Heat Treatment

Heat treatment is the materials engineering technique of controllably heating and cooling a metal or alloy to alter its internal microstructure and thereby change its mechanical properties, such as hardness, strength, ductility or toughness, without changing its shape. Processes grouped under the term include annealing, quenching, tempering and normalizing, each following a different heating and cooling schedule to produce a particular balance of properties for a given application. Heat treatment has been practiced since ancient metalworking, when smiths learned that reheating and cooling iron and steel changed how well it held an edge, and it remains fundamental to modern manufacturing of everything from automotive components to cutting tools.