In this study, the multiaxial ductility factor was analyzed based on the power-law creep grain-boundary cavities growth theory under multiaxial stress states. Based on this theory, the theoretical cavities growth rates under a multiaxial stress state were discussed and the predicting model of a stress-state parameter α was revised by using an empirical fitting expression denoted as αWu, which exhibited a good agreement to analytical results of the stress-state parameter α and multiaxial cavities growth rates. Then, according to the re- lationship between uniaxial and multiaxial creep failure strain, a new empirical predicting model of multiaxial ductility factor MDFWu was established which involved the multiax- ial parameter αWu and uniaxial parameter α0. Besides, the theoretical model of multiaxial ductility factor MDF could also be established. By fitting the theoretical values of MDF, an- other predicting model MDFWM was proposed. The development of two multiaxial ductility factor predicting models could be achieved. Finally, predictions of these two novel multiax- ial ductility factor models and the Cocks-Ashby as well as Wen-Tu model were compared with experimental data, and the prediction accuracy of MDFWu and MDFWM models was significantly improved, especially for the latter one.
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