Arc Additive Manufacturing Research Articles

Thermal Behavior in Wire Arc Additive Manufacturing: A Comparative Study of the Conventional Process and Infrared Heater Use

Thermal Behavior in Wire Arc Additive Manufacturing: A Comparative Study of the Conventional Process and Infrared Heater Use

In-Situ visual reconstruction of strut profiles in pulsed wire arc additive manufacturing of lattice structures

ABSTRACT The wire arc additive manufacturing (WAAM) process often results in geometric inaccuracies in the produced struts, highlighting the need for in-situ monitoring. Industrial cameras struggle to capture accurate images due to interference from arc light and metal radiation. This study introduces a real-time visual reconstruction method that leverages regions of interest (ROI) to enhance profile accuracy. Initially, the melt pool is analyzed and segmented from a series of frames to establish an initial strut profile. This profile then serves as the ROI for segmenting the solidified weld bead regions, yielding a more precise strut profile. Comparative analysis shows that the proposed method achieves a high Intersection Over Union (IOU) score of 0.911 and an Average Symmetric Surface Distance (ASD) error of 0.355 mm, demonstrating both accuracy and robustness. Additionally, the inclination angle and diameter are extracted from the reconstructed profiles.

Effect of Pre-strain on High-Temperature Oxidation Behavior of Inconel 617 Superalloy Fabricated by Wire Arc Additive Manufacturing at 900 °C

Effect of Pre-strain on High-Temperature Oxidation Behavior of Inconel 617 Superalloy Fabricated by Wire Arc Additive Manufacturing at 900 °C

Real-Time Modeling for Design and Control of Material Additive Manufacturing Processes

The use of digital twin and shadow concepts for industrial material processes has introduced new approaches to bridge the gap between physical and cyber manufacturing processes. Consequently, many multidisciplinary areas, such as advanced sensor technologies, material science, data analytics, and machine learning algorithms, are employed to create these hybrid systems. Meanwhile, new additive manufacturing (AM) processes for metals and polymers, based on emerging technologies, have shown promise for the manufacturing of sophisticated parts with complex geometries. These processes are undergoing a major transformation with the advent of digital technology, hybrid physical-data-driven modeling, and fast-reduced models. This study presents a fresh perspective on hybrid physical-data-driven and reduced order modeling (ROM) techniques for the digitalization of AM processes within a digital twin concept. The main contribution of this study is to demonstrate the benefits of ROM and machine learning (ML) technologies for process data handling, optimization/control, and their integration into the real-time assessment of AM processes. Therefore, a novel combination of efficient data-solver technology and an architecturally designed neural network (NN) module is developed for transient manufacturing processes with high heating/cooling rates. Furthermore, a real-world case study is presented, showcasing the use of hybrid modeling with ROM and ML schemes for an industrial wire arc AM (WAAM) process.

Study and Characterisation of Bimetallic Structure (316LSI and S275JR) Made by Hybrid CMT WAAM Process

The main objective of this research is to conduct an experimental investigation of the bimetallic material formed by 316LSI stainless steel and S275JR structural steel, produced via hybrid wire arc additive manufacturing technology with cool metal transfer welding and machining, and with the objective of being able to reduce the industrial cost of certain requirements for one of the materials. A methodological investigation has been carried out starting with welding beads of 316LSI on S275JR plates, followed by overlapping five beads and conducting final experiments with several vertical layers, with or without intermediate face milling. The results achieved optimal bead conditions for wire speeds of 4 m/min and 5 m/min at a travel speed of 400 mm/min. Overlap experiments show that the best deposition results are obtained with an overlap equal to or greater than 28%. Cooling time does not significantly influence the final geometry of the coatings. Regarding metallographic analysis, the filler material presents an austenitic columnar structure. In the base material, a bainitic structure with inferred grain refinement was detected in the heat-affected zone. An increase in hardness is observed in the heat-affected zone. In the results obtained from the tensile tests of the bimetallic material, an increase in mechanical strength and yield strength is observed in the tested specimens.

Effect of an AC-DC composite longitudinal magnetic field on the microstructure and mechanical properties of WAAM Al-5 %Mg alloy

To address issues of poor forming accuracy, high porosity, and inadequate mechanical properties in wire arc additive manufacturing of aluminum alloys, this study applied external direct current (DC) and alternating current (AC) composite magnetic fields (ECMF) (AC+DC) in cold metal transition wire arc additive manufacturing (CMT-WAAM) of Al-5 % Mg alloys. The aim was to enhance the quality of forming and overall mechanical properties of the deposited specimens. Optimal ECMF (AC+DC) parameters-DC 3 A, AC 1 A, and alternating frequency 100 Hz-were determined through orthogonal experiments. Results showed that ECMF (AC+DC) facilitated arc expansion and stirred the molten pool via Lorentz force generation, thereby accelerating molten flow and improving forming precision. Compared to specimens without ECMF (AC+DC), those with ECMF (AC+DC) exhibited reduced porosity (1.07 % to 0.31 %, a decrease of 71.03 %) and finer grain size in the deposited layer (84.80 ±30.5μm to 69.10±25.1μm, an 18.51 % decrease). Additionally, average microhardness increased (83.83 HV to 96.70 HV, a 15.35 % increase), transverse tensile strength improved (239.66±1.6 MPa to 263.00± 1 MPa, a 9.86 % increase), and elongation at break enhanced from 25.50±3.8 % to 27.17±0.33 %. Longitudinal tensile strength also rose (232.33±14.33 MPa to 248.33±8.33 MPa, a 6.88 % increase), with elongation at break increasing from 19.00±7.5 % to 19.40±4.2 %. Moreover, the mechanical properties' anisotropy decreased. Consequently, ECMF (AC+DC) significantly enhanced the overall properties of CMT-WAAM Al-5 % Mg alloy deposition, providing valuable insights for extending engineering applications of Al-5 % Mg alloy WAAM.

A Parametric Study on the Stability, Geometry and Hardness of AISI 308LSi WAAM-GMAW

Wire arc additive manufacturing (WAAM) has been established to be an efficient and cost-effective additive manufacturing technique for fabricating functional metallic parts from scratch. However, there is need to determine optimal processing condition for each material system to produce high-quality parts. In this work, a parametric study of WAAM of AISI 308LSi was performed to determine the processing condition(s) at which single tracks of high dimensional accuracy, excellent geometry, no visible crack and pore, and high hardness required for high-quality multi-track deposition can be achieved. The track geometries were investigated using a combination of optical microscopy and image processing software. The microstructure and hardness of the deposited single tracks were examined using optical microscopy and Vickers hardness tester respectively. A process map predicting the process stability of WAAM of AISI 308LSi was developed within a process window. Continuous single tracks of high dimensional accuracy were produced from a stable deposition process. The process becomes unstable whenever the wire deposition volume per unit length of track is in excess of the available heat energy per unit length of track. The wire feed rate and traverse speed significantly influence the stability and geometry of the single tracks. The processing conditions at which single tracks of low wetting angle (<90◦), high aspect ratio (>1.5), high surface quality, and high hardness (close to the as-received material) can be deposited were determined. These processing conditions were considered suitable for the fabrication, surface modification and repair of functional engineering parts made of 308LSi stainless steel.

Frequency informed convolutional autoencoder for in situ anomaly detection in wire arc additive manufacturing

Frequency informed convolutional autoencoder for in situ anomaly detection in wire arc additive manufacturing

ESTRATEGIAS DE DEPOSICIÓN Y PROGRAMACIÓN PARA ABORDAR LA FABRICACIÓN DE PIEZAS DE GEOMETRÍA COMPLEJA MEDIANTE WAAM (WIRE AND ARC ADDITIVE MANUFACTURING)

This work analyzes the factors that affect the manufacture of complex geometry parts by WAAM (Wire and arc additive manufacturing) with the aim of minimizing the material used, improving the Buy-to-Fly ratio (ratio of raw material weight divided by the weight of the final component) and avoiding part distortions. A study of the different material deposition strategies to manufacture the parts (straight beads, circular path beads, serpentine, overlapping beads...) has been carried out to obtain the desired geometry. Depending on the deposition strategy to be used and the geometry of the part, the best option for the definition of robot trajectories has been analyzed, which can be done by direct programming of the robot or in a CAD-CAM design environment. Another aspect to be considered in manufacturing is the time between layers. This time affects the growth of the parts, since the accumulated heat can cause the growth to be inconsistent and generate distortions. To see the effects of different waiting times, simulation tools have been used. Finally, in order to control the deviations of the real part with respect to the theoretical one, the option of using profilometry has been analysed. This paper aims to analyse the development of new methodologies that respond to the different challenges mentioned above.) Keywords: WAAM, Buy-to-Fly, deposition strategies, robot trajectories, simulation

Effect of laser remelting on the microstructure and properties of an AlCoFeNi eutectic high-entropy alloy fabricated through double-wire arc additive manufacturing

Additive manufacturing (AM) technology is a new method for preparing eutectic high-entropy alloys (EHEAs). The resulting EHEAs have excellent mechanical properties. However, in engineering, material failure, such as wear or fatigue fracture, often occurs on the surfaces of components. There is no report on surface modification and strengthening of additively manufactured EHEAs. Therefore, this study successfully utilized laser remelting (LR) technology to enhance the surface properties of an AlCoFeNi EHEA fabricated by using double-wire arc AM technology. After LR, the distance between adjacent regular eutectic regions and lamellar spacing of the EHEAs significantly decreased, and the proportion of strictly semicoherent face-centered cubic/body-centered cubic interfaces increased. When microhardness increased from 277.7 HV to 302.3 HV, the average friction coefficient and wear rate of the alloys decreased by 32.5% and 51.1%, respectively, and hardness and wear resistance significantly improved. This study has laid a solid foundation for the engineering application of the combination of LR and AM and also provided new ideas for improving the surface performance of additively manufactured EHEAs.

Microstructure and mechanical properties of laminated Ti-TiBw/Ti composites fabricated by wire arc additive manufacturing

To achieve the synergetic improvement of the strength and ductility of titanium matrix composites (TMCs), in this study, flux-cored wires were customized and combined with the wire arc additive manufacturing (WAAM) process to fabricate laminated Ti-TiBw/Ti composites. The diffusion behavior of the reinforcement during the WAAM deposition process was studied in detail. By optimizing the process parameters to regulate the distribution of the reinforcement, the composites presented a laminated structure on the macroscale and a non-uniform distributed network structure on the microscale. Compared with pure titanium, the ultimate tensile strengths and ductility of the laminated Ti-TiBw/Ti composites have both improved. The ultimate tensile strengths of the composites with 5 vol% and 10 vol% TiBw/Ti layers are 574 MPa and 663 MPa, respectively, and the fracture elongation are 27.74 % and 24.95 %, respectively. This heterogeneous structure of TMCs reconciles the contradiction between strength and ductility, mainly attributed to the strengthening effect of in-situ synthesized TiBw and the toughening effect of the laminated structure and the TiBw network structure.

Effect of heat treatment on microstructure and mechanical properties of WE43 alloy fabricated by wire arc additive manufacturing

Heat treatment is an effective method to improve the mechanical properties of Wire Arc Additive Manufacturing (WAAM) WE43 alloy. This study investigates the effects of heat treatment on the microstructure and mechanical properties of the WE43 alloy processed by WAAM. The as-deposited samples exhibit a uniform equiaxed crystal structure, with grain size gradually increasing as the number of deposited layers grows. The as-deposited microstructure comprises eutectics and a small amount of cubic phases, and the phase content escalates as the amount of deposited layers increases, influenced by the cumulative effect of multiple thermal cycles. At lower solid solution temperatures (480 ℃ × 8h), most of the eutectic phase remains undissolved. During tensile testing, undissolved eutectics tend to cause stress concentrations, leading to cracks that result in sample fractures, negatively affecting the mechanical properties. At higher solid solution temperatures (520 ℃ × 8h), most of the eutectic dissolves, but abnormal grain coarsening (AGC) in the interlayer fine-grain region occurs, causing a significant reduction in the sample's mechanical properties. After solid solution treatment at 500 °C for 8hours, only a small amount of eutectics remains undissolved, and the AGC phenomenon is not observed, resulting in an optimal solid solution effect. Subsequently, after aging treatment at 225 °C for 18hours, dense nanoscale β′′ phases precipitated within the alloy grains, significantly improving the mechanical properties. The samples achieved optimal performance, with UTS, YS, and EL of 323±15.2MPa, 225±11.3MPa, and 8.4±1.1%, respectively.

Tailoring the microstructure and mechanical properties of wire arc additively manufactured Ti6Al4V alloy by in-situ microalloying with modified nanocarbon

Carbon alloying is a validated strategy for enhancing the mechanical properties of titanium alloys prepared by wire arc additive manufacturing (WAAM). However, achieving uniform carbon distribution, particularly nanocarbon, in the melt pool via the brushing method is challenging, which limits the improvement of mechanical properties. In this paper, nanocarbon was modified by nitric acid hydrothermal treatment and added into the Ti64 melt pool during the WAAM. The distribution of modified nanocarbon in the melt pool was characterized, and the microstructure and mechanical properties of the nanocarbon-alloyed titanium alloy deposits were studied. The findings revealed that the surface of modified nanocarbon generated oxygen-containing functional groups, which enhanced its dispersion in the melt pool. The addition of 0.1–0.3 wt% modified nanocarbon induced no pores in the deposits compared to unmodified ones. The tensile strength of the deposited alloys was continually enhanced with increasing modified nanocarbon content, while the elongation had a peak value. The Ti64 with 0.1 wt% nanocarbon exhibited a balanced comprehensive performance with an ultimate tensile strength (UTS) of 981 MPa coupled with an elongation of 8 %. The achievement of the balanced mechanical performances was attributed to the refinement of α-Ti and solid solution strengthening of nanocarbon. When 0.3 wt% nanocarbon was added, the UTS increased to 1012 MPa but the elongation sharply decreased to 4.5 % due to the precipitation of TiC.

Submerged friction stir processing of wire arc additively manufactured Al alloy: Microstructure and mechanical properties

Friction stir processing (FSP) significantly improves the microstructure and mechanical properties of wire arc additive manufacturing (WAAM) components. This study pioneers the application of submerged friction stir processing (SFSP) to thin-walled WAAM components fabricated from Al-2319, Al-5087, and Al-6082 alloys. The samples were characterized by optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, electron backscatter diffraction, and microindentation. The results demonstrate that SFSP leads to a break of the eutectic network, the uniform distribution of precipitates originating from the Al matrix, a marked reduction in porosity and cracks, and grain refinement attributed to accelerated dynamic recrystallization, enhancing hardness and ductility across all three alloys. The improvement was most notable in the Al-6082 alloy relative to the others. Water cooling delays precipitates formation and encourages the development of fine particles. The uncoarsened θ' phase in Al-2319 and the fine β' phase in Al-5087 both contribute to superior tensile properties.

Explaining the Anomaly Detection in Additive Manufacturing via Boosting Models and Frequency Analysis

Anomaly detection is an important feature in modern additive manufacturing (AM) systems to ensure quality of the produced components. Although this topic is well discussed in the literature, current methods rely on black-box approaches, limiting our understanding of why anomalies occur, making complex the root cause identification and the consequent decision support about the action to take to mitigate them. This work addresses these limitations by proposing a structured workflow designed to enhance the explainability of anomaly detection models. Using the wire arc additive manufacturing (WAAM) process as a case study, we examined 14 wall structures printed with INVAR36 alloy under varying process parameters, producing both defect-free and defective parts. These parts were classified based on surface appearance and welding camera images. We collected welding current and voltage data at a 5 kHz sampling rate and extracted features from both time and frequency domains using a knowledge-based approach. Isolation Forest, k-Nearest Neighbor, Artificial Neural Network, XGBoost, and LGBM models were trained on these features, and the results shown best performance of boosting models, achieving F1 scores of 0.927 and 0.945, respectively. These models presented higher performance compared to other models like k-Nearest Neighbor, whereas Isolation Forest and Artificial Neural Network posses lower performance due to overfitting, with an F1 score of 0.507 and 0.56, respectively. Then, by leveraging the feature importance capabilities of these models, we identified key signal characteristics that distinguish between normal and anomalous behavior, improving the explainability of the detection process and in general about the process physics.

Influence of parameter variation and interlayer temperature control in wall angle, curvature and measurement methodology of ER70S-6 parts obtained by WAAM

Wire and Arc Additive Manufacturing is characterized for the high deposition rates, enabling the manufacturing of big, complex parts, with smaller relative production cost. However, once the part receives high heat inputs, leading to geometry variation and deformations, it is important to properly measure the part characteristics. Therefore, this work contributes with a measurement methodology for inclined walls deposited by Wire and Arc Additive Manufacturing and its application on walls deposited with different parameters. The main parameter of influence was the use of interlayer temperature control, which increased the angle in 71.0%, and the curvature in 90.3%, lower part.

Intensify the hindrance to gas entrapment on the construction of Al 5356 thin-walled structure by tuning the WAAM process parameters

Abstract Compared to other metallic additive manufacturing methods, Wire Arc Additive Manufacturing (WAAM) has a number of advantages, such as less equipment capital required and more material composition flexibility. However, uneven welding and feed rates, as well as inadequate gas flow, can result in flaws such oxidation, gas entrapment, and humping. This study aims to reduce gas entrapment, maximize tensile strength, and reduced elastic modulus of the WAAM Al5356 wall by optimizing gas flow rate (13, 16 and 19 l min−1) in conjunction with welding and feed rates. The study highlighted gas flow rate as the most important component in pore formation and used the Entropy approach in conjunction with the COmplex PRoportional ASsessment (COPRAS) tool to identify ideal settings. The reduction in gas entrapment to 0.02%, as shown in the confirmation studies, resulted in a 33.9% rise in tensile strength and a 64.7% rise in elastic modulus. To verify these ideal parameters, elastic modulus mapping was done on the printed WAAM Al5356 wall. Moreover, the damage processes connected to gas entrapment and humping development were examined using fractography. Consequently, the research determined the ideal conditions to generate a multi-layer structure free of defects, improving its practicality in aerospace and automotive sectors.

Experimental study on the heat input behavior of wire-arc additively manufactured 316L stainless steel parts for repairing applications

Wire arc additive manufacturing (WAAM) as an emerging manufacturing technique for fabricating large size metallic components with a higher deposition rate and lower material wastage. In this research, a thin walled-part was fabricated from stainless steel 316L with various heat input (HI) (low heat deposited wall (LHDW) and high heat deposited wall (HHDW) using the cold metal transfer (CMT)-based WAAM process. The microstructure characteristics, metallurgical characterization, and mechanical properties of the WAAM manufactured thin-walled component were examined. The deposited wall measuring 120 mm in length and 50 mm in height was fabricated by WAAM using ER316L wire and CMT. Microstructure of the deposit parts consists of the equiaxed, coarse, and columnar grains with epitaxial growth of dendrites were formed. The decrease in HI leads to the improvement of material hardness, yield and ultimate tensile strength (UTS) as well as the percentage elongation after fracture of the material decreases. EBSD analysis demonstrates the average grain size of 0.98 µm in LHDW and 2.43 in HHDW respectively. XRD results shows that main crystal structure found in WAAM thin-walled sample was γ-austenite phases. The microhardness distribution of the fabricated component exhibited the stability characteristics with the average value ranging between 213–237 HV. The tensile studies demonstrate the UTS of the LHDW and HHDW along the horizontal direction are 477 MPa greater than the vertical direction of 468 MPa and observed the anisotropy properties. The fractured surface was characterized by the emergence of obvious dimples revealing the ductile fracture. The lower HI and finer solidification structure of component fabricated by LHDW has greater tensile and hardness properties than that of HHDW. This study presents the initial assessment results for repairing stainless steel components subjected to mechanical damage.

Effect of induction heat treatment on microstructure, mechanical and corrosion properties of stainless steel 308 L fabricated using wire arc additive manufacturing

Induction solution heat treatment can change the mechanical characteristics and corrosion resistance properties of 308 L manufactured via wire arc additive manufacturing (WAAM). Moreover, compare with traditional heat treatment methods, this method can reduce heat treatment time and achieve in-situ local heat treatment. In this paper, in-situ induction heat treatment at 1100 °C for 2, 4, and 6 min were applied on 308 L thin-walled parts produced by WAAM. The result show that ferrite and austenite phase proportions were changed after induction solution heat treatment. Heat treatment at 1100 °C effectively reduced the δ-Fe and σ-Fe content, resulting in a slight decrease in UTS and microhardness, while YS and EL have a certain degree of increase. σ-Fe exhibits a more pronounced strengthening effect than austenite, albeit at the potential expense of steel’s elasticity. At the same time, induction heat treatment alters the ferrite to austenite ratio, which also enhances the anti-corrosion properties of the stainless steel. However, the presence of σ-Fe will cause a worsening of the corrosion resistance of the steel. In addition, as the heat treatment progresses, the ferrite’s microstructure in the deposition direction undergoes a significant transformation, changing from continuous dendrites to a few equiaxed grains.

Improvements in Injection Moulds Cooling and Manufacturing Efficiency Achieved by Wire Arc Additive Manufacturing Using Conformal Cooling Concept.

The plastic injection moulding industry is a constantly developing industrial field. This industrial process requires the manufacturing of metal moulds using complex heating and cooling systems. The purpose of this research is to optimize both the plastic injection moulding process and the mould manufacturing process itself by combining practices in this industry with current additive manufacturing technologies, specifically Wire Arc Additive Manufacturing (WAAM) technology. A mould punch was manufactured by using both WAAM technology, whose internal cooling system has been designed under the concept of Conformal Cooling, and conventional cooling channel designs and manufacturing techniques in order to carry out a comparative analysis. Theoretical results obtained by CAE methods showed an improvement in heat extraction in the WAAM mould. In addition, the WAAM mould was able to achieve better temperature homogeneity in the final part, minimizing deformations in the final part after extraction. Finally, the WAAM manufacturing process was proven to be more efficient in terms of material consumption than the conventional mould, reducing the buy-to-fly ratio of the part by 5.11.