Heat treating and tempering are processes used by metalworkers to improve the physical and mechanical properties of metals. Heat treating is a process of heating and cooling metals, such as steel and aluminum, to obtain desired properties. Tempering is a heat treatment process used to selectively increase the strength and hardness of metals while preserving their ductility and toughness.
Heat Treating: Heat treating is a process used to modify the physical and chemical properties of a metal. This is accomplished by taking the metal through a series of temperature changes. The process must be controlled carefully to ensure that the desired properties are attained. During the heat treatment process, the metal is heated to a precisely controlled temperature and then cooled. Depending on the alloy, the heat treatment may involve quenching, tempering, annealing, or aging.
Quenching is the process of quickly cooling the metal using water, oil, or air. This step is often used in the heat treatment of steel because quenching changes the mechanical properties, such as hardness and yield strength, of the steel.
Tempering is the process of reheating the cooled metal to a slightly lower temperature than the quench, typically in the range of 300 to 1000° F (149 to 538° C), and then allowing it to cool. Tempering softens the metal to the desired properties while preserving the desired mechanical properties.
Annealing is a process used to soften a hard metal and to improve its mechanical, electrical, thermal, and magnetic properties. During the annealing process, the metal is heated for a long period of time, usually to temperatures between 1000 and 1400° F (538-760° C). After the metal is heated, it cools gradually in the furnace, resulting in a softer and more malleable metal.
Aging is a type of heat treatment used to improve the strength and ductility of metals. During this process, the metal is heated to a specific temperature and then cooled slowly to room temperature. After cooling, the metal becomes harder and stronger, but it can also be brittle.
Tempering is a process used to selectively increase the strength and hardness of metals while preserving their ductility and toughness. To temper a metal, the temperature is lowered to a specific range, typically between 300 and 1000° F (149 and 538° C). Depending on the desired path of stress, the metal may also undergo multiple levels of tempering. Tempering helps reduce warping, cracking, brittleness, and other undesirable physical properties.
Heat treating and tempering are important processes used to modify the physical and chemical properties of metals. Heat treating is used to modify the mechanical properties, while tempering introduces the desired mechanical properties. Both processes allow metals to be formed and manipulated to fit specific applications.
