Metal materials on a metal nameplate are difficult and brittle to quench results. Gently heat the hardened metal and allow it to cool slowly to produce metal that is still difficult and not brittle. This process is called tempering. (See Metalworking Activities). As a result, precipitation in many small iron 3C steels hinders the movement of dislocations, thereby strengthening them.

Cold working: due to the movement of dislocations caused by plastic deformation, the metal in the metal nameplate can prevent such movement from being enhanced. When a metal is bent or shaped, dislocations occur and move. As the number of dislocation tangles in the crystal increases, they will gain or be fixed and will not be able to move. This will strengthen the metal and make it difficult to deform. This process is called cold work. Dislocations at higher temperatures can be rearranged, so small enhancements occur.

You can try with a paper clip. Straighten and bend a straight section of a paper clip back and forth several times. Imagine what happened at the atomic level. Note that it is harder to bend the metal in the same place. The formation and entanglement of dislocations increases strength. The paper clip will eventually break in a bend. Cold work obviously only works to a certain extent! Too much dislocation in a tangled, unable to move deformation results, so the metal breaks instead.

Heating removes the effects of cold working. When the cold-worked metal is heated, recrystallization occurs. The formation and growth of new grains consumes the cold worked section. The new particles have fewer dislocations and recovery of the original properties.