| This paper describes the experimental results obtained from mixed mode (I and II) creep crack growth tests in Ti-25Al-10Nb-3V-1Mo alloy at 1033K. Mixed mode crack tip conditions were achieved using the compact mixed mode(CMM) specimen, in which initial crack tip conditions corresponded to K_I / K_(II) = 1.29 (mixed mode) and K_I / K_(II) = 0.06 (or almost pure mode II). Two tests have also been performed under pure mode I conditions using the standard compact tension(CT) specimen. The results of these tests have been compared with mode I data obtained from compact tension(CT) tests, using parameter of C^* and an effective stress intensity factor K_(eff). Mode I data show that K approach correlates the mode I data successfully, compared with C^*. This might be due to the environment brittlement effects. The correlation between the mode I, mode II and mixed mode data is reasonably good with the K_(eff). However, the scatter band is greater than that obtained from the mode I results only. Therefore, the mixed mode creep crack growth rates in Ti₃Al can be correlated with the pure mode I and II data, using an effective stress intensity factor, K_(eff) obtained from K_I and K_(II) , even though it predicted the growth rates conservately. |
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