FABRICATION AND INVESTIGATION OF 3D METALLIC WIRE WELD DEPOSITION USING COLD METAL TRANSFER TECHNIQUE

Abstract

Additive Manufacturing (AM) has revolutionized product formation by minimizing material consumption and replacing traditional methods in some industries. Among various AM processes, Wire Arc Additive Manufacturing (WAAM) stands out for its high deposition rates, material efficiency, shorter lead times, and reduced inventory costs. Resembling welding, WAAM deposits layers to create large, complex parts, making it particularly valuable for high buy-to-fly ratio components in the aviation industry. Despite its lower equipment cost compared to other metal deposition AM processes, achieving defect-free parts with WAAM presents challenges such as deformation, cracking, porosity, and spatter. Significant research has been conducted to enhance material properties and strength, but further experimentation is needed. Future advancements in WAAM design will likely improve efficiency for specific applications, making WAAM a fast, cost-effective alternative for producing heavy metal parts. WAAM utilizes an electric arc as the primary heat source and solid wire as the material feedstock. The performance of WAAM is significantly influenced by various process parameters. Understanding and optimizing these parameters is crucial to achieving high-quality parts with desirable mechanical and structural properties. This study explores the impact of three input process parameters – current (I), welding speed (WS), and Contact Tip to Work Distance (CTWD) - each at three varying levels on three key mechanical properties of SS316L austenitic stainless steel WAAM samples. Through experimentation and analysis, the study evaluates three crucial mechanical properties: ultimate tensile strength (UTS), microhardness (MH), and residual stress (RS). The investigation uses Taguchi's Grey Relational Analysis method, employing an L9 orthogonal array design. Analysis of Variance (ANOVA) has been utilized to assess the impact of parameters on grey relational grade (GRG). A comprehensive set of characterization techniques, including Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), and Energy Dispersive X-ray Spectroscopy (EDS), was employed to investigate the morphological attributes, elemental distribution, and crystalline configuration of the fabricated WAAM samples. vi The findings from Grey Relational Analysis (GRA) highlight that optimal performance in terms of maximum UTS, MH, and RS is achieved when employing specific parameter configurations: a I (110 A), WS (0.7 m/min), and CTWD of (3 mm). The ANOVA analysis for the grey relational grade across various responses indicates that the current is the most significant factor, followed by welding speed and contact tip to-work distance (CTWD). The contributions of current, welding speed, and CTWD are 76%, 21%, and 3%, respectively. X-ray CT results reveals that no porosity was present in either the WAAM or wrought steel samples.