Additive manufacturing最新文献_第2页

On-line inspection of lattice structures and metamaterials via in-situ imaging in additive manufacturing 在增材制造中通过原位成像对晶格结构和超材料进行在线检测

IF 10.3 1区工程技术 Q1 ENGINEERING, MANUFACTURING

Additive manufacturing

Pub Date : 2024-09-05 DOI: 10.1016/j.addma.2024.104538

Bianca Maria Colosimo , Federica Garghetti , Marco Grasso , Luca Pagani

As advanced production capabilities are moving towards novel types of geometries as well as higher customization demands, a new and more efficient approach for process and part qualification is becoming an urgent need in industry. The layerwise nature of additive manufacturing (AM) potentially allows anticipating qualification tasks in-line and in-process, aiming at reducing the time and costs devoted to post-process inspections, enabling at the same time an early detection of defects since their onset stage. Such opportunity is particularly attractive in the presence of highly complex shapes like lattice structures or metamaterials, which have been increasingly investigated for industrial adoption in various sectors, aiming to achieve enhanced mechanical properties and innovative functionalities. This paper presents a novel methodology to inspect the geometry of lattice structures while the part is being built. The method is specifically designed to tackle the natural variability affecting layerwise images gathered in laser powder bed fusion. To this aim, it combines the segmentation of in-situ powder bed images of solidified layers with a data modelling approach to synthesize the 3-D shape of each unit cell into a 1-D profile representation. Such low-dimensional representation is suitable to quickly detect undesired distortions that may have a detrimental impact on final quality and performance. By using post-process X-ray computed tomography as ground truth reference, this study shows the effectiveness of the proposed approach for in-line inspection, opening a novel and cost-efficient way to address complex shape qualification for lattice structures in AM.

由于先进的生产能力正朝着新型几何形状和更高定制化要求的方向发展，工业界迫切需要一种新的、更有效的工艺和零件鉴定方法。增材制造（AM）的分层特性使其有可能预测在线和过程中的鉴定任务，从而减少用于过程后检测的时间和成本，同时在缺陷出现阶段就能对其进行早期检测。这种机会对于晶格结构或超材料等高度复杂的形状尤其具有吸引力，这些形状越来越多地被研究用于各个领域的工业应用，旨在实现更强的机械性能和创新功能。本文介绍了一种在零件制造过程中检测晶格结构几何形状的新方法。该方法专门用于解决影响激光粉末床融合过程中收集的层间图像的自然变化问题。为此，它将凝固层的原位粉末床图像分割与数据建模方法相结合，将每个单元格的三维形状合成为一维轮廓表示。这种低维表示法适用于快速检测可能对最终质量和性能产生不利影响的不良变形。通过使用后处理 X 射线计算机断层扫描作为地面实况参考，本研究显示了所建议的在线检测方法的有效性，为解决 AM 中晶格结构复杂的形状鉴定问题开辟了一种新颖且具有成本效益的方法。

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引用次数: 0

Green synthesis of soybean oil-derived UV-curable resins for high-resolution 3D printing 用于高分辨率 3D 打印的大豆油衍生紫外线固化树脂的绿色合成方法

IF 10.3 1区工程技术 Q1 ENGINEERING, MANUFACTURING

Additive manufacturing

Pub Date : 2024-09-05 DOI: 10.1016/j.addma.2024.104543

Xinqi Wang , Xincin Cai , Jiwen Hu , Jiayi Li , Ruixiang Zhou , Shudong Lin

With the rapid development of 3D printing technology, it has penetrated various fields. In the context of global oil resource scarcity and increasing emphasis on environmental protection, developing high-performance bio-based 3D printing materials is a crucial means to overcome the limitations of petroleum resources and achieve sustainability. This paper proposed a "green" development method for high-performance, sunlight-curable vat photopolymerization 3D printing resins based on soybean oil and itaconic anhydride. Utilizing bio-based itaconic anhydride to replace traditional petroleum-based materials, a novel UV-curable prepolymer, IPESO, with 80.37 % high bio-carbon (C_bio) content and no volatile substances was synthesized. Simultaneously, a series of resins, IPESO-ETPTAx, with high mechanical and thermal properties were obtained utilizing ethoxylated trimethylolpropane triacrylate (ETPTA) as a diluent. Samples printed with IPESO-ETPTA40 achieve a high resolution of 40 µm on the xy-axis. This advanced material has broad application prospects in the field of vat photopolymerization 3D printing and provides a new strategy for the development of plant oil-based vat photopolymerization 3D printing resins.

随着 3D 打印技术的快速发展，它已渗透到各个领域。在全球石油资源紧缺、环境保护日益受到重视的背景下，开发高性能生物基3D打印材料是突破石油资源限制、实现可持续发展的重要手段。本文提出了一种基于大豆油和衣康酸酐的高性能阳光固化大桶光聚合3D打印树脂的 "绿色 "开发方法。利用生物基衣康酸酐替代传统的石油基材料，合成了一种新型紫外光固化预聚物 IPESO，其生物碳（Cbio）含量高达 80.37%，且不含挥发性物质。同时，利用乙氧基化三羟甲基丙烷三丙烯酸酯（ETPTA）作为稀释剂，获得了一系列具有高机械和热性能的 IPESO-ETPTAx 树脂。使用 IPESO-ETPTA40 印刷的样品在 x 轴上的分辨率高达 40 微米。这种先进的材料在大桶光聚合三维打印领域具有广阔的应用前景，并为植物油基大桶光聚合三维打印树脂的开发提供了一种新策略。

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引用次数: 0

An additively manufactured heat-resistant Al-12Si alloy via introducing stable eutectic engineering 通过引入稳定共晶工程实现添加式制造的耐热 Al-12Si 合金

IF 10.3 1区工程技术 Q1 ENGINEERING, MANUFACTURING

Additive manufacturing

Pub Date : 2024-09-05 DOI: 10.1016/j.addma.2024.104523

Jianying Wang , Hailin Yang , M.W. Fu

The poor microstructural stability of crack-free Al alloys synthesized via additive manufacturing typically possesses poor heat resistance. In this work, a novel heat-resistant Al-12Si-1.5Ni-2.0Fe (wt%) alloy was fabricated by additive manufacturing, in which tensile strength reaches 271 MPa and 98.1 MPa at 300 ºC and 400 ºC, respectively. Calculation and electron microscopy characterizations show that Fe/Ni segregation with high partition coefficients and low diffusion rates delivers a high thermally stability, thus providing a robust pinning force to inhibit the broken-up of Si eutectics and a solid barrier for dislocation motion at elevated temperatures. In addition to providing weight reduction by substituting Steel, Ti, and Ni-based alloys at 200–450 °C, the adoption of low-cost and stable eutectic engineering reduces the economic barriers to additive manufacturing applications.

通过快速成型技术合成的无裂纹铝合金微观结构稳定性较差，通常具有较差的耐热性。本研究通过增材制造技术制备了一种新型耐热 Al-12Si-1.5Ni-2.0Fe (wt%) 合金，其在 300 ºC 和 400 ºC 时的抗拉强度分别达到 271 MPa 和 98.1 MPa。计算和电子显微镜表征结果表明，具有高分配系数和低扩散率的铁/镍偏析具有很高的热稳定性，从而提供了强大的钉扎力，抑制硅共晶的破裂，并在高温下为位错运动提供了坚实的屏障。除了在 200-450 °C温度下替代钢、钛和镍基合金减轻重量外，采用低成本和稳定的共晶工程还降低了增材制造应用的经济障碍。

引用次数: 0

A microscale cellular automaton method for solid-state phase transformation of directed energy deposited Ti6Al4V 定向能沉积 Ti6Al4V 固态相变的微尺度细胞自动机方法

IF 10.3 1区工程技术 Q1 ENGINEERING, MANUFACTURING

Additive manufacturing

Pub Date : 2024-09-05 DOI: 10.1016/j.addma.2024.104517

Feiyu Xiong , Yanping Lian , Chinnapat Panwisawas , Jiawei Chen , Ming-jian Li , Anwen Liu

Directed energy deposition is a promising additive manufacturing technology that fabricates complex geometries by fusing feed material layer-by-layer. However, the formation mechanism of the directed energy deposited Ti6Al4V solid-state phase transformation process, which is crucial for understanding the process-structure–property relationship, has remained unclear. In this study, a microscale cellular automaton method is proposed to simulate the microstructure evolution process for Ti6Al4V, specifically the

β \to α / α^{'}

phase transformation process within a few

β

grains. The method is further integrated with the mesoscale cellular automaton method, which predicts the prior

β

grain structure, the solid-state phase transformation kinetics model for the prediction of the phase volume fractions, and the finite volume method, which is used for the thermal-fluid flow modeling, providing a temperature field to the former. The integrated numerical framework not only links the thermal history with the phase volume fractions but also provides the columnar

β

grain structures and acicular

α / α^{'}

grain structures in satisfying agreement with the available experimental observation. Moreover, the predictions shed some light on the formation mechanism of the hierarchical

α / α^{'}

structure and their particular clusters. The influence of the cooling rate on the

α / α^{'}

grain formation is illustrated via the three-layer case simulation. The findings on the formation mechanism of

α / α^{'}

are beneficial in tailoring the microstructure of Ti6Al4V for excellent mechanical properties in directed energy deposited Ti6Al4V.

定向能沉积是一种前景广阔的增材制造技术，可通过逐层熔融进料来制造复杂的几何形状。然而，定向能沉积 Ti6Al4V 固态相变过程的形成机理仍不清楚，而这对于理解工艺-结构-性能关系至关重要。本研究提出了一种微尺度细胞自动机方法来模拟 Ti6Al4V 的微观结构演变过程，特别是几个 β 晶粒内的 β→α/α′ 相变过程。该方法进一步与中尺度蜂窝自动机方法、固态相变动力学模型和有限体积方法进行了集成，前者用于预测先期的 β 晶粒结构，后者用于预测相体积分数，后者用于热流体流动建模，并为前者提供温度场。综合数值框架不仅将热历史与相体积分数联系起来，还提供了柱状 β 晶粒结构和针状 α/α′ 晶粒结构，与现有的实验观测结果完全一致。此外，预测结果还揭示了分层α/α′结构及其特殊晶簇的形成机理。通过三层模拟，说明了冷却速率对 α/α′ 晶粒形成的影响。有关 α/α′ 形成机理的研究结果有助于定制 Ti6Al4V 的微观结构，从而在定向能沉积 Ti6Al4V 中获得优异的机械性能。

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引用次数: 0

Role of powder morphology in liquid phase sintering of binder jet additively fabricated WC–Co composite 粉末形貌在粘合剂喷射添加法制造的 WC-Co 复合材料液相烧结中的作用

IF 10.3 1区工程技术 Q1 ENGINEERING, MANUFACTURING

Additive manufacturing

Pub Date : 2024-09-05 DOI: 10.1016/j.addma.2024.104520

K.N. Chaithanya Kumar , Mohan Sai Ramalingam , Sameehan S. Joshi , Shashank Sharma , Narendra B. Dahotre

The present study explored the computational analysis of capillary forces and capillary pressure experienced by the liquid present between particles of various morphologies during liquid phase sintering of a binder jet additively fabricated WC–10 wt% Co composite. An integrated two-particle computational approach was adopted for morphologies gradually transitioning from spherical to cubical. The capillary forces depended on factors such as curvature of liquid meniscus, volume of liquid present between two neighboring particles, and changes in solid–liquid and liquid–vapor contact areas, which were influenced by the particle morphology. The results indicated that capillary forces increased as particle morphology changed from spherical to non-spherical, while increased particle separation led to a reduction in capillary force. Despite increased particle separation, the overall trend in effect of particle morphology on capillary force remained consistent. Additionally, a probability density function based on Rayleigh distribution was used to represent particle separation distances in a real system and variations in coordination number due to different particle morphologies and separation distances were considered. This model allowed estimation of overall effect of particle morphology on capillary force and capillary pressure in realistic systems. The model-based predictions confirmed the experimental observations of severely limited sintering in binder jet additively fabricated WC–10 wt% Co composite containing spherical particles compared to that containing the particles of irregular morphologies. This study provides valuable insights into the mechanics of capillary forces, capillary pressure, and their role in liquid phase sintering, with potential applications in the design and optimization of components of any material system produced using any additive manufacturing process involving liquid phase sintering.

本研究探讨了在液相烧结粘合剂喷射添加剂制造的 WC-10 wt% Co 复合材料过程中，不同形态的颗粒之间的液体所经历的毛细力和毛细管压力的计算分析。对于从球形逐渐过渡到立方体的形态，采用了一种综合的双颗粒计算方法。毛细力取决于液体半月板的曲率、两个相邻颗粒之间的液体体积以及固液接触面积和液汽接触面积的变化等因素，而这些因素都受到颗粒形态的影响。结果表明，当颗粒形态从球形变为非球形时，毛细管力增大，而颗粒分离度增大则导致毛细管力减小。尽管颗粒分离度增加，但颗粒形态对毛细管力影响的总体趋势保持一致。此外，还使用了基于瑞利分布的概率密度函数来表示实际系统中的颗粒分离距离，并考虑了不同颗粒形态和分离距离导致的配位数变化。通过该模型，可以估算出颗粒形态对实际系统中毛细管力和毛细管压力的总体影响。基于模型的预测结果证实了实验观察结果，即在粘结剂喷射加成法制造的 WC-10 wt% Co 复合材料中，与含有不规则形态颗粒的复合材料相比，含有球形颗粒的复合材料的烧结受到严重限制。这项研究为毛细力力学、毛细管压力及其在液相烧结中的作用提供了宝贵的见解，有望应用于使用任何涉及液相烧结的增材制造工艺生产的任何材料系统部件的设计和优化。

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引用次数: 0

Enhancing thermal conductivity of AlN ceramics via vat photopolymerization through refractive index coupling and oxygen fixation 通过折射率耦合和氧气固定，利用大桶光聚合提高氮化铝陶瓷的热导率

IF 10.3 1区工程技术 Q1 ENGINEERING, MANUFACTURING

Additive manufacturing

Pub Date : 2024-09-05 DOI: 10.1016/j.addma.2024.104522

Maohang Zhang , Chen Zhao , Jiaming Bai , Zhaoyang Hu , Jiawei Cai , Zhirui Zhang , Mingli Qin , Xuanhui Qu , Baicheng Zhang

Despite the growing development of ceramic fabrication by vat photopolymerization (VP), major gaps remain in application. Particularly in the case of VP-printed aluminum nitride (AlN) ceramic, the thermal conductivity is still below 170 W·m⁻¹·K⁻¹, a critical benchmark for efficient heat dissipation. To address this challenge, here we prepared an AlN slurry with high curing thickness through RI coupling between liquid-solid phase, and took into account of the rheological property under high solid loading. Full dense AlN green bodies with solid loading up to 50 vol% were successfully printed. Aiming to to tackle the degradation of thermal conductivity issue caused by oxygen increment of AlN via VP, we systemically studied the form of oxygen in AlN preparation processes. Through the sintering optimization, the oxygen element from the hydrolysis of AlN surface was fixated in the sintering aid Y₂O₃. Eventually, without any special process control or additional treatment, the final sintered AlN ceramics prepared by the developed slurry present a full densification and the highest thermal conductivity (up to 187.9 W∙m⁻¹∙K⁻¹) of any known additive manufactured ceramics.

尽管大桶光聚合（VP）陶瓷制造技术日益发展，但在应用方面仍存在很大差距。尤其是 VP 印刷氮化铝（AlN）陶瓷，其热导率仍低于 170 W-m-1-K-1，而这正是高效散热的关键基准。为了应对这一挑战，我们通过液固相之间的 RI 耦合制备了具有高固化厚度的氮化铝浆料，并考虑了高固体负载下的流变特性。我们成功打印出了固含量高达 50 Vol% 的全致密 AlN 绿色体。为了解决氮化铝通过 VP 增加氧气导致热导率下降的问题，我们系统地研究了氮化铝制备过程中氧气的形式。通过烧结优化，AlN 表面水解产生的氧元素被固定在烧结助剂 Y2O3 中。最终，在没有任何特殊工艺控制或额外处理的情况下，由所开发的浆料制备的最终烧结 AlN 陶瓷呈现出完全致密化，其热导率（高达 187.9 W∙m-1∙K-1）也是所有已知添加剂制造陶瓷中最高的。

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引用次数: 0

Dynamic formation of gradient structure by microparticle impact — A crystal plasticity material point method study 微粒子冲击梯度结构的动态形成--晶体塑性材料点法研究

IF 10.3 1区工程技术 Q1 ENGINEERING, MANUFACTURING

Additive manufacturing

Pub Date : 2024-09-05 DOI: 10.1016/j.addma.2024.104518

Cong Chen, TianYuan Guan, Xianheng Wang, Yan Liu

Metallic materials with unique microstructure can achieve desirable strength-ductility synergy. However, effectively fabricating and precisely controlling microstructure distribution in metals remain challenging. Microparticle impact, the key process of cold spray technique, can lead to a gradient structure in the particle, which may also serve as a promising additive manufacturing technology. To investigate the dynamic formation mechanism of heterogeneous microstructure and its significant influencing factors, the crystal plasticity material point method (CPMPM) is developed, especially for microstructure formation under a high strain rate and large deformation. Our work provides a quantitative analysis of evolution of structural gradient during impact. It is found that decreasing grain size can afford a larger structural gradient and there is negligible influence on the compression ratio of particles. It suggests that microstructure distribution can be tailored by optimizing the impact process without influencing vertical deformation of particles.

具有独特微观结构的金属材料可以实现理想的强度-电导率协同效应。然而，有效制造和精确控制金属中的微观结构分布仍然具有挑战性。微颗粒冲击是冷喷技术的关键过程，可在颗粒中形成梯度结构，这也可作为一种前景广阔的增材制造技术。为了研究异质微观结构的动态形成机制及其重要影响因素，我们开发了晶体塑性材料点法（CPMPM），尤其适用于高应变率和大变形下的微观结构形成。我们的研究对冲击过程中结构梯度的演变进行了定量分析。研究发现，晶粒尺寸越小，结构梯度越大，而对颗粒压缩比的影响则微乎其微。这表明可以通过优化冲击过程来调整微观结构分布，而不会影响颗粒的垂直变形。

引用次数: 0

Abnormal aging behaviors induced by high-density dislocations for an ultra-high-strength titanium alloy prepared by laser-directed energy deposition 激光定向能沉积法制备的超高强度钛合金的高密度位错诱发的异常老化行为

IF 10.3 1区工程技术 Q1 ENGINEERING, MANUFACTURING

Additive manufacturing

Pub Date : 2024-09-05 DOI: 10.1016/j.addma.2024.104559

Junwei Yang , Haibo Tang , Yansong Zhang , Yihe Zhang , Yanyan Zhu , Bingsen Liu , Zhuodan Cui

Additively manufactured high-strength titanium alloys generally possess equal strength and lower plasticity compared to wrought alloys owing to the different microstructures formed in the aging treatment. To examine the formation mechanism of these microstructures, an ultra-high-strength titanium alloy TB18(Ti-4.2Al-5V-5Cr-5Mo-1Nb) was prepared by laser direct energy deposition (LDED) and forging respectively, and the aging behaviors and microstructures were characterized and compared in depth. It is found that during aging, the precipitation of the LDEDed alloy is 1–2 h earlier than that of the wrought alloy, and precipitates primarily form at the reticular sub-grain boundaries. Fine short-rod α laths then form inside the sub-grains due to the inhibition of the reticulations. The sub-grain boundaries in LDEDed alloy are generated due to the local deformation and recovery of the inter-dendritic zone rich of Cr and O atoms and show high thermal stability in the solution treatment, which differs from that of the wrought alloys. These boundaries possess a dislocation density several times higher than that of the inner-grain zones and promote the prior precipitation of α laths with Type 2 orientations at the early stage of aging. In the tensile test of the aged alloys, the dislocations in the LDEDed alloy pile up at the α/β interface, which can cause stress concentration and damage the plasticity.

与锻造合金相比，添加剂制造的高强度钛合金通常具有相同的强度和较低的塑性，这是因为在时效处理过程中形成了不同的微观结构。为了研究这些微观结构的形成机理，分别采用激光直接能量沉积（LDED）和锻造方法制备了超高强度钛合金 TB18（Ti-4.2Al-5V-5Cr-5Mo-1Nb），并对其时效行为和微观结构进行了深入表征和比较。研究发现，在时效过程中，激光直接能量沉积合金的析出时间比锻造合金早 1-2 h，且析出物主要形成于网状亚晶粒边界。由于网状结构受到抑制，亚晶粒内部会形成细小的短棒 α 板条。LDEDed 合金中的亚晶界是由于富含 Cr 原子和 O 原子的树枝状晶间区的局部变形和恢复而产生的，在固溶处理中表现出与锻造合金不同的高热稳定性。这些边界的位错密度比内部晶粒区的位错密度高出数倍，并在时效初期促进了具有 2 型取向的 α 板条的先期析出。在老化合金的拉伸试验中，LDED 化合金中的位错会堆积在 α/β 界面，从而导致应力集中并破坏塑性。

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引用次数: 0

Fabrication of customized microneedle with high 3D capability and high structural precision 制造具有高三维能力和高结构精度的定制微针

IF 10.3 1区工程技术 Q1 ENGINEERING, MANUFACTURING

Additive manufacturing

Pub Date : 2024-09-05 DOI: 10.1016/j.addma.2024.104509

Zhaolun Chen , Zhi Wang , Lan Jiang , Weina Han , Zhuo Zhao , Libo Ren , Lingtao Zhang , Jianhui Jiang , Pei Zuo

Advanced 3D fabrication techniques are essential for the processing of 3D devices, which mainly focusing on excellent 3D fabrication capability and high structural precision. Although 3D printing technology allows for the creation of complex 3D structures with extensive customization, it faces notable challenges in achieving precise micro/nanostructures within materials due to incomplete resin curing bonds. Here, we propose integrating projection micro-stereolithography (PμSL) with femtosecond (fs) laser Bessel beam drilling to create 3D structures with advanced customization, precise structures (including size accuracy and aspect ratio), and efficient processing. Starting with the drilling process using Bessel beams, we have achieved micro-holes with a diameter of approximately 1μm and the aspect ratio reached 1017:1 on 3D printed items by regulating the transparency and elasticity of the products. Furthermore, we have applied this technology to produce tailor-made microneedles, including slanted-tip microneedles and porous microneedles, demonstrating its ability for extensive, efficient micro-hole processing with a peak drilling speed of 200,000 holes per second. This technology offers an innovative approach to creating three-dimensional devices with intricate cavity structures, and its impressive processing capabilities suggest potential for broad industrial implementation.

先进的三维制造技术对于三维设备的加工至关重要，这主要集中在出色的三维制造能力和高结构精度上。虽然三维打印技术可以创建具有广泛定制性的复杂三维结构，但由于树脂固化结合不完全，在材料内部实现精确的微/纳米结构面临着显著的挑战。在此，我们建议将投影微立体光刻技术（PμSL）与飞秒激光贝塞尔光束钻孔技术相结合，以创建具有高级定制功能、精确结构（包括尺寸精度和高宽比）和高效加工的三维结构。从贝塞尔光束钻孔工艺开始，我们通过调节产品的透明度和弹性，在三维打印物品上实现了直径约为 1μm 的微孔，长宽比达到 1017:1。此外，我们还将这项技术应用于生产定制微针，包括斜尖微针和多孔微针，证明了其广泛、高效的微孔加工能力，钻孔速度峰值可达每秒 20 万个。这项技术为制造具有复杂空腔结构的三维设备提供了一种创新方法，其令人印象深刻的加工能力表明它具有广泛的工业应用潜力。

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引用次数: 0

Impact of melt pool geometry variability on lack-of-fusion porosity and fatigue life in powder bed fusion-laser beam Ti–6Al–4V 熔池几何形状的变化对粉末床熔融-激光束 Ti-6Al-4V 中熔融缺乏孔隙率和疲劳寿命的影响

IF 10.3 1区工程技术 Q1 ENGINEERING, MANUFACTURING

Additive manufacturing

Pub Date : 2024-09-05 DOI: 10.1016/j.addma.2024.104506

Justin P. Miner , Austin Ngo , Christian Gobert , Tharun Reddy , John J. Lewandowski , Anthony D. Rollett , Jack Beuth , Sneha Prabha Narra

Powder bed fusion-laser beam (PBF-LB) parts experience a significant decline in fatigue performance when process-induced defects are present. In this work, a decline in 4-point bend fatigue life was observed in PBF-LB Ti–6Al–4V coupons fabricated at constant power with increasing scanning velocity and which underwent subsequent stress relief and surface machining. Specifically, the presence of pores that resemble lack-of-fusion (LoF) and a decline in fatigue life were observed at scanning velocities lower than that expected from prior published work. It was hypothesized that this unexpected presence of LoF pores resulted from melt pool geometry variability that was not considered in prior work when the LoF criterion was implemented. Further, these pores can be small in size and infrequent in their occurrence when the melt pool geometry variability is not severe. Such sparse pores are challenging to characterize using conventional 2D characterization methods. This work leverages tall and narrow coupon geometry and high-resolution X-ray micro computed tomography (X-

μ

CT) to capture LoF porosity. The results show that a modified melt pool overlap-based LoF criterion considering melt pool geometry variability captures the unexpected occurrence of LoF pores observed in X-

μ

CT. In addition, the LoF percent metric displays a strongly negative correlation with fatigue performance. The insights from this work provide guidance on characterizing melt pool geometry variability across scan lines to systematically evaluate processing parameters that generate LoF pores, which, in turn, could lower fatigue performance.

粉末床熔融激光束 (PBF-LB) 零件在出现工艺缺陷时，疲劳性能会显著下降。在这项工作中，以恒定功率制造的 PBF-LB Ti-6Al-4V 试样在扫描速度不断增加的情况下，其 4 点弯曲疲劳寿命出现了下降，随后对试样进行了应力消除和表面加工。具体地说，在扫描速度低于先前发表的研究成果所预期的速度时，观察到了类似于熔合不足（LoF）的孔隙的存在以及疲劳寿命的下降。据推测，这种意外出现的 LoF 孔隙是由于熔池几何形状的变化造成的，而之前的工作在实施 LoF 标准时并没有考虑到这种变化。此外，在熔池几何形状变化不严重的情况下，这些孔隙的尺寸可能很小，出现的频率也不高。使用传统的二维表征方法表征此类稀疏孔隙具有挑战性。这项研究利用高而窄的试样几何形状和高分辨率 X 射线显微计算机断层扫描 (X-μCT) 捕获 LoF 孔隙率。结果表明，考虑到熔池几何形状的可变性，基于熔池重叠的 LoF 标准进行了修改，从而捕捉到了在 X-μCT 中观察到的意外出现的 LoF 孔隙。此外，LoF 百分比指标与疲劳性能呈强烈的负相关。这项工作的启示为描述各扫描线上熔池几何形状的变化提供了指导，以便系统地评估产生 LoF 孔隙的加工参数，而 LoF 孔隙反过来又会降低疲劳性能。

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引用次数: 0