Heattreated

Heat treatment is a group of industrial processes used to alter the physical and sometimes chemical properties of a material, most often metals, by controlled heating and cooling. The objective is to achieve a specific balance of hardness, strength, toughness, ductility, and wear resistance while maintaining the part’s identity and dimensions. The resulting properties depend on alloy composition, the chosen heat treatment temperature, heating and cooling rates, and the atmosphere or medium used.

Common processes include annealing (softening and stress relief through heating and slow cooling), normalizing (refining grain structure by heating and air cooling to improve toughness), quenching (rapid cooling after heating to increase hardness, often followed by tempering to adjust toughness), tempering (reduction of brittleness after quenching), and case hardening (surface hardening by introducing carbon or nitrogen through carburizing, nitriding, or carbonitriding, sometimes followed by additional surface treatments such as induction hardening). Surface-hardening methods such as induction hardening or laser hardening target only the outer layer.

The microstructure and properties resulting from heat treatment are highly dependent on the alloy and process; steels may form martensite after quenching, while annealing or normalizing promotes softer, finer grains and relieved stresses. In addition to property changes, heat treatment can affect residual stresses, distortion, and dimensional stability, and parts may require certification or documentation to verify the process.

Applications span gears, shafts, springs, bearings, tools, fasteners, and other components where a defined combination of hardness and toughness is required.