nontempered

Nontempered is an adjective used to describe materials that have not undergone the tempering process. Tempering is a heat-treatment step applied after hardening to adjust mechanical properties such as toughness, hardness, and residual stress. The term is most often encountered in metallurgy and glass manufacturing, where the absence of tempering can significantly affect performance.

In metallurgy, nontempered steel refers to steel that has been quenched but not tempered. Quenching produces a hard, martensitic structure that is strong but brittle. Without tempering, the material typically exhibits high residual stresses, reduced toughness, and greater risk of brittle fracture under impact or sudden loading. Nontempered steel may be used in applications where extreme hardness is required and subsequent stress relief can be avoided or is not necessary, but it is generally less stable in service than tempered steel.

In glassmaking, nontempered (often described as untreated or annealed) glass has not undergone tempering to increase strength. Untempered glass is more susceptible to breakage from impact and thermal stress and tends to form large, sharp fragments when broken, in contrast to tempered glass, which shatters into small, relatively harmless pieces. Nontempered glass is typically cheaper and used in applications where safety glazing standards do not apply or where post-breakage risk is acceptable.

See also: tempering (metallurgy), martensite, annealing, quenching, tempered glass.