Titanium alloys: production, behavior and application

Abstract

Lightweight materials constitute the backbone of the competitive advantage of modern aerospace structures. These materials are important because they enable achievement of high structural efficiency which is essential for high performance under a variety of operating conditions. The selection of materials and of material conditions for lightweight structures is typically a problem bounded by multiple constraints, requiring a detailed understanding of all the materials characteristics and all aspects of mechanical behavior. The current material choices available to the designers of high performance structures include high strength steel or aluminum alloys, polymer matrix composites and titanium alloys. The factors that determine which of these represent the best choice include: the operating temperature, the design limiting property (strength, stiffness, fatigue, etc.), the volume or space available, cost considerations, the operating environment, fabrication and other manufacturing requirements, the intended service lifetime of the component and the total number of components required (lot size). Obviously, this is a formidable list of constraints, but for a given application, any of these can affect the ultimate choice of material. One objective of this chapter is an attempt at discussing how Ti alloys compare to other materials under these constraints and how such comparisons affect the usage of Ti alloys for high performance aerospace structures, especially aircraft and aircraft engines. Other objectives include a general description of the characteristics of Ti alloys because these affect their behavior which can dictate the limiting conditions under which they can be efficiently used, and a discussion of the range of properties that can be obtained by changes in processing.