Steel and Its Heat Treatment

Book excerpt: Steel and its Heat Treatment: Bofors Handbook describes the fundamental metallographic concepts, materials testing, hardenability, heat treatment, and dimensional changes that occur during the hardening and tempering stages of steel. The book explains the boundaries separating the grain contents of steel, which are the low-angle grain boundaries, the high-angle grain boundaries, and the twinning boundaries. Engineers can determine the hardenability of steel through the Grossman test or the Jominy End-Quench test. Special hardening and tempering methods are employed for steel that are going to be fabricated into tools. The different methods of hardening are manual hardening for a small surface (the tip of a screw); spin hardening for objects with a rotational symmetry (gears with 5 modules or less); and progressive hardening (or a combination with spin hardening) for flat surfaces. The hardening and tempering processes cause changes in size and shape of the substance. The text presents examples of dimensional changes during the hardening and tempering of tool steels such as those occurring in plain-carbon steels and low-alloy steels. The book is a source of reliable information needed by engineers, tool and small equipment designers, as well as by metallurgists, structural, and mechanical engineers.