Study of crack propagation mechanisms during Charpy impact toughness tests on both equiaxed and lamellar microstructures of Ti-6Al-4V titanium alloy

Abstract : The impact toughness of two highly textured rolled plates of Ti-6Al-4V alloy with an alpha equiaxed and an alpha lamellar microstructures has been investigated. The results show a strong anisotropy of the fracture energy for both materials and underline that a coincidence of the prismatic planes with the shear bands at the notch tip is favorable for higher fracture energies. Moreover, it is pointed out, as it was already done by previous studies, that the alpha lamellar microstructure presents higher fracture energy than the alpha equiaxed one. Thanks to electron back scattering diffraction, and tensile tests, local microstructure heterogeneities, called macrozones, have been observed and characterized. Their size depends on microstructure element and is larger for alpha lamellar microstructure than for the alpha equiaxed. High strain is localized on the macrozones favorably oriented for prismatic slip with respect to the direction of impact and leads to a particular dimple free zone on the fracture surface. The contribution of these macrozones in the fracture behavior, and more precisely on the crack propagation rate was evaluated; thus the effects of the macroscopic texture and of the microstructure element on the impact toughness are discussed separately.
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Materials Science and Engineering: A, Elsevier, 2014, 618, pp.546-557. 〈10.1016/j.msea.2014.09.048〉
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https://hal.univ-lorraine.fr/hal-01513632
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Soumis le : mardi 25 avril 2017 - 12:29:29
Dernière modification le : mercredi 12 septembre 2018 - 01:28:08

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Christophe Buirette, Julitte Huez, Nathalie Gey, Alain Vassel, Eric Andrieu. Study of crack propagation mechanisms during Charpy impact toughness tests on both equiaxed and lamellar microstructures of Ti-6Al-4V titanium alloy. Materials Science and Engineering: A, Elsevier, 2014, 618, pp.546-557. 〈10.1016/j.msea.2014.09.048〉. 〈hal-01513632〉

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