Effect of heat input on bead geometry and mechanical properties in wire arc additive manufacturing of a nickel aluminum bronze alloy

Wire arc additive manufacturing (WAAM) stands as an efficient and cost-effective method for producing largescale engineering components while minimizing waste. This study explores the influence of WAAM process parameters on nickel aluminum bronze (NAB) parts, focusing on the wire feed rate (WFR) as a key factor governing heat input and its effects on bead geometry, microstructure, and mechanical properties. The investigation involved depositing a single bead from NAB alloy while varying the WFS within the 2-7 m/min range, resulting in heat inputs ranging from 20.600 to 57.960 kJ/m. The results revealed that increasing heat input up to 34.944 kJ/m led to an augmentation in the bead dimensions and increased hardness due to kappa-precipitates formation within the alpha-Cu matrix. However, with further increments in heat input to 49.088 kJ/m and 57.960 kJ/m, the bead dimensions and hardness exhibited a decline as the uniformity of intermetallic kappa distribution lessened. Through optimization of WAAM process parameters, a defect-free single-wall NAB was successfully manufactured with enhanced properties. The tensile strength along the horizontal direction for the single-wall NAB alloy was found to be superior to that of the vertical direction, irrespective of the specimen's extraction regions. Additionally, the bottom specimen exhibited slightly higher tensile strength than the center and upper specimens due to being the initial layers of the wall deposited on the substrate plate, undergoing a faster cooling rate. These findings underscore the potential of WAAM as a robust method for the fabrication of larger NAB components with precision and efficiency.