Design and Simulation of Cold Metal Transfer (CMT) Based WAAM Samples of Titanium Alloys for Process Optimization

Abstract

Additive manufacturing (AM) has become an important manufacturing technique for producing complex metallic
components, reducing material waste and improving production efficiency. Among various AM methods, Wire Arc
Additive Manufacturing (WAAM) is widely used for fabricating large-scale titanium alloy structures because of its high deposition rate and cost-effectiveness. Ti-6Al-4V is extensively utilized in aerospace and biomedical industries due to its excellent mechanical strength and corrosion resistance. However, conventional arc-based WAAM processes often deliver excessive heat input, leading to residual stresses, distortion, unstable solidification, and non-uniform microstructures. 

To overcome these limitations, Cold Metal Transfer (CMT)-based WAAM has emerged as an effective alternative
because of its lower heat input and improved process stability. In CMT-WAAM, controlling the interpass temperature is critical for reducing thermal accumulation and maintaining dimensional accuracy. In this study, high-fidelity numerical simulations were performed to evaluate the thermal and mechanical behaviour of Ti-6Al-4V samples fabricated under different interpass thermal gradients. Gaussian Process Regression (GPR) was further employed to predict deposition characteristics, including the EA ratio and the deposit angle. The results demonstrated that thermal gradient control significantly influences phase transition, solidification behaviour, hardness distribution, and overall structural integrity of the deposited titanium alloy components.