Search Results (606)

Sustainable manufacturing performance is increasingly influenced by the quality of decisions embedded in Quality Management System (QMS) activities, particularly those related to problem analysis and preventive action. In industrial environments such as welded bus chassis production, recurring quality defects—although involving small components—can generate sustainability impacts through rework, inspection effort, and energy consumption. Although artificial intelligence (AI) is increasingly adopted to support quality-related tasks, its contribution is often assessed in terms of automation rather than its effect on decision quality. This study presents an AI-supported, prompt-driven decision framework designed to strengthen preventive performance within QMS. The framework is implemented through a deterministic software application that formalizes prompt engineering as a rule-based process, transforming informal human problem descriptions into structured prompts suitable for external AI reasoning tools. The application itself does not embed AI and does not generate decisions; instead, it functions as a transparent decision interface that reduces variability in problem formulation and supports methodological consistency. The framework was validated through an industrial case study conducted in a bus chassis manufacturing plant experiencing recurring defects related to missing or incorrectly positioned welded brackets. Quantitative evaluation using Key Performance Indicators demonstrates reduced analysis cycle time, improved completeness of problem definitions, higher corrective action implementation rates, and lower defect recurrence. Full article

Beam-to-column connections govern both seismic performance and post-earthquake repairability of steel moment-resisting frames. Yet direct, apples-to-apples comparisons among welded, bolted, and repair-oriented replaceable-fuse moment connections are still scarce, which hinders rational selection for resilient construction. This study conducts a unified finite-element comparison of three representative joint archetypes—W-RBS, Bolted, and Prefab-web-fuse—under monotonic and cyclic loading. Consistent moment-rotation definitions are adopted, and normalized indices are introduced to compare hysteresis shape, degradation, and energy dissipation across joint concepts with different strength scales. Component-wise plastic dissipation is also extracted to quantify damage localization and assess main-frame protection and replaceability. Results reveal clear trade-offs: W-RBS provides the highest strength and dissipation but degrades most in stiffness; the bolted joint shows pinching due to interface compliance; and the web-fuse concept concentrates inelastic demand in a replaceable segment, supporting repairability-oriented design. The proposed framework offers mechanism-based guidance for selecting steel moment connections toward resilient and repairable frames. Full article

Friction stir-welding (FSW) is widely recognized as a modern solid-state technology used to join dissimilar materials by solid-state mechanical mixing. Such mechanical mixing can be exploited to fabricate in situ composite structures through solid-state deformation mechanisms. The present investigation highlights the microstructural evolution and mechanical properties of an in situ composite structure fabricated by FSW of aluminum (Al) to titanium (Ti) incorporating a thin Nickel (Ni) interlayer. A 0.1 mm thick Ni foil was placed across the full butt interface between 4 mm thick Al and Ti plates before friction stir-welding. Properties of the composite were investigated in detail, and the results revealed that fragmented Ti and Ni particles of different sizes were consolidated in the weld nugget. Al, on the other hand, exhibited substantial microstructural refinement and developed an equiaxed microstructure with random grain orientation, mixed grain boundaries and low micro-strain accumulation in the weld nugget. At the processing temperature, Al reacted with both Ti and Ni to form multiple intermetallic compounds. Tensile testing indicated that the tensile properties of the weld were close to those of the base aluminum. This retention of mechanical properties in spite of recrystallization is attributed to the following mechanisms: (1) Ti and Ni undergo severe deformation, forming fine particles with varying sizes and shapes; (2) at particle interfaces, diffusion and chemical reactions produce interlayers and intermetallic compounds; (3) these particles are consolidated within dynamically recrystallized Al, imparting composite characteristics to the weld nugget; and (4) the particles containing intermetallic compounds act as dispersoids in the Al matrix. Quantitatively, the weld retained 98% (104.2 ± 3.3 MPa) UTS and 90% (17.1 ± 1.2) ductility of base aluminum, demonstrating the effectiveness of the Ni interlayer approach in controlling brittle intermetallic formation. Full article

Weld root reinforcement is a critical geometric parameter governing stress concentration and structural performance in thin-walled stainless-steel piping systems designed to ASME B31.3. While current codes specify permissible dimensional limits, they do not explicitly quantify how incremental variations in root height influence stress distribution under realistic service loading conditions. This study integrates finite element analysis (FEA) with experimentally validated GTAW weld profiles to evaluate the structural influence of weld root height in 316L stainless-steel pipe joints. An experimentally manufactured 4 in schedule 10S joint with a measured root height of less than 1.5 mm was adopted as the baseline geometry. Additional models with reinforcement heights of 1.138, 2.0, 2.5, and 3.0 mm were evaluated under two representative load cases: (i) internal pressure combined with drag and axial thrust (LC-1), and (ii) internal pressure with thrust only (LC-2). The results demonstrate that reinforcement heights exceeding 2.0 mm increase von Mises, hoop, longitudinal, and radial stress gradients, with peak stresses shifting toward the weld toe under drag-inclusive loading. In contrast, reinforcement ≤2 mm provides smoother load transfer and reduced stiffness discontinuity across the weld interface. The combined numerical and experimental findings support a stress-informed upper limit of 2 mm for weld root reinforcement in thin-walled stainless-steel pipelines, offering a performance-based complement to existing dimensional acceptance criteria. Full article

In many densely populated towns and semi-urban areas, masonry buildings often stand close to busy roads, exposing them to blasts from improvised explosives or other localized sources. Such structures are rarely designed to resist sudden explosive forces, making severe damage or even progressive collapse likely. Even moderate-intensity blasts can weaken walls, endanger occupants, and cause significant property loss. Unlike reinforced concrete, masonry is highly susceptible to explosive impact. Therefore, understanding how these buildings behave under blast loads and developing affordable protection methods is crucial. Low-rise unreinforced masonry (URM) structures, usually up to about 13 m in height (roughly 2–4 stories), common in villages, semi-urban regions, and conflict-prone zones, are particularly at risk. In many areas, these poorly constructed buildings lack proper engineering design and are therefore highly vulnerable to blast damage. Non-load-bearing internal dividers and perimeter enclosures are especially prone to lateral displacement, which can initiate instability and, in severe cases, lead to overall structural failure. This research focuses on reducing catastrophic damage in URM walls when exposed to close-proximity blast forces using concrete-based protective coatings, both with and without embedded steel-welded wire mesh. The study references a previously tested laterally supported clay brick wall built with cement–sand mortar as the baseline model, with its behavior validated against experimental findings from existing literature. Two blast cases were considered corresponding to scaled stand-off distances of 2.19 m/kg^1/3 and 1.83 m/kg^1/3, representing moderate flexural-shear cracking and full structural failure, respectively. To replicate the observed behavior, a comprehensive 3D numerical simulation was developed using the ABAQUS/Explicit 2020 solver. The model’s predictions were benchmarked and verified through comparison with reported test data. While both blast intensities were used to confirm computational accuracy, the effectiveness of UHPC and UHPFRC protective coatings with and without embedded wire mesh was specifically evaluated under the more severe collapse scenario (Z = 1.83 m/kg^1/3). Results indicated that at a scaled distance of 1.83 m/kg^1/3, the uncoated URM wall could not withstand the blast because of poor tensile and bending capacity. In contrast, the UHPC- and UHPFRC-coatings provided improved confinement and better stress distribution. When welded wire mesh was embedded, crack control improved further, the interface bond strengthened, and a larger portion of blast energy was absorbed and dissipated. Full article

Welding copper (Cu) and aluminum (Al) is highly demanded for lightweight and cost-effective manufacturing. However, it faces significant challenges. First, substantial differences in physical properties may lead to high residual stresses and distortion. Second, brittle intermetallic compounds (IMCs) readily form at the interface, severely compromising the joint’s mechanical properties and electrical conductivity. Third, the native oxide film on Al impedes effective wetting and bonding. Therefore, effective control over the interfacial microstructure of the welded joint is essential. This review provides a critical analysis and comparison of several typical welding techniques, including laser welding (LW), friction stir welding (FSW), ultrasonic welding (UW), brazing and soldering, and welding–brazing. These analyses focus on their process characteristics, joint microstructures, and corresponding formation mechanisms. Furthermore, this review synthesizes key strategies for enhancing joint quality, including process parameter optimization, introduction of functional interlayers, and external assistance, aimed at optimizing joint microstructure and minimizing defects. Based on the analysis, this work provides comparative insights into process selection and microstructure control, and highlights future directions: advancing novel methods such as magnetic pulse welding and transient liquid phase bonding; developing intelligent real-time process control to suppress brittle IMCs and associated defects; promoting sustainable practices and establishing standardized performance evaluation; and systematically investigating long-term reliability to support the industrial application of robust Cu/Al joints. Full article

In the coarse grain heat-affected zone (CGHAZ) of welded pipe steel joints, hydrogen damage is a key factor limiting the high-pressure hydrogen transportation performance of the pipeline. This study employed multi-dimensional characterization methods (including microstructure, mechanical properties, and hydrogen distribution) to investigate the influence of welding heat input on the hydrogen embrittlement (HE) sensitivity of X60 pipeline steel in the CGHAZ. The results showed that as the heat input increased, the grains in the CGHAZ became coarser, and the microstructure changed from bainitic ferrite (BF) to granular bainite (GB) and polygonal ferrite (PF). Among them, the BF + GB composite structure had the best resistance to HE (HE sensitivity was 29.8%). At low heat input, the reversible hydrogen distribution occurred at the interfaces between the grain boundaries and the BF blocks, while at high heat input, it would accumulate around the martensite/austenite (M/A) constituents. For the 16 kJ/cm heat input experimental steel, the increase in Σ3 grain boundary density accelerated hydrogen diffusion and reduced its enrichment, thereby resulting in the lowest HE sensitivity. Full article

The formation of hard/brittle layers (HBLs) forming in proximity to the transition-layer interface during the welding process of stainless steel clad plates constitutes a pivotal element in determining the limitations on joint homogeneity and toughness. In order to elucidate their formation mechanisms and develop viable suppression routes, S31603/Q420qENH clad plates were utilised to fabricate five butt joints. This was achieved by varying the carbon content of the welding consumables and the heat input in the transition layer. A programme was conducted that combined microstructural and microhardness characterisation, mechanical testing, and numerical welding simulations. The findings indicate that base-layer consumables with comparatively elevated carbon content (w(C) ≥ 0.06%) expeditiously engender a constricted, localised hardened band in close proximity to the transition-layer interface. This is characterised by the predominance of martensite and Cr-rich compounds of the M_xCr_y type, which function as the principal genesis of bending cracks. Conversely, the utilisation of low-carbon welding consumables has been shown to markedly reduce interfacial carbon activity and C-Cr segregation, thereby suppressing the precipitation of M_xCr_y phases and effectively decreasing the overall thickness of the HBLs. Further numerical analysis shows that moderately increasing the transition-layer heat input lowers the T_8/5 cooling rate and shifts the cooling path away from the martensite region. This transforms the interfacial microstructure from a localised hardened band into a more uniform, graded structure. These findings provide an engineerable process-control strategy for enhancing both microstructural uniformity and toughness in stainless steel clad joints. Full article

Duplex-phase low-density steels are attracting interest for lightweight structural applications, as reducing vehicle mass is an effective route to lower fuel consumption and emissions. This review summarizes recent progress in alloy design, processing, microstructure control, and performance of duplex-phase low-density steels. The roles of major alloying elements are discussed in terms of phase stability and precipitation tendency, followed by an overview of typical processing routes from melting to hot and cold rolling and subsequent heat treatments used to tailor phase fractions and defect structures. Strengthening mechanisms are reviewed with emphasis on precipitation control, including the beneficial contribution of fine intragranular κ′ precipitates and the ductility penalty associated with coarse intergranular κ* films, as well as the use of B2-based particles for high specific strength. Deformation behavior is then discussed in terms of transformation-/twinning-induced plasticity (TRIP/TWIP), planar versus wavy slip, and strain partitioning between ferrite and austenite. Finally, key challenges are outlined, including quantitative interface-based mechanism description, gaps in service property data, stable industrial production and compositional uniformity, and the development of forming and welding windows for engineering implementation. Full article

The effect of process inputs in the friction welding of Ti6Al4V alloy rods was investigated through the analysis of residual stresses, microstructure, chemical phases and hardness testing of the weld joints. The rods were welded using different combinations of process inputs. The results revealed variations in residual stresses, hardness and microstructure of the weld joints when weld inputs were varied. Peak compressive residual stresses were obtained at the centre of the weld interface, where the grains were very fine. The joints with a greater volume fraction of martensitic grains had elevated residual stress values. The maximum compressive residual stress values were obtained at the weld interface, with high hardness results. A further investigation was conducted to study the relationship between the residual stresses, microstructure and mechanical properties of the weld joint. Full article

This study investigates the joint characteristics of a 60-layered copper foil stack using linear vibration ultrasonic welding for lithium-ion pouch cell applications. With increasing demand for high-capacity electric vehicle batteries, ensuring the reliability of multilayer electrode joints is essential. Experiments were conducted by varying vibrational amplitude, welding time, and clamping pressure. Weld quality was analyzed based on indentation profiles, joint strength, and failure modes. Results revealed that optimal welding energy (500–900 J) produced well-formed joints without surface cracks or tearing. Excessive welding energy (>900 J) led to material thinning and interfacial failure. The maximum T-peel peak load of 138.7 N was obtained at the 30th joining interface under 25 µm amplitude, 0.8 s welding time, and 1.5 bar clamping pressure. Interface-dependent optimum conditions were observed, reflecting thickness–direction variations in deformation and bonding within the 60-layer stack. Indentation length and depth correlated linearly with welding energy. Failure modes transitioned from no adhesion to tearing and button-pull types. The findings provide guidelines for optimizing welding parameters for high-quality multilayer foil joints in battery manufacturing. Full article

This study presents a comparative analysis of cylindrical lithium-ion cell architectures, tracing the evolution from the conventional tabbed design (18650/21700) to the large-format 4680 cell with its tabless current collectors. This architectural shift is driven by the imperative to minimise internal ohmic resistance and enhance thermal management in high-power automotive battery applications. Forensic investigation reveals that the 4680 design replaces localised, high-resistance tab connections with a distributed, low-impedance interface, necessitating the adoption of advanced manufacturing techniques, including long ultrasonic torsional welding and highly controlled high-power density laser welding. Crucially, the welding of external aluminium busbars to the cell relies on sophisticated microstructural engineering, particularly for the challenging dissimilar Aluminium-Steel (Al-Steel) anode weld. This weld format employs a spiral laser path to limit the formation of brittle aluminium-iron (Al-Fe) intermetallic compounds (IMCs), leveraging the steel cell casing’s nickel plating to promote a more ductile Al-Fe-Ni phase for improved joint reliability. Furthermore, the 4680 cell incorporates a significantly thicker casing (≈0.54 to 0.7 mm) for enhanced mechanical strength. In conclusion, the 4680 cell achieves superior performance through robust mechanical design and advanced welding processes that prioritise microstructurally sound, low-resistance interfaces. Full article

In response to thermal failure risks in ultra-high voltage (UHV) bushing online monitoring devices and maintenance equipment—caused by high heat generation of electronic components and the intrinsically low thermal conductivity of conventional resin encapsulation materials—this study proposes a novel modification strategy based on flash Joule heating (FJH). Distinct from conventional interface modification methods, the proposed approach enables cross-scale, in situ microsoldering between multi-walled carbon nanotubes (MWCNTs) and carbon fibers (CFs), constructing a multiscale reinforcement network with integrated thermal transport and mechanical load transfer pathways. The transient ultra-high-temperature thermal shock generated by FJH not only effectively removes inert impurities on CF surfaces but also drives carbon structural reconstruction, enabling graphitic-level welding of MWCNTs onto the fiber surface. This micro-welded architecture fundamentally differs from traditional filler dispersion or interface coating strategies, which often suffer from the trade-off between interfacial thermal transport and mechanical bonding. By contrast, the FJH-induced carbon–carbon bonded nodes form a continuous conductive and load-bearing network at the micro–nano scale. Characterizations using scanning electron microscopy (SEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) confirm successful in situ welding of MWCNTs onto CF surfaces. Meanwhile, FJH treatment effectively removes oxygen-containing functional groups and surface impurities. Analysis of carbon bonding evolution indicates that the welding efficiency reaches its maximum at 90 V. Macroscopic performance tests demonstrate that, compared with epoxy resin, the thermal conductivity of the multiscale reinforced system increases by approximately 168%, while the mechanical strength improves by 62.72%. This study provides new theoretical insights and technical pathways for the development of next-generation polymer composite materials with both high thermal conductivity and high mechanical strength. Full article

Aimed at improving the mechanical performance of welded joints in stainless steel composite materials, this research investigates the evolutionary characteristics of microstructure at the interface between the transition layer weld and base layer weld through electron backscatter diffraction (EBSD) and X-ray diffraction (XRD) analytical techniques. In addition, molecular dynamics simulation methods are employed to conduct an in-depth study on the atomic diffusion behavior during the welding process. The results show that carbon and chromium atoms undergo asymmetric diffusion at the interface, forming a decarburized and a carburized zone. The diffusion coefficient of carbon atoms was the largest, with the diffusion mechanism being interstitial diffusion. Followed by chromium atoms, the diffusion coefficient of Fe was the smallest. On the base layer weld side, two structural zones with different grain sizes were formed; the zone close to the interface was a coarse ferrite microstructure with the lower geometrically necessary dislocation density, the zone far from the interface was a finer-grained ferrite and pearlite microstructure. As the welding heat input of the transition layer weld increases, the average density of geometrically necessary dislocations, the decarburized layer thickness, the average grain size, and the diffusion coefficients of Cr and C atoms at the interface all exhibit a concomitant upward trend. Concurrently, a carbon–chromium compound precipitates at the interface. Full article

In response to the challenge of achieving highly reliable interface fabrication in the fields of microelectronics and micro-electromechanical system (MEMS) packaging, this study harnesses the superior characteristics of solid-state bonding inherent in explosive welding (EXW) technology. This study investigates the precise EXW of milligram-scale metallic foils by employing focused laser energy to control the explosion behavior of liquid energetic materials, thereby generating shockwaves that induce high-velocity oblique collisions between metallic foils and base plates. Laser-focused energy was utilized to regulate energetic materials for conducting precision EXW experiments on Al/Cu couples. The technical feasibility and interfacial quality of this method for fabricating Al/Cu bonding interfaces were systematically evaluated through in situ observation of the dynamic welding process, comprehensive analysis of interfacial microstructures, and numerical simulations. The results reveal distinct Al/Cu elemental diffusion at the bonding interface, confirming the technical viability of the approach. However, an unloading rebound phenomenon is observed at the interface, which is inherently associated with the dynamic impact process, indicating the need for further optimization in the precise control of impact loading. Full article