Journal of Manufacturing and Materials Processing

18 pages, 40074 KB

Open AccessArticle

Role of Inherent Heterostructure in Hydrogen-Induced Cracking of API X70 Pipeline Steel Under Pressurized CH₄-H₂ Mixed-Gas Environments

by Chun Kang, Yufa Deng, Mingji Huang, Hongzou Chao, Jinsong Liu, Guangming Chen, Tianle Liu and Tingshu Chen

J. Manuf. Mater. Process. 2026, 10(9), 315; https://doi.org/10.3390/jmmp10090315 - 25 Aug 2026

Abstract

In this study, the hydrogen embrittlement (HE) susceptibility and hydrogen-induced cracking behavior of X70 pipeline steel were investigated in CH₄–H₂ mixed-gas environments containing 5–20% H₂ at a total pressure of 7 MPa. Slow strain rate tensile tests, thermal desorption [...] Read more.

In this study, the hydrogen embrittlement (HE) susceptibility and hydrogen-induced cracking behavior of X70 pipeline steel were investigated in CH₄–H₂ mixed-gas environments containing 5–20% H₂ at a total pressure of 7 MPa. Slow strain rate tensile tests, thermal desorption spectroscopy, fractography, and electron backscatter diffraction (EBSD) were employed to correlate hydrogen uptake, mechanical degradation, fracture morphology, and crack evolution. The results showed that increasing the hydrogen fraction progressively deteriorated the mechanical performance of X70 pipeline steel, as evidenced by reductions in tensile strength and elongation. This degradation was accompanied by a fracture-mode transition from micro-void coalescence to quasi-cleavage fracture. More importantly, EBSD analysis revealed a hydrogen-content-dependent change in the role of the heterogeneous microstructure. At relatively low hydrogen fractions, fine-grained regions and microstructural heterogeneity acted as effective barriers to hydrogen-induced crack propagation. However, at higher hydrogen fractions, this intrinsic crack-arresting capability was substantially weakened. Newly formed cracks were observed to initiate ahead of pre-existing cracks and propagate preferentially along grain boundaries, with limited local plastic deformation. These findings demonstrate that the increased HE susceptibility of X70 pipeline steel under high-H₂ mixed-gas conditions is associated with the progressive loss of the crack-arresting resistance provided by its heterogeneous microstructure. Full article

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16 pages, 1573 KB

Open AccessArticle

Suitability of Different Anodic Aluminum Oxide Layer Morphologies and Metallization Processes for the Assembly of Surface Mount Devices by Reflow Soldering on Aluminum-Based Substrates

by Simon Petillon, Dominik Koch, Andrea Knöller, Kai Werum, Wolfgang Eberhardt and André Zimmermann

J. Manuf. Mater. Process. 2026, 10(9), 314; https://doi.org/10.3390/jmmp10090314 - 25 Aug 2026

Abstract

Circuit carriers perform various functions within electrical systems and products. This includes being the assembly platform for various components. To mount these components, soldering processes are predominantly used because of economic and technical benefits compared to other assembly technologies. Therefore, novel circuit carrier [...] Read more.

Circuit carriers perform various functions within electrical systems and products. This includes being the assembly platform for various components. To mount these components, soldering processes are predominantly used because of economic and technical benefits compared to other assembly technologies. Therefore, novel circuit carrier technologies should be compatible with soldering processes to compete with the state of the art. One of these innovative circuit carrier technologies is based on anodized aluminum substrates, which are characterized by their low cost and low thermal resistance. In this article, circuit carriers made of anodized aluminum with two different oxide morphologies being investigated. In addition, three different metallization processes were compared with regard to their suitability for a reflow soldering process for the assembly of surface mount devices (SMDs). In order to evaluate the assemblies, the force required to shear off the SMDs was measured before and after a cyclic thermal shock test (TST). One of the three investigated metallization processes yielded circuit carriers based on anodic aluminum oxide that enabled reflow soldering of the given SMD components. It was determined that both, the layer morphology and the metallization process, had an influence on the measured shear forces before and after TST. Full article

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17 pages, 6376 KB

Open AccessArticle

Microstructural and Mechanical Properties of Titanium Boride Coatings Fabricated by an Electron Beam Surface Modification

by Fatme Padikova, Ivana Ilievska, Lyubomira Veleva, Tatyana Koutzarova, Georgi Kotlarski, Nikolay Nedyalkov, Maria Ormanova, Vladimir Dunchev, Borislav Stoyanov and Stefan Valkov

J. Manuf. Mater. Process. 2026, 10(9), 313; https://doi.org/10.3390/jmmp10090313 - 25 Aug 2026

Abstract

The development of titanium-based surface alloys and coatings that combine extreme hardness with sufficient toughness remains a major challenge for components operating under severe friction and wear conditions. In this work, titanium–boride composite coatings were synthesized on commercially pure titanium by scanning electron [...] Read more.

The development of titanium-based surface alloys and coatings that combine extreme hardness with sufficient toughness remains a major challenge for components operating under severe friction and wear conditions. In this work, titanium–boride composite coatings were synthesized on commercially pure titanium by scanning electron beam surface alloying of preplaced boron. The influence of beam power (900, 1200, and 1500 W) on phase formation, microstructural evolution, and mechanical performance was systematically investigated. At 900 W, insufficient melting resulted in chemically and structurally heterogeneous coatings containing unreacted boron. Increasing the beam power to 1200 W promoted the formation of TiB and TiB₂ phases, leading to a maximum microhardness of approximately 5500 HV_0.2. At 1500 W, complete boron incorporation produced a graded architecture consisting of a Ti/TiB surface layer and a TiB₂-rich sublayer. This hierarchical microstructure exhibited a favorable combination of high hardness and the lowest coefficient of friction (0.21), representing a reduction of more than 50% compared with the untreated titanium substrate. These findings establish a clear relationship between electron beam processing conditions, microstructural development, and mechanical performance, demonstrating that scanning electron beam surface alloying is an effective strategy for tailoring high-performance Ti–B composite surfaces. The developed coatings show strong potential for aerospace and other advanced engineering applications requiring lightweight materials with high hardness and low friction. Full article

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24 pages, 8474 KB

Open AccessArticle

A Simulation-Based Optimization Framework of Stochastic Manufacturing Systems Using External Optimizer

by Gábor Ruzicska and Levente Czégé

J. Manuf. Mater. Process. 2026, 10(9), 312; https://doi.org/10.3390/jmmp10090312 - 24 Aug 2026

Abstract

In this paper, we investigate a simulation-based optimization framework that implements discrete-event simulation with evolutionary search methods to optimize stochastic manufacturing systems efficiently. The proposed methodology couples a Tecnomatix Plant Simulation model with a MATLAB R2025b-based optimization environment using a data exchange interface, [...] Read more.

In this paper, we investigate a simulation-based optimization framework that implements discrete-event simulation with evolutionary search methods to optimize stochastic manufacturing systems efficiently. The proposed methodology couples a Tecnomatix Plant Simulation model with a MATLAB R2025b-based optimization environment using a data exchange interface, allowing for the iterative assessment of complex manufacturing systems. The study examines an adaptive replication strategy designed to manage stochastic variability in simulation outcomes. In the proposed method, the required number of simulation runs are determined dynamically based on confidence interval estimation. The stopping criterion is specified using a 95% confidence interval, ensuring adequate statistical accuracy while decreasing excess computational effort. The framework allows multiple performance indicators, such as throughput, congestion levels, and machine failures, which are built into an objective function. The optimization is driven by a (1, λ)-evolution strategy with Gaussian mutation and adaptive step-size control, allowing robust search in noisy objective function. However, thanks to the framework presented, it is also possible to apply other optimization algorithms. A case study of a manufacturing system was built and modeled in Tecnomatix Plant Simulation to validate the proposed methodology. In comparison with the baseline production configuration in one of the simulation runs, the suggested framework reduced the objective function by 43.36%. Benchmark experiments demonstrated that the adaptive replication strategy achieved a solution quality comparable to fixed replication schemes while requiring fewer simulation evaluations on average, thereby reducing the computational effort without compromising statistical reliability. The benchmark comparison showed that the adaptive replication strategy improved the objective value by up to 17.20% compared with fixed-replication strategies while requiring substantially less computational time than the fixed-20 and fixed-30 strategies. The robustness analysis further demonstrates that the adaptive replication strategy produces consistent optimization results across independent runs despite the stochastic nature of both the simulation model and the optimization process. From an industrial perspective, the proposed framework provides a practical decision-support tool for the optimization of manufacturing systems under uncertainty, enabling more reliable parameter tuning with reduced computational effort and facilitating the implementation of digital twin technologies. Full article

(This article belongs to the Special Issue The Future of Manufacturing: Embracing Digitalization and Smart Technologies)

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28 pages, 23305 KB

Open AccessReview

A Review on Metallurgical and Mechanical Issues in Al/Steel Transition Joints Produced by Explosive Welding

by Girolamo Costanza, Fabio Giudice, Severino Missori, Andrea Sili and Maria Elisa Tata

J. Manuf. Mater. Process. 2026, 10(9), 311; https://doi.org/10.3390/jmmp10090311 - 23 Aug 2026

Abstract

Transition joints between lightweight aluminum alloys and high-strength steel are widely employed in the transportation industry, and especially in shipbuilding, as intermediate inserts between structural components made of dissimilar metals. While traditional fusion welding presents considerable difficulties in joining such metals, explosive welding [...] Read more.

Transition joints between lightweight aluminum alloys and high-strength steel are widely employed in the transportation industry, and especially in shipbuilding, as intermediate inserts between structural components made of dissimilar metals. While traditional fusion welding presents considerable difficulties in joining such metals, explosive welding is particularly suitable for producing thick plates with large contact surfaces between aluminum and steel. The process setup and the various parameters involved have been described in several articles, as also documented by some recent overviews. However, there has been no review of the most recent papers specifically dealing with the metallurgical characteristics of these interfaces, as well as with their mechanical properties. Thus, the present article aims to fill this gap by outlining a review on the state of the art to correlate the process parameter setting, interface characteristics, and weldability of aluminum/steel transition joints, and then focusing on the most relevant studies concerning the mechanical behavior under static and fatigue conditions of trimetallic joints (Al alloy/commercially pure Al/structural steel) for shipbuilding applications. The effects of welding-induced thermal fields during structural joint insertion are also taken into account, and the most recent proposals for strategies to improve mechanical performance are examined. Full article

(This article belongs to the Special Issue Advanced Welding Processes, Additive Manufacturing and Numerical Models: 2nd Edition)

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30 pages, 5930 KB

Open AccessArticle

Simulation-Based Prediction of Milling-Induced Shape Errors on Compliant, Additively Manufactured Components

by Berend Denkena, Klaas Maximilian Heide, Roland Lachmayer, Jens Niedermeyer and Fabian Schlenker

J. Manuf. Mater. Process. 2026, 10(8), 310; https://doi.org/10.3390/jmmp10080310 - 21 Aug 2026

Abstract

Additively manufactured components require machining of functional surfaces to meet geometric requirements. Due to low stiffness and non-nominal as-built geometry, they are susceptible to milling-induced shape deviations. This paper presents a geometric–numerical milling process simulation for predicting shape errors in compliant metallic laser [...] Read more.

Additively manufactured components require machining of functional surfaces to meet geometric requirements. Due to low stiffness and non-nominal as-built geometry, they are susceptible to milling-induced shape deviations. This paper presents a geometric–numerical milling process simulation for predicting shape errors in compliant metallic laser powder bed fusion components. The method combines real-geometry-based technological numerical control simulation, quasi-static force prediction, finite element-based structural response simulation, and surface reconstruction between roughing and finishing to enable multistage operation. The approach is validated for linear and non-linear toolpaths with varying immersion angles and compliance conditions. The results show reproduced force profiles, while magnitude deviations highlight the relevance of deformation-dependent engagement feedback in high-compliance regions. An analytical back-calculation based on the effective engagement cross-section reveals that accounting for deflection-induced engagement reduction reduces force deviations. During roughing, maximum shape errors for linear and non-linear toolpaths are overestimated by 4–5%, and critical high-error regions are identified. The reconstructed intermediate geometry after roughing is essential for finishing, since neglecting geometry feedback underestimates finishing forces. With geometry feedback, the maximum finishing shape error is predicted as 0.090 mm, while the measured value is 0.086 mm. The simulation captures dominant quasi-static shape-error regimes and supports process-chain-oriented prediction in additive–subtractive manufacturing. Full article

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21 pages, 22912 KB

Open AccessArticle

Filament Heating Voltage Effects on Cathode Operation and Weld Formation in Thin-Sheet Ti-6Al-4V Electron-Beam Welding

by Xinmin Shi, Junbiao Zhao, Zhiqiang Cao, Xueying Zhang, Ruonan Wang and Defeng Mo

J. Manuf. Mater. Process. 2026, 10(8), 309; https://doi.org/10.3390/jmmp10080309 - 21 Aug 2026

Abstract

Filament heating voltage governs thermionic electron emission in electron-beam guns, but its influence on weld formation under fixed electron-beam welding settings has received limited quantitative investigation. In this study, Ti-6Al-4V thin sheets were welded at filament heating voltages of 2.8–3.4 V, while the [...] Read more.

Filament heating voltage governs thermionic electron emission in electron-beam guns, but its influence on weld formation under fixed electron-beam welding settings has received limited quantitative investigation. In this study, Ti-6Al-4V thin sheets were welded at filament heating voltages of 2.8–3.4 V, while the accelerating voltage, beam current, focusing current, and welding speed were kept constant. Weld cross-sections were characterized experimentally, and the resulting thermal process was analyzed using a simplified cathode-emission calculation and finite element thermal analysis. A clear change in weld penetration behavior was observed within approximately 3.2–3.3 V. The weld aspect ratio increased from approximately 0.4 below this region to approximately 0.6 at 3.3 V and further to approximately 0.63 at 3.4 V. Concurrent changes in the required bias voltage, calculated equivalent cathode area, and weld geometry were consistent with a change toward a more stable cathode operating condition. The weld-geometry changes were also consistent with a change in the effective beam-energy distribution, although the beam profile was not measured directly. These results show that filament heating voltage should be treated as an independent equipment-side control variable even when the main electron-beam welding settings remain unchanged. Although the specific transition range depends on the electron gun, beam-current setting, and cathode condition, the electrical-response-based identification approach may provide a practical method for identifying the filament operating range when direct beam diagnostics are unavailable. Full article

(This article belongs to the Special Issue Advances in Welding Technology: 2nd Edition)

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28 pages, 633 KB

Open AccessReview

Smart Factories, Smarter Research: A Critical Review of Manufacturing 4.0 Technologies, Sustainability, and the Road to Industry 5.0

by Ahmed S. Alghamdi

J. Manuf. Mater. Process. 2026, 10(8), 308; https://doi.org/10.3390/jmmp10080308 - 20 Aug 2026

Abstract

Industry 4.0 has produced one of the fastest-growing bodies of engineering and management research; much of this output remains siloed by technology domain. This study addresses that fragmentation through a structured critical review (a review-of-reviews), synthesising 70 peer-reviewed review articles and foundational sources [...] Read more.

Industry 4.0 has produced one of the fastest-growing bodies of engineering and management research; much of this output remains siloed by technology domain. This study addresses that fragmentation through a structured critical review (a review-of-reviews), synthesising 70 peer-reviewed review articles and foundational sources (2003–2026) spanning 14 technology domains. The review introduces the I4.0-STS framework, an original four-layer structure organising evidence across physical, cyber, cognitive, and socio-organisational dimensions. Five principal findings emerge. The physical and cyber layers show consistent evidence of maturity. Industry-reported lighthouse IIoT deployments show 20–30% energy and up to 39% lead-time reductions. AI-driven predictive maintenance shows 30–50% unplanned-downtime reductions. The cognitive layer (LLM-augmented digital twins and generative AI interfaces) is technically feasible but outpaces its governance frameworks. Cybersecurity remains insufficiently governed, with documented ransomware incidents in manufacturing OT environments underscoring the risks of OT–IT convergence. SME adoption and developing-economy manufacturing transformation remain comparatively under-addressed. Finally, 12 research gaps are assessed as of June 2026, five rated Open, with future research directions proposed for each, framed against the emerging Industry 5.0 agenda. All findings are second-order interpretations from the source reviews, and their limitations are stated explicitly. Full article

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18 pages, 4282 KB

Open AccessArticle

Experimental Investigation and Artificial Neural Network-Based Prediction of Tensile Strength in Fused Filament-Fabricated Carbon Fiber-Reinforced PETG

by Ahmed Hadi, Abdulkader Kadauw, Mohanned M. H. AL-Khafaji and Henning Zeidler

J. Manuf. Mater. Process. 2026, 10(8), 307; https://doi.org/10.3390/jmmp10080307 - 20 Aug 2026

Abstract

Fused filament fabrication (FFF) has become an important additive manufacturing technique for producing functional polymer-composite components. The tensile performance of carbon fiber-reinforced polyethylene terephthalate glycol (PETG/CF) fabricated by FFF depends on multiple printing parameters. This study presents an integrated experimental and predictive framework [...] Read more.

Fused filament fabrication (FFF) has become an important additive manufacturing technique for producing functional polymer-composite components. The tensile performance of carbon fiber-reinforced polyethylene terephthalate glycol (PETG/CF) fabricated by FFF depends on multiple printing parameters. This study presents an integrated experimental and predictive framework for investigating the effects of extrusion temperature, printing speed, layer height, infill pattern, and infill density on the tensile strength of PETG/CF containing 15 wt.% carbon fiber. A mixed-level Taguchi L36 orthogonal array was employed, comprising 36 experimental runs with three independently printed specimens per run, resulting in 108 ASTM D638 Type V specimens. Analysis of variance showed that the printing speed had the largest contribution to tensile strength (20.51%), followed by layer height (18.29%). The highest tensile strength of 33.225 MPa was obtained using grid infill, 60% infill density, 270 °C extrusion temperature with 40 mm/s printing speed, and 0.3 mm layer height. An artificial neural network (ANN) was developed for the tensile-strength prediction, achieving R = 0.9801, R² = 0.9569, and MAPE = 1.52% for the overall dataset. Scanning electron microscopy qualitatively revealed bead-interface defects, fiber pullout, and localized void-like features. The proposed framework provides a systematic approach for evaluating process-parameter effects and predicting tensile strength within the investigated PETG/CF parameter domain. Full article

(This article belongs to the Special Issue Recent Advances in Optimization of Additive Manufacturing Processes)

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26 pages, 10274 KB

Open AccessArticle

Crystal Plasticity Assessment of Texture Discretization and Lamellar Grain Morphology for Predicting the Anisotropic Behavior of LPBF IN718

by José David Pérez-Ruiz, Jorge Pinzón, Andres Gonzalez, Luis Norberto Lopez de LaCalle and Jorge Bris

J. Manuf. Mater. Process. 2026, 10(8), 306; https://doi.org/10.3390/jmmp10080306 - 20 Aug 2026

Abstract

The anisotropic mechanical behavior of laser powder bed fused (LPBF) IN718 results from the combined effects of crystallographic texture and grain morphology, although their individual contributions remain difficult to quantify. In this work, six representative volume elements (RVEs) are systematically compared using a [...] Read more.

The anisotropic mechanical behavior of laser powder bed fused (LPBF) IN718 results from the combined effects of crystallographic texture and grain morphology, although their individual contributions remain difficult to quantify. In this work, six representative volume elements (RVEs) are systematically compared using a unified EBSD–Dream3D–DAMASK crystal plasticity framework to separate the effects of texture and morphology. The microstructures include two EBSD-derived RVEs, two discretized columnar RVEs, and two discretized lamellar RVEs generated from identical orientation distributions. Predicted elastic moduli and yield strengths are validated against experiment, while Taylor factor analysis, directional effective grain size, slip compatibility, KAM, and local crystal plasticity fields are used to identify the governing deformation mechanisms. The results show that crystallographic texture predominantly controls the elastic response, whereas grain morphology governs the onset of plastic deformation. Lamellar RVEs provide the closest agreement with the experimental yield-strength anisotropy by reproducing the directional effective grain size, the connectivity of mechanically hard domains, and the resulting redistribution of stress and plastic strain. Furthermore, texture discretization preserves the dominant anisotropic trends while substantially reducing the computational cost of full EBSD reconstructions, establishing an efficient and physically meaningful framework for crystal plasticity simulations of LPBF materials. Full article

(This article belongs to the Special Issue Next-Generation Machine Tools and Machining Technology)

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18 pages, 13132 KB

Open AccessArticle

PCD Tool Wear Mechanism and Prediction in Laser–Ultrasonic Synergistic Milling of High-Volume-Fraction SiC_p/Al Composites

by Liquan Yang, Kun Zhao, Jianhao Qi, Erbo Liu, Sen Yuan, Qingqing Lü and Guangxi Li

J. Manuf. Mater. Process. 2026, 10(8), 305; https://doi.org/10.3390/jmmp10080305 - 19 Aug 2026

Abstract

To address severe PCD tool wear during the milling of high-volume-fraction SiC_p/Al composites, a synergistic milling process coupling pulsed laser pretreatment with ultrasonic vibration was proposed. Five-factor, four-level orthogonal experiments were conducted on 70 vol.% SiC_p/Al composites to investigate [...] Read more.

To address severe PCD tool wear during the milling of high-volume-fraction SiC_p/Al composites, a synergistic milling process coupling pulsed laser pretreatment with ultrasonic vibration was proposed. Five-factor, four-level orthogonal experiments were conducted on 70 vol.% SiC_p/Al composites to investigate the effects of milling speed, feed per tooth, cutting depth, laser power, and ultrasonic amplitude on milling forces and tool wear, and a tool wear prediction model was established. The results showed that the factors influencing tool wear, in descending order, were feed per tooth, cutting depth, milling speed, laser power, and ultrasonic amplitude. Appropriate laser power and ultrasonic amplitude reduced cutting loads and suppressed tool wear. The model achieved a coefficient of determination of 0.7887 and was statistically significant overall. The optimal parameter combination was 50 m/min, 0.02 mm/z, 0.1 mm, 60 W, and 3.5 μm, under which the tool wear loss was 1.0 mg, representing a reduction of 61.54% compared with the maximum-wear condition. The main wear modes of the PCD tool included rake-face grooving and fatigue spalling, flank-face abrasive wear, and cutting-edge micro-chipping. These findings provide a useful reference for the precision milling of SiC_p/Al composites. Full article

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26 pages, 67124 KB

Open AccessArticle

Drilling Performance Evaluation and Mechanism Analysis of Diamond-Coated Drills in Ice-Supported CFRP Machining

by Bohan Yuan, Yixin Jin, Ming Jin, Wenjie Zhang, Bin Wan, Huaxing Yang and Zhao Zhang

J. Manuf. Mater. Process. 2026, 10(8), 304; https://doi.org/10.3390/jmmp10080304 - 18 Aug 2026

Abstract

Diamond-coated tools are suitable for CFRP machining because of their high hardness, sharp cutting edge, and good wear resistance. However, the anisotropic and heterogeneous nature of CFRP makes drilling-induced defects, such as burrs, tearing, fiber pull-out, and delamination, difficult to avoid, especially at [...] Read more.

Diamond-coated tools are suitable for CFRP machining because of their high hardness, sharp cutting edge, and good wear resistance. However, the anisotropic and heterogeneous nature of CFRP makes drilling-induced defects, such as burrs, tearing, fiber pull-out, and delamination, difficult to avoid, especially at the hole exit. In this study, an ice-supported drilling method was proposed for CFRP hole machining using diamond-coated drills. An ice layer was formed beneath the CFRP laminate to provide simultaneous low-temperature cooling and mechanical support during drilling. Comparative drilling experiments were conducted at spindle speeds of 400, 1200, and 2000 r/min. The results showed that the ice-supported drilling method markedly improved the hole surface quality and inner-wall integrity of CFRP laminates. Compared with conventional dry drilling, the drilling temperature was reduced by 22.03%, 10.70%, and 11.45% at 400, 1200, and 2000 r/min, respectively, while the hole-exit delamination factor decreased by 41.68%, 27.45%, and 57.04%, respectively. Moreover, after the same number of drilled holes, the diamond-coated drill used under ice-supported conditions exhibited less severe surface wear and cutting-edge blunting than that used under conventional dry conditions. The observed improvements were interpreted as being associated with the combined thermal-regulation and temporary mechanical-backing effects of the ice-supported condition. Full article

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24 pages, 8073 KB

Open AccessArticle

Repair of a Complex Ti-6Al-4V Groove by Coaxial Wire Laser Metal Deposition: Process Window, Tensile, and Very-High-Cycle Fatigue Evaluation

by Owen Sutherland, Ryan Devine and Yevgen Gorash

J. Manuf. Mater. Process. 2026, 10(8), 303; https://doi.org/10.3390/jmmp10080303 - 18 Aug 2026

Abstract

Ti-6Al-4V has seen widespread adoption in the aerospace industry due to its advantageous material properties, but the alloy is costly to produce with vulnerable supply chains. Repair and remanufacture offer economic and environmental benefits over scrapping components. Powder-based additive-manufacturing processes have been investigated; [...] Read more.

Ti-6Al-4V has seen widespread adoption in the aerospace industry due to its advantageous material properties, but the alloy is costly to produce with vulnerable supply chains. Repair and remanufacture offer economic and environmental benefits over scrapping components. Powder-based additive-manufacturing processes have been investigated; however, coaxial wire laser metal deposition (LMD) remains understudied in repair scenarios, and the transfer of planar process parameters to inclined geometries for complex repairs has not been established. This paper identifies a process window for 1.2 mm Ti-6Al-4V wire and applies the parameters to repair a trapezoidal groove. Tensile and fatigue properties are evaluated, and fractography is conducted using optical and scanning electron microscopy. Findings show the transfer from planar to inclined geometry induces evolving geometric and thermal boundary conditions, including underbuilding and thermal accumulation. Nonetheless, the repair exhibited a yield strength of 868.2 MPa, an ultimate tensile strength of 920.5 MPa, and an elongation of 8.9%. Moreover, UFT revealed a fatigue performance of the repairs that was consistent with heat-treated SLM materials. Fractographic analysis revealed triangular defects and feedstock contamination that contribute to reduced repair properties. As such, this paper demonstrated that coaxial wire-LMD can be used to deposit material into complex geometries, but a complete, defect free repair was not achieved. Full article

(This article belongs to the Special Issue Advancements in Metal Additive Manufacturing: Technologies and Applications)

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16 pages, 4197 KB

Open AccessArticle

Influence of CNT Reinforcement and Fiber Orientation on the Mechanical Performance of Woven Kevlar/Epoxy Composites

by Muhammad Umair Najeem, Zarak Khan, Muhammad Younas and Taimoor Asim

J. Manuf. Mater. Process. 2026, 10(8), 302; https://doi.org/10.3390/jmmp10080302 - 18 Aug 2026

Abstract

Carbon nanotubes (CNTs) are widely used as nanoscale reinforcements in polymer composites because of their high stiffness, high aspect ratio, and ability to enhance interfacial stress transfer. In woven Kevlar/epoxy composites, however, the mechanical benefit of CNT addition depends not only on nanotube [...] Read more.

Carbon nanotubes (CNTs) are widely used as nanoscale reinforcements in polymer composites because of their high stiffness, high aspect ratio, and ability to enhance interfacial stress transfer. In woven Kevlar/epoxy composites, however, the mechanical benefit of CNT addition depends not only on nanotube presence, but also on whether the fabric Fiber orientation enables the CNT-modified interface to participate effectively in the dominant load path. In this study, woven Kevlar/epoxy composites with and without 4 wt.% multi-walled carbon nanotube (MWCNT) treatment were investigated under three displacement rates, namely 1, 10, and 100 mm/s, for two specimen orientations relative to the woven yarn directions: 0°/90° and ±45°. The 0°/90° Fiber orientation represents a tension-dominant load path, whereas the ±45° Fiber orientation promotes yarn rotation and matrix-shear-dominant deformation. The experimental results show that CNT treatment produces a clear increase in elastic modulus in the 0°/90° composites, with an improvement of approximately 40–50% at the lowest loading rate and continued enhancement at higher rates. In contrast, only limited gains are observed in the ±45° composites. The calculated CNT engagement index reached 0.8667 in the 0°/90° Fiber orientation but remained low or negative in some ±45° loading conditions, indicating that the effectiveness of CNT reinforcement depends strongly on Fiber orientation relative to the woven yarn directions. To interpret this behavior in a design-oriented manner, three Fiber orientation-sensitive comparison parameters are introduced: the CNT engagement index, the Fiber orientation sensitivity factor, and the rate amplification factor. These descriptors distinguish absolute stiffness from actual reinforcement utilization and indicate that modulus improvements depend on specimen orientation relative to the woven yarn directions. This study indicates that fabric Fiber orientation governs whether the CNT-modified interface is effectively mobilized or largely bypassed. This provides a useful framework for selectively deploying CNT reinforcement in woven protective composite systems and for rethinking nanotube reinforcement as a load-path-dependent design feature rather than a universally effective additive. Full article

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

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20 pages, 7895 KB

Open AccessArticle

A Rapid Separation Method of Spindle Radial Error Motion Under Cutting Conditions

by Xinping Xu, Yue Tao, Tao Geng and Tao Tao

J. Manuf. Mater. Process. 2026, 10(8), 301; https://doi.org/10.3390/jmmp10080301 - 18 Aug 2026

Abstract

Measuring the radial error motion of a spindle during the cutting process is important for monitoring the machining quality of the workpiece and spindle running condition. The problem of long separation time encountered in the application of traditional methods is analyzed under cutting [...] Read more.

Measuring the radial error motion of a spindle during the cutting process is important for monitoring the machining quality of the workpiece and spindle running condition. The problem of long separation time encountered in the application of traditional methods is analyzed under cutting conditions. A rapid separation strategy based on step separation is studied. Combining the advantages of the bidirectional measurement and multi-probe methods, a rapid separation method for spindle radial error motion is proposed. Based on the characteristics of the first harmonic components at high and low spindle speeds, an extraction method for the installation eccentricity is developed. The spindle built-in encoder acquisition technology and angle position resampling method are used to reduce the influence of cutting conditions on error separation. Finally, an actual cutting experiment is conducted to verify the effectiveness of the proposed method, and it is shown that the proposed method cannot only achieve rapid separation but also obtain better separation accuracy under cutting conditions. Full article

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26 pages, 6267 KB

Open AccessArticle

Modeling and Prediction of the Forming Limits of AA5052 Sheets Under Cryogenic Conditions Using a Modified M-K Model

by Haolei Zhang, Zeng Tan, Zhide Li, Denis Pustovoytov, Alexander Pesin and Hailiang Yu

J. Manuf. Mater. Process. 2026, 10(8), 300; https://doi.org/10.3390/jmmp10080300 - 17 Aug 2026

Abstract

Cryogenic forming overcomes room-temperature limitations by leveraging the enhanced strength–ductility synergy in Al alloys. To explore the forming limits of AA5052 sheet under cryogenic forming conditions, quasi-in situ tensile tests were conducted and digital image correlation techniques were employed to examine strain distribution, [...] Read more.

Cryogenic forming overcomes room-temperature limitations by leveraging the enhanced strength–ductility synergy in Al alloys. To explore the forming limits of AA5052 sheet under cryogenic forming conditions, quasi-in situ tensile tests were conducted and digital image correlation techniques were employed to examine strain distribution, surface roughness evolution, and forming limit curves of the AA5052 sheet in the tensile deformation process. Experimental results show that the maximum equivalent forming limit at −196 °C increases to 50.7% from 19.9% at room temperature, representing a 250% increase. At the same time, the surface roughness evolution rate increases by 60% from 2713 nm at room temperature to 4414 nm at −196 °C. Cryogenic conditions suppress dislocation annihilation and dynamic recovery, enhancing strain hardening, resulting in higher forming limits. Additionally, intensified grain rotation and more dislocation slip accelerate surface roughening, which influences the development of the geometric heterogeneity coefficient. By introducing a strain-dependent surface roughening coefficient, the Marciniak–Kuczyński (M-K) model was modified and was used to quantitatively characterize the heterogeneity during deformation, and subsequently analyzes its impact on the prediction of forming limits for AA5052 from room temperature (25 °C) to cryogenic temperature (−196 °C). The modified model reduces the prediction standard deviation by more than 70% and the identified mechanisms offer theoretical guidance for optimizing cryogenic forming process parameters for Al alloy components with complex geometries. Full article

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14 pages, 2831 KB

Open AccessArticle

Microstructural Features and Defect Formation in Plasma-Sprayed Al₂O₃ Coatings Deposited by a Water-Stabilized Plasma Torch

by Jozef Výboch, Samuel Mikita and Ján Viňáš

J. Manuf. Mater. Process. 2026, 10(8), 299; https://doi.org/10.3390/jmmp10080299 - 15 Aug 2026

Abstract

Al₂O₃ coatings were deposited on S235J2 steel substrates using a water-stabilized plasma (WSP) spraying system equipped with a WSP PAL-160 plasma torch. The microstructure, phase composition and adhesion behaviour of the deposited coatings were investigated. Cross-sectional and surface observations were [...] Read more.

Al₂O₃ coatings were deposited on S235J2 steel substrates using a water-stabilized plasma (WSP) spraying system equipped with a WSP PAL-160 plasma torch. The microstructure, phase composition and adhesion behaviour of the deposited coatings were investigated. Cross-sectional and surface observations were performed using scanning electron microscopy (SEM), while phase composition was evaluated by X-ray diffraction analysis. The coatings exhibited a characteristic lamellar architecture formed by successive deposition and rapid solidification of molten particles. The most frequently observed defects were interlamellar pores, isolated rounded pores and fine microcracks located within individual lamellae. Despite the presence of these discontinuities, the coating formed a continuous layer without extensive delamination. X-ray diffraction analysis revealed that the deposited coating consisted predominantly of γ-Al₂O₃, whereas only a minor fraction of α-Al₂O₃ was detected. The predominance of γ-Al₂O₃ was attributed to rapid cooling of molten particles after impact on the substrate surface. Adhesion testing performed according to ASTM C633 yielded an average adhesion strength of approximately 10.58 ± 0.36 MPa and revealed a mixed adhesive–cohesive failure mode. The obtained results confirm that water-stabilized plasma spraying is capable of producing Al₂O₃ coatings with a typical lamellar microstructure, adequate adhesion and phase composition characteristic of rapidly solidified alumina deposits. Full article

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20 pages, 3195 KB

Open AccessArticle

Importance of Characterizing Heat Transfer in Both the Tool and Workpiece for Friction Stir Welding Thermal Model Validation

by Muhammad Taha, Matthew Goodson, Ryan Melander, Troy Munro and Michael P. Miles

J. Manuf. Mater. Process. 2026, 10(8), 298; https://doi.org/10.3390/jmmp10080298 - 15 Aug 2026

Abstract

Accurate thermal modeling of friction stir welding (FSW) requires correct representation of heat generation and heat partitioning at the workpiece/tool interface. However, most published models are validated against temperature measurements from only one side of this interface, so agreement with experiment does not [...] Read more.

Accurate thermal modeling of friction stir welding (FSW) requires correct representation of heat generation and heat partitioning at the workpiece/tool interface. However, most published models are validated against temperature measurements from only one side of this interface, so agreement with experiment does not guarantee that interfacial heat transfer is correctly represented. This study evaluates whether one-sided temperature validation is sufficient, using steady-state FSW of AA 6061-T6 aluminum with an H13 steel tool. Temperatures were measured with thermocouples embedded in both the workpiece and the tool, and a Eulerian thermomechanical model was developed in ForgeNxt. The viscoplastic friction coefficient and the workpiece/tool heat transfer coefficient were calibrated against tool temperatures only, workpiece temperatures only, and both simultaneously. Tool-only calibration reproduced tool temperatures within 2.5% but overpredicted workpiece temperatures by 18% on average; workpiece-only calibration achieved 5% average workpiece error but underpredicted tool temperatures by 26%. Sensitivity analysis showed that workpiece temperatures were governed primarily by the friction coefficient, while tool temperatures were sensitive to both friction coefficient and heat transfer coefficient. No single parameter pair reproduced both temperature sets, indicating that one-sided validation can produce misleading agreement and that two-sided validation is necessary to achieve accurate interfacial heat partitioning. Full article

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15 pages, 7194 KB

Open AccessArticle

Thermal Aging and Geometry-Driven Changes in Strength of 3D-Printed Polymers

by Mohammad Reza Khosravani, Payam Soltani, Morteza Mohammadzaheri and Majid R. Ayatollahi

J. Manuf. Mater. Process. 2026, 10(8), 297; https://doi.org/10.3390/jmmp10080297 - 14 Aug 2026

Abstract

The benefits of additive manufacturing (AM, i.e., 3D printing) have made it one of the most widely used and favored production techniques across a variety of industries. In the current study, the influence of geometry and thermal aging on the mechanical strength of [...] Read more.

The benefits of additive manufacturing (AM, i.e., 3D printing) have made it one of the most widely used and favored production techniques across a variety of industries. In the current study, the influence of geometry and thermal aging on the mechanical strength of AMed parts has been investigated. In this context, specimens based on fused deposition modeling were printed using polylactic acid material. The specimens with three distinct geometries were created and analyzed since the geometry of AMed parts affects their mechanical performance. In this study, tensile tests were conducted under static loading circumstances, specifically on dumbbell-shaped, smooth, and V-notched test coupons. Furthermore, we conducted accelerated thermal aging between

- 5 °

C and 35 °C, which is below the glass temperature of the material under investigation, to assess the impact of the thermal environment. In addition, a series of finite element models were developed to study the stress distribution and deformation in the examined components. According to the results, for unaged specimens, smooth samples demonstrated the highest fracture load at 1980.5 N, while dumbbell-shaped samples recorded the lowest at 1173.9 N. Moreover, the V-notched specimens sustained higher fracture loads compared to dumbbell-shaped samples across both aged and unaged conditions. This study’s findings demonstrate that in designing 3D-printed parts, consideration must be given to their geometric appearance and environmental operating circumstances. Full article

(This article belongs to the Special Issue Next-Generation Material Designs and Processes for Additive Manufacturing)

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