate our methodology with material extrusion, it is applicable to any g-code based system. This work provides a robust, open-source, and automated framework for designing and fabricating advanced FGMs, accelerating research in multi-material additive manufacturing.
{"title":"Implicit toolpath generation for functionally graded additive manufacturing via gradient-informed slicing","authors":"Charles Wade , Devon Beck , Robert MacCurdy","doi":"10.1016/j.addma.2025.104963","DOIUrl":"10.1016/j.addma.2025.104963","url":null,"abstract":"<div><div>This paper presents a novel gradient-informed slicing method for functionally graded additive manufacturing (FGM) that overcomes the limitations of conventional toolpath planning approaches, which struggle to produce truly continuous gradients. By integrating multi-material gradients into the toolpath generation process, our method enables the fabrication of FGMs with complex gradients that vary seamlessly in any direction. We leverage OpenVCAD’s implicit representation of geometry and material fields to directly extract iso-contours, enabling accurate, controlled gradient toolpaths. Two novel strategies are introduced to integrate these gradients into the toolpath planning process. The first strategy maintains traditional perimeter, skin, and infill structures subdivided by mixture ratios, with automated ’zippering’ to mitigate stress concentrations. The second strategy fills iso-contoured regions densely, printing directly against gradients to eliminate purging and reduce waste. Both strategies accommodate gradually changing printing parameters, such as mixed filament ratios, toolhead switching, and variable nozzle temperatures for foaming materials. This capability allows for controlled variation of composition, density, and other properties within a single build, expanding the design space for functionally graded parts. Experimental results demonstrate the fabrication of high-quality FGMs with complex, multi-axis gradients, highlighting the versatility of our method. We showcase the successful implementation of both strategies on a range of geometries and material combinations, demonstrating the potential of our approach to produce intricate and functional FGMs. Although we demonstrate our methodology with material extrusion, it is applicable to any g-code based system. This work provides a robust, open-source, and automated framework for designing and fabricating advanced FGMs, accelerating research in multi-material additive manufacturing.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"112 ","pages":"Article 104963"},"PeriodicalIF":11.1,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145413642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-25DOI: 10.1016/j.addma.2025.104983
Jovid Rakhmonov , Obaidullah Rahman , Sumit Bahl , Amir Koushyar Ziabari , Alex Plotkowski , Amit Shyam
Tensile creep response and cavitation damage evolution in an additively manufactured Al-7.5Ce-4.5Ni-0.4Mn-0.7Zr (wt%) alloy with peak-aging and overaging treatments were investigated in the 300–400 ºC range. Microstructural heterogeneity and its response to heat treatment and subsequent creep deformation were studied to understand the interplay between cavity formation, creep lifetime and ductility. Increasing the applied stress activated the nucleation of more cavities, an experimental observation that is well described using the vacancy accumulation model. Cavities nucleated prematurely due to localized plasticity in the denuded zones that formed at/near melt-pool or grain boundaries. Microstructure/deformation heterogeneity with consequent evolution of stress triaxiality, especially at lower stresses, causes accelerated cavitation, thus producing low creep ductility (∼ 0.2–2.4 %), compared to (∼12–21 %) ductility of the alloy measured by regular tensile tests at equivalent temperatures. A constrained diffusional cavity growth mechanism with continuous cavity nucleation during creep is established as the dominant mechanism, implying that cavitation involves vacancy diffusion, yet its growth rate is dictated by the minimum creep rate. The ductility-limiting creep and cavitation mechanisms discussed here provide new insight into the creep behavior of 3D-printed metallic alloys.
{"title":"Creep ductility limiting mechanisms in an additively manufactured Al-Ce-Ni-Mn-Zr alloy","authors":"Jovid Rakhmonov , Obaidullah Rahman , Sumit Bahl , Amir Koushyar Ziabari , Alex Plotkowski , Amit Shyam","doi":"10.1016/j.addma.2025.104983","DOIUrl":"10.1016/j.addma.2025.104983","url":null,"abstract":"<div><div>Tensile creep response and cavitation damage evolution in an additively manufactured Al-7.5Ce-4.5Ni-0.4Mn-0.7Zr (wt%) alloy with peak-aging and overaging treatments were investigated in the 300–400 ºC range. Microstructural heterogeneity and its response to heat treatment and subsequent creep deformation were studied to understand the interplay between cavity formation, creep lifetime and ductility. Increasing the applied stress activated the nucleation of more cavities, an experimental observation that is well described using the vacancy accumulation model. Cavities nucleated prematurely due to localized plasticity in the denuded zones that formed at/near melt-pool or grain boundaries. Microstructure/deformation heterogeneity with consequent evolution of stress triaxiality, especially at lower stresses, causes accelerated cavitation, thus producing low creep ductility (∼ 0.2–2.4 %), compared to (∼12–21 %) ductility of the alloy measured by regular tensile tests at equivalent temperatures. A constrained diffusional cavity growth mechanism with continuous cavity nucleation during creep is established as the dominant mechanism, implying that cavitation involves vacancy diffusion, yet its growth rate is dictated by the minimum creep rate. The ductility-limiting creep and cavitation mechanisms discussed here provide new insight into the creep behavior of 3D-printed metallic alloys.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"112 ","pages":"Article 104983"},"PeriodicalIF":11.1,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145278293","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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