Titanium alloy Ti-6242 for high temperature structural application. Static and dynamic mechanical properties and impact of ageing

¹ Institut de Recherche Technologique (IRT) Saint-Exupéry, Bâtiment B612, Toulouse, FRANCE
² Laboratoire Génie de Production (LGP), Université de Toulouse, INP-ENIT, Tarbes, FRANCE

Abstract

Increasing the efficiency of aero-engines by increasing the engines’ working temperatures requires, in turn, the adaptation of the materials used in structural parts surrounding the engines. Specifically, improvement of the mechanical properties, resistances to specific operational loading conditions and good durability are required in the targeted range of temperatures. Building upon work on titanium alloys that are resistant to high temperatures—already used by engine designers—studies have been carried out to find alloy + microstructure combinations that are likely to meet structural requirements. Guided by targeted mechanical specifications, various industrialized thermo-mechanical processes have been performed to produce Ti-6242 pancakes of different initial microstructures. For each manufacturing route investigated, the microstructure, tensile properties, crack propagation resistance and fracture toughness have been evaluated, either as-manufactured or after ageing for 5000 hours at 500°C. The different types of microstructures do not exhibit the same initial mechanical resistances, and the sensitivity of alloy Ti-6242 to high temperature ageing phenomena proves to be highly microstructure dependent. Nevertheless, among these different microstructures, some show properties that comply with targeted specifications and show interesting long duration thermal stability, which makes them promising candidates for future industrial future needs.