Effect of solution treatment on the microstructure, micromechanical properties, and kinetic parameters of the β → α phase transformation during continuous cooling of Ti-6Al-4V titanium alloy

Type : Publication
Auteur(s) :  Nabil KHERROUBA, Denis CARRON, Mabrouk BOUABDALLAH, Riad BADJI
Année :  2019
Domaine : Métallurgie
Revue : Journal of Materials Engineering and Performance
Résumé en PDF :  (résumé en pdf)
Fulltext en PDF :  (.pdf)
Mots clés :  Ti-6Al-4V, solution treatment, ledge mechanism, interface instability, Nanoindentation, partitioning

Résumé : 

The aim of this study is to examine the effect of solution treatment temperature (STT) on the microstructure, the micromechanical properties, and the kinetic parameters of the β → α phase transformation during continuous cooling of the dual phase titanium alloy Ti-6Al-4V. Increasing the STT from 1050 °C to 1200 °C delays the formation of the α phase during cooling and increases the value of its activation energy. The microstructural analysis reveals the emergence of αW platelets from protuberances on the αGB / αW interface. The investigation of the morphology of the αW platelets reveals the presence of ledges on their longest side showing a sharp extremity. The micromechanical properties determined by nanoindentation and microhardness tests are almost insensitive to the cooling rate but are strongly affected by the STT; the higher the STT, the lower the overall microhardness of the Ti-6Al-4V alloy. In addition, the STT affects the microhardness and the Young’s modulus of both α and β phases differently; when the STT increases, the microhardness and the Young’s modulus of the α phase decrease whereas those of the β phase increase.