What is the primary purpose of annealing in metallurgy?

The primary purpose of annealing in metallurgy is to relieve stress and improve ductility. This heat treatment process involves heating metal to an elevated temperature and then allowing it to cool slowly. During this process, the internal stresses within the metal structure that may have been induced during processes like work hardening or casting are relieved.

As a result, the microstructure of the metal undergoes a significant transformation, leading to a softer material. This reduction in hardness and the improvement in ductility are critical because they enhance the material's ability to deform without breaking, making it easier to work with in manufacturing processes and leading to better performance in applications where flexibility and resilience are important.

While there are other processes designed for hardening, increasing tensile strength, or improving corrosion resistance, these are not the primary purposes of annealing. The key takeaway is that annealing is fundamentally about managing stress and enhancing the ductility of metals.