MIL-HDBK-5H
1 December 1998
5-1
CHAPTER 5
This chapter contains the engineering properties and related characteristics of titanium and titanium
alloys used in aircraft and missile structural applications.
General comments on engineering properties and the considerations relating to alloy selection are
presented in Section 5.1. Mechanical- and physical-property data and characteristics pertinent to specific
alloy groups or individual alloys are reported in Sections 5.2 through 5.5.
Titanium is a relatively lightweight, corrosion-resistant structural material that can be strengthened
greatly through alloying and, in some of its alloys, by heat treatment. Among its advantages for specific
applications are: good strength-to-weight ratio, low density, low coefficient of thermal expansion, good
corrosion resistance, good oxidation resistance at intermediate temperatures, good toughness, and low heat-
treating temperature during hardening, and others.
— The coverage of titanium and its alloys in this chapter has been divided
into four sections for systematic presentation. The system takes into account unalloyed titanium and three
groups of alloys based on metallurgical differences which in turn result in differences in fabrication and
property characteristics. The sections and the individual alloys covered under each are shown in Table 5.1.
— The material properties of titanium and its alloys are determined
mainly by their alloy content and heat treatment, both of which are influential in determining the allotropic
forms in which this material will be bound. Under equilibrium conditions, pure titanium has an “alpha”
structure up to 1620F, above which it transforms to a “beta” structure. The inherent properties of these two
structures are quite different. Through alloying and heat treatment, one or the other or a combination of these
two structures can be made to exist at service temperatures, and the properties of the material vary
accordingly.