1. Softening treatments

1.1 General

Steel is softened to make it easier to process, but the softening treatments used differ to meet the specific requirements of the various machining and forming processes. For example, before extrusion, steel is required to be as malleable as possible, whereas before machining, it is preferred to retain a hardness significantly higher than the minimum value it can assume.

These characteristics are generally obtained when the steel structure consists of a dispersion of carbides in a ferritic matrix. The properties are then adapted to the requirements of the application by varying the shape, dimensions and dispersion of these carbides.

The heat treatments used to achieve these structural states are of two types: