Corrosion behavior and microstructural effects on passivation film mechanisms in forged Ti-5Al-5Mo-5V-1Cr-1Fe titanium alloy under laser surface remelting

This study examines the corrosion behavior of Ti-5Al-5Mo-5V-1Cr-1Fe (Ti-55511), comparing forged and LSRed (laser surface remelting) samples. LSR via 0.02 mm laser interval eliminates surface macro defects, enhances element homogenization, and converts primary and secondary α to β on forged Ti-55511 surface, yielding a thicker passivation film with higher stability than that of as-forged counterpart. This study investigates corrosion mechanisms by comparing the phase type, elemental homogeneity, grain size, morphology, and defects in relation to corrosion behavior. Galvanic corrosion predominates in the as-forged sample, with intensified pitting on the α phase and oxygen accumulation near α/β phase interface, while LSR-treated sample experiences β grain boundary corrosion.