Which quality does tempering primarily enhance in metal?

Tempering primarily enhances toughness in metal. The process involves heating the metal to a specific temperature and then allowing it to cool, which helps to relieve stresses that may have developed during processes like hardening. When metals are initially hardened, they can become very hard but also more brittle. Tempering helps to reduce this brittleness by allowing for a more ductile structure, which enhances the material's ability to absorb energy and deform without fracturing. This is particularly important in applications where the metal will be subjected to impact or stress.

While strength relates to a material's ability to withstand forces without failing, tempering primarily works to improve the balance between strength and brittleness, leading to an overall enhancement in toughness. Toughness is the property that allows a material to endure stress without cracking, making it crucial for many engineering applications, where failure could have serious consequences. Thus, the emphasis on toughness as the primary quality enhanced by tempering clearly defines the value of this heat treatment process in metalworking.