What is the primary purpose of annealing metal?

The primary purpose of annealing metal is to improve ductility. Annealing is a heat treatment process that involves heating the metal to a specific temperature and then allowing it to cool slowly. This process helps to relieve internal stresses, reduce hardness, and enhance the ability of the material to deform without breaking.

When metals are worked or processed, they can become hard and brittle through strain hardening, which diminishes their ductility. By undergoing annealing, the metal's structure changes at the atomic level, leading to an increase in ductility, which is crucial for applications requiring bending, shaping, or further machining of the material without fracture.

In contrast, the other options focus on different properties that annealing does not primarily address. While annealing can affect hardness, brittleness, and strength, its main goal is to allow the material to be more ductile and workable.