Abstract

Titanium alloys are widely employed in aerospace applications owing to superior properties such as a high specific strength and a good corrosion resistance. In particular, the variety of dual phase microstructures obtained through different thermo-mechanical processing routes enables tailoring of mechanical properties. Pioneering studies have rationalized relationships between microstructures and mechanical properties using the concept of effective slip length, which corresponds to the mean free path for dislocation glide. However, a quantitative prediction of mechanical properties remains elusive for heterogeneous microstructures such as those found in engineering components. In this presentation, we report clarifications of the role of the microstructure in the mechanical behavior of Ti alloys subjected to monotonic and cyclic loadings. Deformation was studied in relation to the microstructure with an emphasis on configurations leading to strain localization. Specific approaches including in situ DIC, large scale EBSD mapping and FFT-based crystal plasticity simulations were employed to consider representative regions. In addition, the identification of damage mechanisms was undertaken to clarify the interplay between heterogeneous deformation and critical microstructure arrangements. New insights into an improved understanding of relationships between the microstructure and the mechanical properties in Ti alloys are illustrated using different examples.

Samuel Hemery:

Is an assistant professor at Institut Pprime and ISAE-ENSMA (Poitiers, France) since 2014. After engineering studies, he completed a doctoral thesis in materials science (2013) at Ecole Centrale Paris. Early works focused on liquid metal embrittlement of steels in liquid Na for fast-breeder reactors at CEA. His current research interests are mainly focused on Ti alloys employed in aerospace applications. This includes the analysis of mechanisms involved in deformation and fracture. A specific attention is paid to the behavior of Ti alloys subjected to fatigue and dwell-fatigue loadings. Relationships between microstructure and mechanical properties are examined using different characterization (SEM, EBSD, DIC, in-situ testing) and simulation (CP-FFT) techniques. He is also assistant editor for Metallurgical and Materials Transactions A (Key Reader) since 2017.