Alternate materials choices—some challenges to the increased use of Ti alloys

Abstract

Ti alloys are used in a variety of high-performance applications. Properties that lead to the selection of Ti alloys include modulus, chemical inertness, density, static strength, fatigue strength and damage tolerance (fracture toughness and fatigue crack growth). The reasons that Ti alloys are selected for a wide range of products have been widely discussed. Reasons for not selecting Ti alloys have been less widely discussed, and are the focus of this paper. This paper describes examples where alternate materials have been chosen in lieu of Ti alloys. The reason for these choices include elevated temperature creep strength, the tendency for combustion, raw material cost and article manufacturing cost. Specific examples of aircraft engine and aircraft components will be described and the reasoning behind the selection of alternate materials will be outlined. The paper concludes by suggesting factors that could re-balance the decision making process in favor of Ti alloys.