Changes in the material microstructure and material properties of the workpiece resulting from an internal material load. These are due to mechanisms such as dynamic recyrstallization and phase transformation. Examples of material modifications on the microstructural level include a change in grain size or the formation of additional phases. On the polycrystalline level, these are in many cases changes in the residual stress states. Chemical reactions that occur during the manufacturing process also result in material modification. As a result of this process, modified surface layer properties are generated.