Manufatura aditiva de parede fina de aço inoxidável duplex via deposição a arco com e sem resfriamento ativo

Abstract

Metal Additive Manufacturing (AM) has been consolidated as a strategic technology for the production of complex components, promoting production efficiency and cost reduction compared to conventional processes. Among its techniques, the Arc Deposition Additive Manufacturing (WAAM) process stands out for its high deposition rate and applicability in large parts. Thermal control during metal AM is even more relevant in thin-walled components, where steep thermal gradients and high localized temperatures can generate defects such as distortions, high residual stresses, and mechanical anisotropy. In this context, cooling techniques play a crucial role. In this context, the present study aimed to perform a comparative study between the Arc Deposition Additive Manufacturing of 2209 duplex stainless steel deposited by pulsed current using active cooling in water with natural air cooling. Duplex stainless steel was selected due to its two-phase ferrite/austenite microstructure, which provides an excellent combination of mechanical and corrosion resistance, which is widely required in critical industrial applications. The methodology involved the deposition of thin walls of duplex stainless steel by additive manufacturing via MADA process with pulsed current, using solid wire and commercially pure argon shielding gas. Two cooling conditions were compared: natural air cooling, similar to conventional welding processes, and near-immersion active cooling (NIAC), which consists of keeping the lower layers partially submerged in water or an aqueous mixture in order to reduce heat input. The samples produced underwent microstructural analyses, mechanical tests (tensile, bending, Charpy-V impact and hardness) and chemical characterizations by EDS and GDS. The results indicated that both cooling conditions allowed the fabrication of thin walls with good structural integrity and interlayer cohesion. The NIAC process showed better microstructural homogeneity, lower dispersion of mechanical results and reduced anisotropy, while natural cooling exhibited slightly higher hardness due to thermal heterogeneity. The chemical analysis confirmed the stability of the alloy and the preservation of the PREN (Pitting Resistance Equivalent Number) index, ensuring resistance to localized corrosion. It is concluded that MADA with pulsed current is a viable alternative for the manufacture of duplex stainless-steel components, and that active cooling by near-immersion represents an efficient strategy to improve thermal control, reduce residual stresses and increase process reliability.