In the present study, an attempt is made to investigate and optimize the bead geometries of bead width (BW) and bead height (BH) of SS-309L using an SS316L substrate by employing a gas metal arc welding (GMAW)-based wire-arc additive manufacturing (WAAM) process. The Box–Behnken design approach was used to conduct the trials of single-layer depositions with input variables of travel speed (TS), voltage (V), and gas mixture ratio (GMR). The developed multi-variable regression models were tested for feasibility using ANOVA and residual plots. The data obtained indicated that V had the most significant impact on BW, followed by TS and GMR. For BH, TS had the most significant impact, followed by GMR and V. The results of single-response optimization using a passing vehicle search (PVS) algorithm showed a maximum BH of 9.48 mm and a minimum BW of 5.90 mm. To tackle the contradictory situation, a multi-objective PVS algorithm was employed, which produced non-dominated solutions. A multi-layered structure was successfully fabricated at the optimal parametric settings of TS at 20 mm/s, of voltage at 22 V, and of GMR at 3. For multi-layer structures, fusion among the layers was observed to be good, and they were found to be free from the disbonding of layers. This revealed the suitability of the PVS algorithm for generating suitable optimal WAAM variables. We consider the current work highly beneficial for users fabricating multi-layer structures.

In the present study, an attempt was made to build a thin-walled structure consisting of 10 layers using nitinol wire on a titanium substrate via a gas–metal arc welding (GMAW)-based wire-arc additive manufacturing (WAAM) process. A thin-walled structure was fabricated by using nitinol wire on a titanium substrate at the optimized parameters of a wire feed speed of 6 m/min, a travel speed of 12 mm/s, and a voltage of 20 V. In a microstructural study, the heat-affected zone was observed to have coarse grains and be columnar in shape, and the first layer exhibited a mix of dendritic structures. The mid-layers demonstrated a mix of coarse and fine columnar grains with dendritic colonies, while the last few layers demonstrated fairly equiaxed grains as well as a finer microstructure, as the cooling rates were very slow. The ultimate tensile strengths (UTSs) obtained at the bottom and top portions were found to be 536.22 MPa and 586.31 MPa. Elongation (EL) degrees of 10.72% and 11.57% were observed in the bottom and top portions, respectively. The fractography of the tensile specimen showed good toughness and ductility of the fabricated nitinol specimen. A microhardness examination showed a minimum value of 236.56 HV in the bottom layer and a maximum value of 316.78 HV in the topmost layer.

Multi-material additive manufacturing (MMAM) have the capability to directly fabricate three-dimensional (3D) parts consisting of more than one material. Multi-

In the present study, an L-shaped multi-walled structure of NiTi shape memory alloy (SMA) was fabricated by using the wire arc additive manufacturing (WAAM) method on a titanium substrate. The present study aims to investigate the fabricated structure for microstructure, macrostructure, and mechanical properties. The 40 layers of L-shaped structure were successfully fabricated at optimized parameters of wire feed speed at 6 m/min, travel speed at 12 mm/s, and voltage at 20 V. The macrographs demonstrated the continuous bonding among the layers with complete fusion. The microstructure in the area between the two middle layers has exhibited a mixture of columnar grains (both coarse and fine), interspersed with dendritic colonies. The microstructure in the topmost layers has exhibited finer colonial structures in relatively greater numbers. The microhardness (MH) test has shown the average values of 283.2 ± 3.67 HV and 371.1 ± 5.81 HV at the bottom and topmost layers, respectively. A tensile test was conducted for specimens extracted from deposition and build directions, which showed consistent mechanical behavior. For the deposition direction, the average ultimate tensile strength (UTS) and elongation (EL) were obtained as 831 ± 22.91 MPa and 14.32 ± 0.55%, respectively, while the build direction has shown average UTS and EL values of 774 ± 6.56 MPa and 14.16 ± 0.21%, respectively. The elongation exceeding 10% in all samples suggests that the fabricated structure demonstrates properties comparable to those of wrought metal. Fractography of all tensile specimens has shown good ductility and toughness. Lastly, a differential scanning calorimetry test was carried out to assess the retention of shape memory effect for the fabricated structure. The authors believe that the findings of this work will be valuable for various industrial applications.

The aim of the current study is to optimize the bead geometries of 80B2, namely, the bead height (BH) and bead width (BW), utilizing a mild steel substrate and a wire-arc additive manufacturing (WAAM) technique based on gas metal arc welding (GMAW). Single-layer depositions with different wire feed speed (WFS), voltage (V), and travel speed (TS) were accomplished by applying the Box–Behnken design methodology. Multivariable nonlinear regression models were developed and validated through ANOVA, revealing WFS as the most significant parameter influencing both BW and BH. The minimal influence of the error factor on each response proved the accuracy of the ANOVA findings. The favorable assessment of residual plots confirmed the appropriateness and reliability of the developed regression equations and ANOVA results. A metaheuristic Passing Vehicle Search (PVS) algorithm was applied for single-objective and multi-objective optimization, yielding a minimum BW of 5.874 mm and a maximum BH of 14.153 mm. Main effect and residual plots confirmed the accuracy and reliability of the predictive models. The parametric settings of WFS: 18 mm/min, TS: 7 mm/s, V: 19 V were obtained for simultaneous optimization of BW with 7.78 mm and BH with 10.87 mm. Pareto points were also generated, which provide non-dominated unique solutions. The study emphasizes the critical role of precise process parameter control in improving WAAM build quality and offers a robust framework for optimizing bead morphology, ultimately enhancing the efficiency and applicability of WAAM for structural component fabrication. These optimized parameters will be used in the future to manufacture a thin-walled, multi-layered structure.

In the present study, the gas metal arc welding (GMAW) process was used to investigate the effect of bead morphologies of SS316L. Single-layer deposition forms the base for manufacturing metal additive structures using a GMAW-based wire-arc additive manufacturing (WAAM) process. Thus, the current work focused on the analysis of bead morphologies of SS316L through single-layer depositions. Experimental trials were conducted using Taguchi’s L9 approach with travel speed (TS), gas mixture ratio (GMR), and voltage as input WAAM variables, and bead width (BW) and bead height (BH) as output responses. The effect of WAAM variables on output measures was studied using main effect plots. The relevance and reliability of the derived regressions were verified using ANOVA analysis. For the BH response, TS was found to be the most significant factor, followed by voltage, while GMR did not have any contributing impact on the output response variable. For the BW response, voltage was found to be the largest contributing factor, followed by GMR and TS. The R² values were measured at 0.9276 and 0.9962 for BH and BW, respectively. The outcomes proved that the model fits the data well and can successfully predict new observations, as the R² values for all responses were near one. Lastly, the best input set of WAAM variables was determined for individual output variables.