Chapter 2 - Aluminum

Abstract

This chapter begins with some of the general metallurgical considerations for aluminum alloys, along with an introduction to precipitation hardening, the main method of strengthening the aerospace structural alloys. It depicts a typical material distribution for a modern commercial airliner, which illustrates the heavy dominance of aluminum alloys. The attractiveness of aluminum is that it is a relatively low cost, light weight metal that can be heat treated to fairly high strength levels, and it is one of the more easily fabricated of the high performance materials, which usually results in lower costs. The advantages of aluminum as a high performance material have been summarized. The chapter then discusses the designation system and tempers for the various series of aluminum alloys. It discusses some of the specific alloys used for aerospace applications, primarily the 2XXX, 6XXX, 7XXX, and 8XXX aluminum-lithium alloys. It also discusses melting and primary fabrication, which are mill processes. The chapter deals with the main fabrication processes—heat treatment, forging, forming, casting, machining, and joining.