Effect of microstructure characteristic on mechanical properties and corrosion behavior of new high strength Ti-1300 beta titanium alloy

The effect of microstructural characteristic on mechanical properties of Ti-1300 alloy is investigated to reveal the strengthening mechanism of precipitated α phase, and its corrosion behavior is emphatically examined in 2 M HCl solution using potentiodynamic polarization and immersion tests. The results shows that the strength property of Ti-1300 alloy is sharply increased with the precipitation of acicular secondary α phase (αs), and many αs phases intersect each other and keep the Burgers orientation relationship with β phase in the local colony, which prevent the dislocation motion. The lamellar microstructure exhibits the highest strengthening effect, but the ductility worsens. The corrosion resistance of the alloy with different microstructure is also significantly different. Ti-1300 alloy with bimodal/lamellar microstructure is presented a high corrosion rate from corrosion current density and weight loss, indicating the inferior corrosion resistance and passive behavior. SEM morphology analysis of Ti-1300 alloy after immersion tests revealed α phase and α+β interphase boundary act as the preferential dissolution locations, and the formed microgalvanic cells between the precipitated αs phase and β matrix as well as the accumulative of β stabilizing element in β phase are identified as the main factor affecting the corrosion performance of Ti-1300 alloy.