Optimizing Microstructure of Cold Metal Transfer‐Wire Arc Additive Manufactured ER2594 Super Duplex Stainless Steel through a Novel Active Cooling Technique

Super duplex stainless steel has excellent mechanical properties and corrosion resistance, but wire arc additive manufacturing super duplex stainless steel generally suffers from a two‐phase ratio imbalance, which limits its application. This study implemented three distinct cooling strategies during the manufacturing process: natural cooling, common interlayer forced cooling with compressed air (AC) and a novel vortex tube cooling of compressed air (VC). Through systematic comparison, investigation is done on how these thermal management approaches influence the microstructure and mechanical properties of wire arc additive manufactured duplex stainless steel, with particular focus on phase ratio optimization. The findings demonstrate that the interlayer forced cooling process effectively enhances ferrite content, achieving phase ratio optimization. Furthermore, it is revealed that over 80% of ferrite/austenite phase boundaries conform to the Kurdjumov–Sachs orientation relationship. This characteristic induces plastic coordinated deformation behavior, thereby enabling the material to exhibit concurrent excellent strength (UTS ≈ 850 MPa and YS ≈ 600 MPa) and elongation (EL ≈ 40%).