In friction stir processing (FSP), a rotating tool is used with a pin and a shoulder to a single piece of material to make specific property enhancement, such as improving the materials toughness or flexibility, in a specific area in the micro-structure of the material via fine grain of a second material with properties that improve the first.(Ma) Friction between the tool and workpieces results in localized heating that softens and plasticizes the workpiece. A volume of processed material is produced by movement of materials from the front of the pin to the back of the pin. During this process, the material undergoes intense plastic deformation and this results in significant grain refinement. (Mishra) FSP changes physical properties without changing physical state which helps engineers create things such as “high-strain-rate superplasticity”. The grain refinement occurs on the base material improving properties of the first material, while mixing with the second material. This allows for a variety of materials to be altered to be changed for things that may require other difficult to acquire conditions. The processes branches off of friction stir welding (FSW) which uses the same process to weld two pieces of different materials together without heating, melting, or having to change the materials physical state.