Journal of Manufacturing and Materials Processing

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18 pages, 11154 KiB

Open AccessArticle

Influence of the Processing Parameters on the Microstructure and Mechanical Properties of 316L Stainless Steel Fabricated by Laser Powder Bed Fusion

by Germán Omar Barrionuevo, Jorge Andrés Ramos-Grez, Xavier Sánchez-Sánchez, Daniel Zapata-Hidalgo, José Luis Mullo and Santiago D. Puma-Araujo

J. Manuf. Mater. Process. 2024, 8(1), 35; https://doi.org/10.3390/jmmp8010035 - 9 Feb 2024

Cited by 3 | Viewed by 3144

Abstract

Complex thermo-kinetic interactions during metal additive manufacturing reduce the homogeneity of the microstructure of the produced samples. Understanding the effect of processing parameters over the resulting mechanical properties is essential for adopting and popularizing this technology. The present work is focused on the [...] Read more.

Complex thermo-kinetic interactions during metal additive manufacturing reduce the homogeneity of the microstructure of the produced samples. Understanding the effect of processing parameters over the resulting mechanical properties is essential for adopting and popularizing this technology. The present work is focused on the effect of laser power, scanning speed, and hatch spacing on the relative density, microhardness, and microstructure of 316L stainless steel processed by laser powder bed fusion. Several characterization techniques were used to study the microstructure and mechanical properties: optical, electron microscopies, and spectrometry. A full-factorial design of experiments was employed for relative density and microhardness evaluation. The results derived from the experimental work were subjected to statistical analysis, including the use of analysis of variance (ANOVA) to determine both the main effects and the interaction between the processing parameters, as well as to observe the contribution of each factor on the mechanical properties. The results show that the scanning speed is the most statistically significant parameter influencing densification and microhardness. Ensuring the amount of volumetric energy density (125 J/mm³) used to melt the powder bed is paramount; maximum densification (99.7%) is achieved with high laser power and low scanning speed, while hatch spacing is not statistically significant. Full article

(This article belongs to the Special Issue Laser-Based Manufacturing II)

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17 pages, 11909 KiB

Open AccessArticle

Picosecond Laser-Induced Bump Formation on Coated Glass for Smart Window Manufacturing

by Savely Ioffe, Andrey Petrov and Grigory Mikhailovsky

J. Manuf. Mater. Process. 2024, 8(1), 1; https://doi.org/10.3390/jmmp8010001 - 19 Dec 2023

Viewed by 2209

Abstract

We report a study on the process of the formation of bubble-like structures on a coated glass surface using 50 ps laser pulses. The high-intensity interaction of laser radiation on the film–glass interface allowed us to develop a process for efficient glass bump [...] Read more.

We report a study on the process of the formation of bubble-like structures on a coated glass surface using 50 ps laser pulses. The high-intensity interaction of laser radiation on the film–glass interface allowed us to develop a process for efficient glass bump formation. The high peak energy of the picosecond pulses has allowed us to merge the processes of coating evaporation and bubble growth into one. A parameter window was established within which efficient bump formation can be achieved. Well-defined spherical structures with a height up to 60 μm and a diameter up to 250 μm were obtained at pulse energy E_pulse = 2.5 ÷ 4 μJ and laser fluence F = 2.5–0.41 J/cm²). The key aspects of the bump formation process were studied and are explained. Full article

(This article belongs to the Special Issue Laser-Based Manufacturing II)

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15 pages, 6183 KiB

Open AccessArticle

Kerf Geometry and Surface Roughness Optimization in CO₂ Laser Processing of FFF Plates Utilizing Neural Networks and Genetic Algorithms Approaches

by John D. Kechagias, Nikolaos A. Fountas, Konstantinos Ninikas and Nikolaos M. Vaxevanidis

J. Manuf. Mater. Process. 2023, 7(2), 77; https://doi.org/10.3390/jmmp7020077 - 18 Apr 2023

Cited by 9 | Viewed by 2419

Abstract

This work deals with the experimental investigation and multi-objective optimization of mean kerf angle (A) and mean surface roughness (Ra) in laser cutting (LC) fused filament fabrication (FFF) 3D-printed (3DP), 4 mm-thick polylactic acid (PLA) plates by considering laser feed (F) and power [...] Read more.

This work deals with the experimental investigation and multi-objective optimization of mean kerf angle (A) and mean surface roughness (Ra) in laser cutting (LC) fused filament fabrication (FFF) 3D-printed (3DP), 4 mm-thick polylactic acid (PLA) plates by considering laser feed (F) and power (P) as the independent control parameters. A CO₂ laser apparatus was employed to conduct machining experiments on 27 rectangular workpieces. An experimental design approach was adopted to establish the runs according to full-combinatorial design with three repetitions, resulting in 27 independent experiments. A customized response surface experiment was formulated to proceed with regression equations to predict the responses and examine the solution domain continuously. After examining the impact of F and P on mean A and mean Ra, two reliable prediction models were generated to model the process. Furthermore, since LC is a highly intricate, non-conventional machining process and its control variables affect the responses in a nonlinear manner, A and Ra were also predicted using an artificial neural network (NN), while its resulting performance was compared to the predictive regression models. Finally, the regression models served as objective functions for optimizing the responses with an intelligent algorithm adopted from the literature. Full article

(This article belongs to the Special Issue Laser-Based Manufacturing II)

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15 pages, 8325 KiB

Open AccessCommunication

Laser Additive Manufacturing of Oxide Dispersion-Strengthened Copper–Chromium–Niobium Alloys

by Markus B. Wilms and Silja-Katharina Rittinghaus

J. Manuf. Mater. Process. 2022, 6(5), 102; https://doi.org/10.3390/jmmp6050102 - 16 Sep 2022

Cited by 5 | Viewed by 3348

Abstract

Copper is a key material for cooling of thermally stressed components in modern aerospace propulsion systems, due to its high thermal conductivity. The use of copper materials for such applications requires both high material strength and high stability at high temperatures, which can [...] Read more.

Copper is a key material for cooling of thermally stressed components in modern aerospace propulsion systems, due to its high thermal conductivity. The use of copper materials for such applications requires both high material strength and high stability at high temperatures, which can be achieved by the concept of oxide dispersion strengthening. In the present work, we demonstrate the oxide reinforcement of two highly conductive precipitation-strengthened Cu-Cr-Nb alloys using laser additive manufacturing. Gas-atomized Cu-3.3Cr-0.5Nb and Cu-3.3Cr-1.5Nb (wt.%) powder materials are decorated with Y₂O₃ nanoparticles by mechanical alloying in a planetary mill and followed by consolidation by the laser additive manufacturing process of laser powder bed fusion (L-PBF). While dense specimens (>99.5%) of reinforced and nonreinforced alloys can be manufactured, oxide dispersion-strengthened alloys additionally exhibit homogeneously distributed oxide nanoparticles enriched in yttrium and chromium next to Cr₂Nb precipitates present in all alloys examined. Higher niobium contents result in moderate increase of the Vickers hardness of approx. 10 HV0.3, while the homogeneously dispersed nanometer-sized oxide particles lead to a pronounced increase of approx. 30 HV0.3 in material strength compared to their nonreinforced counterparts. Full article

(This article belongs to the Special Issue Laser-Based Manufacturing II)

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19 pages, 7179 KiB

Open AccessArticle

Areal Analysis Investigation of Selective Laser Melting Parts

by Alberto Boschetto, Luana Bottini and Nahal Ghanadi

J. Manuf. Mater. Process. 2022, 6(4), 83; https://doi.org/10.3390/jmmp6040083 - 4 Aug 2022

Cited by 2 | Viewed by 3052

Abstract

Selective laser melting is an additive manufacturing technology used to fabricate metal parts characterized by complex geometries that are difficult or impossible to produce with conventional production methods. One of the major drawbacks of laser melting is the poor surface quality that typically [...] Read more.

Selective laser melting is an additive manufacturing technology used to fabricate metal parts characterized by complex geometries that are difficult or impossible to produce with conventional production methods. One of the major drawbacks of laser melting is the poor surface quality that typically is not satisfactory for functional applications. The aim of this work is to use areal analysis to characterize selective laser melting surfaces. The results highlight a marked variability and anisotropy that cannot be evaluated through traditional measurement. The building orientation and secondary finishing operations are analyzed and discussed. Findings demonstrate how areal analysis can be used to determine how to implement barrel finishing with the aim of reducing anisotropy and increasing surface quality. Full article

(This article belongs to the Special Issue Laser-Based Manufacturing II)

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20 pages, 13406 KiB

Open AccessEditor’s ChoiceArticle

Laser Additive Manufacturing of Duplex Stainless Steel via Powder Mixture

by Chengsong Cui, Louis Becker, Eric Gärtner, Johannes Boes, Jonathan Lentz, Volker Uhlenwinkel, Matthias Steinbacher, Sebastian Weber and Rainer Fechte-Heinen

J. Manuf. Mater. Process. 2022, 6(4), 72; https://doi.org/10.3390/jmmp6040072 - 2 Jul 2022

Cited by 18 | Viewed by 3994

Abstract

Laser additively manufactured duplex stainless steels contain mostly ferrite in the as-built parts due to rapid solidification of the printed layers. To achieve duplex microstructures (ferrite and austenite in roughly equal proportions) and, thus, a good combination of mechanical properties and corrosion resistance, [...] Read more.

Laser additively manufactured duplex stainless steels contain mostly ferrite in the as-built parts due to rapid solidification of the printed layers. To achieve duplex microstructures (ferrite and austenite in roughly equal proportions) and, thus, a good combination of mechanical properties and corrosion resistance, an austenitic stainless steel powder (X2CrNiMo17-12-2) and a super duplex stainless steel powder (X2CrNiMoN25-7-4) were mixed in different proportions and the powder mixtures were processed via PBF-LB/M (Laser Powder Bed Fusion) under various processing conditions by varying the laser power and the laser scanning speed. The optimal process parameters for dense as-built parts were determined by means of light optical microscopy and density measurements. The austenitic and ferritic phase formation of the mixed alloys was significantly influenced by the chemical composition adjusted by powder mixing and the laser energy input during PBF-LB/M. The austenite content increases, on the one hand, with an increasing proportion of X2CrNiMo17-12-2 in the powder mixtures and on the other hand with increasing laser energy input. The latter phenomenon could be attributed to a slower solidification and a higher melt pool homogeneity with increasing energy input influencing the phase formation during solidification and cooling. The desired duplex microstructures could be achieved by mixing the X2CrNiMo17-12-2 powder and the X2CrNiMoN25-7-4 powder at a specific mixing ratio and building with the optimal PBF-LB/M parameters. Full article

(This article belongs to the Special Issue Laser-Based Manufacturing II)

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11 pages, 3285 KiB

Open AccessArticle

Effects of Heat Treatment on Microstructure and Mechanical Properties of AlSi10Mg Fabricated by Selective Laser Melting Process

by Catherine Dolly Clement, Julie Masson and Abu Syed Kabir

J. Manuf. Mater. Process. 2022, 6(3), 52; https://doi.org/10.3390/jmmp6030052 - 22 Apr 2022

Cited by 15 | Viewed by 5836

Abstract

AlSi10Mg is the most widely additively manufactured and commercialized aluminum alloy and has been used in this study to analyze the effect of heat treatment on its microstructure and mechanical properties. Although research indicates AlSi10Mg parts produced by selective laser melting have characteristically [...] Read more.

AlSi10Mg is the most widely additively manufactured and commercialized aluminum alloy and has been used in this study to analyze the effect of heat treatment on its microstructure and mechanical properties. Although research indicates AlSi10Mg parts produced by selective laser melting have characteristically very fine microstructures, there is a need for more intensive study to comprehend the effect of heat treatment on the mechanical properties of this alloy by analyzing its microstructure. In this study, AlSi10Mg specimens heat-treated at varying temperatures were analyzed by optical and electron microscopes. Micro-indentation hardness and tensile tests were performed to evaluate mechanical properties while considering the specimen build orientation. Observation shows that it is nearly impossible to completely dissolve the evolved second phase silicon-rich particles, which may have significant effects on the mechanical characteristics. Electron microscopy images show the evolution of iron-rich particles in the Al matrix, which may have a significant influence on the mechanical properties of the alloy. Full article

(This article belongs to the Special Issue Laser-Based Manufacturing II)

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13 pages, 4718 KiB

Open AccessArticle

Flexural Fatigue Test—A Proposed Method to Characterize the Lifetime of Conductor Tracks on Polymeric Substrates

by Simon Petillon, Andrea Knöller, Philipp Bräuer, David Helm, Tobias Grözinger, Sascha Weser, Wolfgang Eberhardt, Jörg Franke and André Zimmermann

J. Manuf. Mater. Process. 2022, 6(2), 41; https://doi.org/10.3390/jmmp6020041 - 1 Apr 2022

Viewed by 2975

Abstract

High quality and long product life are two fundamental requirements for all circuit carriers, including molded interconnect devices (MID), to find application in various fields, such as automotive, sensor technology, medical technology, and communication technology. When developing a MID for a certain application, [...] Read more.

High quality and long product life are two fundamental requirements for all circuit carriers, including molded interconnect devices (MID), to find application in various fields, such as automotive, sensor technology, medical technology, and communication technology. When developing a MID for a certain application, not only the design, but also the choice of material as well as the process parameters need to be carefully considered. A well-established method to evaluate the lifetime of such MID, respective of their conductor tracks, is the thermal shock test, which induces thermomechanical stresses upon cycling. Even though this method has numerous advantages, one major disadvantage is its long testing time, which impedes rapid developments. Addressing this disadvantage, this study focuses on the laser direct structuring of thermoplastic LCP Vectra E840i LDS substrates and the subsequent electroless metallization of the commonly used layer system Cu/Ni/Au to force differences in the conductor tracks’ structure and composition. Performing standardized thermal shock tests alongside with flexural fatigue tests, using a customized setup, allows comparison of both methods. Moreover, corresponding thermomechanical simulations provide a direct correlation. The flexural fatigue tests induce equivalent or even higher mechanical stresses at a much higher cycling rate, thus drastically shorten the testing time. Full article

(This article belongs to the Special Issue Laser-Based Manufacturing II)

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Review

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26 pages, 4456 KiB

Open AccessReview

Laser Scribing of Photovoltaic Solar Thin Films: A Review

by Farzad Jamaatisomarin, Ruqi Chen, Sajed Hosseini-Zavareh and Shuting Lei

J. Manuf. Mater. Process. 2023, 7(3), 94; https://doi.org/10.3390/jmmp7030094 - 10 May 2023

Cited by 17 | Viewed by 8336

Abstract

The development of thin-film photovoltaics has emerged as a promising solution to the global energy crisis within the field of solar cell technology. However, transitioning from laboratory scale to large-area solar cells requires precise and high-quality scribes to achieve the required voltage and [...] Read more.

The development of thin-film photovoltaics has emerged as a promising solution to the global energy crisis within the field of solar cell technology. However, transitioning from laboratory scale to large-area solar cells requires precise and high-quality scribes to achieve the required voltage and reduce ohmic losses. Laser scribing has shown great potential in preserving efficiency by minimizing the drop in geometrical fill factor, resistive losses, and shunt formation. However, due to the laser induced photothermal effects, various defects can initiate and impact the quality of scribed grooves and weaken the module’s efficiency. In this regard, much research has been conducted to analyze the geometrical fill factor, surface integrity, and electrical performance of the laser scribes to reach higher power conversion efficiencies. This comprehensive review of laser scribing of photovoltaic solar thin films pivots on scribe quality and analyzes the critical factors and challenges affecting the efficiency and reliability of the scribing process. This review also covers the latest developments in using laser systems, parameters, and techniques for patterning various types of solar thin films to identify the optimized laser ablation condition. Furthermore, potential research directions for future investigations at improving the quality and performance of thin film laser scribing are suggested. Full article

(This article belongs to the Special Issue Laser-Based Manufacturing II)

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