Additive manufacturing letters最新文献

{"title":"A non-melting additive approach to structural repair of aluminum aircraft fastener holes","authors":"R. Joey Griffiths ,&nbsp;David Garcia ,&nbsp;Greg D. Hahn ,&nbsp;Jim Lua ,&nbsp;Nam Phan ,&nbsp;Hang Z. Yu","doi":"10.1016/j.addlet.2024.100249","DOIUrl":"10.1016/j.addlet.2024.100249","url":null,"abstract":"<div><div>The damage to fastener holes in aerospace aluminum structures presents significant challenges for aircraft durability, and conventional bushing methods for repairing oversized holes often fall short due to the lack of metallurgical bonding and limited edge distance availability. This study investigates additive friction stir deposition, a non-melting additive process, as a viable alternative for the structural repair of aerospace fastener holes. The repair process, demonstrated on AA7050 (Al-Zn-Mg-Cu-Zr) hole structures, involves filling oversized holes with new material and machining to restore the original hole size. The repaired hole coupons are defect-free and exhibit good fatigue performance under fully reversed tension-compression loading (<em>R</em> = -1). At a nominal stress amplitude of 123.5 MPa, the average number of cycles to failure is 12,666 for unrepaired baseline coupons and 17,372 for effectively repaired coupons. Restoring complex geometries without compromising fatigue performance has been difficult in aerospace applications; this study marks the first demonstration of additive repair that consistently outperforms the unrepaired baseline coupons. Notably, the result is achieved through a low-energy, cost-effective solution without the need for post-repair heat treatment. Except for a few outliers, the post-repair fatigue performance generally remains inferior to that of undamaged, pristine coupons, likely due to precipitate evolution in AA7050 caused by the thermomechanical processing nature of additive friction stir deposition. This evolution weakens the repair region and the adjacent base material, leading to faster crack initiation and growth compared to the properly aged base material, AA7050-T7451.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"11 ","pages":"Article 100249"},"PeriodicalIF":4.2,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enabling tailored microstructures by hybrid directed energy deposition processing of a nickel-based superalloy","authors":"Clemens Johannes Müller ,&nbsp;Klaus Büßenschütt ,&nbsp;Alexander Schwedt ,&nbsp;Johannes Henrich Schleifenbaum ,&nbsp;Markus Sudmanns","doi":"10.1016/j.addlet.2024.100248","DOIUrl":"10.1016/j.addlet.2024.100248","url":null,"abstract":"<div><div>The technological advances in additive manufacturing, particularly laser based directed energy deposition (DED), revolutionized the production of complex metal components. Despite this progress, the oriented heat flux and several reheating thermal cycles can induce a strongly textured microstructure, which induces an anisotropic mechanical behavior. In addition, considerable residual stresses typically require additional post-processing. Therefore, hybrid process chains for additive manufacturing (AM) are being developed, which aim at integrating conventional post-processing into the AM process. However, a detailed investigation of thermal and mechanical effects of such hybrid processes on the mechanical properties and their interrelation is lacking. In an experimental study, we explore the integration of thermal and mechanical processing steps within the DED process chain to locally tailor microstructures and mechanical properties. Through electron backscatter diffraction measurements, we demonstrate significant microstructural changes of DED-manufactured nickel-based superalloy samples using deep rolling and laser heat treatment. A mechanical surface deformation induces microstructural misorientation leading to an increase in hardness down to substantial depth of several hundred micrometers. Additionally, the targeted management of heat input during laser heat treatment results in different grain morphologies and sizes, affecting average microhardness within a significant depth. The results demonstrate the potential for microstructural tailoring using hybrid AM process chains, while a substantial sensitivity of the microstructure to thermal and mechanical load emphasizes the importance of a precise process control. This work provides an understanding of the process-microstructure-property relationship required for developing new process pathways in hybrid AM that integrate thermal and mechanical processes into DED manufacturing.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"11 ","pages":"Article 100248"},"PeriodicalIF":4.2,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142445366","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An integrated hybrid wire-arc directed energy deposition, friction stir processing, and milling system for multi-track, multi-layer part manufacturing","authors":"Dinh Son Nguyen ,&nbsp;Jie Song ,&nbsp;Yao Fu ,&nbsp;Albert C. To","doi":"10.1016/j.addlet.2024.100247","DOIUrl":"10.1016/j.addlet.2024.100247","url":null,"abstract":"<div><div>Wire-based Directed Energy Deposition (DED) is a widely-used manufacturing method due to its high productivity and large part fabrication capability. Meanwhile, Friction Stir Processing (FSP) is a solid-state joining process that can modify microstructure and weld lightweight alloys. Additionally, wire-based DED printed parts need machining process to achieve the desired dimensional accuracy. To take advantage of all these three processes, this work proposes an integrated hybrid system by combining the wire-arc DED, FSP, and milling processes into a standalone system which can fabricate superior materials in a multi-track, multi-layer manner for the first time. The integrated system can improve dimensional accuracy and productivity by processing the workpiece without the need to move it between different systems. It is demonstrated that a 150 × 40 × 21 mm³ block of aluminum alloy AA5183 can be fabricated using the hybrid wire-DED/FSP/milling process from wire feedstock. Material characterization shows that the hybrid process is able to refine the grain size by two orders of magnitude to sub-micron scale, while eliminating all the pores and microcracks produced by the DED process. These enhancements result in significantly improved mechanical properties including Young's modulus (15 %), yield strength (161 %), ultimate strength (33 %), and hardness (55 %) without compromising ductility.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"11 ","pages":"Article 100247"},"PeriodicalIF":4.2,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142433430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of laser power during laser powder bed fusion on microstructure of joining interface between Tungsten and AISI 316L steel","authors":"Seung-Hoon Lee ,&nbsp;Ji-Hoe Koo ,&nbsp;Omer Cakmak ,&nbsp;Jung-Wook Cho","doi":"10.1016/j.addlet.2024.100246","DOIUrl":"10.1016/j.addlet.2024.100246","url":null,"abstract":"<div><div>This study investigates the deposition of tungsten (W) onto a 316L steel substrate by laser powder bed fusion (L-PBF), to optimize process parameters and analyze the interface between W and 316L. To obtain high-density W structure (98.89%), the optimal laser power was 350 W, and scan speed was 500 mm/s, but these parameters cause significant dilution of W in the W-316L interface; as a result, Fe₇W₆ intermetallics form, despite L-PBF being a non-equilibrium solidification process. These intermetallics which are brittle could degrade joint strength. By reducing laser power below 250 W, the dilution of W can be mitigated, and potentially minimize formation of intermetallics and increase joint stability for advanced manufacturing applications.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"11 ","pages":"Article 100246"},"PeriodicalIF":4.2,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Preparation of continuous carbon fiber reinforced PA6 prepreg filaments with high fiber volume fraction","authors":"Ming Zhang ,&nbsp;Zhonggang Sun ,&nbsp;Yingbing Liang ,&nbsp;Yanhua Guo ,&nbsp;Guoqing Dai ,&nbsp;Keyuan Wei ,&nbsp;Ming Li ,&nbsp;Xiping Li ,&nbsp;Igor V. Alexandrov","doi":"10.1016/j.addlet.2024.100245","DOIUrl":"10.1016/j.addlet.2024.100245","url":null,"abstract":"<div><div>High-performance continuous carbon fiber prepreg filaments have been a research hotspot in the field of additive manufacturing in recent years, and are considered to be an effective option for improving the mechanical strength of thermoplastic composite parts. However, the effect of fiber volume fraction on the microstructure and tensile properties of 3D printed prepreg filaments remains miss. Therefore, this study selected suitable impregnation processes and materials to prepare prepreg filaments with different fiber volume fraction and investigated their mechanical properties and microscopic morphologies. The results show that the increase of fiber volume fraction effectively promoted the interface bonding between fiber and resin, and increased capacity for load transfer. When the fiber volume fraction was 54.0 %, the tensile strength of the prepreg filaments and specimens reached 1977 MPa and 334 MPa, respectively. This study can provide a process optimization strategy for the preparation of more types of continuous fiber prepreg filaments with high fiber volume fraction, as well as a data reference for the preparation of high-performance 3D-printed thermoplastic composites.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"11 ","pages":"Article 100245"},"PeriodicalIF":4.2,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deep learning for melt pool depth contour prediction from surface thermal images via vision transformers","authors":"Francis Ogoke ,&nbsp;Peter Pak ,&nbsp;Alexander Myers ,&nbsp;Guadalupe Quirarte ,&nbsp;Jack Beuth ,&nbsp;Jonathan Malen ,&nbsp;Amir Barati Farimani","doi":"10.1016/j.addlet.2024.100243","DOIUrl":"10.1016/j.addlet.2024.100243","url":null,"abstract":"<div><div>Anomalous melt pools during metal additive manufacturing (AM) can lead to deteriorated mechanical and fatigue performance. In-situ monitoring of the melt pool subsurface morphology requires specialized equipment that may not be readily accessible or scalable. Therefore, we introduce a machine learning framework to correlate in-situ two-color thermal images observed via high-speed color imaging to the two-dimensional profile of the melt pool cross-section. We employ a hybrid CNN-Transformer architecture to establish a correlation between single bead off-axis thermal image sequences and melt pool cross-section contours measured via optical microscopy. Specifically, a ResNet model embeds the spatial information contained within the thermal images to a latent vector, while a Transformer model correlates the sequence of embedded vectors to extract temporal information. The performance of this model is evaluated through dimensional and geometric comparisons to the corresponding experimental no-powder melt pool observations. Our framework is able to model the curvature of the subsurface melt pool structure, with improved performance in high energy density regimes compared to analytical models. Additionally, the use of ratiometric temperature estimates improves the accuracy of the model predictions compared to monochromatic imaging. This work establishes a framework extensible towards powder-based AM builds.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"11 ","pages":"Article 100243"},"PeriodicalIF":4.2,"publicationDate":"2024-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of laser parameters and shielding gas flow on co-axial photodiode-based melt pool monitoring signals in laser powder bed fusion","authors":"Joni Reijonen","doi":"10.1016/j.addlet.2024.100244","DOIUrl":"10.1016/j.addlet.2024.100244","url":null,"abstract":"<div><div>Melt pool monitoring using co-axial photodiodes is increasingly used for online quality monitoring in PBF-LB AM. However, the fundamental correlations between different processing conditions and the co-axial photodiode signals are not well understood. In this study the impact of laser parameters and the shielding gas flow speed on co-axial photodiode-based melt pool monitoring signals is established. It is shown that laser power has positive linear correlation with the photodiode signal, while the correlation with scanning speed is non-linear in the form of <em>y</em>=ax^–b. The focal point position, scanning orientation and shielding gas flow speed have highly non-linear response on the photodiode signal, depending on the combinatorial effects of the parameters. These underlying physical correlations should be carefully assessed and taken into consideration when trying to establish correlations between photodiode-based melt pool monitoring signal and defect formation in the PBF-LB process.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"11 ","pages":"Article 100244"},"PeriodicalIF":4.2,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772369024000525/pdfft?md5=cbf9c1ba3b0f65a2fea5968c1f650aaa&pid=1-s2.0-S2772369024000525-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142316051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Additively manufactured Nb-Ti-Si based alloy: As-built and heat-treated conditions","authors":"Runqi Gao ,&nbsp;Hui Peng ,&nbsp;Hongbo Guo ,&nbsp;Bo Chen","doi":"10.1016/j.addlet.2024.100242","DOIUrl":"10.1016/j.addlet.2024.100242","url":null,"abstract":"<div><p>This work aims to fully characterise the Nb-Ti-Si based alloy (Nb-26Ti-16Si-2.2Al-2Cr), processed by the electron-beam powder-bed-fusion in both as-built and heat-treated conditions, to elucidate the microstructure-property relationships. The as-built condition has [001]-oriented columnar grains of the Nb₃Si phase with the Nbss phase dispersed throughout the microstructure. The microhardness is 645.2 ± 6.7 HV_0.5, and the indentation fracture toughness shows distinct directionality: 7.7 MPa·m^1/2 in the horizontal direction compared to 5.3 MPa·m^1/2 in the vertical direction. Both properties are comparable to the cast version. The directionality is attributed to the underlying mechanisms such as crack bridging, arrest, and micro-crack formation. By contrast, in the heat-treated condition, the alloy exhibits a dual-phase microstructure (Nbss and Nb₅Si₃ phases) with near-equiaxed grain shape due to the Nb₃Si phase decomposition. The fracture toughness increases to 12.1 MPa·m^1/2, at the expense of a reduced microhardness of 564.4 ± 15.0 HV_0.5.</p></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"11 ","pages":"Article 100242"},"PeriodicalIF":4.2,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772369024000501/pdfft?md5=4e9a54c3bc27837b474f34dc47844f58&pid=1-s2.0-S2772369024000501-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142272232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Jet on demand—A pneumatically driven molten metal jetting method for printing crack-free aluminum components","authors":"Eric S. Elton,&nbsp;Kellen D. Traxel,&nbsp;Andrew J. Pascall,&nbsp;Jason R. Jeffries","doi":"10.1016/j.addlet.2024.100240","DOIUrl":"10.1016/j.addlet.2024.100240","url":null,"abstract":"<div><div>Additive manufacturing (AM) of many traditional aluminum alloys is difficult due to hot cracking during cooling, which motivates investigating alternative AM methods that can mitigate this challenge. Here we demonstrate a new pneumatically driven molten metal jetting (MMJ) AM technique which uses a longer pressure pulse width to produce a jet of liquid metal that reaches the heated build plate. The “jet on demand” technique is utilized to build Al-6061 parts on heated build plates. Due to the large thermal mass contained in each jet, excellent adhesion is observed between droplets and layers while still maintaining dimensional control to produce parts with high relative densities (&gt;98%). While as-printed parts exhibit different microstructure and hardness than traditional Al-6061, both microstructure and hardness are restored to traditionally processed values through a traditional T6 heat treatment. Microhardness values of 104 HV were obtained for printed Al-6061, which compares well to wrought properties. We observe that high build plate temperatures allow for lower solidification rates and eliminate hot cracking. These results point to a method for additively manufacturing traditional aluminum or other alloys that cannot currently be additively manufactured due to hot cracking.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"11 ","pages":"Article 100240"},"PeriodicalIF":4.2,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772369024000483/pdfft?md5=2d587638c9808e9d5184e4e2c4bcff5b&pid=1-s2.0-S2772369024000483-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142310901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deep learning based automated quantification of powders used in additive manufacturing","authors":"K.V. Mani Krishna ,&nbsp;A. Anantatamukala ,&nbsp;Narendra B. Dahotre","doi":"10.1016/j.addlet.2024.100241","DOIUrl":"10.1016/j.addlet.2024.100241","url":null,"abstract":"<div><p>This study proposes a novel deep learning technique for efficient powder morphology characterization, crucial for successful additive manufacturing. The method segments powder particles in microscopy images using Pix2Pix image translation model, enabling precise quantification of size distribution and extraction of critical morphology parameters like circularity and aspect ratio. The proposed approach achieves high accuracy (Structural Similarity Index of 0.8) and closely matches established methods like laser diffraction in measuring particle size distribution (within a deviation of ∼7 %) and allows determination of additional particle attributes of aspect ratio and circualarity in a reliable, repeated, and automated way. These findings highlight the potential of deep learning for automated powder characterization, offering significant benefits for optimizing additive manufacturing processes.</p></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"11 ","pages":"Article 100241"},"PeriodicalIF":4.2,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2772369024000495/pdfft?md5=a06b16d12821379b2ce34780bd3cbcfc&pid=1-s2.0-S2772369024000495-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142241253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}