Wire Arc Additive Manufacturing Research Articles

Multi-response optimisation of wire-arc additive manufacturing process parameters for AISI 4130 steel during remanufacturing process

Wire-arc additive manufacturing (WAAM) has emerged as a critical tool for remanufacturing industrial components. A limited understanding of this technique for quality product manufacturing has hindered its utilisation for industrial applications. This study reports on the optimisation of WAAM process parameters for AISI 4130 steel towards remanufacturing of high-quality products for industrial applications. AISI 4130 steel was selected for this study due to its high strength-to-weight ratio, excellent weldability, and suitability for the WAAM process. Taguchi’s Grey Relational Analysis (GRA) used four factors and three levels in the multiple response optimisation process. The study considered process parameters voltage, current, travel speed and gas flow in the gas metal arc welding (GMAW)-based WAAM technique. Analysis of Variance (ANOVA) results show that voltage, travel speed and gas flow significantly affect material deposition. Voltage had the highest significance (31.61%) compared to other parameters. The optimised process parameters were found to be: voltage –23 V, current –100 A, travel speed −350 mm min−1, and gas flow −10 L min−1. These parameters resulted in tensile residual stresses of 25 ± 74 MPa, microhardness of 171.4 ± 12.2 HV0.3, and a relative density of 98.21%. The microstructural analysis reveals the existence of predominant ferritic and pearlitic colonies. This is due to compounded thermal stresses during the deposition process and alloy composition resulting in tailored microstructure and mechanical properties. The study provides some insights into the WAAM remanufacturing process for producing highly quality industrial components.

The effect of weld heat input on the microstructure and mechanical properties of wire arc additively manufactured 15-5PH stainless steel

AbstractPrecipitation hardening (PH) stainless steels, such as 15-5PH, have a high strength combined with excellent corrosion resistance. These properties make them valuable in critical industries such as defence, construction, aerospace, energy and maritime. Recent advancements in additive manufacturing (AM) technology enable the rapid and cost-effective production of components. In the case of 15-5PH components manufactured using wire arc additive manufacturing (WAAM), the as-deposited mechanical properties are not suitable at present for industrial applications. This paper explores the mechanical properties of this process and alloy combination without post weld heat treatment with the aim of eventual adoption in this condition by industry. The impact of weld heat input on the microstructure and mechanical properties of stainless steel 15-5PH produced using WAAM was investigated. The microstructure was examined using hardness testing in addition to optical and electron microscopy. Furthermore, mechanical properties were measured with tensile and impact testing. Investigations were conducted on material produced using weld heat inputs of 0.223 kJ/mm and 0.565 kJ/mm. These results indicate that reducing the weld heat input leads to a minor decrease in strength but an 80% increase in impact toughness. This reduction in weld heat input is correlated with a 50% reduction in volume fraction of δ-ferrite while also noting a 55% increase in carbide precipitates. In addition, the fracture surfaces were predominantly cleavage or quasi-cleavage in morphology.

Dimension Prediction and Microstructure Study of Wire Arc Additive Manufactured 316L Stainless Steel Based on Artificial Neural Network and Finite Element Simulation

The dimensional accuracy and microstructure affect the service performance of parts fabricated by wire arc additive manufacturing (WAAM). Regulating the geometry and microstructure of such parts presents a challenge. The coupling method of an artificial neural network and finite element (FE) is proposed in this research for this purpose. Back-propagating neural networks (BPNN) based on optimization algorithms were established to predict the bead width (BW) and height (BH) of the deposited layers. Then, the bead geometry was modeled based on the predicted dimension, and 3D FE heat transfer simulation was performed to investigate the evolution of temperature and microstructure. The results showed that the errors in BW and BH were less than 6%, and the beetle antenna search BPNN model had the highest prediction accuracy compared to the other models. The simulated melt pool error was less than 5% with the experimental results. The decrease in the ratio of the temperature gradient and solidification rate induced the transition of solidified grains from cellular crystals to columnar dendrites and then to equiaxed dendrites. Accelerating the cooling rate increased the primary dendrite arm spacing and δ-ferrite content. These results indicate that the coupling model provides a pathway for regulating the dimensions and microstructures of manufactured parts.

In situ process monitoring of multi-layer deposition in wire arc additive manufacturing (WAAM) process with acoustic data analysis and machine learning

In situ process monitoring of multi-layer deposition in wire arc additive manufacturing (WAAM) process with acoustic data analysis and machine learning

Quasi-Isotropy Structure and Characteristics of the Ultrasonic-Assisted WAAM High-Toughness Al Alloy

Wire Arc Additive Manufacturing (WAAM) has emerged as a highly promising method for the production of large-scale metallic structures; nonetheless, the presence of microstructural inhomogeneities, anisotropic properties, and porosity defects within WAAM Al alloys has substantially hindered their broader application. To surmount these obstacles, ultrasonic-assisted WAAM was applied in the fabrication of thin-wall structures utilizing 7075 Al alloy. This study investigates the effects of ultrasonic-assisted Wire Arc Additive Manufacturing (WAAM) on the structural and mechanical properties of 7075 Al alloy specimens. Microstructural analysis showed a significant refinement in grain distribution, with the average grain size notably reduced, enhancing the material’s homogeneity. Porosity across the specimens was quantified, showing a decrease in values from the upper (0.02151) to the middle (0.01347) and lower sections (0.01785), correlating with the rapid cooling effects of WAAM. Mechanical testing revealed that ultrasonic application contributes to a consistent hardness pattern, with measurements averaging 70.71 HV0.1 horizontally and 71.23 HV0.1 vertically, and significantly impacts tensile strength; the horizontally oriented specimen exhibited a tensile strength of 236.03 MPa, a yield strength of 90.29 MPa, and an elongation of 31.10% compared to the vertically oriented specimen which showed reduced mechanical properties due to the presence of defects such as porosity and cracks. The fracture morphology analysis confirmed a predominantly ductile fracture mode, supported by the widespread distribution of dimples on the fracture surface. The integration of ultrasonic vibrations not only refined the grain structure but also modified the secondary phase distribution, enhancing the quasi-isotropic properties of the alloy. These results underline the potential of ultrasonic-assisted WAAM in improving the performance of the 7075 Al alloy for critical applications in the aerospace and automotive industries, suggesting a promising direction for future research and technological advancement in additive manufacturing processes.

Enhanced high-temperature strength and ductility of wire arc additive manufactured Al–Ce–Mg alloys with fine α-Al/Al11Ce3 eutectics

Here, wire-arc additive manufacturing (WAAM) is employed to fabricate Al–Ce–Mg heat-resistant aluminum alloy, considering its capability to manufacture large complex structures more efficiently. Large-sized faceted Al11Ce3 intermetallic compounds are formed in the as-cast alloy with a hypereutectic microstructure. The microstructure is transformed to a eutectic microstructure by non-equilibrium solidification of WAAM, consisting lamellar α-Al/A111Ce3 eutectics. The WAAM alloy shows enhanced mechanical strength and ductility at 200 °C, compared with the as-cast alloy. The significant improvements of ultimate tensile strength and elongation for the WAAM alloy are correlated with its higher strain hardening rate, along with the transition from cleavage fracture to dimple fracture. The cracking of All1Ce3 particles occurs preferentially during the elastic deformation stage, as revealed by in-situ testing, and the strain hardening capability of the as-cast alloy is reduced. Pore defects, 0.15 % in volume fraction, are produced via WAAM processing, and the plastic deformation promotes the pore growth and mergence, increases the pore volume fraction, and decreases the pore sphericity. Our results demonstrate that WAAM is strongly attractive for the fabrication of Al–Ce–Mg alloys, due to the enhanced high-temperature strength-ductility synergy.

Enhancing mechanical properties and defects elimination in 2024 aluminum alloy through interlayer friction stir processing in wire arc additive manufacturing

In this study, a hybrid wire arc additive manufacturing (WAAM) and interlayer friction stir processing (IFSP) approach was utilized to enhance the quality of 2024 aluminum alloy components. The defects characteristic, microstructure evolution, and mechanical properties of the fabricated components and after T6 heat treatment were analyzed systematically. Our analysis reveals that IFSP can break and dissolve the eutectic phases, significantly reduce porosity defects and refine the grain size of the as-deposited materials, thus improving the overall mechanical properties. Notably, compared to the WAAM as-deposited component, the yield strength (YS) and ultimate tensile strength (UTS) in the top-layer stir zone (SZ) of IFSP component increased from 154 ± 3 to 267 ± 2 MPa, and from 258 ± 12 to 360 ± 3 MPa, respectively. However, in the middle-layer SZ, S-phase precipitation and coarsening induced by thermal cycling during additive manufacturing slightly reduced the tensile properties. Post-T6 heat treatment led to uniformly distributed properties in the IFSP component along both horizontal and vertical directions, with the YS, UTS, and elongation (EL) averaging 353 ± 9 MPa, 470 ± 4 MPa, and 10.5 ± 1.6%, closely matching those of wrought counterparts. The significant improvements in mechanical properties are primarily attributed to the elimination of porosity and precipitation of fine needle-like S-phase. This research not only demonstrates the potential of IFSP in enhancing the mechanical properties of WAAM-fabricated 2024 aluminum alloy but also offers a promising technique for producing high-quality components suitable for high-performance aerospace applications.

Microstructural heredity of Mg-Y-Nd-Al alloys prepared by WAAM

This study investigated the microstructure of Mg-4Y-3Nd-1.5Al alloys refined with Al and processed via wire arc additive manufacturing (WAAM). The size of the Al2RE particles in the initial wire significantly affects the grain size during WAAM. Larger Al2RE particles in the wire are resistant to dissolution, resulting in fewer reprecipitated Al2RE particles and, consequently, larger grains. Therefore, precise control of the Al2RE particle size as small as possible in the initial wire is essential for optimizing the refinement effect of magnesium-rare (Mg-RE) alloys in the WAAM process. This research is essential for advancing the development of Mg-RE alloys tailored for WAAM applications.

Benchmarking the quality improvement strategies of wire arc additive manufacturing process using fuzzy QFD approach

Purpose The purpose of this paper is to improve the productivity and quality of the wire arc additive manufacturing process by benchmarking the strategies from the selected six strategies, namely, heat treatment process, inter pass cooling process, inter pass cold rolling process, peening process, friction stir processing and oscillation process. Design/methodology/approach To overcome the lack of certainty associated with correlations and relationships in quality functional deployment, fuzzy numbers have been integrated with the quality functional deployment framework. Twenty performance measures have been identified from the literature under five groups, namely, mechanical properties, physical properties, geometrical properties, cost and material properties. Using house of quality weights are allocated to performance measures and groups, relationships are established between performance measures and strategies, and correlations are assigned between strategies. Finally, for each strategy, relative importance, score and crisp values are calculated. Findings Inter pass cold rolling process strategy is computed with the highest crisp value of 15.80 which is followed by peening process, heat treatment process, friction stir processing, inter pass cooling process,] and oscillation process strategy. Originality/value To the best of the authors’ knowledge, there has been no research in the literature that analyzes the strategies to improve the quality and productivity of the wire arc additive manufacturing process.

Microstructure and tribological properties of solid lubricant-doped CMT-WAAMed Stellite deposits

AbstractA large share of the world’s total energy consumption is used to overcome friction. Therefore, low friction wear-resistant materials are needed. Solid lubricants are solid-phase materials that can reduce friction at different temperatures between two surfaces sliding against each other without the need for a grease or liquid oil medium. In this study, Cold Metal Transfer Wire Arc Additive Manufacturing (CMT-WAAM) was used to deposit solid lubricant (WS2, MoS2, CaF2) doped hypoeutectic Stellite alloy. Fabricated deposits possessed crack- and pore-free microstructures consisting of γ-Co and M7C3 carbide eutectics embedded with chromium sulfides and microhardness values of ~ 530 HV1. They were also tested in self-mated unidirectional sliding wear tests in dry conditions at room temperature (RT) and at 300 °C in an air atmosphere. The results showed that the dynamic coefficient of friction (COF) decreased ~ 27% at RT and ~ 21% at 300 °C without losing the wear properties. During sliding wear tests severe strain hardening occurred and γ-Co was found to transform to ε-Co. The developed deposits can be used as hard facings or 3D printed components in applications that require good sliding wear properties at different temperatures such as metal forming tools, power transmission components, valves, and internal parts of combustion engines.

RETROFIT: Real-Time Control of Time-Dependent 3D Point Cloud Profiles

Abstract In modern manufacturing processes, ensuring the precision of 3D profiles of products is crucial. Nonetheless, achieving this accuracy is challenging due to the complex interactions between process inputs and the data structure of the 3D profile data. Our solution, a 3D profile-based control framework, addresses this challenge by actively adapting and controlling the manufacturing process to enhance 3D shape accuracy. 3D profile scans represent the ultimate measure of desired part quality. Therefore, utilizing them as the system responses for control purposes yields the most direct and effective feedback. We leverage recent advancements from Koopman operator theory to create an effective model-based control strategy. Initially, we estimate the process model by exploring the relationship between 3D profiles and heterogeneous process inputs. Then, we formulate an online model predictive control law. Challenges include dealing with unstructured, high-dimensional 3D point cloud data, capturing spatial and temporal structures, and integrating heterogeneous, high-dimensional process input data into the control model. To overcome these challenges, we introduce RETROFIT, a solution designed for the real-time control of time-dependent 3D point cloud profiles. Unlike traditional models, RETROFIT is not bound by linear assumptions and can handle unstructured 3D point cloud data directly. We demonstrate its effectiveness through a wire arc additive manufacturing case study, highlighting its potential to enhance 3D profile accuracy in manufacturing processes.

Microstructural evolution and mechanisms affecting the mechanical properties of wire arc additively manufactured Al-Zn-Mg-Cu alloy reinforced with high-entropy alloy particles

The mechanical properties of Al-Zn-Mg-Cu alloys produced via wire arc additive manufacturing (WAAM) are often weakened by the presence of continuous and coarse precipitated phases, which significantly limits their practical applications. In this study, high-entropy alloy (HEA) particles were incorporated into Al-Zn-Mg-Cu alloy during the WAAM process, which inhibits the continuity of precipitated phase, and the mechanism of microstructure evolution and macroscopic mechanical properties optimization of the components are explored. The results show that HEA particles promote grain refinement, and disrupt the formation of continuous precipitated phase along the grain boundary by generating plenty of fine spot-like precipitated phases, thus inhibiting grain boundary segregation. The spot-like precipitated phases are connected via a slender second-phase-band. The primary precipitates include the metastable η', stable η, and T phases, and the diffusion of solute atoms forms the Al3Ni and Al3(Ni, Cu)2 phases. The tensile strength increases from 247.4±5.9 MPa to 326.2±19.7 MPa in the horizontal direction and from 273.0±13.7 MPa to 335.4±11.1 MPa in the vertical direction, which correspond to increases of 31.9 % and 22.9 % respectively. The enhancement of mechanical properties is mainly attributed to Hall-Petch, Orowan, load-transfer, solid-solution and dislocation strengthening mechanisms. Only slight variation occurred in the elongation, the increased number of fine spot-like precipitated phases and grain boundaries hinder the crack propagation, while the increased number of pores facilitates the crack propagation, and these effects almost balance each other out in competition. These findings are expected to provide new insights into the microstructure optimization of WAAM components, thereby meeting more practical applications.

Multi-material stainless steel fabrication using plasma wire arc additive manufacturing

Layered stainless steel samples were manufactured using Plasma Wire Arc Additive Manufacturing by depositing alternating layers of two dissimilar stainless steels onto an AISI 316L substrate. The selected materials were the M430 ferritic and M316L austenitic stainless steels. Comprehensive microstructural characterization in different areas, including interfaces between the two different materials, was achieved through optical microscopy and electron backscatter diffraction. Results revealed good weldability among the two-layered steels and on the substrate. Also, a gradient duplex structure was observed mainly at the layer interfaces, suggesting a nuanced blending of properties in the deposited zone. To establish a direct correlation with mechanical properties in the observed structures, macro and micro-hardness tests were conducted along the cross-section. These tests evidenced the presence of a harder phase along the interface compared to the individual materials. The microstructural analysis corroborated the presence of mixing between phases in conjunction with some areas of delta ferrite.

Investigation on dual wire TIG Arc additive manufacturing of IN625 and SS316L FGM for continuous gradient and sandwich structures

Fabrication of functionally graded material (FGM) has been studied using dual wire WAAM-TIG (wire arc additive manufacturing - tungsten inert gas) process. The experimental research aims to perform the feasibility study of different designs of FGMs, including continuous gradient (CG-FGM) and sandwich structures (SW-FGMs). The weight percentage of two wire materials, SS316L and IN625, was precisely controlled using individual wire feeding systems. Process parameters were identified to obtain the defect-free deposition for the desired combination of weight percentage. The governing elements, i.e., Ni and Fe, showed a gradual variation in the case of CG-FGM and alternate peaks for SW-FGMs while examined using energy-dispersive X-ray spectroscopy (EDS). The alternate material distinction was noticeable with the increase in the number of individual layers for each set of SW-FGMs. The microstructure evolution of CG-FGM showed a smooth transition from equiaxed to columnar dendrites along the build direction, while SW-FGM showed heterogeneous behaviour. The hardness was steadily increasing in CG-FGMs and formed a wavy pattern in SW-FGMs. X-ray diffraction (XRD) analysis confirmed the formation of the austenitic phase, and variation in peak heights correlates to the change in microstructure and hardness. The conducted tribological study showed the specific wear rate gradually decreased with an increase of Ni content in CG-FGM, whereas in SW-FGM, it showed a strong dependency on the adopted design. The alloying effect in SW-FGM with different design modalities and its comparison with equal weight percentages were also studied in detail and presented.

Fatigue Crack Growth Rates and Crack Tip Opening Loads in CT Specimens Made of SDSS and Manufactured Using WAAM.

Additive manufacturing offers greater flexibility in the design and fabrication of structural components with complex shapes. However, the use of additively manufactured parts for load-bearing structural applications, specifically involving cyclic loading, requires a thorough investigation of material fatigue properties. These properties can be affected by many factors, including residual stresses and crack tip shielding mechanisms, which can be very different from those of conventionally manufactured materials. This research focuses on super duplex stainless steels (SDSSs) fabricated with wire arc additive manufacturing (WAAM) and investigates their fatigue crack growth rates and the net effect of crack tip shielding mechanisms. Using the compliance-based method, we measured crack tip opening loads in compact tension (CT) specimens with cracks propagating longitudinally and transversely to the WAAM deposition direction. It was found that fatigue crack growth rates were very similar in both directions when correlated by the effective stress intensity factor range. However, the differences in crack tip opening loads explain a quite significant influence of the deposition direction on the fatigue life.

Effect of C-Mn-Cu on microstructure and properties of wire arc additive manufacturing of high-manganese steels

Effect of C-Mn-Cu on microstructure and properties of wire arc additive manufacturing of high-manganese steels

On the fabrication of finer grain structure through using finer wire diameter for wire arc additive manufacturing of AZ31B magnesium alloy

Magnesium (Mg) alloys are the lightest structural metallic material, but it is hard to be applied to various industrial fields due to the crystallographic nature that is composed with hexagonal closed packed (HCP). Wire arc additive manufacturing (WAAM) could be a key to fabricating Mg parts with large sizes and complex designs. It has numerous advantages such as high material efficiency, short-delivery time by faster manufacturing speed, easy to modify, etc. Yet, most of the research mentioned the grain coarsening and degradation in mechanical properties when fabricating WAAM products using Mg alloy wires. To solve the problems, a solution was suggested with supposition that the lessen the deposit metal size a little by changing to the finer wire diameter can reduce the actual heat input and heat accumulation during the WAAM process. In this research, the WAAM of AZ31B has been conducted using a wire diameter of 1.0 mm rather using the 1.2 mm that is used in common. It was found that the finer (about 90 %) and equiaxed microstructure was composing the WAAM product made of wire diameter of 1.0 mm, and it results in about two times higher mechanical strength.

Simulation-based process parameter optimization for wire arc additive manufacturing

AbstractDuring manufacturing of components using wire arc additive manufacturing, specific cooling times are required to prevent overheating of the structure and geometrical distortions. Currently, these cooling times are inserted based on experience at certain interlayer temperatures — which reduces the reproducibility, leads to unwanted component properties, and increases the process time. In this contribution, instationary thermal finite element simulations are applied to compute the temperature evolution of additively manufactured components using the inactive element method. This allows to optimize the process parameters, which are — in our considerations here — the welding velocity and the cooling time of each layer, to reduce the total process time while achieving sufficient component properties. The optimization is carried out with the gradient-free Nelder–Mead simplex algorithm, where certain constraints of the process parameters are considered via penalty functions. To obtain reasonable simulation results, the temperature-dependent heat transfer of the experimental setup is modeled and calibrated with experimental data beforehand. It becomes apparent that thermal finite element simulations combined with a gradient-free optimization procedure are a suitable numerical tool to perform the optimization of process parameters for wire arc additive manufacturing. The optimized process parameters fulfill certain requirements regarding the cooling of the manufactured component. Moreover, the optimized parameters can significantly reduce the process time compared to manually chosen parameters. In our example, this is around 48 %.

Cold metal transfer-based wire arc additive manufacturing of pure copper with ultra high tensile strength

Copper is used in various heating and cooling applications by exploiting its excellent thermal and electrical conductivities. Powder- and laser-based additive manufacturing (AM) of pure copper is challenging as it encounters porosity because of its low absorptivity. The present research reports the feasibility of cold metal transfer-based wire arc additive manufacturing (CMT-WAAM) for the manufacturing of pure copper thin wall. The microstructure of the deposit is examined at three distinct locations. The mechanical properties (including ultimate tensile strength, yield strength, elongation and hardness) are examined in both scanning direction (SD) and build direction (BD). The thermal and electrical properties of the deposit are also measured. The deposited thin wall is reported to be firm and straight without any bulging and collapsing. The CMT-WAAM fabricated pure Cu samples exhibit superior tensile strength (310 ± 12 MPa in SD and 265 ± 9 in BD) than all other AM techniques. The thermal and electrical conductivities of the built copper wall are comparable to the previously reported conductivities of pure copper fabricated by other AM routes.

Prediction of Tensile Properties in Inconel 625 Superalloy Fabricated by Wire Arc Additive Manufacturing Using Improved Artificial Neural Network

This study exhibits the possibility of using an artificial neural network (ANN) to model the mechanical behavior of wire arc additive manufacturing (WAAM) for Inconel 625. For this reason, tensile tests of Inconel 625 superalloy as-built (AB) samples and samples after heat treatment at 1200 °C (HT-1200) by WAAM were performed. For the HT-1200 samples, the yield stress decreased, and the elongation increased significantly due to grain refinement and the formation of annealed twins. A new hybrid model combining a swarm intelligence optimization algorithm with a back propagation neural network (BPNN) was developed to simulate the flow behavior of the superalloy. Compared with other hybrid BPNN models that have been reported, the proposed BPNN model is in better agreement with the experimental data and provides a better description of the flow stress of the Inconel 625 superalloy. The excellent predictive ability of the model may be attributed to the optimization of the weights and thresholds of the BPNN, which obtains the optimal global solution in the search space more efficiently.