Improving the high temperature oxidation resistance of Ti-β21S by mechanical surface treatment

The improvement of the high temperature oxidation resistance of titanium alloys is currently a technological challenge. Mechanical surface treatments as shot-peening (SP) have shown their ability to improve the behaviour of pure zirconium and titanium. However, shot-peening treatments can induce a significant surface contamination. Laser shock peening (LSP) appears as a good alternative. Here, we have investigated the effect of SP and LSP treatments on the HT oxidation behavior of Ti-β21S. Samples treated by these methods have been compared to untreated ones for long exposures (3000 h) at 700 °C in dry air. The samples placed in a furnace at 700 °C were periodically extracted to be weighed. The results have been compared to that of pure commercial titanium (Ti-α) samples studied in the same conditions. The higher performances of the Ti-β21S alloy, and the beneficial effect of the SP treatment, and even more of the LSP one, on the HT oxidation resistance of Ti-β21S have been clearly shown. The effect of the mechanical treatments on the microstructure of the Ti-β21S samples and the changes induced by the long duration exposure at high temperature have been mainly studied by scanning electron microscopy combined with energy and wavelength dispersive spectrometry

Improving the high temperature oxidation resistance of Ti-β21S by mechanical surface treatment

The improvement of the high temperature oxidation resistance of titanium alloys is currently a technological challenge. Mechanical surface treatments as shot-peening (SP) have shown their ability to improve the behaviour of pure zirconium and titanium. However, shot-peening treatments can induce a significant surface contamination. Laser shock peening (LSP) appears as a good alternative. Here, we have investigated the effect of SP and LSP treatments on the HT oxidation behavior of Ti-β21S. Samples treated by these methods have been compared to untreated ones for long exposures (3000 h) at 700 °C in dry air. The samples placed in a furnace at 700 °C were periodically extracted to be weighed. The results have been compared to that of pure commercial titanium (Ti-α) samples studied in the same conditions. The higher performances of the Ti-β21S alloy, and the beneficial effect of the SP treatment, and even more of the LSP one, on the HT oxidation resistance of Ti-β21S have been clearly shown. The effect of the mechanical treatments on the microstructure of the Ti-β21S samples and the changes induced by the long duration exposure at high temperature have been mainly studied by scanning electron microscopy combined with energy and wavelength dispersive spectrometry