In this study, the mechanical and tribological behavior of ER70S-6 low-carbon structural steel multi-layer wall structures fabricated using two GMAW (gas metal arc welding)-WAAM (wire arc additive manufacturing) arc transfer modes, Control Weld (high-capacity spray transfer) and Speed Weld (voltage-controlled pulsed transfer), is investigated. Walls are fabricated using a CLOOS GMAW-WAAM system, and their properties are systematically evaluated through hardness, tensile, and Charpy impact toughness testing, complemented by microstructural characterization, X-ray diffraction (XRD), fractography, and wear analysis. Results show that Speed Weld produces finer, more equiaxed grains (11.80 & micro;m) than Control Weld (13.75 & micro;m), indicating 14% refinement and a more uniform phase distribution. Both modes predominantly exhibit alpha-ferrite; however, Speed Weld specimens show slightly broadened and less intense XRD peaks, higher average hardness (170.98 HV5 vs. 165.52 HV5) consistently along the build height, modestly improved tensile strength (509.33 MPa vs. 492.73 MPa), 11% greater uniform elongation, and over 8% higher impact energy. Fractography confirms ductile fracture in both conditions, with finer, more uniformly distributed dimples in the Speed Weld specimens. Additionally, Speed Weld specimens demonstrate superior tribological performance, reducing wear volume by 21.6% and wear rate by 21.5% compared to Control Weld specimens. These findings demonstrate that Speed Weld in GMAW-WAAM refines the microstructure while simultaneously enhancing mechanical and tribological properties, enabling more reliable, durable, and wear-resistant low-carbon steel components for structural and industrial applications.

In this work, a detailed investigation of the tribological performance of low-carbon structural steel deposited by pulsed gas metal arc–direct energy deposition (DED) was conducted. The study examined the effect of build-height-dependent microstructural variations and hardness on friction and wear behavior. Coupons from different regions along the build height were characterized for microstructure and hardness using optical microscopy and Vickers hardness testing, while their tribological performance was evaluated via linear reciprocating sliding tests. Wear was quantified using volumetric and gravimetric methods, enabling the determination of wear volume, specific volumetric wear rate, mass loss, and specific gravimetric wear rate. Results show moderate variation in grain size (11.39-14.87 µm) and hardness (164.65-183.45 HV2) across the build height. The top region exhibits the lowest coefficient of friction (0.514 at 25 N load, 900 s test duration) and specific wear rates (volumetric: 0.5900 × 10−4 mm3/N m; gravimetric: 7.11 × 10−10 g/N mm), whereas the lower–middle region shows the highest wear (volumetric: 0.9538 × 10−4 mm3/N m; gravimetric: 10.20 × 10−10 g/N mm). Increasing load and sliding duration intensifies wear depth, width, and specific wear rate, widening the performance differences among regions. Field-emission scanning electron microscopy (FESEM) and energy-dispersive x-ray spectroscopy (EDS) analyses confirm that abrasive wear is the primary mechanism, with contributions from adhesive and oxidative wear, revealing minor variations in wear mechanisms across the regions.

This study presents a comparative evaluation of AA6061-based aluminium metal matrix hybrid nanocomposites reinforced with B4C/Gr and SiC/Gr nanoparticles, fabricated using a novel stir - ultrasonic - squeeze casting route. Five compositions - as cast AA6061 alloy (AA6061), AA6061 + 2 wt.% B4C + 2 wt.% Gr (AA2B2G), AA6061 + 3 wt.% B4C + 2 wt.% Gr (AA3B2G), AA6061 + 2 wt.% SiC +2 wt.% Gr, (AA2S2G), and AA6061 + 3 wt.% SiC +2 wt.% Gr (AA3S2G) - were synthesised. SiC - Gr composites exhibited superior grain refinement (minimum grain size of 35.49 & micro;m), attributed to enhanced heterogeneous nucleation and favourable interfacial thermal characteristics. Hardness increased from 52.67 BHN (as-cast) to a maximum of 69.55 BHN for AA3S2G. Tensile properties showed similar improvement. Hall - Petch analysis revealed that variations in the slope coefficient (k) reflect interface-controlled dislocation blocking rather than grain refinement alone. Although B4C-Gr composites exhibited a higher Hall - Petch slope, SiC-Gr systems achieved higher absolute hardness and tensile strength due to improved dispersion and more effective interfacial load transfer. Tribological studies showed that SiC-Gr composites promote a stable, adherent graphite-rich tribofilm, resulting in lower friction and wear, whereas B4C-Gr systems exhibited tribofilm disruption due to interfacial debonding and third-body abrasion.

Laser transmission welding (LTW) is a promising method for fusing polymers and hybrid structures, widely used in automotive, aerospace, and healthcare applications due to its localized heating and process efficiency. Acrylonitrile–butadiene–styrene (ABS) polymer is widely utilized due to its favorable mechanical and chemical properties. This study develops a hybrid intelligence approach by coupling an artificial neural network (ANN) with the non-dominated sorting genetic algorithm II (NSGA-II) to simultaneously predict, analyze, and optimize weld quality in LTW of ABS. Experiments are conducted to generate welding parameter–weld quality data for ANN by varying laser power, scanning speed, stand-off distance, and clamp pressure, with weld strength and weld width as performance responses. The ANN with a 4-5-2 architecture, trained using the Levenberg–Marquardt algorithm, demonstrates high predictive accuracy, validated by strong regression (R ≈ 0.99) across training, validation, and test datasets, along with low error metrics (RMSE and MAE) on independent test data. The model is further utilized to analyze parametric interactions and quantify sensitivity, identifying scanning speed as the most influential parameter governing both responses. The proposed ANN–NSGA-II framework generates a Pareto front with 19 optimal trade-off solutions, capturing distinct thermo-physical regimes governed by heat input and energy distribution. The best trade-off solution yields a maximum weld strength of 47.52 N/mm and a minimum weld width of 2.31 mm, effectively balancing conflicting objectives. Experimental validation confirms close agreement with predictions, demonstrating the robustness and practical applicability of the proposed approach.

This study presents the fabrication and characterization of a nickel-aluminium bronze (NAB)-high-strength lowalloy (HSLA) steel bimetallic structure produced using wire arc additive manufacturing (WAAM). Tailored gas metal arc welding (GMAW) parameters, incorporating a voltage-controlled pulsed arc, controlled torch oscillation, and a bidirectional deposition strategy, are employed to achieve robust metallurgical bonding at the dissimilar-metal interface. Comprehensive characterization using optical and electron microscopy, energydispersive spectroscopy, X-ray diffraction, hardness mapping, and tensile testing is conducted to evaluate interfacial microstructure, phase evolution, and mechanical integrity. A defect-free, compositionally graded interface is formed through controlled interfacial remelting and elemental interdiffusion between NAB and HSLA steel, avoiding an abrupt transition. Distinct Cu-rich and Fe-rich dilution zones form, with the coexistence of alpha-Cu, alpha-Fe, and kappa phases confirmed at the interface, while elemental mapping reveals continuous Cu-Fe diffusion, contributing to a smooth hardness transition. The bimetallic structure retains tensile strength comparable to monolithic materials and predominantly ductile fracture behavior, confirming effective load transfer across the interface. The results establish GMAW-WAAM as a reliable route for producing NAB-HSLA bimetallics with graded, diffusion-controlled interfaces and effective load transfer, enabling structurally sound components for demanding marine and load-bearing applications. These findings highlight the effectiveness of controlled GMAW-WAAM processing in achieving robust interfacial bonding and property gradients in NAB-HSLA steel bimetallics, supporting their integration into advanced multi-material structures.

This study investigates the surface cladding of AISI 1020 low-carbon steel using the arc-DED (direct energy deposition) process with Rockit (R) 431SR martensitic stainless-steel powder and AM 70 feedstock wire. The powder is overlaid onto the substrate surface and fused by the heat generated during the MIG (metal inert gas)-WAAM (wire arc additive manufacturing) process using AM 70 wire, forming a clad layer. The study evaluates the microhardness distribution, phase composition, residual stress, and electrochemical corrosion behavior of the Rockit (R) 431SR + AM 70 clad, comparing it with the AISI 1020 substrate and AM 70-clad AISI 1020 without powder addition. The results show that the Rockit (R) 431SR + AM 70 cladding significantly improves microhardness and corrosion resistance, making it a promising solution for industries requiring high wear and corrosion resistance. The findings include superior microhardness in the clad layers, compressive residual stress, and enhanced electrochemical properties, including higher corrosion potential and improved pitting resistance. It has been found that Rockit (R) 431SR + AM 70 cladding offers enhanced durability and corrosion resistance compared to AM 70-clad AISI 1020 and the AISI 1020 substrate, enhancing its applicability across the automotive, marine, and infrastructure sectors.

Achieving optimal mechanical performance in wire arc additive manufacturing (WAAM) of high-strength lowalloy (HSLA) steels is critical for the structural integrity of load-bearing and pressure-retaining components. This study compares the effects of high-capacity Spray Arc and voltage-controlled Pulsed Arc gas metal arc welding (GMAW) modes on the microstructure, residual stress distribution, and mechanical behavior of AM70 HSLA steel, an alloy formulated for enhanced arc stability and deoxidation. Comprehensive characterization using optical/electron microscopy, X-ray diffraction, mechanical testing, and fractography reveals distinct process-structure-property relationships. Pulsed Arc mode produces a refined acicular ferrite matrix with more uniform crystallite size and elemental homogeneity, leading to superior hardness (236-246 HV5 vs. 223-235 HV5), tensile strength (743-793 MPa vs. 687-710 MPa), and Charpy impact toughness (78.5-103 J vs. 59.3-78.2 J) compared to Spray Arc. Additionally, compressive residual stresses are more uniformly distributed under Pulsed Arc (-134 to -288 MPa), whereas Spray Arc introduces steeper gradients (-66 to -311 MPa), which could affect long-term structural performance. Although Spray Arc yields higher ductility (34.7-36.4 % vs. 29.1-32.9 %), Pulsed Arc offers a better balance of strength and toughness. Fractographic analysis confirms ductile failure modes in both cases, with finer dimple morphology observed in Pulsed Arc samples. These findings demonstrate the potential of Pulsed Arc WAAM with AM70 steel for manufacturing pressure-resilient and structurally reliable HSLA steel components.

Metal-Polymer-Metal (MPM) sandwich composites are gaining increasing attention for lightweight structural applications due to their customizable mechanical properties and multifunctionality. In this study, AISI 1018-polyamide 6 (PA6)-AISI 1018 sandwich composites are fabricated using a laser-based fabrication technique to achieve controlled heat input and well-adhered steel-polymer interfaces. Surface texturing of the steel sheets is introduced to further enhance interfacial bonding. Mechanical characterization of bond strength is carried out through lap-shear testing, while interfacial morphology and chemical interactions are examined using field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Results reveal that laser-based fabrication provides adequate bond strength even in untextured specimens, whereas surface texturing markedly improves both interfacial strength and consistency. Interfacial morphology and chemical analyses confirm that polymer melting, wetting, and adhesion, combined with mechanical interlocking and chemical interactions, contribute to the overall bond strength at the interface. These findings demonstrate that laser-based joining combined with optimized surface texturing offers a promising approach for fabricating high-performance MPM sandwich composites for engineering applications.

Wire arc additive manufacturing (WAAM) has emerged as a cost-effective directed energy deposition technique for fabricating and repairing large metallic components. However, controlling bead geometry remains a critical challenge affecting dimensional accuracy and process reliability. This study systematically investigates the influence of key WAAM process parameters on bead geometry in low-carbon structural steel, establishing predictive and optimization frameworks applicable from single-bead to multi-layer wall fabrication. A central composite design is employed to vary wire feed rate, torch travel speed, torch tip distance, and gas flow rate. Second-order regression models are developed for bead height and width, demonstrating excellent predictive accuracy (R2 > 0.99, predicted R2 > 0.95) with prediction errors below 6.5

The high-cycle fatigue and tribological performance of wire arc additive manufacturing (WAAM)-fabricated AM70 high-strength low-alloy (HSLA) steel, a modified ER100S-G filler wire, are systematically investigated. Fatigue behavior is evaluated in horizontal and vertical specimens with detailed fractographic analysis to understand crack initiation and propagation mechanisms. Fatigue tests are conducted under tension–tension loading with a stress ratio of R = 0.1, and applied stress amplitudes are set between one-third and one-half of the yield strength to ensure high-cycle fatigue conditions and prevent compressive buckling. Tribological performance is also assessed across different build regions under varying loads and temperatures, and the results are correlated with local microstructure and mechanical properties to support the structural application of WAAM-fabricated AM70 HSLA steel components. Results show that horizontally built specimens exhibit higher fatigue strength (204 MPa) and longer fatigue life than vertically built specimens (194 MPa), and that Basquin regression analysis predicts fatigue limits with deviations of less than 5%. Microscopic analysis indicated that cracks primarily originated at surface defects and inclusions, which influenced propagation patterns. Tribological testing shows the middle region has the highest wear and friction, increasing with load and temperature, while microscopy and spectroscopy analyses reveal a transition from mild adhesive–oxidative wear at room temperature to adhesive–abrasive wear at elevated temperatures.

Advancements in engineering materials are continually driven by the need to meet specific industry requirements, such as seawater resistance in marine environments, a balance of strength and lightweight properties in structural applications, and non-toxicity and biocompatibility for the food industry. Achieving desired characteristics, such as high strength, impact, and corrosion resistance, chemical and fire resistance, electrical conductivity, and sound/vibration dampening, relies on careful material selection and fabrication techniques. Metal-polymer structural composites (MPSCs) have gained significant attention due to their lightweight and versatile properties, making them adaptable across diverse applications. This paper presents a focused review of MPSCs, focusing on laminates and sandwich composites, and examines their fabrication methods, characterization, and applications. The review explores how various metal-polymer combinations yield tailored properties, analyzes the performance and limitations of different fabrication techniques, and discusses key characterization methods used to assess performance. Additionally, the paper addresses the challenges and future prospects of MPSCs, offering a comparative analysis of fabrication techniques to guide the selection of the most suitable approach for different applications.

This study investigates the process-structure-property relationships of a GMAW (gas metal arc welding)-based WAAM (wire arc additive manufacturing)-fabricated HSLA (high-strength low-alloy) steel wall using 3D Print AM 70 steel wire (8MnNiMoCrSi7-6-5). The aim is to evaluate the performance of the optimized ER100S-G solid wire in WAAM, focusing on potential anisotropy along the build direction and different loading orientations. Detailed microstructural and crystallographic characterization of the WAAM-fabricated AM70 steel wall is conducted to assess microstructural features, phase evolution, crystallite size, and internal strain. Mechanical performance is studied through hardness, tensile, and Charpy impact tests, while corrosion resistance is analyzed using potentiodynamic polarization and electrochemical impedance spectroscopy. The results show that bainitic ferrite, martensite, and retained austenite phases are consistently observed across all regions (top, middle, bottom) of the wall, with cooling rate variations in multilayer deposition influencing phase proportions without significant anisotropy. Crystallite size and microstrain vary slightly across regions, with the top region exhibiting finer grains and higher microstrain. Hardness, tensile properties, and impact toughness are generally uniform with limited anisotropy, although yield strength and impact toughness show some directional variation. Corrosion analysis indicates marginal anisotropy, with slight differences in charge transfer resistance and anodic and cathodic responses.

This work presents the manufacturing and detailed evaluation of AA6061‐based aluminium metal matrix hybrid nanocomposites (AMMHNCs) reinforced with boron carbide (B 4 C) and graphite (Gr) nanoparticles, produced through an integrated stir–ultrasonic–squeeze (S + U + Sq) casting process. Eight compositions were fabricated with B 4 C varied from 1–4 wt.% and a constant 2 wt.% Gr, including single (B 4 C/ Gr) and hybrid (B 4 C + Gr) nanocomposites. The influence of reinforcements (both hybrid and single reinforcement) on the microstructure, hardness, tensile strength, and dry sliding wear behavior was systematically investigated. The integrated casting process enabled uniform nanoparticle dispersion, refined equiaxed grains, and minimized porosity. The A3B2G composite (3 wt.% B 4 C + 2 wt.% Gr) achieved peak hardness (68.61 BHN) and tensile strength (232.59 MPa), while the A2B2G variant (2 wt.% B 4 C + 2 wt.% Gr) offered the best balance of strength and wear resistance, with lower wear rate and friction. These results validate the process efficiency and highlight the importance of reinforcement optimization for various applications.

Wire Arc Additive Manufacturing (WAAM) is a direct energy deposition-based additive manufacturing process that uses an arc welding power source to fabricate large-scale 3D components from wire feedstock. In order to optimize the WAAM process, it is crucial to understand how process variables, such as shielding gas composition, affect build quality. This study investigates the effects of pure Ar, pure CO2, and Ar+CO2 (80:20) shielding gases on single- and multi-layer depositions using a six-axis robotic WAAM system equipped with an automated wire feeder. The objective is to evaluate how these gases influence the bead profile, microstructure, and mechanical properties of WAAM-deposited low-carbon steel. Results show that Ar+CO2 shielding yields the widest bead profiles with a uniform surface finish, while CO2 shielding enhances penetration but results in coarser microstructures and lower alloy retention. Ar shielding produces finer grains and the highest hardness, while tensile strength remains comparable under Ar and Ar+CO2, with the latter providing higher elongation. Charpy impact tests reveal that Ar-shielded builds have the highest toughness, CO2-shielded ones the lowest with brittle features, and Ar+CO2-shielded builds exhibit toughness and fracture behavior similar to those under Ar shielding. These findings provide valuable insights for selecting shielding gases to tailor the geometric and mechanical performance of WAAM builds.

This paper examines the fatigue and wear performance of low-carbon steel plates remanufactured with ER70S-6 steel wire using GMAW (gas metal arc welding) -WAAM (wire arc additive manufacturing). The repair technique involves filling pre-fabricated trapezoidal grooves that simulate defects in flat plate test coupons. Fatigue testing is conducted on both base and repaired plates, with high-cycle fatigue and fully reversed conditions employed for performance analysis. Wear characteristics, including wear rate, mechanisms, and friction coefficients, are evaluated for both the base plate and the WAAM-repaired plate. Despite showing higher tensile strength, WAAM-repaired coupons exhibit lower fatigue strength and life compared to base plate coupons. The S-N curve, derived from the Marin equation with correlation factors, aligns closely with fatigue test results, showing better agreement for base plate coupons than WAAM-repaired ones. Fractography reveals cracks in WAAM-repaired coupons due to surface imperfections, edges, and internal pores, indicating stress concentrations and defects impacting fatigue life. Crack initiation in base plate coupons consistently occurs at the edge ends, particularly at the end of the gauge length near curvature, due to high-stress concentrations. The WAAM-repaired zone is found to have a lower wear rate and higher coefficient of friction than the base plate, with adhesive wear predominating in both specimens.

Electro-discharge machining (EDM) is a widely used advanced machining process used to create complex profiles on electrically conductive but difficult-to-machine materials. EDM has evolved over time to meet industrial demands and has become widely accepted across industries, while the growing use of advanced materials has prompted researchers to enhance the process further. This paper presents a comprehensive review of current research trends and techniques aimed at enhancing machining performance, covering various innovative approaches across EDM variants. It also scrutinizes challenges encountered in EDM operations, presents solutions proposed by researchers to optimize performance, and identifies various approaches to reduce machining time and enhance machining quality. Environmental concerns related to the sustainability and biodegradability of dielectrics used in EDM, alongside advancements in electro-discharge coatings, are thoroughly addressed. This paper synthesizes insights from diverse sources, aiding researchers with current trends and providing summative remarks on study objectives in each section. The review concludes by summarizing its findings and suggesting directions for future research.

Wire arc additive manufacturing (WAAM) is a promising technique for producing and repairing large, complex metal components with high deposition rates and cost-effectiveness. This study investigates the effect of torch oscillation on the bead profile, microstructure, and mechanical properties of low-carbon steel fabricated via gas metal arc welding (GMAW)-WAAM. A CLOOS® GMAW welding unit with a six-axis robotic arm and ER70S-6 low-carbon, low-alloy steel wire is used for deposition. The study examines bead width, height, penetration, surface roughness, and microstructure under oscillation. Results show that torch oscillation increases bead width and surface quality while reducing bead height and penetration compared to non-oscillated deposition. Microstructural analysis reveals fine-grained ferritic phases and uniform grain distribution in oscillated samples. Improved hardness, tensile strength, and elongation are also observed in oscillated deposits. These findings demonstrate the potential of torch oscillation in enhancing bead quality and mechanical performance, making it beneficial for optimizing GMAW-WAAM.

In this study, a novel multi-stage framework is explored for laser transmission welding of polypropylene by integrating the design of experiments (DoE), artificial neural networks (ANN), non-dominated sorting genetic algorithm-II (NSGA-II), and multi-objective optimization by ratio analysis (MOORA). The framework enables comprehensive experimental investigation, process modeling, and multi-objective optimization. The response surface method (RSM) based DoE is used to develop correlations between welding parameters and responses, which form the foundation for experimental investigations. ANN models, incorporating additional fractional factorial DoE data, are employed for precise non-linear mapping of process parameters and responses, with predictive accuracy surpassing that of RSM models. The 3-6-1 ANN architecture is demonstrated to predict weld strength with high precision, while the 3-7-2-1 model is found to predict weld width accurately. These ANN models are used as objective functions for simultaneous optimization via NSGA-II, generating Pareto-optimal sets. These sets are further prioritized by MOORA, with an optimal parameter set of 220 W laser power, 81.29 mm/s scanning speed, and 63.97 mm defocus distance, yielding a weld strength of 63.86 N/mm and a weld width of 3.24 mm. The proposed synergistic DoE-ANN-NSGA-II-MOORA framework not only confirms its efficacy in this particular case but is also adaptable for other materials and processing applications.

This study investigates the influence of Inconel 625 and chromium (Cr) powders on the mechanical and corrosion performance of AM70 (8MnNiMoCrSi7-6-5) steel clads, produced via the arc-directed energy deposition process on AISI 1020 substrates. The surface properties of AM70 clads are enhanced with the addition of Inconel 625, a nickel superalloy, and chromium powders. Three clad compositions, AM70, AM70 with Inconel 625, and AM70 with Cr are tested and compared with each other and the substrate material. Results show that the GMAW (gas metal arc welding)-WAAM (wire arc additive manufacturing) produces dense, homogeneous cladding layers with smooth interfaces, ensuring strong bonding and defect-free fusion zones. The addition of Cr and Inconel 625 significantly improves microhardness through solid solution strengthening, with Cr+AM70 reaching 463.14 HV 0.5 , three times harder than the substrate. Corrosion evaluations reveal that IN625+AM70 exhibits the best performance, with minimal corrosion current density, the highest positive corrosion potential, and the greatest impedance modulus. These findings demonstrate that powder-infused GMAW-WAAM clads are promising for use in sectors such as aviation, automotive, and maritime.