Notch Effects on HCF Strength of Gamma Titanium Aluminides

摘要

The effect of notches and mechanical surface treatments on the HCF performance of a titanium aluminide γ(TiAl) and the near-a titanium alloy TIMETAL 1100 is compared and contrasted. Generally, the observed notch sensitivity in fatigue of γ(TiAl) was much lower than that of TIMETAL 1100. This was attributed to the marked differences in work-hardening capability of the two materials. TIMETAL 1100 exhibited the typical low work-hardening of the near-α alloy group, while very marked dislocation strengthening was found in γ(TiAl). Furthermore, γ(TiAl) responded much more beneficially to shot peening. This again is explained by pronounced surface layer strengthening due to the extraordinary work-hardening capability and cyclically stable residual compressive stresses.