This International Standard defines the terms used in the heat treatment of ferrous products. The vocabulary is divided into a main part (clause 3) and a complementary section (clause 4). The main part gives an alphabetical list of the terms with their definitions and, where appropriate, comments. A definition of a foreign term for which the language in question has no equivalent is given at the end of the main part. The complementary section comprises the definitions of terms necessary to understand the main part. The comments are given in note form in order to differentiate them from the definitions. Any term defined in the main part of this International Standard and used elsewhere in a definition or a comment is printed in bolder type than the main text. Figures 1 and 2 show graphical representations of certain terms.