Electrochemical Corrosion Behavior, Mathematical Modeling, and Multicriteria Assessment of Ti-Alloyed Martensitic Stainless Steels

Five experimental Ti-alloyed martensitic stainless steels derived from 17-4PH, with nominal Ti additions of 1–5 wt.%, were investigated to compare electrochemical corrosion behavior, Vickers microhardness, and exploratory numerical assessments. The alloys were produced by vacuum arc melting, solution-treated, and subjected to selected aging schedules. Optical microscopy, SEM–BSE/EDS characterization, image-derived descriptors, microhardness measurements, and potentiodynamic polarization tests in 3.5 wt.% NaCl were employed. The five alloy–aging conditions constituted a non-factorial design with simultaneous compositional and processing variations. P5–H900 exhibited the lowest reported corrosion current density (0.419 µA cm−2) and highest polarization resistance (61.67 kΩ cm2), together with a mean microhardness of 570.6 HV0.2. Its corrosion current density was approximately 93.3-fold lower than that of P1–H900. Stern–Geary recalculation demonstrated internal numerical consistency, whereas leave-one-out cross-validation revealed substantial regression instability. Multicriteria rankings depended on criterion selection, normalization, and weighting assumptions. The absence of independent electrochemical replication and a processing-matched unmodified reference limits causal interpretation and statistical validation. These results support condition-specific comparisons and identify candidates for further controlled investigation rather than establishing an isolated titanium effect or validated predictive optimization.