Near Immersion active cooling assisted WAAM of 5356 aluminum Alloy: Formability and microstructural evolution

Aluminum alloy wire arc additive manufacturing (WAAM) is broadly used in various industrial fields. However, conventional natural air cooling during layer-by-layer deposition induces significant thermal accumulation that compromises geometric accuracy and deteriorates mechanical properties. This study employed a thermal control strategy integrating low-heat-input cold metal transfer (heat source for WAAM) with the Near Immersion Active Cooling (NIAC) technique, systematically investigating the influence of three distinct cooling media (water, solid-CO 2 , and liquid-N 2 ) on deposition quality and mechanical performance. Liquid-N 2 failed to produce effective cooling during deposition due to its rapid vaporization. What is worse, it promoted the formation of AlN impurities, deteriorating mechanical properties. In contrast, both solid-CO 2 and water exhibited superior cooling efficiency, leading to remarkable grain refinement. Water-cooled specimens displayed the highest tensile strength, thanks to minimal surface oxidation and low porosity. Conversely, solid-CO 2 cooling induced substantial surface oxidation and high porosity levels, ultimately deteriorating tensile strength.