The Effect of Solution Treatment Temperature on Hardness, Microstructure, and Corrosion Resistance of Ti-6Al-4V ELI

Abstract

Ti-6Al-4V ELI (Ti64 ELI) has been widely used as metal-based biomedical implants as it has ductility and fracture toughness that surpasses the commercial Ti-6Al-4V. Casting process is one of the most cost-effective ways to produce near-net-shape Ti64 ELI implants. Nevertheless, previous study has found that grain coarsening occurred in an as-cast Ti64 ELI, which lowered its mechanical properties. To improve the properties, in this work, the samples were heat-treated in three different temperatures that varied above and below β-transus temperature for 30 minutes and then water-quenched. Following the solution treatment, each sample was artificially aged in 500 °C for four hours and left cooled inside the furnace. Hardness Vickers, microstructure, and XRD analyses were conducted to determine the effect of solution treatment regarding to its phase and properties. The result of microstructure observation showed transformation in different temperatures. The highest result of hardness value was obtained in the solution treatment variation of 1050 °C, which was 474 HVN. The XRD pattern showed that the intensity of the α/α’ phase of temperatures 850 °C, 950 °C, and 1050 °C were 92.84%, 72.65%, and 86.78%, respectively, with the intensity of the β phase were 7.16%, 27.35%, and 13.22%. The corrosion resistance performance was measured by the potentiodynamic polarization method using Ringer’s solution with pH ± 7,4 and the best corrosion resistance result was 0.093 mmpy in variation 950 °C as β phase was predominantly appeared in this temperature.