The process of altering the physical, chemical, and mechanical properties of a metal by applying controlled heating and cooling is known as heat treatment. It is a procedure that is applied to improve or restore a product’s manufacturability. Heat treatments are most commonly applied in metallurgy, manufacturing, hot forming, and welding.
Heat treatment might be applied to raw materials, as in the metal itself, or on finished products. The methodology involves heating materials to severe temperatures to increase internal stress. Subsequently, cooling is done at an extremely low temperature, a process that is also known as quenching. This strengthens the internal lattice structure. It also brings out finery in the grains that have an increased tensile strength.
Heat treatment is commonly carried out to soften, harden, and materially modify a product. Softening reduces the hardness of a material while improving ductility and resistance. It brings out toughness and also improves grain size. This is more commonly known as annealing or normalizing. Typically, it is carried out to restore ductility and to relax metal stresses within a material. Later techniques include tempering and quenching, which toughen and rapidly cool off the materials.
Hardening is mostly carried out on steel to increase its wear and tear properties and potency. Sufficient carbon and alloy content is required in order to carry out the hardening process. When it is present in adequate amounts, the steel is directly hardened. If there is insufficient carbon content, however, a method of carbon enrichment can be used, which increases the carbon ration in carbon steel components.
Selective hardening is a variation in the hardening process where different areas are subjected to different temperatures. It is also known as differential hardening. It is mostly applied to manufacture instruments like swords, knives, and tongs. Material modification is a heat treatment methodology that modifies the behavioral properties of a material. Mostly applied on steel, it is used to enhance aging and serving life, as well as strength and reliability.
Heat treatment is most often applied on large carbon steel components. Steel responds well to heat treatments, due to its extreme manageability, and increases in commercial efficiency after the application of a heat treatment. This makes steel heat treatment a widely popular process in the metallurgical industry. Other than steel, aluminum is another metal on which heat treatment is vastly applied. Unlike with steel, heat treatment of aluminum is carried out in specially designed furnaces under extremely controlled thermal conditions.