Low‐Voltage Pulsed GMA‐AM Application for Controlling Heat Input and Improving Deposition Quality of 309LSi Multilayered Structures

Austenitic stainless steels are extensively used in wire arc additive manufacturing (WAAM) for producing large‐sized components. However, dimensional control and geometric stability are challenges related to this process, especially in pulsed gas metal arc (GMA) using conventional voltages. More specifically, there is a lack of systematic studies addressing heat input (HI) control and geometric stability of 309LSi deposits under low‐voltage (LV) pulsed spray‐transfer conditions. This study evaluates the feasibility of LV pulsed GMA (WAAM‐GMA‐P‐LV) to reduce HI and improve process predictability. A three‐factor full factorial design with a center point and a composite‐desirability optimization was used, considering arc voltage, arc frequency, and travel speed as factors, using an ER 309LSi wire. The LV mode enables reduced voltages (14–24 V) deposits, stable pulsed spray‐transfer regime and hIHI of 0,25 kJ/mm, lower than those obtained under conventional conditions (>0.50 kJ/mm), a 29.7%–32.1% reduction relative to the high‐voltage within the DOE domain. This reduction enabled the fabrication of a 7 mm‐thick and 160 mm‐high multilayered structure, with decreased HI, presenting dimensional consistency throughout 114 deposited layers, without common defects. These findings provide a controllable thermal window for 309LSi components, enhancing geometric resolution and process robustness in multilayer WAAM‐GMA‐P‐LV fabrication.