Annealing is a form of heat treatment. It is commonly applied to specific metals to achieve changes in the mechanical or physical properties of a metal. The process of annealing makes the item less hard but, contrary to popular perception, this is not an undesirable quality. In fact, metal annealing produces less brittle and more ductile components. However, as is the case with many heat treatments, more than one type of the procedure exists.
Basic Types of Metal Annealing Treatments
Application of basic metal annealing treatments varies. The following are those frequently used:
* Full Annealing: This is the most basic type of annealing. It is used so frequently it is simply called “annealing.” This form of metal annealing heats the metal to between 50 and 100 degrees Fahrenheit above the set upper transformation temperature. The material is held for a long time then cooled in an oven at the rate of 100° F per hour. The rate of cooling may also be slower if time is not a major factor in arriving at the intended results.
* Process Annealing: The alternative name for this type of metal annealing is “stress relief annealing.” It is actually a compromise between full-blown and no annealing at all. It is a practical and very economical solution for removing the greater amount of stresses in a short time. Besides stress relief, process annealing is used as an intermediate heat-treating step during the manufacturing of specific components.
* Spheroidizing Annealing: Of all the kinds of metal annealing, this is the most rapid. It is almost identical to process annealing but is faster. Metal treating companies use it for both low carbon (cementite) and high carbon steel (ferrite).
Some metal treating companies use other forms of metal annealing. Among the potential types for the process are bright annealing and isothermal annealing.
Metals Employed in Metal Annealing
Not all metals are annealed. Metal annealing is most commonly applied on stainless steel. Aluminum alloy, copper and copper alloys, nickel and titanium and titanium alloys are also subjected to the annealing process. The intent varies but generally focuses on the advantages to the final product including ductility and improved machinability.
Metal Annealing Results
Annealing is favored by many industries for its ability to produce improved products. The process results in:
* Internal stress reduction
* Improved material structure
* Enhanced magnetic properties
* Decrease of hardness possible
* Enriched properties for welding
* Improved resistance to corrosive elements
* Better accuracy regarding dimensions and shapes
* Clean process
* Resulting bright components
These are all advantageous results of the process known as metal annealing.
