Industrial heat treatment applications are wide and varied and can provide processing to many different sectors across industries. These sectors include, but not limited to, agriculture, tool marking, mining, engineering, construction and oil and gas.
During metalworking, manufacturing and equipment fabrication, various heat treatment techniques can be used to alter the physical and mechanical properties of materials.
There are some common forms of heat treatment that are used across all industries.
Hardening
Hardening is undertaken to improve the hardness of a metal, resulting in a stronger and more durable components. Hardening is often followed by tempering of the metal to reduce internal stresses. In case hardening of steels, carbon is introduced to harden the outer layer of material, leaving a soft core but a harder exterior for wear resistance.
Annealing
During the annealing process, metals are heated to a specified temperature and held there for a long period of time. They are then cooled, at either a fast or slow rate, depending on the type of material and required characteristics. This process changes the grain structure, making it easier to work with.
Quenching
Quenching involves cooling a metal at a fast rate. Its impact on metal properties varies depending on the alloy. Ferrous alloys will harden when quenched, and non-ferrous alloys will become softer. Cooling can be facilitated by air, nitrogen or liquid. Liquids like water or oil are used more commonly. Due to the fast rate of cooling, tempering is required after annealing to relieve the stresses in the material.
Tempering
Tempering is a process that reduces the stresses built up in the material during other heat treatment processes. Metals are reheated at a low temperature to reach a combination of strength, hardness and durability. Furnace time and temperature are controlled to produce the required properties. Steels are tempered after quenching to relieve stress and reduce brittleness.