Optimizing mechanical and corrosion properties in L-PBF fabricated 17-4 PH stainless steel via interlayer remelting

In this study, interlayer remelting strategies were utilized to optimize the microstructure and properties of laser powder bed fused (L-PBF) 17-4PH stainless steel (SS). Parallel remelting reduced retained austenite (RA) from 34.9% to 25.6%, promoted uniform RA distribution, and significantly enhanced yield strength (from 825 MPa to 1020 MPa) and hardness (from 379 HV 0.1 to 402 HV 0.1 ), though at the cost of ductility (from 14.6% to 10.7%) and corrosion resistance in 5 wt% HCl (corrosion rate increased by ∼3.9 times). In contrast, orthogonal remelting further reduced RA to 12.3%, induced RA grain coarsening (4.3 μm) with a pronounced <101>//Z texture, and transformed the columnar martensitic matrix into a coarser blocky morphology (6.4 μm). This strategy achieved a more balanced combination of properties, with yield strength of 917 MPa, hardness of 390 HV 0.1 , preserved ductility (13.6%), and a >30% reduction in corrosion rate in 5 wt% HCl, attributed to the more localized RA distribution. However, no significant improvement in corrosion resistance was observed in concentrated 15 wt% HCl, where the intrinsic material properties dominated. These results demonstrate that interlayer remelting provides a versatile approach to precisely control the microstructure, optimizing both mechanical and corrosion properties in L-PBF fabricated 17-4PH SS for a range of service conditions.