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Exploring the strength-ductility space of Ti-6Al-4V through a quenching and partitioning approach

par Dumas, Odeline ;Malet, Loïc ;Martin, Guilhem;Kwaśniak, Piotr;Prima, Frédéric;Godet, Stéphane
Référence Materials science & engineering. A, Structural materials: properties, microstructure and processing, 925, 147859
Publication Publié, 2025-03-01

Article révisé par les pairs

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Résumé :

The microstructure-mechanical property relationships of α+α′ dual phase microstructures are studied in Ti-6Al-4V. Various annealing temperatures in the α+β field are analyzed and the decomposition of the metastable martensite phase is also investigated. Low annealing temperatures lead to large work-hardening that is attributed to the occurrence of the concurrent deformation of a composite structure where the martensite is the softer phase and the occurrence of Reorientation Induced Plasticity in the martensite (RIP effect). This is studied by Electron Backscattered Diffraction (EBSD) and in-situ tensile testing combined with Digital Image Correlation (DIC). High annealing temperatures lead to a large decrease in work hardening due to the disappearance of RIP and of the mechanical contrast between α and α’. Further annealing of the α+α’ microstructures goes along with the disappearance of RIP associated with the decomposition of the metastable martensite. The decomposition mechanism is shown to be a reversion phenomenon with the β phase precipitating within the martensite and at interfaces while retrieving its high temperature orientation. The precipitation of the β phase is shown to largely increase the strain to fracture of the samples annealed at high temperatures. The precipitates act as reinforcement of the larger laths that form within the large β grains associated with the high annealing temperatures.