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Defect Monitoring of Complex Geometries Through Machine Learning in LPBF Metal Additive Manufacturing
The Influence of Heat and Holding Time on the Warm Forming of Al–Mg–Si Alloys

Journal Description

Journal of Manufacturing and Materials Processing

Journal of Manufacturing and Materials Processing is an international, peer-reviewed, open access journal on the scientific fundamentals and engineering methodologies of manufacturing and materials processing published monthly online by MDPI.

Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
High Visibility: indexed within Scopus, ESCI (Web of Science), Inspec, CAPlus / SciFinder, Ei Compendex and other databases.
Journal Rank: JCR - Q2 (Engineering, Mechanical) / CiteScore - Q1 (Mechanical Engineering)
Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 15.9 days after submission; acceptance to publication is undertaken in 3.5 days (median values for papers published in this journal in the second half of 2025).
Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
Journal Cluster of Mechanical Manufacturing and Automation Control: Aerospace, Automation, Drones, Journal of Manufacturing and Materials Processing, Machines, Robotics and Technologies.

Impact Factor: 3.3 (2024); 5-Year Impact Factor: 3.6 (2024)

Imprint Information Journal Flyer Open Access ISSN: 2504-4494

Latest Articles

22 pages, 20244 KB

Open AccessArticle

Microstructural Evolution and Mechanical Behavior of L-PBF Al-Cu 224 Alloy: Role of Process Parameters and Heat Treatment

by Esmaeil Pourkhorshid, Paul Rometsch, Mousa Javidani, Alexandre Bily and X.-Grant Chen

J. Manuf. Mater. Process. 2026, 10(6), 205; https://doi.org/10.3390/jmmp10060205 (registering DOI) - 12 Jun 2026

This study investigates the effect of laser powder bed fusion (L-PBF) parameters and T7 heat treatment on the defect formation, microstructure, and mechanical properties of a high-strength Al-Cu 224 aluminum alloy. The laser power (200–370 W), scanning speed (130–1900 mm/s), and hatch spacing [...] Read more.

This study investigates the effect of laser powder bed fusion (L-PBF) parameters and T7 heat treatment on the defect formation, microstructure, and mechanical properties of a high-strength Al-Cu 224 aluminum alloy. The laser power (200–370 W), scanning speed (130–1900 mm/s), and hatch spacing (90–130 μm) were varied to evaluate their influence on hot cracking and porosity. Microstructural characterization using optical microscopy, scanning electron microscopy, and electron backscatter diffraction revealed that an energy density of 400 J/mm³ substantially reduced visible hot cracking in the examined microscopic regions by reducing the thermal gradients. However, this resulted in increased keyhole porosity, thereby limiting the relative density to 95%. The as-built samples exhibited a yield strength of 152 MPa and an elongation of 9.2%, and the T7 heat treatment improved the yield strength to 233 MPa, whereas the elongation remained unchanged. Keyhole pores served as primary crack initiation/propagation sites during tensile loading, reducing ductility. Lower energy densities increased the geometrically necessary dislocation density and promoted cracking because of higher residual stresses due to greater accumulated plastic strain and lattice curvature. These results clarify process–structure–property relationships, emphasize the trade-offs between defect types and performance, and provide a robust framework for optimizing L-PBF processing of high-strength Al alloys through parameter tuning and post-heat treatment. Full article

(This article belongs to the Special Issue Recent Progress and Scientific Challenges in Laser-Based Additive Manufacturing)

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29 pages, 28942 KB

Open AccessArticle

Development of a Launch Mechanism for Small Satellites Using Laser Powder Bed Fusion Process

by Cosmin Gogu, Cătălin-Gheorghe Amza and Cristina Pupăză

J. Manuf. Mater. Process. 2026, 10(6), 204; https://doi.org/10.3390/jmmp10060204 - 11 Jun 2026

The deployment of CubeSats requires reliable, lightweight, and space-efficient launch mechanisms. Traditional spring-based deployers often rely on standard off-the-shelf components, limiting the design flexibility. This study presents a pilot design-to-verification workflow for a CubeSat deployment mechanism manufactured by Laser Powder Bed Fusion from [...] Read more.

The deployment of CubeSats requires reliable, lightweight, and space-efficient launch mechanisms. Traditional spring-based deployers often rely on standard off-the-shelf components, limiting the design flexibility. This study presents a pilot design-to-verification workflow for a CubeSat deployment mechanism manufactured by Laser Powder Bed Fusion from 316L stainless steel. The workflow integrates analytical sizing, kinematic and numerical force assessment, FEM-based LPBF process simulation employed as a design-support tool to predict thermal displacements and residual stress that occur during manufacturing, prototype manufacturing and optical inspection. Optical scanning indicated that the main envelope dimensions remained close to the nominal CAD values, while the support-plate warping was localized at the plate corners due to the residual thermal stress after the support removal. The study validates the manufacturability of a single LPBF orbital-deployer lunch mechanism and assesses its dimensional accuracy and workflow feasibility, rather than its functional mechanical performance. It also includes mitigation strategies for deployer distortions. Full article

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28 pages, 9487 KB

Open AccessArticle

Multi-Objective Optimization of a Composite FRP Laminated Sandwich Structure Using Artificial Neural Network and Particle Swarm Optimization Algorithm

by Muhammad Ali Sadiq and György Kovács

J. Manuf. Mater. Process. 2026, 10(6), 203; https://doi.org/10.3390/jmmp10060203 - 11 Jun 2026

Designing lightweight composite sandwich structures is challenging due to the conflicting objectives of minimizing structural weight and cost while satisfying strength and stiffness requirements. The optimization procedure becomes more complex when multiple discrete design variables and nonlinear material behavior are involved. This study [...] Read more.

Designing lightweight composite sandwich structures is challenging due to the conflicting objectives of minimizing structural weight and cost while satisfying strength and stiffness requirements. The optimization procedure becomes more complex when multiple discrete design variables and nonlinear material behavior are involved. This study presents a newly developed optimization methodology for a sandwich structure composed of Fiber Reinforced Polymer (FRP) laminated facesheets and an aluminum honeycomb core. To reduce the computational cost associated with repeated high-fidelity Finite Element (FE) analyses, a surrogate modeling strategy based on Artificial Neural Networks (ANNs) is employed to approximate the structural response. The applied dataset is generated using Monte Carlo simulation in which combinations of design variables are used as inputs, and the corresponding structural responses obtained from the analytical formulation are used as outputs for training the ANN surrogate model. The trained ANN model is integrated with a Multi-Objective Niching Memetic Particle Swarm Optimization (MO-NMPSO) algorithm to simultaneously minimize structural weight and material cost while satisfying constraints on facesheet strength, wrinkling, intra-cell buckling, deflection, core shear failure and structural thickness. The resulting Pareto-optimal solutions are validated through detailed FE simulations, demonstrating the reliability of the newly elaborated optimization framework. The results of the newly developed computationally efficient optimization procedure provide a diverse set of optimal design solutions for the investigated sandwich structure. Full article

(This article belongs to the Special Issue Processing, Mechanical Properties, and Manufacturing Techniques of Advanced Composite Materials)

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26 pages, 4784 KB

Open AccessArticle

Microstructural Diversity in Dispersed Composites Governed by Inclusion Distribution

by Vladimir Mityushev, Pawel Kurtyka, Zhanat Zhunussova and Akylkerey Sarvarov

J. Manuf. Mater. Process. 2026, 10(6), 202; https://doi.org/10.3390/jmmp10060202 - 10 Jun 2026

The microstructure of metal matrix composites is inherently governed by fabrication routes and processing parameters, yet technological and physical constraints often prevent the realization of intended structural designs. In particle-reinforced composites produced via casting, interactions between the solidification front and inclusions frequently lead [...] Read more.

The microstructure of metal matrix composites is inherently governed by fabrication routes and processing parameters, yet technological and physical constraints often prevent the realization of intended structural designs. In particle-reinforced composites produced via casting, interactions between the solidification front and inclusions frequently lead to agglomeration, segregation, and hence, a non-uniform distribution of the inclusions concentration. To mitigate these effects, post-processing techniques such as Friction Stir Processing offering particular promise for cast materials by refining microstructures and enhancing phase homogeneity. This study addresses these challenges by application of Fourier transform analysis to characterize stochastic inclusion distributions. Building on the Windows Washing method, we extend its application to heterogeneous media with varying inclusion concentrations. Through computer simulations and experimental analysis of real composites, we demonstrate that discrete Fourier transform can reveal hidden stochastic periodicity. The proposed framework provides a pathway toward improved predictive models and optimization strategies for metal matrix composites processing and performance. Full article

(This article belongs to the Special Issue Processing, Mechanical Properties, and Manufacturing Techniques of Advanced Composite Materials)

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21 pages, 5558 KB

Open AccessArticle

Sustainable 3D Printing of Recycled PET: Influence of Infill Architecture and Layer Thickness on Mechanical Behavior

by Rahmat Doni Widodo, Muhammad Irfan Nuryanta and Muhammad Akhsin Muflikhun

J. Manuf. Mater. Process. 2026, 10(6), 201; https://doi.org/10.3390/jmmp10060201 - 8 Jun 2026

The utilization of polyethylene terephthalate (PET) waste from single-use packaging offers potential for sustainable manufacturing. This study evaluates recycled PET (rPET) from bottles as an FDM filament by varying infill architectures (honeycomb, gyroid, grid, and triangles) and layer thicknesses (0.20, 0.25, and 0.30 [...] Read more.

The utilization of polyethylene terephthalate (PET) waste from single-use packaging offers potential for sustainable manufacturing. This study evaluates recycled PET (rPET) from bottles as an FDM filament by varying infill architectures (honeycomb, gyroid, grid, and triangles) and layer thicknesses (0.20, 0.25, and 0.30 mm), with commercial PETG as a benchmark. Compared with previous rPET FDM studies, which were limited to reporting mechanical strength, the novelty of this study lies in the fact that it not only reports mechanical strength performance, but also compares printing time requirements and material efficiency. Efficiency calculations are obtained by comparing the weight of the filament to the weight of the printed specimen, which then correlates with optimizing processing time and costs. Overall, rPET produced densities of 1.11–1.22 g/cm³, tensile strengths of 12.5–22.5 MPa, flexural strengths of 12.5–30 MPa, impact strengths of 0.032–0.060 J/mm², and surface roughnesses of Ra 5.2–7.1 μm, while PETG showed higher mechanical performance (tensile 30–39.5 MPa, flexural 30–50 MPa, impact 0.037–0.065 J/mm²) and comparable density (1.15–1.27 g/cm³). Within rPET, gyroid provided the best optimal performance; the gyroid (0.20 mm) variation achieved the highest impact response (0.060 J/mm²) and the lowest Ra (5.2 μm) and the gyroid (0.25 mm) variation maximized flexural strength (30 MPa) and the gyroid (0.30 mm) variation maximized tensile strength (22.5 MPa). Material utilization efficiency was consistently higher for rPET (65–68%) than for PETG (46–56%). These results provide an integrated rPET-specific assessment and practical parameter recommendations for functional 3D printing, while also aligning with SDG 12 by pro-moting resource-efficient circular-economy practices through the utilization of waste materials in additive manufacturing. Full article

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16 pages, 16748 KB

Open AccessArticle

Roll Bonding of Aluminium Coupons Using the Established Fully Fledged Offline Fabrication Facilities

by Joseph Moema, Charles Siyasiya, Veronica Morudu, Maje Phasha and Mbavhalelo Maumela

J. Manuf. Mater. Process. 2026, 10(6), 200; https://doi.org/10.3390/jmmp10060200 - 8 Jun 2026

The South African aluminium industry faces technical challenges related to cladded ingots used in automotive heat exchangers, creating a need for offline processing methods that can replicate rolling processes like roll bonding, as large-scale industrial trials are costly and difficult to control. To [...] Read more.

The South African aluminium industry faces technical challenges related to cladded ingots used in automotive heat exchangers, creating a need for offline processing methods that can replicate rolling processes like roll bonding, as large-scale industrial trials are costly and difficult to control. To address this, Mintek established a comprehensive offline manufacturing facility for process and product development of rolled metal products, focusing on the thermomechanical processing of aluminium alloys. In this study, stacked AA4045/AA3003mod coupons were processed under controlled conditions by varying thickness reduction, temperature, and reheating, aiming to investigate the effect of isothermal soaking time on microstructure and mechanical properties. Tensile tests were performed on clad sheets before and after brazing heat treatment, and fracture surfaces were examined via scanning electron microscopy. Samples heated at 505 °C for ≥38 h, followed by cold rolling and annealing, fell at the lower end of the 9031-H24 specification for yield strength, which is important for this application (i.e., the minimum tensile yield strength of 145 MPa and the ultimate tensile strength (UTS) range of 190 to 230 MPa). Fracture surface analysis revealed a dimple-dominated structure in cold-rolled and annealed samples, indicating ductile fracture. The study concludes that the offline roll-bonding method successfully replicates industrial cladding processes, and that isothermal soaking duration significantly influences mechanical performance, though careful control of thermal exposure is necessary to meet the specified mechanical properties. Full article

(This article belongs to the Topic Advances in Processing, Microstructure and Mechanical Properties of Lightweight Alloys)

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17 pages, 10205 KB

Open AccessArticle

Mechanical and Thermal Performance of Sustainable PETG/Cork Composites Processed by Fused Filament Fabrication Technology

by Saltanat Bergaliyeva, Daniel Correro-Cabrera, Ismael Romero-Ocaña, Nuria Baladés, Natalia Fernández Delgado, Sergio I. Molina and David L. Sales

J. Manuf. Mater. Process. 2026, 10(6), 199; https://doi.org/10.3390/jmmp10060199 - 8 Jun 2026

Despite major advances in polymer composites for Fused Filament Fabrication (FFF), designing environmentally sustainable materials from bio-based resources remains a key research priority. The objective of this study is to check the processability and properties of sustainable PETG/cork composites processed via FFF technology. [...] Read more.

Despite major advances in polymer composites for Fused Filament Fabrication (FFF), designing environmentally sustainable materials from bio-based resources remains a key research priority. The objective of this study is to check the processability and properties of sustainable PETG/cork composites processed via FFF technology. Filaments with 5 and 10% of cork were created using a twin-screw extruder. Samples from these filaments were printed by FFF technology, and subsequently subjected to morphological, thermal and mechanical testing. As a result of the study, it was proved that the 3D-printing process did not result in a tensile strength decrease with an increasing cork percentage, as observed in mechanical testing of the filament. The addition of cork significantly increased plasticity without decreasing tensile strength when introducing 10% of cork particles. The interfacial temperatures of the prepared composites did not differ much from the polymer matrix and were 79.55 °C, 77.56 °C, 76.67 °C for PET-G, PET-G + 5% cork, and PET-G + 10% cork, respectively. Thermal conductivity decreased significantly as the percentage of cork increased. This work shows that FFF technology is one of the most suitable manufacturing options for PETG + 10% cork composites to produce things with low conductivity and the same thermal and mechanical properties as pure PETG. Full article

(This article belongs to the Special Issue Innovative and Sustainable Advances in Polymer Composites for Additive Manufacturing: Processing, Microstructure, Machining, and Mechanical Properties)

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19 pages, 9330 KB

Open AccessArticle

Manufacturing of 3D Auxetic Structures Through Perforations of Corrugated Systems

by Libera Vitiello, Gianluca Cicala, Giovanni Filippone, Pietro Russo, Ruben Gatt, Joseph N. Grima and Pierre-Sandre Farrugia

J. Manuf. Mater. Process. 2026, 10(6), 198; https://doi.org/10.3390/jmmp10060198 - 4 Jun 2026

Fabrication of auxetic structures has always been a limiting factor in their availability. Their complex shape, a requirement originating from the deformation mechanism that leads to a negative Poisson’s ratio, has also limited their manufacturability. In the case of auxetic systems that deform [...] Read more.

Fabrication of auxetic structures has always been a limiting factor in their availability. Their complex shape, a requirement originating from the deformation mechanism that leads to a negative Poisson’s ratio, has also limited their manufacturability. In the case of auxetic systems that deform through the rotating semi-rigid mechanism—which allows for the concurrent deformation and rotation of their constituent element—the situation is even more complicated. Relatively few examples of these types of structures are known, with most work on them being largely theoretical. This includes their use in explaining the auxetic mechanism in certain molecules. Nevertheless, these systems can, in principle, offer added functionalities, as they undergo a shape change while still exhibiting a negative Poisson’s ratio. To this end, this work presents a practical scheme for the manufacturing of 3D rotating semi-rigid units, whereby these are produced through perforations of corrugated sheets. For the purpose of this investigation, diamond-shaped perforations were chosen, and the side profile of the corrugated sheet consisted of successive semicircles that alternate in orientation. Analysis of the system indicated that a 3D negative Poisson’s ratio can be obtained while allowing the distance between the hinges to change during deformation. Full article

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Graphical abstract

18 pages, 9138 KB

Open AccessArticle

Design and Computational Efficiency of a GPU-Resident Integrated Execution Pipeline for Explicit Large-Deformation Finite Element Analysis

by Honglae Kim, Seokmoo Hong and Naksoo Kim

J. Manuf. Mater. Process. 2026, 10(6), 197; https://doi.org/10.3390/jmmp10060197 - 3 Jun 2026

We describe a GPU-resident execution pipeline for explicit large-deformation finite element analysis in which every stage of the timestep—internal force evaluation, contact processing, nodal update, time integration, and minimum edge-length reduction—operates on arrays that remain in device memory, so per-step bulk transfers across [...] Read more.

We describe a GPU-resident execution pipeline for explicit large-deformation finite element analysis in which every stage of the timestep—internal force evaluation, contact processing, nodal update, time integration, and minimum edge-length reduction—operates on arrays that remain in device memory, so per-step bulk transfers across PCIe are avoided. Contact is handled on the device through a shared-memory brute-force proximity search with warp-ballot stream compaction. We exercise the solver on a hemisphere compression benchmark at six mesh resolutions (83 K–1.89 M elements). On an NVIDIA L40, per-step speedups over a single CPU core range from about 99× to 138×, increasing with problem size and approaching a plateau near 137× for the largest meshes (above roughly 1 M elements); the contact-enabled configuration adds a net ON/OFF overhead of +13% to +21% to the step time. Against LS-DYNA running in SMP mode on the same problem, the proposed solver is roughly 94× faster than the best 8-core configuration, a margin consistent with the multicore saturation observed in the SMP measurements. The remaining limitations—single-GPU execution, FP32 arithmetic, and rigid-body contact search without a BVH broad phase—are identified as specific targets for multi-GPU, mixed-precision, and scalable-contact extensions. Full article

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19 pages, 36761 KB

Open AccessArticle

Synergistic Strengthening of Copper by In Situ Graphene Growth and Severe Plastic Deformation

by Junaid Dar, Laxman Bhatta, Islam Hafez, Megumi Kawasaki and Dong Lin

J. Manuf. Mater. Process. 2026, 10(6), 196; https://doi.org/10.3390/jmmp10060196 - 2 Jun 2026

High-purity copper features excellent electrical conductivity but generally low mechanical properties. Adding a three-dimensional graphene network as reinforcement to make a copper–graphene metal matrix composite is promising for a wide range of applications with better mechanical performance and functional capabilities. However, direct application [...] Read more.

High-purity copper features excellent electrical conductivity but generally low mechanical properties. Adding a three-dimensional graphene network as reinforcement to make a copper–graphene metal matrix composite is promising for a wide range of applications with better mechanical performance and functional capabilities. However, direct application in a metal matrix is difficult due to unfavorable wetting, which causes poor dispersion and weak interfacial bonding in the graphene–metal system. Here, the powder metallurgy method was used to construct a three-dimensional continuous graphene network in the copper matrix combined with high-pressure torsion. Optimized deformation/thermomechanical treatment enhanced the microstructural development processed by the severe plastic deformation method of high-pressure torsion. The primary advantage of this hybrid process is that it enables us to achieve grains with a size in the ultra-fine or even nanoscale. A homogeneous equiaxed nanostructure without segregation was observed during microstructural characterization, with a grain size of ~300 nm. This study investigated structural development during progressive deformation, and the samples were evaluated from the viewpoint of grain size and grain boundaries. The process significantly increased the microhardness of the copper–graphene composite. The tensile strength reached ~500 MPa at room temperature. The interpenetrating structural feature of graphene promoted interfacial shear stress to a high level, whereas plastic deformation increased the dislocation density and grain boundaries, thus resulting in significantly enhanced load transfer strengthening and crack-bridging toughness simultaneously. Full article

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24 pages, 41455 KB

Open AccessReview

An Overview of Plastic Deformation Preparation Methods and Application of Gradient-Structured Materials

by Zhenhai Xu, Jiajia Wang, Shaoxi Xue, Debin Shan, Jie Xu and Bin Guo

J. Manuf. Mater. Process. 2026, 10(6), 195; https://doi.org/10.3390/jmmp10060195 - 31 May 2026

Gradient-structured materials have attracted considerable attention due to their gradient microstructural distribution and the resulting unique mechanical properties, showing great potential in aerospace, marine, and energy applications. This review presents a comprehensive overview of plastic deformation methods for fabricating gradient-structured materials, according to [...] Read more.

Gradient-structured materials have attracted considerable attention due to their gradient microstructural distribution and the resulting unique mechanical properties, showing great potential in aerospace, marine, and energy applications. This review presents a comprehensive overview of plastic deformation methods for fabricating gradient-structured materials, according to the loading conditions and resulting deformation modes, which are categorized into localized loading-localized deformation, localized loading-localized/global deformation, and global loading-localized/global deformation strategies. The applications of gradient-structured materials are further summarized in terms of surface properties, bulk mechanical properties, and forming performance. Finally, the current challenges and future research directions are discussed, focusing on quantitative structure-property relationships for inverse design, efficient and scalable fabrication strategies, and the synergistic effects of multi-level microstructures. This review offers significant insights into plastic-deformation-based fabrication methods and the diverse application properties of gradient-structured materials. Full article

(This article belongs to the Topic Advances in Manufacturing and Mechanics of Materials)

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24 pages, 6830 KB

Open AccessArticle

A Numerical and Experimental Analysis of Large Interference Fitting Cylinders

by Iñigo Llavori, Alaitz Zabala, Joseba Mendiguren, Xuban Telleria, Nagore Otegi and Eneko Saenz-de-Argandoña

J. Manuf. Mater. Process. 2026, 10(6), 194; https://doi.org/10.3390/jmmp10060194 - 31 May 2026

This research analyses the mechanical behaviour of the insertion process between two cylinders that are commonly employed in non-rigid joints. Through comprehensive analysis, the study reveals the dynamics of insertion force, particularly by highlighting the impact of initial collisions on subsequent deformations and [...] Read more.

This research analyses the mechanical behaviour of the insertion process between two cylinders that are commonly employed in non-rigid joints. Through comprehensive analysis, the study reveals the dynamics of insertion force, particularly by highlighting the impact of initial collisions on subsequent deformations and the ultimate evolution of insertion forces. Contrary to intuitive assumptions, our findings reveal that higher interference levels between cylinders do not uniformly correlate with increased maximum insertion force levels; instead, for certain cylinder combinations, higher interference generates lower maximum insertion force levels. Additionally, the significance of the thickness ratio as a pivotal determinant in predicting overall behaviour and insertion force, which is a variable that is often overlooked in conventional analyses, has been underscored. Furthermore, it has been demonstrated that the applicability of analytical equations that were developed as part of thick-walled cylinder theory diminishes when mechanical joints undergo plasticity, which underscores the need for alternative modelling approaches. Through finite element simulations, fidelity when representing insertion processes, with errors below 15%, not only capturing peak insertion forces but also delineating the nuanced evolution of forces and cylinder deformations, has been attained. Conversely, the analytical method employed from the examined literature yielded unrealistic insertion force estimations that proved inadequate for scenarios that involve substantial interference. Full article

(This article belongs to the Topic Advances in Manufacturing and Mechanics of Materials)

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21 pages, 11811 KB

Open AccessArticle

Deep CNN-Based Multi-Class TIG Welding Defect Classification Using HDR Images with Explainable AI

by Deepika Nikam, Sagar Nikam, Tejaswini Bhosale, Declan Harkin, Mayur Sawant and Cormac McGarrigle

J. Manuf. Mater. Process. 2026, 10(6), 193; https://doi.org/10.3390/jmmp10060193 - 30 May 2026

Recent advances in deep convolutional neural networks (D-CNNs) have improved automated welding defect inspection. This study presents an explainable comparative framework for multi-class classification of defects in Aluminium 5083 TIG weld joints using High Dynamic Range (HDR) image data, integrating a transfer-learning model, [...] Read more.

Recent advances in deep convolutional neural networks (D-CNNs) have improved automated welding defect inspection. This study presents an explainable comparative framework for multi-class classification of defects in Aluminium 5083 TIG weld joints using High Dynamic Range (HDR) image data, integrating a transfer-learning model, stratified five-fold cross-validation, computational-time analysis, and Grad-CAM-based visual interpretation. Five transfer-learning-based D-CNN architectures such as VGG16, VGG19, Inception V3, MobileNet, and DenseNet were trained, validated, and tested under a common evaluation protocol to assess their suitability for welding defect classification. The dataset was organised into classes such as good weld, contamination, lack of fusion, lack of penetration, and misalignment. Model performance was compared using multiple evaluation metrics. Stratified five-fold cross-validation was also performed to assess model stability. Alongside the cross-validation, training/inference times were also recorded to evaluate computational feasibility. Grad-CAM was used as an explainable artificial intelligence (XAI) technique in order to provide visual interpretation of weld regions. Among evaluated models, DenseNet achieved the best overall performance, with a classification accuracy of 98%, and showed the least confusion across defect classes. The Grad-CAM visualisations showed that the model focused on defect-relevant weld regions, demonstrating that transfer-learning D-CNNs with XAI can support TIG welding defect classification and effective visual quality assessment. Full article

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14 pages, 912 KB

Open AccessArticle

Comparative Life Cycle Assessment of Hull Manufacturing for Small-Size Crafts

by Paolo De Sio, Vittorio Rosanova, Vitantonio Esperto, Antonello Astarita and Fausto Tucci

J. Manuf. Mater. Process. 2026, 10(6), 192; https://doi.org/10.3390/jmmp10060192 - 30 May 2026

In recent years, environmental sustainability has become a key issue in the shipbuilding industry, driving research towards a reduction in the environmental impact throughout the entire life cycle of vessels. In this context, composite materials are a solid alternative to achieve mechanical performance [...] Read more.

In recent years, environmental sustainability has become a key issue in the shipbuilding industry, driving research towards a reduction in the environmental impact throughout the entire life cycle of vessels. In this context, composite materials are a solid alternative to achieve mechanical performance optimization and energy consumption reduction. This study compares two hull configurations, one in a glass fiber-reinforced thermoset composite and one in a thermoplastic composite sandwich structure, through life cycle assessment. The aim is to assess the influence of material choice and structural configuration on overall environmental impacts by analyzing energy and material inputs and emissions throughout the entire life cycle, from “cradle to grave” excluding the end-of-life treatment. The results evidence a 36% average reduction in the impact categories analyzed. Moreover, economic benefits emerged, with a 35% reduction in the cost of energy required during the analyzed life cycle phases and 9% reduction in the material supply. This work aims to contribute to the definition of more sustainable design strategies to produce hulls and naval components, promoting a transition towards a more efficient and environmentally friendly nautical sector. Full article

(This article belongs to the Special Issue Processing, Mechanical Properties, and Manufacturing Techniques of Advanced Composite Materials)

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18 pages, 52572 KB

Open AccessArticle

Machining-Induced Surface Deformation Layer and the Impact on Tensile Plasticity of 316L Stainless Steel

by Bokai Lou, Jing Ni, Jinghui Zhou, Lihua He, Zhenbing Cai and Zefei Zhu

J. Manuf. Mater. Process. 2026, 10(6), 191; https://doi.org/10.3390/jmmp10060191 - 29 May 2026

316L stainless steel is widely used in aerospace components because of its mechanical properties and corrosion resistance. Standard tensile specimens are commonly used to evaluate material behavior, yet their measured tensile response can be affected by the final turning process. This study investigated [...] Read more.

316L stainless steel is widely used in aerospace components because of its mechanical properties and corrosion resistance. Standard tensile specimens are commonly used to evaluate material behavior, yet their measured tensile response can be affected by the final turning process. This study investigated the effects of cutting speed and depth of cut on the surface integrity and tensile properties of small standard 316L tensile specimens. Cutting-temperature measurement, optical surface characterization, EBSD analysis, fracture observation, and quasi-static tensile testing were combined to evaluate the machined specimens. A cutting speed of 45 m/min produced the most stable thermal response after repeated tool–workpiece contacts, with a temperature variation of 40.3%. Lower cutting speeds suppressed vibration-induced micro-pits and improved the morphology consistency between Area I and Area II. At the maximum depth of cut, increasing the cutting speed from 15 m/min to 60 m/min reduced the tensile strength from 1136.02 MPa to 1082.75 MPa and the tensile elongation from 56.6% to 53.5%. These results show that the tensile properties of turned specimens are governed by the combined effects of thermal response, surface morphology, deformation-layer microstructure, and fracture behavior. Among the tested conditions,

V_{c}

= 15 m/min,

a_{p}

= 0.4 mm, and

f

= 0.1 mm/rev are recommended when tensile properties are the main requirement. Full article

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33 pages, 1507 KB

Open AccessReview

Soil–Cement Mixtures with Fiber Reinforcement in 3D Printing: Challenges and Opportunities for Sustainable Construction

by Juan D. Trujillo, Sandra Villamizar and Daniel Gomez

J. Manuf. Mater. Process. 2026, 10(6), 190; https://doi.org/10.3390/jmmp10060190 - 29 May 2026

Additive manufacturing with soil–cement mixtures is emerging as a disruptive approach to advancing sustainable manufacturing processes. However, its industrial scalability remains limited by material brittleness and a lack of process standardization. This study presents an integrative literature review that critically evaluates the influence [...] Read more.

Additive manufacturing with soil–cement mixtures is emerging as a disruptive approach to advancing sustainable manufacturing processes. However, its industrial scalability remains limited by material brittleness and a lack of process standardization. This study presents an integrative literature review that critically evaluates the influence of fiber reinforcement on the 3D printing process and the mechanical performance of soil–cement mixtures within the context of sustainable construction and circular economy principles. The analysis integrates fresh-state rheological behavior with hardened-state performance, showing that an optimized fiber dosage (0.3–0.5% by volume) shifts the failure mode from brittle to quasi-ductile while reducing crack propagation by approximately 60%. Additionally, the study compares various fiber types, including synthetic and natural alternatives. The results show that synthetic fibers used at low dosages (0.5–1.0% by volume) provide the greatest improvements in tensile strength and post-cracking ductility. In contrast, natural fibers, typically used at higher dosages (8.0–13.0% by volume), mainly improve toughness and thermal performance, with more limited gains in strength. The review also identifies key gaps in the existing literature, such as a lack of standardized protocols for measuring process parameters and the need for studies that address long-term durability and comprehensive lifecycle assessments. These findings outline a clear research roadmap to support the consolidation of reinforced soil–cement as a resilient and sustainable material for next-generation additive manufacturing. Full article

(This article belongs to the Special Issue Application of 3D Printing Technology in Manufacturing and Material Processing)

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16 pages, 5865 KB

Open AccessArticle

Thermal and Athermal Effects of High-Density Pulsed Electric Current on Strain-Hardening Relief in Cold-Rolled A6061 Under Liquid Nitrogen

by Shaojie Gu, Xiaoming Yu, Yanhong Peng, Lusheng Wang, Sungmin Yoon, Yi Cui, Yasuhiro Kimura, Yasuyuki Morita, Yuhki Toku and Yang Ju

J. Manuf. Mater. Process. 2026, 10(6), 189; https://doi.org/10.3390/jmmp10060189 - 29 May 2026

Understanding the respective roles of thermal and athermal effects during electric current treatment is critical for advancing current-assisted processing of metallic materials. In this study, strain hardening in cold-rolled A6061 was effectively relieved using high-density pulsed electric current. By conducting comparative experiments under [...] Read more.

Understanding the respective roles of thermal and athermal effects during electric current treatment is critical for advancing current-assisted processing of metallic materials. In this study, strain hardening in cold-rolled A6061 was effectively relieved using high-density pulsed electric current. By conducting comparative experiments under room-temperature and liquid-nitrogen conditions, the thermal and athermal contributions were quantitatively evaluated. The results indicate that thermal effects dominate over athermal effects in dislocation density reduction and strain-hardening relief. Nevertheless, the athermal effect, driven by electron wind force, is capable of promoting dislocation motion and annihilation. This work provides a practical framework for evaluating thermal and athermal contributions and offers new insights into microstructure control via electric current, with implications for the design of advanced structural materials. Full article

(This article belongs to the Special Issue Integrated Forming, Treatment and Modelling of Lightweight Alloys)

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14 pages, 5655 KB

Open AccessArticle

Nitinol 3D Printed by Micro Gas Metal Arc-Based Direct Energy Deposition

by Paulo Henrique Grossi Dornelas, Tadeu Castro Silva, João Pedro Oliveira, Ana S. Ramos, Maria Reis and Telmo G. Santos

J. Manuf. Mater. Process. 2026, 10(6), 188; https://doi.org/10.3390/jmmp10060188 - 29 May 2026

Additive manufacturing of NiTi shape memory alloys is challenging due to their sensitivity to composition and thermal history. The gap between high-resolution powder-based AM and high-productivity wire-based processes for NiTi remains a challenge. This study investigates the technical feasibility of depositing Ni-rich NiTi [...] Read more.

Additive manufacturing of NiTi shape memory alloys is challenging due to their sensitivity to composition and thermal history. The gap between high-resolution powder-based AM and high-productivity wire-based processes for NiTi remains a challenge. This study investigates the technical feasibility of depositing Ni-rich NiTi (56 wt.% Ni) using a micro gas metal arc-based directed energy deposition (µ-GMA-DED) process with a 300 µm wire. The investigation was conducted on a single-bead, single-layer geometry deposited onto a titanium substrate. The deposited layer exhibited a heterogeneous microstructure with dendritic and eutectic-like regions, where phase analysis revealed a mixture of NiTi and Ni₃Ti intermetallics. Differential scanning calorimetry showed suppression of the martensitic transformation in the as-deposited condition, likely due to the high fraction of non-transformable Ni₃Ti, compositional redistribution during rapid solidification, and potential substrate dilution. The nanoindentation results reflected this heterogeneity, with Young’s modulus ranging from 64 to 151 GPa. While post-deposition heat treatment partially restored the martensitic transformation, these results demonstrate the preliminary feasibility of the µ-GMA-DED process, noting that strict control over chemistry and dilution is required before the route can be applied to functional components. Full article

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29 pages, 18319 KB

Open AccessArticle

Effect of Porosity and Post-Processing on the Mechanical Performance of Additively Manufactured PEEK Osteoconductive Scaffolds

by Samreen Dallal, Babak Eslami and Saeed Tiari

J. Manuf. Mater. Process. 2026, 10(6), 187; https://doi.org/10.3390/jmmp10060187 - 29 May 2026

Additive manufacturing enables the fabrication of porous polyetheretherketone (PEEK) structures with controlled architectures for biomedical applications. In particular, porous PEEK scaffolds have attracted significant attention due to their potential to enhance osteoconductivity while maintaining mechanical compatibility with bone. However, the relationship between porosity, [...] Read more.

Additive manufacturing enables the fabrication of porous polyetheretherketone (PEEK) structures with controlled architectures for biomedical applications. In particular, porous PEEK scaffolds have attracted significant attention due to their potential to enhance osteoconductivity while maintaining mechanical compatibility with bone. However, the relationship between porosity, post-processing conditions, and mechanical performance remains insufficiently understood, especially at high porosity levels. In this study, the effects of porosity (49–81%) and post-processing heat treatment (4 and 6 h at 300 °C) on the mechanical performance of additively manufactured PEEK osteoconductive scaffolds were experimentally investigated. Compression and three-point bending tests were conducted to evaluate strength and elastic modulus. Results demonstrated a strong inverse relationship between porosity and mechanical properties, with significant reductions observed beyond critical thresholds of approximately 66% in compression and 59% in bending. Heat treatment improved mechanical performance at lower porosity levels, likely due to enhanced crystallinity and interlayer bonding, while its effect diminished at higher porosities due to reduced load-bearing material and ligament thinning. These findings highlight the importance of optimizing porosity and post-processing conditions to achieve a balance between mechanical integrity and osteoconductive potential in PEEK scaffolds. The results provide practical design guidelines for the development of additively manufactured PEEK structures for load-bearing orthopedic applications. Full article

(This article belongs to the Special Issue Processing, Mechanical Properties, and Manufacturing Techniques of Advanced Composite Materials)

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16 pages, 13233 KB

Open AccessArticle

Influence of Zr Addition on the Phase Composition, Mechanical Properties, Deformation Behavior and Crystallographic Texture of the Al−Gd−Cr−Ti Alloy for Thermal Neutron Absorption

by S. M. Amer, A. El-Khouly, Dmitry Nikolayev, T. A. Lychagina, Amr. B. ElDeeb, L. E. Gorlov, O. A. Yakovtseva, R. Yu. Barkov, M. V. Glavatskikh and A. V. Pozdniakov

J. Manuf. Mater. Process. 2026, 10(6), 186; https://doi.org/10.3390/jmmp10060186 - 28 May 2026

In the present study, a distinct core–shell structure comprising an Al₂₁GdCrTi core and an Al₃(Gd,Zr) shell was produced in the Al-7.9Gd-0.6Zr-0.2Cr-0.2Ti alloy after homogenization at 615 °C for 1 h. Concurrently, L1₂ nanoprecipitates (Al₃(Gd,Zr)) of 20–25 [...] Read more.

In the present study, a distinct core–shell structure comprising an Al₂₁GdCrTi core and an Al₃(Gd,Zr) shell was produced in the Al-7.9Gd-0.6Zr-0.2Cr-0.2Ti alloy after homogenization at 615 °C for 1 h. Concurrently, L1₂ nanoprecipitates (Al₃(Gd,Zr)) of 20–25 nm in size were formed. The neutron absorption reduction factor was evaluated at the Dubna research reactor, where a 1 mm thick rolled layer reduced the intensity of neutrons scattered from pure aluminum by a factor of 17 to 36. Cold rolling enhanced yield strength (175 ± 6 MPa) compared to hot–cold rolling (164 ± 2 MPa) but reduced elongation (11.9 ± 1.1% vs. 13.5 ± 0.2%), while ultimate tensile strength remained similar at 203 MPa. Full article

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