TABLE OF CONTENTS 
Shuttle flame. (Image courtesy of C. Michael Holoway, NASA Langley, USA.)
Material properties change with temperature. Some do so in a simple linear way, easy to allow for in design: the density, the modulus and the electrical conductivity are examples. But others, particularly the yield strength and the rates of oxidation and corrosion, change in more sudden ways that, if not allowed for, can lead to disaster.
This chapter explores the ways in which properties change with temperature and design methods to deal with the changes. To do this we must first understand diffusion the intermixing of atoms in solids and the ways it allows creep and creep fracture. This understanding lies behind procedures for high-temperature design with metals and ceramics. Polymers are a little more complicated in their behavior, but semi-empirical methods allow safe design with these too.
First, the simplest measure of tolerance to temperature: the maximum and minimum service temperatures, T max and T min. The former tells us the highest temperature at which the material can reasonably be used without oxidation, chemical change or excessive deflection or 'creep' becoming a problem (the continuous use temperature, or CUT, is a similar measure). The latter is the temperature below which the material becomes brittle or otherwise unsafe to use. These are empirical, with no universally accepted definitions. The minimum service temperature for carbon steels is the...
