Stochastic Geometric Model for Overlapping Beads Fabricated using Wire Arc Additive Manufacturing under uncertainties

Wire arc additive manufacturing (WAAM), leveraging traditional gas metal arc welding (GMAW) technology, offers a promising approach for fabricating large-scale metallic components with high deposition rates. Among GMAW-based processes, cold metal transfer (CMT) and pulsed metal inert gas (MIG) techniques differ significantly in their metal transfer mechanisms and thermal inputs, which directly influence the resulting material properties. This study systematically compares the microstructural, mechanical, tribological, and corrosion characteristics of 316L stainless steel walls produced using CMT and pulsed MIG WAAM processes under similar heat input conditions (CMT: 323.48 J/mm, pulsed MIG: 329.14 J/mm). The CMT process produced finer grains (11.16 µm) compared to pulsed MIG (14.14 µm), contributing to slightly higher microhardness (171.90 HV versus 171.14 HV) and improved mechanical properties. Charpy impact toughness, yield strength, and ultimate tensile strength were all higher for the CMT process by 16.4%, 3.4%, and 1.3%, respectively, while pulsed MIG showed slightly higher elongation (56% versus 52.25%). Fractographic analysis revealed finer, more uniform dimples in the CMT samples, indicating ductile fracture behavior. In terms of tribological performance, the CMT process exhibited a lower coefficient of friction (0.216 versus 0.249) and a significantly reduced wear-rate (3.4 × 10−3 mm3/m versus 5.5 × 10−3 mm3/m). Corrosion resistance was also marginally better in the CMT samples, with a corrosion rate of 0.05235 mm/year compared to 0.05524 mm/year for pulsed MIG. Overall, the CMT process consistently outperformed pulsed MIG across multiple performance metrics, making it a more favorable choice for high-integrity additive manufacturing of stainless steel components.

Laser-CMT (Cold Metal Transfer) arc hybrid additive manufacturing (LHAM) of 316L austenitic stainless steel (316SS) was studied. Surface roughness (R) and the minimum processing margin (dmin) of deposited thin-wall were calculated by the data measured via laser displacement sensor. Microstructure and fracture surface were observed by optical microscope and scanning electron microscope. The scanning speed of LHAM could be increased to 1.2 m/min, 3 times higher than that of wire arc additive manufacturing (WAAM). The R and dmin of LHAMed 316SS were reduced to 40% and 60% of the WAAM, respectively. The microstructure of LHAMed 316SS was composed of columnar or equiaxed grains, which were characterized by δ-ferrite and austenite. The tensile strength of LHAMed sample was higher, but the elongation is lower than that of WAAMed sample because of the formation of the porosity.Laser-CMT (Cold Metal Transfer) arc hybrid additive manufacturing (LHAM) of 316L austenitic stainless steel (316SS) was studied. Surface roughness (R) and the minimum processing margin (dmin) of deposited thin-wall were calculated by the data measured via laser displacement sensor. Microstructure and fracture surface were observed by optical microscope and scanning electron microscope. The scanning speed of LHAM could be increased to 1.2 m/min, 3 times higher than that of wire arc additive manufacturing (WAAM). The R and dmin of LHAMed 316SS were reduced to 40% and 60% of the WAAM, respectively. The microstructure of LHAMed 316SS was composed of columnar or equiaxed grains, which were characterized by δ-ferrite and austenite. The tensile strength of LHAMed sample was higher, but the elongation is lower than that of WAAMed sample because of the formation of the porosity.

Wire Arc Additive Manufacturing (WAAM) is a metallic additive manufacturing process based on the fusion of metallic wire using an electric arc as a heat source. The challenge associated with WAAM is heat management and understanding bead geometry. The printing process involves high temperatures, which results in the build-up of residual stresses can often cause deformations in a component. All of the process variables, such as torch speed (TS), wire feed speed (WFS), idle time, combine to produce the geometry of the deposit bead that results in the desired component shape. So, determining a method for choosing a good combined parameter process is very important to obtain a high-quality part. This article presents a study on how to use the WAAM process to produce a complexity part of aluminium alloys. The step of the determination process parameter is concentrated to develop in this study. An experimental design is determined to study the influence between the process parameters, for example, WFS, TS, high layer, length of bead. Different samples are made using the Yaskawa robot, using the classic CMT (Cold Metal Transfer) as a manufacturing method, using zigzag filling as a manufacturing strategy with the same WFS and same idle times and different TS, different bead lengths. A new manufacturing method using the zigzag filling strategy is proposed by adding an important step in determining the process parameters. The results indicate that the length of the bead has a significant impact on another parameter of the process.

In the present study, the effect of process parameters in Wire Arc Additive Manufacturing (WAAM) of Stainless Steel 304 as filler wire and mild steel as a substrate has been investigated. The deposition was made by using the Cold Metal Transfer (CMT) process. Single-pass beads are most useful for remanufacturing and repairing purposes. The quality of cladding for additive manufacturing predominantly depends on bead geometry. Hence, it is required to have an optimum range of bead parameters to ensure the desired mechanical properties. Response surface methodology and ANOVA were used to estimate the effects of current, weld speed, standoff distance on bead characteristics. Multiple regression models were developed to relate process parameters to bead quality.

Wire-arc additive manufacturing (WAAM) is a prominent technique for producing large metallic components due to its high deposition rate.Utilizing austenitic stainless steels in this process not only reduces production costs but also provides greater design freedom.Among these steels, SS310, known as heat-resistant steel in the industry, offers excellent oxidation resistance and high-temperature performance.However, it is highly susceptible to hot cracking during welding and additive manufacturing processes.In this study, the microstructure and mechanical properties of SS310 fabricated using WAAM with Cold Metal Transfer (CMT) and Gas Metal Arc Welding (GMAW) processes were compared.The results revealed that the CMT process, due to its lower heat input, effectively reduces the susceptibility of SS310 to hot cracking compared to the GMAW process.These findings emphasize the importance of selecting an appropriate process to achieve high-quality components and minimize structural defects.

The main objective of this work was to propose and evaluate a methodology for shielding-gas selection in additive manufacturing assisted by wire arc additive manufacturing (WAAM) with an austenitic stainless steel as feedstock. To validate the proposed methodology, the impact of multi-component gases was valued using three different Ar-based blends recommended as shielding gas for GMA (gas metal arc) of the target material, using CMT (cold metal transfer) as the process version. This assessment considered features that potentially affect the building of the case study of thin walls, such as metal transfer regularity, deposition time, and geometrical and metallurgical characteristics. Different settings of wire-feed speeds were conceived to maintain a similar mean current (first constraint for comparison's sake) among the three gas blends. This approach implied different mean wire-feed speeds and simultaneously forced a change in the deposition speed to maintain the same amount of material deposited per unit of length (second comparison constraint). The composition of the gases affects the operational performance of the shielding gases. It was concluded that by following this methodology, shielding-gas selection decision-making is possible based on the perceived characteristics of the different commercial blends.

Objectives: Fabrication of a cylinder-shaped High-Strength Low Alloyed steel wall component through wire (metal cored) arc additive manufacturing and assess the homogeneity and integrity of the built component. Method: Mechanical testing and microstructural characterizations such as optical microscopy, scanning electron microscopy and electron backscattered diffraction techniques were performed at distinct regions (namely, bottom and top). Findings: The conducted tensile test at the bottom area recorded a tensile strength of 864 MPa, which is 5.9 % higher than the top region but with a lower total elongation. The microhardness study revealed that the average hardness at the bottom region was 266 HV0.5, while the top region was 241 HV0.5. The microstructural analysis conducted in both areas indicates that the bottom region exhibits better hardness and strength due to the presence of a high value of geometrically necessary dislocations, High-Angle Grain Boundaries and increased grains with reduced size. However, the built component proves to have better homogeneity with marginal deviations in the properties estimated. Novelty: Solid wire was used as a predominant filler material for the Wire-Arc Additive Manufacturing (WAAM) process, which requires high heat input to melt the material. Hence, to reduce the heat input, metal-cored wire was used instead of solid wire for the Gas Metal Arc -WAAM process. Keywords: Gas metal arc welding, Metal cored wire, Mechanical properties, Direct energy deposition, Wire-arc additive manufacturing

Modulation of characteristic zones in NiTi alloys fabricated via wire arc additive manufacturing

Integrating robotic arm technology with cold metal transfer (CMT) has revolutionized wire arc additive manufacturing (WAAM). The research work consists of the fabrication of SS 316L WAAM using the CMT technique. Investigations of mechanical and microstructural properties, i.e. residual stress measurement (RSM), microhardness (MH), ultimate tensile strength (UTS), percentage elongation (PE), and microstructure of WAAM sample and cold rolled (CR) plate, results were compared. WAAM attained an UTS of 590 MPa, with an average yield strength (YS) of around 302 MPa, exceeding the CR plate’s UTS of 557 MPa while maintaining a similar YS of 305 MPa. WAAM and the CR plate exhibited nearly identical PE, with 64% and 62% values, respectively. Residual stress analysis revealed that the WAAM sample showed an average compressive residual stress of 124 MPa, accounting for 87% of the average residual stress observed in the CR plate, which measured 142 MPa. The MH profile of WAAM revealed an average value of 230 HV0.5, accounting for 88% of the MH observed in the CR plate at 260 HV0.5. The performance of WAAM closely matched that of the CR plate in terms of residual stress and MH.

An economic evaluation of hybrid WAAM-subtractive manufacturing in relation to deposition process parameters

The usage of additive manufacturingAdditive manufacturing as a process for component production is becoming increasingly important, as it offers enormous potential for material savings and therefore cost reduction. In particular, Wire Arc Additive ManufacturingWire-arc additive manufacturing (WAAM) processes are arousing a great deal of interest in several industries by its high deposition rates at low equipment acquisition costs and the low buy-to-fly ratio. This process is being specifically investigated for aerospace and space applications, as it allows the production of large structural complex near-net-shape components in small batches. However, a major drawback of this technology is the high anisotropic behaviour of the manufactured structures in the as-welded state. Since the Ni–Fe alloy Inconel 718Inconel 718 is an anisotropic material, in which introduced textures strongly influence the mechanical propertiesMechanical properties, the impact of the WAAM processing route on the mechanical propertiesMechanical properties as well as the underlying microstructureMicrostructures is specifically focused on in this study. Using a plasma arc as heat source and Inconel 718Inconel 718 wire as feedstock material, test walls are produced in order to characterize the created material. In addition to the identification of factors influencing the process, temperature cycles are measured at different positions during the build-up. The resulting microstructureMicrostructures is subsequently evaluated macroscopically as well as microscopically and examined regarding pores and precipitates. SEM/EDS analysis is carried out to investigate the underlying microstructureMicrostructures of the additively manufactured parts. Furthermore, mechanical propertiesMechanical properties are evaluated in the build-up direction as well as transversal to this direction in order to characterize the anisotropyAnisotropy of the material.

Wire arc additive manufacturing of a novel ATZM31 Mg alloy: Microstructure evolution and mechanical properties

Cold metal transfer (CMT)–based wire-arc additive manufacturing (WAAM) is increasingly popular for the production of large and complex metallic components due to its high deposition rate, low heat input, and excellent material efficiency. The accurate prediction of the bead geometry is of great importance to enhance the stability of the process and its dimensional accuracy. Besides the wire feed speed (WFS) and travel speed (TS), the interlayer temperature is another key factor in determining the bead geometry because of the heat accumulation in the multilayer deposition. In this paper, considering the varying interlayer temperature, WFS, and TS as inputs, an artificial neural network (ANN) is developed to predict the bead width, height, and contact angle; then, by connecting the ANN model with a bead geometric model, a combined model is established to improve the ANN model. Based on experimental test data, with random combinations of input parameters, the combined model is demonstrated to be able to accurately predict the bead geometry (mean error < 5.1%). The general effect of interlayer temperature on the bead geometry was also investigated by experiment.

Additive Manufacturing (AM) has drawn abundant attention over the past decades in the manufacturing and fabrication industries, especially to make part models and prototypes. This chapter introduces a potential welding based AM process called Wire Arc Additive Manufacturing (WAAM) for the fabrication of near-net shaped metal components including stainless steel components. To start with traditional AM processes, various fundamental traditional AM for the fabrication of components have been presented. Wire Arc Additive Manufacturing (WAAM) has been explained with its variants, synonyms, different welding processes to suit WAAM particularly to weld stainless steel metal; primary process selections for working with WAAM, important metals, and alloys that could be used in WAAM have been elaborated. A case study for WAAM fabrication of AISI 316 L stainless steel plate is included to introduce the fabrication of metal components using WAAM. Further, the most common defects which possibly play a vital role in WAAM components fabrication and a few of the future challenges regarding WAAM development are discussed. Fundamental information covered in this chapter could be more beneficial to beginners for the understanding of WAAM process generally including stainless steel component fabrication in a lucid tactic.

Microstructures and mechanical properties of NiTi shape memory alloys fabricated by wire arc additive manufacturing