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Vincent Renon defended his thesis on αβ titanium alloys

On 5th April 2019, Vincent Renon defended his thesis. Awarded by ISAE-ENSMA Poitiers, his work was supervised by Pprime Institute (P’), the SI-MMEA (Sciences et Ingénierie en Matériaux, Mécanique, Energétique et Aéronautique) Doctoral School, and IRT Saint Exupéry.
The high quality and the relevance of Vincent’s thesis contributed to get significant results as a part of Metaltechnics project.

Thesis Subject

“Identification of relationships between microstructures and damage tolerance properties of αβ titanium alloys”

About this thesis

Weight reduction are required in order to reduce ecological footprint of aeronautic transports, therefore, the current study is about interactions between microstructures and damage tolerance properties of αβ titanium alloys. Thus, a better understanding of these relationships could allow to offer potential improvement solutions of fatigue crack propagation resistance properties of these alloys through microstructure control.

In this purpose, this thesis studies focus on the generation of various lamellar microstructures from initial bimodal microstructures. Damage tolerance properties of these different microstructures have then been compared by crack propagation tests, highlighting strong properties differences between bimodal and lamellar microstructures. However, the characteristic parameters of lamellar microstructures do not seem to have any influences on these properties. Furthermore, two crack propagation regime have been identified in lamellar microstructures, separated by a visible transition on the crack propagation versus stress intensity factor curves. In particular it is shown that better resistance of lamellar microstructures can be attributed to higher closure effects and crack deflections linked to crystallographic propagation, especially in the “low speed” regime.

Further studies then aimed to link that propagation regime change to deformation mechanism at crack tips. SEM in-situ testing on micro-sample collect at crack tips on crack propagation macro-sample allows observation of differences in plasticity localization before and after transitions, which bring to the suggestion of a scenario explaining this change in regime propagation.

METALTECHNICS PROJECT

Considering the new generation of titanium alloys and high performance light alloys.

Jury

Moukrane DEHMAS Rapporter Professor at CIRIMAT, INP Toulouse
Marion RISBET Rapporter Professor at Roberval laboratory, UTC
Benjamin DOD Examiner Engineer at Airbus Operations
Catherine MABRU Examiner Professor at ICA, Toulouse INP
Yvon MILLET Examiner Engineer at TIMET
Simon PERUSIN Examiner Engineer at IRT Saint Exupéry
Patrick VILLECHAISE Examiner Researcher at Pprime Institute
Gilbert HENAFF Thesis director Professor at Pprime Institute, ISAE-ENSMA Poitiers
Céline LARIGNON Thesis co-director Engineer at IRT Saint Exupéry

Related Publications

  • V. Renon, G. Henaff, C. Larignon, S. Perusin and P. Villechaise Identification of relationships between heat treatment and fatigue crack growth of αβ titanium alloys – EUROMAT 2017 (European Congress and Exhibition on Advanced Materials and Processes) – Thessaloniki, Greece
  • V. Renon, G. Henaff, C. Larignon, S. Perusin and P. VillechaiseIdentification des relations microstructure/propriétés de tolérance aux dommages d’alliages de titane de type αβ – MECAMAT 2017 – Aussois, France
  • V. Renon, G. Henaff, C. Larignon, S. Perusin and P. VillechaiseIdentification of relationships between microstructure and fatigue crack growth of αβ titaniums alloys – Fatigue 2018 (12th international Fatigue congress) – Poitiers, France