Research Information System
Materials Science and Engineering: A, vol.943, 2025 (SCI-Expanded, Scopus)
A major challenge in wire arc additive manufacturing (WAAM) is microstructural anisotropy caused by columnar grain growth due to predominant heat transfer toward the substrate, which compromises mechanical performance. This study investigates the effectiveness of the switch-back (SB) welding strategy in reducing anisotropy and enhancing the mechanical properties of WAAM-fabricated duplex stainless steel (ER 2209). Two walls were fabricated using identical process parameters, differing only in torch movement: conventional (Norm) and SB paths. Microstructural analysis revealed a marked reduction in columnar grains and increased equiaxed grain fraction in the SB samples. EBSD IPF maps showed an 83 % and 70 % reduction in crystallographic alignment for δ-ferrite and γ-austenite, respectively. Numerical simulations demonstrated that the SB strategy generated higher peak temperatures and greater melt turbulence, reducing the G/R ratio and promoting dendrite fragmentation and equiaxed grain formation. Mechanical testing confirmed improved performance of SB samples, with SB-H achieving the highest UTS (816 MPa) and impact energy (74.7 J). Fractographic analysis revealed ductile failure in all samples, with SB samples exhibiting finer and more uniform dimples, indicating enhanced toughness. Overall, the switch-back strategy is a simple yet effective method for improving structural and mechanical performance in WAAM without requiring additional equipment.