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In recent years, Wire and Arc Additive Manufacturing (WAAM), is gaining attractions both from academia and industry, because it has the potential to substitute or complement the traditional manufacturing methods. Traditional materials and methods are reaching their limitation when demanding and special applications are considered.The current growth...
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... Currently, the determination of M s temperature contains two aspects: experimental measurement and model prediction. Experimental methods mainly include metallography [5,6], dilatation [7,8], hardness, and thermal analysis [9,10] while commonly used prediction models are machine learning (ML) [11][12][13][14], empirical formulas [15][16][17][18][19], and thermodynamic models [20][21][22][23][24]. M s determination with metallography is normally related to the content characterization for austenite and martensite under microscopy. The dilatation way contains a complex influence on the resulting M s by too many parameters such as heating and cooling rate. ...
Three methods are used to predict the martensitic transformation start temperature (Ms ) of steel. Based on the database containing 832 compositions and corresponding Ms data, prediction models are built, modified, and trained. Firstly, Ms was re-calculated by establishing a thermodynamic model to link the martensitic transformation driving force (Gibbs free energy difference of martensite and austenite) with resistance (elastic strain energy, plastic strain energy, interface energy, and shearing energy). Secondly, the existing Ms data is cleaned and re-predicted using traditional empirical formulas within different composition application ranges. Thirdly, four different algorithms in machine learning including random forest, k nearest neighbor, linear regression, and decision tree are trained to predict 832 new Ms values. By comparing the Ms results re-predicted by the mentioned three methods with the original Ms values, the accuracy is evaluated to identify the optimal prediction model.
... As a 3D printing technique, wire and arc additive manufacturing (WAAM) uses an electric or plasma arc as the heat source to melt metal wires layer by layer to form 3D metal parts that approximate the shape and size of a product, then supplemented by a small amount of post mechanical processing to meet the final product design. Compared with other 3D printing technologies, WAAM features low equipment investment, low operating costs, high deposition efficiency, and high metal utilization, making it possible to manufacture moderately complicated large parts with high efficiency and low cost [1][2][3][4]. This provides a new idea to solve the cost problem of manufacturing large components. ...
Low-temperature transformation (LTT) welding wire was initially developed to mitigate residual stress in the weld. It could also be used for internal stress optimization in Wire and Arc Additive Manufacturing (WAAM) process. In this study, a 26 layers LTT wall sample fabricated by using the WAAM technique was investigated. The microstructure of the LTT deposited wall includes elongated cellular martensite and reticular residual austenite. With the accumulation of deposition height, the prior austenite grain size increases, and the volume fraction of residual austenite and the density of dislocations in martensite decreases. According to the model of martensite transformation kinetics, the original austenite grain size is the main reason that affects the austenite fraction. In addition, the presence of a thermal cycle leads to the refinement of the martensitic microstructure and the increase in the boundary density, as well as the elimination of the sub-stable austenitic phase resulting in higher tensile properties in the middle samples than in the top ones. From the current work, it is clear that the unique thermal cycle treatment of WAAM is beneficial in improving the performance of LTT materials.
... WAAM is an additive manufacturing process particularly suitable for industrial-scale production. As one of the most influential and valuable direct energy deposition (DED) technologies, WAAM has various advantages, including a high deposition rate, short production lead time, and a high material utilization rate [69,70]. WAAM is mainly used for repairing metal parts and printing metal of a clean shape. ...
Owing to excellent high-temperature mechanical properties, i.e., high heat resistance, high strength, and high corrosion resistance, Ti alloys can be widely used as structural components, such as blades and wafers, in aero-engines. Due to the complex shapes, however, it is difficult to fabricate these components via traditional casting or plastic forming. It has been proved that additive manufacturing (AM) is an effective method of manufacturing such complex components. In this study, four main additive manufacturing processes for Ti alloy components were reviewed, including laser powder bed melting (SLM), electron beam powder bed melting (EBM), wire arc additive manufacturing (WAAM), and cold spraying additive manufacturing (CSAM). Meanwhile, the technological process and mechanical properties at high temperature were summarized. It is proposed that the additive manufacturing of titanium alloys follows a progressive path comprising four key developmental stages and research directions: investigating printing mechanisms, optimizing process parameters, in situ addition of trace elements, and layered material design. It is crucial to consider the development stage of each specific additive manufacturing process in order to select appropriate research directions. Moreover, the corresponding post-treatment was also analyzed to tailor the microstructure and high-temperature mechanical properties of AMed Ti alloys. Thereafter, to improve the mechanical properties of the product, it is necessary to match the post-treatment method with an appropriate additive manufacturing process. The additive manufacturing and the following post-treatment are expected to gradually meet the high-temperature mechanical requirements of all kinds of high-temperature structural components of Ti alloys.
... Wire-arc directed energy deposition (Wire-arc DED) has been regarded as a practical and cost-effective processing method for academic research and engineering applications [1][2][3]. It has distinctive advantages, including high deposition rate and materials utilization, short production cycle, and lead time, as well as being competent for fabricating large-scale metallic components with strongly complex shapes [4]. ...
... Metallic materials are common structural materials to bear the load in construction, civil, and maritime engineering due to their excellent mechanical properties [1]. For applications such as next-generation heat exchangers, high-end electronics, highspeed rail contact wires, and high-speed pulse magnets, developing and designing new alloys that exhibit a combination of extremely high strength and good electrical and thermal conductivity is necessary [2]. ...
A new way of preparing graphite/silicon carbide-reinforced metal composite materials is presented. SiC and pure iron diffusion couple were heated to 720 ℃ and held at such temperature for 60 seconds to prove the concept. The experimental result shows that a graphite layer successfully forms on the surface of pure iron. The kinetic simulation was carried out using Thermal-Calc software, showing potential graphite formation in an iron matrix. The simulation result indicates that graphite can also form inside an iron matrix within 60 seconds at 720 ℃.
... Several alloys have been employed on WAAM processes, for example, steels, aluminum alloys, nickel alloys, titanium alloys, and various kinds of functionally gradient alloys such as Al-Cu, Fe-Ni, Ni-Ti, and Fe-Al, etc [9][10][11][12][13][14][15][16]. With the scope of such structural alloys, titanium alloy has superior comprehensive properties including low density, lightweight, high fracture toughness, high heat resistance, high specific strength ratio, high fatigue strength, high crack growth resistance, and corrosion resistance [17]. ...
In this paper, a Ti-6Al-4V wall was fabricated using wire and arc additive manufacturing to be as-deposited (AD) coupons for investigating the effect of post-heat treatments on microstructure and mechanical properties. A Gleeble thermal-mechanical simulator was used to create a microstructure gradient in the sample with different heat treatment temperatures to efficiently determine the optimal post-treatment temperature, which is followed by furnace heat treatments to find proper aging (Age) conditions. Solid solution at 830 ℃ for 2 hrs followed by water cooling + aging at 500 ℃ for 4 hours followed by furnace cooling was considered to be the optimal post-heat treatment candidate because it gained a 12.85% improvement of yield strength (YS) and 3.33% improvement of the ultimate tensile strength (UTS), though tensile fracture elongation (EL) decreased 3.37% compared to the as-deposited samples. With this condition, microstructure evolution including β grains, α widmanstätten, grain boundary α (GB α), and α’ martensite was characterized at the same position of the sample experienced deposition (AD), solid-solution treatment (AD-ST), and aging (AD-ST-Age) respectively. The relationship between such step-by-step microstructure evolution with tensile strength as well as hardness change was analyzed and established. In the end, brittle fracture surfaces of AD, AD-ST, and AD-ST-Age samples were observed to find the factors that contribute to failure.
... However, it is a good indicator of the excess energy input that contributes to melting the substrate or the previous layer instead of melting the added material [11]. The dilution was found to be 10% to 30% with WAAM and about 8% with LWMD at optimized parameters [12,13]. The aim of this study is to analyze the dilution of the drops with the substrate and the material properties obtained in order to know if the present process with only incremental wire feeding is sufficiently energy efficient, or if laser power modulation should also be applied to increase the energy efficiency. ...
Additive Manufacturing has become a field of high interest in the industry, mostly due to its strong freedom of design and its flexibility. Numerous Additive Manufacturing techniques exist and present different advantages and disadvantages. The technique investigated in this research is a drop-by-drop deposition alternative to Laser Metal Wire Deposition. This technique is expected to induce a better control over the power input in the material, resulting in a better power efficiency and tailorable material properties. The aim of this research is to investigate selected material properties of the structures produced with the drop-by-drop deposition technique. Multi-drops structures were deposited from 316L, Inconel 625 (NW6625) and AlSi5 (AW4043) wires. Two drop deposition methods were investigated: (i) a contactless recoil pressure driven detachment for 316L and Inconel 625, (ii) a contact-based surface tension driven detachment for AlSi5. A material characterization including optical microscopy, EDS and hardness measurements was performed in transverse and longitudinal cross-sections. The microstructure of the deposited material, the dilution with the substrate and the heat affected zone were analysed. The contactless detachment showed a higher dilution than the contact-based technique due to the laser irradiating the substrate between two drop detachments, which melts the substrate that then mixes with the deposited drops.
... With the assistance of automation and digitization techniques, it has been employed in various industrial fields [4][5][6][7][8]. As one of the most effective and valuable direct energy deposition (DED) techniques, the advantages of WAAM include a high deposition rate, short production lead time, and high material utilization [7,9]. The high deposition rate and consequently reduced production lead time contribute to the improvement of manufacturing efficiency greatly so that it provides the opportunity to fabricate large-scale components. ...
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.
TX-80 low-transformation-temperature (LTT) welding wire was used to replace the traditional ER 307Si welding wire to realize the connection of 22SiMn2TiB armor steel in manual overlay welding. The previously existing issues, such as welding cracks, large welding deformation, and severe welding residual stress, were solved to ensure good strength and ductility requirements. In particular, with the same welding conditions, TX-80 LTT wire eliminates welding cracks. It reduces the welding deformation no matter the base pretreatment of pre-setting angle or no pre-setting angle. By comparison, it was found that the microstructure at the TX-80 weld is mainly composed of martensite and a small amount of retained austenite. In contrast, the microstructure of the ER 307Si weld consists of a large amount of austenite and a small amount of skeleton-like ferrite. The variation trend of residual stress and microhardness from the weld to the base were investigated and compared with the mechanical properties of base materials. The TX-80 and the ER 307Si tensile samples elongation is 6.76% and 6.01%, while the ultimate tensile strengths are 877 and 667 MPa, respectively. The average impact toughness at room temperature of the ER 307Si weld is 143.9 J/cm2, much higher than that of the TX-80 weld, which is only 36.7 J/cm2. The relationship between impact and tensile properties with microstructure species and distribution was established. In addition, the fracture surface of the tensile and the impact samples was observed and analyzed. Deeper dimples, fewer pores, larger radiation zone, and shear lips of TX-80 samples indicate better tensile ductility and worse impact toughness than those of ER 307Si weld.
