Pub Date : 2024-08-01DOI: 10.1088/1757-899x/1310/1/012041
M R L Zwicker, N S Tiedje, T Dahmen, V K Nadimpalli
Overspray powder is a bi-product of the spray forming process and is commonly considered as scrap material. This study, however, assessed the feasibility of the use of spray-formed AISI H13 overspray as powder feedstock for LPBF as part of a circular economy concept. The overspray powder presented a suitable particle size distribution for LPBF applications and showed the capability of being printed crack free. X-ray diffraction was used to show that ferritic/austenitic overspray powder transformed into a martensitic austenitic microstructure in the as-printed conditions. Furthermore, texture analysis revealed a preferred crystallographic orientation in <100> parallel to the build direction for martensite while the retained austenite presents a preferred orientation in <110> along the build direction.
{"title":"Integration of spray-formed AISI H13 overspray powder in additive manufacturing to enable a circular ecosystem","authors":"M R L Zwicker, N S Tiedje, T Dahmen, V K Nadimpalli","doi":"10.1088/1757-899x/1310/1/012041","DOIUrl":"https://doi.org/10.1088/1757-899x/1310/1/012041","url":null,"abstract":"Overspray powder is a bi-product of the spray forming process and is commonly considered as scrap material. This study, however, assessed the feasibility of the use of spray-formed AISI H13 overspray as powder feedstock for LPBF as part of a circular economy concept. The overspray powder presented a suitable particle size distribution for LPBF applications and showed the capability of being printed crack free. X-ray diffraction was used to show that ferritic/austenitic overspray powder transformed into a martensitic austenitic microstructure in the as-printed conditions. Furthermore, texture analysis revealed a preferred crystallographic orientation in <100> parallel to the build direction for martensite while the retained austenite presents a preferred orientation in <110> along the build direction.","PeriodicalId":14483,"journal":{"name":"IOP Conference Series: Materials Science and Engineering","volume":"59 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01DOI: 10.1088/1757-899x/1310/1/012012
M V Upadhyay, S Gaudez, W Pantleon
Dislocation structures are abundantly present in any additively manufactured alloy and they play a primary role in determining the mechanical response of an alloy. Until recently, it was understood that these structures form due to rapid solidification during AM. However, there was no consensus on whether they evolve due to the subsequent solid-state thermal cycling that occurs with further addition of layers. In order to design alloy microstructures with desired mechanical responses, it is crucial to first answer this outstanding question. This question was answered in a recent work [1] involving a novel experiment employing high resolution reciprocal space mapping, a synchrotron based X-ray diffraction technique, in situ during AM of an austenitic stainless steel. The study revealed that dislocation structures formed during rapid solidification undergo significant evolution during subsequent solid-state thermal cycling, in particular during addition of the first few (up to 5) layers above the layer of interest. A summary of the findings of this study are presented in this work. A possible pathway (involving experiment and modelling synergy) to better understanding dislocation structure formation during AM is presented.
差排结构大量存在于任何添加制造的合金中，它们在决定合金的机械响应方面发挥着主要作用。直到最近，人们还认为这些结构的形成是由于 AM 过程中的快速凝固。然而，对于这些结构是否会因后续的固态热循环（随着层数的进一步增加而发生）而发生演变，还没有达成共识。为了设计出具有理想机械响应的合金微结构，首先必须回答这个悬而未决的问题。最近的一项研究[1]回答了这一问题，该研究采用了一种新颖的实验方法，即在奥氏体不锈钢 AM 加工过程中现场使用基于同步辐射的 X 射线衍射技术--高分辨率倒易空间图谱。研究发现，在快速凝固过程中形成的位错结构在随后的固态热循环过程中发生了显著的演变，尤其是在相关层之上的前几层（最多 5 层）的添加过程中。这项研究的结果摘要见本论文。本文提出了更好地理解 AM 过程中位错结构形成的可能途径（涉及实验和建模协同作用）。
{"title":"Dislocation structure evolution during metal additive manufacturing","authors":"M V Upadhyay, S Gaudez, W Pantleon","doi":"10.1088/1757-899x/1310/1/012012","DOIUrl":"https://doi.org/10.1088/1757-899x/1310/1/012012","url":null,"abstract":"Dislocation structures are abundantly present in any additively manufactured alloy and they play a primary role in determining the mechanical response of an alloy. Until recently, it was understood that these structures form due to rapid solidification during AM. However, there was no consensus on whether they evolve due to the subsequent solid-state thermal cycling that occurs with further addition of layers. In order to design alloy microstructures with desired mechanical responses, it is crucial to first answer this outstanding question. This question was answered in a recent work [1] involving a novel experiment employing high resolution reciprocal space mapping, a synchrotron based X-ray diffraction technique, <italic toggle=\"yes\">in situ</italic> during AM of an austenitic stainless steel. The study revealed that dislocation structures formed during rapid solidification undergo significant evolution during subsequent solid-state thermal cycling, in particular during addition of the first few (up to 5) layers above the layer of interest. A summary of the findings of this study are presented in this work. A possible pathway (involving experiment and modelling synergy) to better understanding dislocation structure formation during AM is presented.","PeriodicalId":14483,"journal":{"name":"IOP Conference Series: Materials Science and Engineering","volume":"33 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01DOI: 10.1088/1757-899x/1310/1/012017
C Ozdogan, R A Yildiz, L Tavares, M Malekan
Compared to traditional production techniques, additive manufacturing (AM) of metallic components has several benefits, mainly little material waste and more design freedom. AM process based on laser powder bed fusion has many key process parameters including scanning speed, layer thickness, build direction, and printing power. Each one of these parameters influences microstructure, and hence macro-mechanical behavior of the manufactured part, as the part microstructure plays a critical role in determining the mechanical properties. This work aims to address a relationship between micro-structure and macro-mechanical behavior of AM fabricated parts made of 316L Stainless Steel. Both as-built and heat-treated samples are being used for experimental testing and microstructure characterizations. Arcan fixture is used to evaluate the macro-mechanical fracture behavior of the material under mode-I, mode-II, and mixed-mode conditions. Microstructure evaluations of the fracture surfaces are done using scanning electron microscopy and X-Ray diffraction techniques. Finally, a correlation between micro-scale characteristics and macro-mechanical behavior is obtained together with different AM process parameters.
与传统生产技术相比，金属部件的增材制造（AM）技术有许多优点，主要是材料浪费少、设计自由度高。基于激光粉末床熔融技术的增材制造工艺有许多关键的工艺参数，包括扫描速度、层厚、构建方向和打印功率。这些参数中的每一个都会影响微观结构，进而影响制造部件的宏观机械性能，因为部件的微观结构在决定机械性能方面起着至关重要的作用。本研究旨在探讨由 316L 不锈钢制成的 AM 制品的微观结构与宏观机械性能之间的关系。坯件和热处理样品都被用于实验测试和微观结构表征。Arcan 夹具用于评估材料在模式 I、模式 II 和混合模式条件下的宏观机械断裂行为。使用扫描电子显微镜和 X 射线衍射技术对断裂表面的微观结构进行评估。最后，结合不同的 AM 工艺参数，得出了微观尺度特征与宏观力学行为之间的相关性。
{"title":"Micro-macro relationship between microstructure and mechanical behavior of 316L stainless steel fabricated using L-PBF additive manufacturing","authors":"C Ozdogan, R A Yildiz, L Tavares, M Malekan","doi":"10.1088/1757-899x/1310/1/012017","DOIUrl":"https://doi.org/10.1088/1757-899x/1310/1/012017","url":null,"abstract":"Compared to traditional production techniques, additive manufacturing (AM) of metallic components has several benefits, mainly little material waste and more design freedom. AM process based on laser powder bed fusion has many key process parameters including scanning speed, layer thickness, build direction, and printing power. Each one of these parameters influences microstructure, and hence macro-mechanical behavior of the manufactured part, as the part microstructure plays a critical role in determining the mechanical properties. This work aims to address a relationship between micro-structure and macro-mechanical behavior of AM fabricated parts made of 316L Stainless Steel. Both as-built and heat-treated samples are being used for experimental testing and microstructure characterizations. Arcan fixture is used to evaluate the macro-mechanical fracture behavior of the material under mode-I, mode-II, and mixed-mode conditions. Microstructure evaluations of the fracture surfaces are done using scanning electron microscopy and X-Ray diffraction techniques. Finally, a correlation between micro-scale characteristics and macro-mechanical behavior is obtained together with different AM process parameters.","PeriodicalId":14483,"journal":{"name":"IOP Conference Series: Materials Science and Engineering","volume":"59 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01DOI: 10.1088/1757-899x/1310/1/012038
K Swaminathan, J Andersson
Increasing layer thickness in Laser Powder Bed Fusion (PBF-LB) process of metals enable increasing productivity and facilitate industrialisation of metal additive manufacturing (AM) process. Understanding of microstructure in as-built stage and possible post-processing steps to modify the microstructure is critical for metal AM components. Haynes 282 Nickel based superalloy, typically used in aerospace and energy industries, was manufactured using PBF-LB process at 60 microns layer thickness. Two different solution treatment temperatures were studied to analyse the recrystallization behaviour of the as-built material. The as built microstructure consisted high dislocation density given the rapid cooling in PBF-LB process. Solution treatment at 1150°C resulted in reduced dislocation density but similar morphology to grains in as built condition with visible residual melt pool boundaries. Solution treatment at 1250°C resulted in recrystallised grain structure. The recrystallisation behaviour is discussed with relation to manufacturing process and kinetic behaviour of alloying elements.
{"title":"Effect of solution treatment temperature on recrystallisation behaviour of Haynes 282 manufactured through laser powder bed fusion","authors":"K Swaminathan, J Andersson","doi":"10.1088/1757-899x/1310/1/012038","DOIUrl":"https://doi.org/10.1088/1757-899x/1310/1/012038","url":null,"abstract":"Increasing layer thickness in Laser Powder Bed Fusion (PBF-LB) process of metals enable increasing productivity and facilitate industrialisation of metal additive manufacturing (AM) process. Understanding of microstructure in as-built stage and possible post-processing steps to modify the microstructure is critical for metal AM components. Haynes 282 Nickel based superalloy, typically used in aerospace and energy industries, was manufactured using PBF-LB process at 60 microns layer thickness. Two different solution treatment temperatures were studied to analyse the recrystallization behaviour of the as-built material. The as built microstructure consisted high dislocation density given the rapid cooling in PBF-LB process. Solution treatment at 1150°C resulted in reduced dislocation density but similar morphology to grains in as built condition with visible residual melt pool boundaries. Solution treatment at 1250°C resulted in recrystallised grain structure. The recrystallisation behaviour is discussed with relation to manufacturing process and kinetic behaviour of alloying elements.","PeriodicalId":14483,"journal":{"name":"IOP Conference Series: Materials Science and Engineering","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01DOI: 10.1088/1757-899x/1310/1/012022
H Zhang, D A Venero, J Park, S V Petegem, A Özsoy, G Soundarapandiyan, S Robertson, X Zhang, B Chen
Additively manufactured (AM) high-speed steels were investigated, focusing specifically on the microstructure evolution during post-treatment in S390 steel and the rapid solidification process in M50 steel. An improved understanding of the processing-microstructure-property relationship for AM high-speed steel is achieved through a combination of post-mortem microstructure characterisation on precipitates and in-situ tracking of phase evolution. Quantitative characterisation of primary carbides and nanoprecipitates highlights the strengthening through nanoprecipitates that contribute to the exceedingly high hardness of 921 HV. Phase evolution during tempering was examined through in-situ synchrotron diffraction and ex-situ small-angle neutron scattering, revealing primary carbide growth by 60 nm within 2 minutes and nanoparticle precipitation with a size of 1.4 nm after 60-minute tempering. Additionally, the microstructure evolution of AM M50 steel was investigated by operando synchrotron diffraction, unveiling cooling rates in the order of 105 K/s during liquid-solid transformation. After printing, the carbon content of 0.47 wt.% in the matrix was derived from the martensite tetragonality. The insights gained serve as a valuable guide for designing future steel groups and developing heat treatment procedures tailored for the AM process.
对快速成型（AM）高速钢进行了研究，重点是 S390 钢后处理期间的微观结构演变和 M50 钢的快速凝固过程。通过结合析出物的死后微观结构表征和相演化的原位跟踪，加深了对 AM 高速钢的加工-微观结构-性能关系的理解。原生碳化物和纳米析出物的定量表征凸显了纳米析出物对 921 HV 超高硬度的强化作用。通过原位同步辐射衍射和原位小角中子散射对回火过程中的相变进行了研究，结果表明原生碳化物在 2 分钟内增长了 60 纳米，60 分钟回火后析出的纳米颗粒大小为 1.4 纳米。此外，还通过操作同步辐射衍射研究了 AM M50 钢的微观结构演变，揭示了液固转化过程中 105 K/s 的冷却速度。打印后，基体中 0.47 wt.% 的碳含量来自马氏体的四方性。所获得的见解为设计未来的钢组和开发适合 AM 工艺的热处理程序提供了宝贵的指导。
{"title":"Microstructure Evolution and Precipitation Strengthening Behaviour of Additively Manufactured High-speed Steels","authors":"H Zhang, D A Venero, J Park, S V Petegem, A Özsoy, G Soundarapandiyan, S Robertson, X Zhang, B Chen","doi":"10.1088/1757-899x/1310/1/012022","DOIUrl":"https://doi.org/10.1088/1757-899x/1310/1/012022","url":null,"abstract":"Additively manufactured (AM) high-speed steels were investigated, focusing specifically on the microstructure evolution during post-treatment in S390 steel and the rapid solidification process in M50 steel. An improved understanding of the processing-microstructure-property relationship for AM high-speed steel is achieved through a combination of post-mortem microstructure characterisation on precipitates and in-situ tracking of phase evolution. Quantitative characterisation of primary carbides and nanoprecipitates highlights the strengthening through nanoprecipitates that contribute to the exceedingly high hardness of 921 HV. Phase evolution during tempering was examined through in-situ synchrotron diffraction and ex-situ small-angle neutron scattering, revealing primary carbide growth by 60 nm within 2 minutes and nanoparticle precipitation with a size of 1.4 nm after 60-minute tempering. Additionally, the microstructure evolution of AM M50 steel was investigated by operando synchrotron diffraction, unveiling cooling rates in the order of 10<sup>5</sup> K/s during liquid-solid transformation. After printing, the carbon content of 0.47 wt.% in the matrix was derived from the martensite tetragonality. The insights gained serve as a valuable guide for designing future steel groups and developing heat treatment procedures tailored for the AM process.","PeriodicalId":14483,"journal":{"name":"IOP Conference Series: Materials Science and Engineering","volume":"34 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01DOI: 10.1088/1757-899x/1310/1/012035
K Yamanaka, M Mori, Y Onuki, S Sato
Additive manufacturing (AM) involves an unprecedented thermal history during solidification and post-melt high-temperature exposure, leading to unique microstructural evolution. In this study, we employed neutron-diffraction-based microstructural analysis to better understand the microstructural evolution and mechanical behavior of AM alloys, with a particular focus on multiphase alloys. Samples of Ti−6Al−4V alloy used as a model material were prepared using electron beam powder bed fusion (EB-PBF) under varying building conditions. Time-of-flight neutron diffraction (TOF-ND) measurements were performed using an iMATERIA (BL20), J-PARC, Japan. Using Rietveld texture analysis (RTA), we revealed the textural evolution during hierarchical microstructural development from solidification to solid-state phase transformations in the EB-PBF process. The effects of building conditions on the textures in the as-built states and their evolution during subsequent tensile loading were analyzed.
增材制造（AM）在凝固和熔化后高温暴露过程中会产生前所未有的热历史，从而导致独特的微观结构演变。在本研究中，我们采用了基于中子衍射的微观结构分析方法，以更好地了解 AM 合金的微观结构演变和力学行为，特别是多相合金。作为模型材料的 Ti-6Al-4V 合金样品是在不同的构建条件下使用电子束粉末床熔融（EB-PBF）制备的。使用日本 J-PARC 的 iMATERIA（BL20）进行了飞行时间中子衍射（TOF-ND）测量。利用里特维尔德纹理分析（RTA），我们揭示了 EB-PBF 过程中从凝固到固态相变的分层微结构发展过程中的纹理演变。我们分析了建筑条件对竣工状态纹理的影响，以及在随后的拉伸加载过程中纹理的演变。
{"title":"Neutron diffraction analysis of microstructural evolution and mechanical behavior in an additively manufactured multiphase alloy","authors":"K Yamanaka, M Mori, Y Onuki, S Sato","doi":"10.1088/1757-899x/1310/1/012035","DOIUrl":"https://doi.org/10.1088/1757-899x/1310/1/012035","url":null,"abstract":"Additive manufacturing (AM) involves an unprecedented thermal history during solidification and post-melt high-temperature exposure, leading to unique microstructural evolution. In this study, we employed neutron-diffraction-based microstructural analysis to better understand the microstructural evolution and mechanical behavior of AM alloys, with a particular focus on multiphase alloys. Samples of Ti−6Al−4V alloy used as a model material were prepared using electron beam powder bed fusion (EB-PBF) under varying building conditions. Time-of-flight neutron diffraction (TOF-ND) measurements were performed using an iMATERIA (BL20), J-PARC, Japan. Using Rietveld texture analysis (RTA), we revealed the textural evolution during hierarchical microstructural development from solidification to solid-state phase transformations in the EB-PBF process. The effects of building conditions on the textures in the as-built states and their evolution during subsequent tensile loading were analyzed.","PeriodicalId":14483,"journal":{"name":"IOP Conference Series: Materials Science and Engineering","volume":"26 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01DOI: 10.1088/1757-899x/1310/1/012023
Y Zhang, M Defer, W Liu, E F F Knipschildt-Okkels, J Oddershede, A Slyamov, F Bachmann, E Lauridsen, D Juul Jensen
Additive manufacturing of metals using for example laser powder bed fusion systems generally results in grains of complex shapes with cellular structure of submicron sizes, accompanied by a high dislocation density. This paper presents preliminary results from characterizing an AlSi10Mg alloy manufactured by L-PBF using non-destructive three-dimensional X-ray Laue micro-beam diffraction. Both synchrotron and laboratory X-ray methods are used. The aim is to identify challenges in characterizing these microstructural features and to propose future research directions to address them.
使用激光粉末床熔融系统等进行金属增材制造，通常会产生具有亚微米级蜂窝状结构的复杂形状晶粒，并伴有较高的位错密度。本文介绍了利用非破坏性三维 X 射线 Laue 微束衍射技术表征 L-PBF 制造的 AlSi10Mg 合金的初步结果。文中使用了同步加速器和实验室 X 射线方法。目的是找出表征这些微观结构特征所面临的挑战，并提出解决这些问题的未来研究方向。
{"title":"Challenges in characterizing additively manufactured AlSi10Mg using X-ray Laue micro-beam diffraction","authors":"Y Zhang, M Defer, W Liu, E F F Knipschildt-Okkels, J Oddershede, A Slyamov, F Bachmann, E Lauridsen, D Juul Jensen","doi":"10.1088/1757-899x/1310/1/012023","DOIUrl":"https://doi.org/10.1088/1757-899x/1310/1/012023","url":null,"abstract":"Additive manufacturing of metals using for example laser powder bed fusion systems generally results in grains of complex shapes with cellular structure of submicron sizes, accompanied by a high dislocation density. This paper presents preliminary results from characterizing an AlSi10Mg alloy manufactured by L-PBF using non-destructive three-dimensional X-ray Laue micro-beam diffraction. Both synchrotron and laboratory X-ray methods are used. The aim is to identify challenges in characterizing these microstructural features and to propose future research directions to address them.","PeriodicalId":14483,"journal":{"name":"IOP Conference Series: Materials Science and Engineering","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01DOI: 10.1088/1757-899x/1312/1/012011
Simone Ghiglia, Marco Mazzuoli, Joel Guerrero
The mass transport properties of the blood flow in the aortic arch are investigated by means of direct numerical simulations. The aortic arches in human and murine cases are assumed to be similar (with similarity factor equal to 20) and characterised by constant diameter, while the axis lays on a plane. The simulations were carried out using OpenFOAM (v.10). The flow regime appears remarkably different in the two cases because flow separation and vortical structures appear during the systolic phases in the human case, which are absent at the mouse scale. Consequently, peaks of the wall-shear-stress occur at different phases and, in the murine case, are characterised by a magnitude nearly 4 times larger than in the human case. The trajectories of fluid particles are computed in order to evaluate the dispersion efficiency exploited by biomedical applications (e.g. drug delivery or solid micro carriers). Despite the different flow regimes, in both system particles uniformly released at the inlet preserve a homogeneous distribution as they flow in the aortic arch. In particular, during the early decelerating phases of systole, the fluid trajectories are found frequently to approach the zones of the wall where the shear-stress is large.
{"title":"Lagrangian properties of the blood flow through human and murine aortic arches: towards improved customised therapies and diagnostic techniques","authors":"Simone Ghiglia, Marco Mazzuoli, Joel Guerrero","doi":"10.1088/1757-899x/1312/1/012011","DOIUrl":"https://doi.org/10.1088/1757-899x/1312/1/012011","url":null,"abstract":"The mass transport properties of the blood flow in the aortic arch are investigated by means of direct numerical simulations. The aortic arches in human and murine cases are assumed to be similar (with similarity factor equal to 20) and characterised by constant diameter, while the axis lays on a plane. The simulations were carried out using OpenFOAM (v.10). The flow regime appears remarkably different in the two cases because flow separation and vortical structures appear during the systolic phases in the human case, which are absent at the mouse scale. Consequently, peaks of the wall-shear-stress occur at different phases and, in the murine case, are characterised by a magnitude nearly 4 times larger than in the human case. The trajectories of fluid particles are computed in order to evaluate the dispersion efficiency exploited by biomedical applications (e.g. drug delivery or solid micro carriers). Despite the different flow regimes, in both system particles uniformly released at the inlet preserve a homogeneous distribution as they flow in the aortic arch. In particular, during the early decelerating phases of systole, the fluid trajectories are found frequently to approach the zones of the wall where the shear-stress is large.","PeriodicalId":14483,"journal":{"name":"IOP Conference Series: Materials Science and Engineering","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01DOI: 10.1088/1757-899x/1310/1/012024
M Schreiber, C Brice, K Findley, J Klemm-Toole, J Gockel
The processing-structure-properties relationships in laser beam powder bed fusion (PBF-LB) additive manufacturing (AM) are complex with multiple aspects of the processing impacting the microstructure and mechanical properties. Though, the influences of process parameters on strengthening mechanisms are less clear. In this work, laser power, scanning velocity, and hatch spacing were varied to promote PBF-LB 316L microstructures with distinctive thermal histories to vary microstructures and tensile properties. Tensile data were collected for over 100 different processing parameters on a single PBF-LB platform. Across the process parameter matrix yield strength, work hardening behavior, and ductility varied considerably. In this work, the effect of process parameters on initial dislocation density was studied. By quantifying the dislocation density with X-ray diffraction and line profile analysis, a relationship between processing parameters and initial dislocation densities was established. The contribution of dislocation density and other strengthening mechanisms to the yield strength is discussed.
激光束粉末床熔融（PBF-LB）增材制造（AM）中的加工-结构-性能关系非常复杂，加工的多个方面都会对微观结构和机械性能产生影响。不过，工艺参数对强化机制的影响还不太清楚。在这项工作中，通过改变激光功率、扫描速度和舱口间距来促进具有独特热历史的 PBF-LB 316L 微结构，从而改变微结构和拉伸性能。在单个 PBF-LB 平台上收集了 100 多个不同加工参数的拉伸数据。不同工艺参数下的基体屈服强度、加工硬化行为和延展性差异很大。在这项工作中，研究了工艺参数对初始位错密度的影响。通过 X 射线衍射和线剖面分析对差排密度进行量化，建立了加工参数与初始差排密度之间的关系。讨论了位错密度和其他强化机制对屈服强度的贡献。
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Pub Date : 2024-08-01DOI: 10.1088/1757-899x/1310/1/012010
M Seita
One of the de*ining features of fusion-based additive manufacturing (AM) is the localized melting of metal by a high-energy source, which fuses the material together point by point and layer by layer into a 3D object. The rapid solidi*ication velocity, directional thermal gradients, and site-speci*ic thermal build-ups produced by this process yield parts with complex and heterogeneous microstructure. This heterogeneity is a double-edged sword. On the one hand, it leads to large property scatter and casts uncertainty over parts performance, hindering the adoption of additive technologies by the industry. On the other hand, it may impart exceptional mechanical properties and new functionalities, which are not found in conventionally produced materials. In this paper, we present two ongoing research endeavours aimed at mitigating the detrimental effects of microstructure heterogeneity in AM, and at capitalizing on the opportunities it offers in the design of novel metal alloys, respectively. The *irst consists of developing a high-throughput characterization technique to enable large-scale microstructure analysis of AM builds. The second consists of a new strategy to control the material’s microstructure site-speci*ically during laser powder bed fusion.
基于熔融技术的增材制造（AM）的一个显著特点是通过高能源对金属进行局部熔化，将材料逐点逐层熔合成三维物体。这种工艺所产生的快速凝固速度、定向热梯度和特定部位的热堆积，使零件具有复杂的异质微观结构。这种异质性是一把双刃剑。一方面，它会导致较大的属性分散，给零件性能带来不确定性，阻碍行业采用添加剂技术。另一方面，它也可能赋予传统材料所不具备的特殊机械性能和新功能。在本文中，我们将介绍两项正在进行的研究工作，其目的分别是减轻 AM 中微观结构异质性的不利影响，以及利用其为新型金属合金设计提供的机遇。第一项研究包括开发一种高通量表征技术，以实现对 AM 制件的大规模微观结构分析。第二项研究包括在激光粉末床熔融过程中控制材料微观结构的新策略。
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