TABLE OF CONTENTS This chapter is composed of two sections; the first is concerned with the heat treatment of steels and the second with age hardenable aluminium alloys. All compositions are given as wt. % unless specified otherwise. Related information may be found at the following locations:
Information on alloy specifications and designations Chapter 1.
Crystallographic data on some of the phases discussed here, information on relevant metallographic techniques and phase diagrams Chapters 6, 10 and 11 respectively.
Diffusion data Chapter 13.
Data relevant to temperature measurement by thermocouple and pyrometer techniques Chapters 17 and 18, respectively.
Mechanical property data Chapter 22.
Furnace design and vacuum systems Chapter 40.
Heat treating is defined by the IFHTSE (International Federation for Heat Treating and Surface Engineering) as: 'a process in which the entire object, or a portion thereof, is intentionally submitted to thermal cycles and, if required, to chemical and additional physical actions, in order to achieve desired (change in the) structures and properties'.1 Krauss has added the additional caveat that 'heat treatment for the sole purpose of hot-working is excluded from the meaning of this definition'.2 The thermal cycles referred to in this definition are the various heat treatment steps which include: stress relieving, austenitising, normalising, annealing, quenching, and tempering. Steel is heat treated to: control the microstructure, increase the strength and toughness, release residual stresses and prevent cracking, control hardness (and softening), improve machinability and to improve mechanical properties including: yield and tensile strength, corrosion resistance...
