By definition, heat treatment is the controlled heating and cooling of metals for the purpose of altering their properties. Because both physical and mechanical properties can be althered by heat treatment, it is one of the most important and widely used manufacturing processes. However, if the heat treatment is performed improperly, more harm than good can result.www.mapeng.net马棚网机械资讯

Although the term heat treatment is often associated only with those thermal processes designed to increase strength, the definition permits inclusion of a set of processes called processing heat treatments. These are performed with the major goal of preparing the material for fabrication. Specific objectives may be the improvement of machining characteristics, the reduction of forming force, or the restoration of ductility to enable further processing. Thus, heat treatment becomes even more attractive. The same metal can now be softened for ease of fabrication and then, by another heat treatment, given a totally different set of properties for actual service.www.mapeng.net马棚网机械资讯

Most processing heat treatments involve rather slow cooling or extended times at elevated temperatures, thus tending to approximate equilibrium conditions. The resulting structures, therefore, can be reasonably predicted by the use of equilibrium phase diagrams. The diagram indicates the temperatures that must be attained to achieve a desired structure and the change that will occur on subsequent cooling. It should be remembered, however, that the diagram is for true equilibrium conditions, and the departures from equilibrium may lead to substantially different results.www.mapeng.net马棚网机械资讯