The monograph outlines the theoretical foundations of metal science and heat treatment. Methods of selection and assignment of metals and alloys depending on the type of structures and conditions of loaded parts of machines and devices, as well as tools are described. Data on structural and tool steels and alloys with special physical and chemical properties, non-ferrous metals and their alloys, antifriction alloys and ceramic-metal materials are given.Also considered are types of heat treatment of steels and alloys intended for parts operating for a long time at high temperatures. The results of studies of heat treatment effect on heat resistance of pearlitic, ferritic and austenitic steels and nickel-chromium alloys are collected and generalized. Issues of the theory of heat treatment of heat-resistant alloys are considered.