Wire and arc additive manufacturing (WAAM) has proven that it can produce medium to large components because of its high-rate deposition and potentially unlimited build size. Like all additive ...manufacturing (AM) technologies, however, an optimized process planning that provides uniform, defect-free deposition is key for the production of parts. Moreover, AM, particularly WAAM, is no longer just a prototyping technology, and most of today's attention is on its transformation to a viable and cost-effective production. With this transformation, a number of issues need to be addressed, including the accuracy and effectiveness of the manufactured components. Therefore, the emphasis should be on dimensional precision and surface finish in WAAM. This paper covers heat input and management concept, related to the resulting shrinkage, deformation, and residual stresses, which is particularly critical. In addition, we focus on process planning including build orientation, slicing, and path planning, as well as the definition of process parameter selection from a single track to multi-track and multilayer, and finally geometric features from a thin-wall to lattice structures with several case studies. Central to addressing component quality and accuracy, we summarize guiding designs and future needs through numerous WAAM-specific issues, which require for manufacturing of complex components.
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•We review recent progress in wire and arc additive manufacturing with a focus on the part quality and accuracy.•We cover heat input and management concept, related to the resulting deformation and part quality.•We study process planning for different geometrical features, including several case studies.•We summarize guiding designs and future needs through the numerous WAAM geometrical issues.
Wire and arc additive manufacturing (WAAM) is considered to be an economic and efficient technology that is suitable to produce large-scale metallic components. In the past few decades, it has been ...widely investigated in different fields such as aerospace, automotive, and marine industries. Due to its relatively high deposition rate, low machinery cost, high material efficiency, and shortened lead time compared to other powder-based additive manufacturing (AM) techniques, WAAM has been significantly noticed and adopted by both academic researchers and industrial engineers. Titanium alloys as valuable metallic materials have been increasingly applied in aeronautics and astronautics fields owing to their excellent comprehensive properties. However, there are many challenges to fabricate large-scale titanium components with traditional manufacturing methods, particularly in consideration of complex component geometries and high Buy-To-Fly (BTF) ratio. Therefore, due to the advantages of relatively low manufacturing cost, good quality, and high efficiency, WAAM is becoming popular to fabricate near-net-shape and large-scale titanium alloy in recent years. This paper provides an overview of the 3D metallic printing of titanium alloy by employing WAAM as the deposition method. At first, the review introduces titanium alloys and WAAM technique, followed by WAAM systems which are used to manufacture titanium, and post-treatment which aims to optimize microstructure, improve mechanical properties, and eliminate residual stress of the WAAM deposited titanium components. Afterward, the economic applicability of applying WAAM on titanium alloys is also discussed. In the end, applications in various fields of WAAM titanium components are displayed.
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•Defect-free functionally graded material of HSLA steel to Cu-based alloy was successfully produced.•By synchrotron X-ray diffraction the interface revealed a mixture of Cu (FCC), Fe ...(BCC), and Fe(FCC) in the interface region.•Microhardness ranged from 260 HV1 to 120 HV1.
In this work, a functionally graded material (FGM) part was fabricated by depositing a Cu-based alloy on top of a high strength low alloy (HSLA) steel by twin-wire and arc additive manufacturing (T-WAAM). Copper and steel parts are of interest in many industries since they can combine high thermal/electrical conductivity, wear resistance with excellent mechanical properties. However, mixing copper with steel is difficult due to mismatches in the coefficient of thermal expansion, in the melting temperature, and crystal structure. Moreover, the existence of a miscibility gap during solidification, when the melt is undercooled, causes serious phase separation and segregation during solidification which greatly affects the mechanical properties. Copper and steel control samples and the functionally graded material specimen were fabricated and investigated using optical microscopy, scanning electron microscopy, and high energy synchrotron X-ray diffraction. Retained δ-ferrite was found in a Cu matrix at the interface region due to regions with mixed composition. A smooth gradient of hardness and electric conductivity along the FGM sample height was obtained. An ultimate tensile strength of 690 MPa and an elongation at fracture of 16.6% were measured in the FGM part.
Wire and arc additive manufacturing (WAAM) is a method of metal 3D printing that is suited to the requirements of the construction industry in terms of scale, speed and cost. Using this technology, a ...10.5 m span footbridge, the first of its kind, has been printed. The testing, analysis and initial verification of the bridge and its components are described herein. The experiments performed included advanced geometric analysis, material testing, compressive testing of cross-sections and full-scale load testing of the bridge at various stages throughout and post construction. Parallel finite element modelling of the full bridge and its constituent elements has also been performed as part of the verification. Confirmation that the bridge was able to sustain its full serviceability design load enabled to the bridge to be unveiled to the public, with controlled access, for Dutch Design Week 2018. Further testing under ultimate limit state design loading is planned before the bridge is placed in its final location and fully opened to the public. The project highlights the potential for metal 3D printing in structural engineering, as well as the necessary considerations for design.
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•Initial verification of the world's first metal 3D printed bridge is undertaken.•Material behaviour of the bridge is determined by tensile coupon testing.•Compressive structural response of the key bridge components is assessed by stub column testing.•Full-scale structural load testing of the bridge both during and after construction under different load cases is described.•Finite element simulations of the bridge are carried out and comparisons are made with the test results.
Wire and arc additive manufacturing (WAAM) is an emerging manufacturing technology that is widely used in different manufacturing industries. To achieve fully automated production, WAAM requires a ...dependable, efficient, and automatic defect detection system. Although machine learning is dominant in the object detection domain, classic algorithms have defect detection difficulty in WAAM due to complex defect types and noisy detection environments. This paper presents a deep learning-based novel automatic defect detection solution, you only look once (YOLO)-attention, based on YOLOv4, which achieves both fast and accurate defect detection for WAAM. YOLO-attention makes improvements on three existing object detection models: the channel-wise attention mechanism, multiple spatial pyramid pooling, and exponential moving average. The evaluation on the WAAM defect dataset shows that our model obtains a 94.5 mean average precision (mAP) with at least 42 frames per second. This method has been applied to additive manufacturing of single-pass, multi-pass deposition and parts. It demonstrates its feasibility in practical industrial applications and has potential as a vision-based methodology that can be implemented in real-time defect detection systems.
•Propose a defect detection method in additive manufacturing based on deep learning.•Use attention model, multiple spatial pyramid pooling and exponential moving average.•Establish a wire and arc additive manufacturing defect dataset to verify the effect.•YOLO-attention achieves a mean average precision of 94.5%.
Wire and arc additive manufacturing (WAAM), known for efficiently producing large-scale components, is predominantly applied to traditional alloys. However, the use of WAAM to fabricate high-entropy ...alloys and medium-entropy alloys (MEAs) remains less explored. This study demonstrates the successful fabrication of a VCoNi MEA with a relative density exceeding 99.9 % using elemental wires through WAAM. The fabricated VCoNi MEA exhibits a face-centered cubic structure with columnar grains aligned in the building direction, characterized by a high dislocation density, several stacking faults (SFs), and a high density of L12 domains within the grains. Notably, this VCoNi MEA achieves an ultimate tensile strength of 951.9 MPa, while maintaining an impressive tensile elongation of 35 % and superior strain-hardening capability. Microstructural analysis indicates that the synergy of dislocation network substructures, L12 domains and the activation of SFs and Lomer-Cottrell locks contributes to its high strain hardening capacity and excellent ductility. This work underscores the potential to produce near full-density components with superior mechanical performance using elemental wire, highlighting its significance for industrial applications.
•VCoNi medium entropy alloy was fabricated via element wire and arc additive manufacturing.•Repeated thermal input results in the generation of chemical ordering structures.•The VCoNi MEA exhibits an ultimate strength of 951.9 MPa and elongation of 35 %.•The formation of dislocation networks and L12 domains contribute to its excellent properties.
•First report of NiTi parts created by WAAM using dedicated Ni-rich NiTi wire.•The as-built parts exhibit superelasticity.•The as-deposited material is fully austenitic at room temperature.•Potential ...of using WAAM to deposit advanced functional materials is demonstrated.
Wire and Arc Additive Manufacturing (WAAM) was used for fabrication of NiTi parts using a commercialy available Ni-rich NiTi wire as the feedstock material. The as-built parts are near fully austenitic at room temperature as confirmed by differential scanning calorimetry, X-ray diffraction and superelastic cycling. The as-built microstructure changed from collumnar, in the first deposited layers, to equiaxed in the last deposited ones as a result of the different thermal cycle conditions. This is the first work where WAAM NiTi parts exhibit superelastic behavior under tensile conditions, highlighting the potential use of the technique for the creation of parts shaped in a complex manner based on this material and process. The potential to use WAAM for deposition of advanced functional materials is demonstrated.
Additive manufacturing has revolutionized the manufacturing paradigm in recent years due to the possibility of creating complex shaped three-dimensional parts which can be difficult or impossible to ...obtain by conventional manufacturing processes. Among the different additive manufacturing techniques, wire and arc additive manufacturing (WAAM) is suitable to produce large metallic parts owing to the high deposition rates achieved, which are significantly larger than powder-bed techniques, for example. The interest in WAAM is steadily increasing, and consequently, significant research efforts are underway. This review paper aims to provide an overview of the most significant achievements in WAAM, highlighting process developments and variants to control the microstructure, mechanical properties, and defect generation in the as-built parts; the most relevant engineering materials used; the main deposition strategies adopted to minimize residual stresses and the effect of post-processing heat treatments to improve the mechanical properties of the parts. An important aspect that still hinders this technology is certification and nondestructive testing of the parts, and this is discussed. Finally, a general perspective of future advancements is presented.
In the present study Inconel 625 alloy fabricated using Cold Metal Transfer (CMT) Wire Arc Additive Manufacturing (WAAM) has been investigated. The microstructure and mechanical properties of the ...fabricated Inconel625 alloy, and the influence of torch travel speed on the properties of the manufactured specimens were researched. Microstructural studies revealed variation in microstructure in different layers of the specimen, with the bottom layer consisting of fine primary cellular grains. Mechanical properties that include hardness and tensile properties showed that with the increase in the travel speed, average micro-hardness of the manufactured specimens slightly improved from 248 HV to 253 HV. The ultimate tensile strength (UTS) increased from 647 MPa to 687 MPa, while yield strength (YS) increased from 376 MPa to 400 MPa. Results showed that the mechanical performance of the manufactured components by CMT-WAAM method was better than the mechanical properties of Inconel 625 alloy casting parts except UTS, which demonstrated that the Inconel 625 alloys can be fabricated by cold metal transfer process.
•Inconel 625 alloy is first time to fabricate by WAAM.•Location dependence microstructure is revealed.•The mechanical performance except UTS is better than those within casting parts.
Wire and arc additive manufactured (WAAM) metal parts usually contain large columnar grains and detrimental tensile residual stress, affecting their mechanical performance. In this work, a ...post-treatment method combining heat treatment (HT) and laser shock peening (LSP) was employed to alter the microstructure and mechanical properties of WAAM Ti17 titanium alloy. The results show severe plastic deformation was induced in the surface layer, which, in turn, led to a high-level surface compressive residual stress (~−763 MPa) by combination treatment of HT and LSP. Meanwhile, high-density dislocations and mechanical twins were observed in coarse α phases after treatment by laser shock wave, and gradually evolved into refined α phases. The elongation of samples was significantly improved by 15% while ensuring original ultimate tensile strength (UTS, 1153 ± 13 MPa) after HT and LSP treatment. This combined HT and LSP method helps enhance the mechanical performance of WAAM parts through changing their microstructure and residual stress distribution.
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•The post-treatment method combining heat treatment and laser shock peening is effective for additive manufacturing.•Surface tensile residual stresses can be modified to beneficial compressive residual stresses.•High-density dislocations and mechanical twins are generated.•The tensile strength is improved with large elongation retained.
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