For many alloys, including carbon steel, the crystal grain size and phase composition, which ultimately determine the material properties, are dependent on the heating, and cooling rate. Hot-working or cold working after the annealing process alters the metal structure, so further heat treatments may be used to achieve the properties required. In the cases of copper, steel, silver, and brass, this process is performed by heating the material (generally until glowing) for a while and then slowly letting it cool to room temperature in still air. The metal is softened and prepared for further work—such as shaping, stamping, or forming.