Almost everything that surrounds us in our life today traces its manufacture by man to the ability to smelt iron, and to refine and shape it into the many modifications of what is called steel. Any manufactured article may be chosen and then questioned as to whether iron or steel has had anything to do with its appearance in its present form. The answer is convincing. It is indispensable alike in peace and war. Steel that comes direct from the rolls, the forge, or the mold is restricted in use to a very narrow field. Improvement in, and gradation of, the properties of steel, conferred by controlled heating and cooling, fit heat treated steel for myriads of uses which raw steel will not satisfactorily serve. Finer and finer gradations of properties are being and will continue to be demanded by the user of steel and much effort and development must be expended to meet these demands. This is Volume I of a two volume set of books. It is devoted to those principles, processes, and fundamentals of control which relate to heat treatment of steel in general, including both carbon and alloy steel. Steels that are not amenable to heat treatment are passed by with scant attention. The book is in its fourth edition containing new information and a restatement up-to-date of sound old principles.
There are three sections. The first, on metallurgical principles, begins with an explanation of tests made on steel for various properties, then there follows a description of the constituents of steel with special reference to the changes that take place when steel is subjected to a change in temperature. General annealing practice is given space which concludes with interesting charts containing a condensed summary of the methods of annealing previously discussed. Spheroidizing, normalizing, hardening, tempering and toughening, and grain size are subsequent headings. The last named is a topic under which the greatest advance in theory and practice of heat treatment Was had in recent years. The advance is well reflected in the book.
The second section is devoted to surface-reaction processes, the intentional alteration of the surface so as to give the metal hardness and wear resistance. Case carburizing, heat treatment of carburized steel, controlled atmospheres, and cyaniding, nitriding, surface hardening, and coating are topics under this heading. The control of heat treating reactions is section three. Here is pointed out the importance of control from a practical standpoint, the precautions necessary, the proper fuels and furnaces to use, the way to handle furnaces in the application of heat to the charge, control of the cooling phase, and a final word with regard to the human element which enters into the operation of heat treating, and which, it is stated, is a controling factor and the weakest link in present day practice.