Corrosion behaviour of investment cast and friction stir processed Ti–6Al–4V

The corrosion behaviour of investment cast and friction stir (FS) processed Ti–6Al–4V alloy was studied in HCl solution. FS processing was performed with the peak temperatures both above and below the β transus. All of the samples exhibited active–passive transitions in deaerated 5% HCl at room temperature, but the β FS processed samples exhibited superior corrosion behaviour. The corrosion morphology after immersion in 20% HCl was rationalized on the basis of a difference in partitioning of the alloying elements, which controls the composition of the α and β phases.