Study on microstructure and properties of super martensitic stainless steel fabricated by hot wire laser additive manufacturing

To address the deposition efficiency and heat input limitations of Cold Wire-Laser Metal Deposition (CW-LMD), this study investigates the Hot Wire-Laser Metal Deposition (HW-LMD) of Super Martensitic Stainless Steel (SMSS). A comparative analysis of microstructure and mechanical properties reveals that the HW-LMD process significantly refines martensite grains, reducing grain size by 32%–43% compared to CW-LMD. Additionally, HW-LMD samples exhibit lower Kernel Average Misorientation (KAM) values, indicating reduced lattice distortion. Although the average hardness (291.6 HV) and tensile strength (>900 MPa) of HW-LMD samples are marginally lower than those of CW-LMD, ductility is notably improved, achieving a maximum elongation of 20.7%. These findings demonstrate that HW-LMD effectively optimizes the strength-toughness balance in SMSS components through microstructural refinement and uniform heat input.