Tungsten is predestined as an optimal material for high temperature applications, because of its high melting point (3410°C). Further advantages of tungsten are the low vapour pressure, the high temperature strength and the good workability at high temperatures. The main problem of tungsten is the low oxidation stability, so then tungsten can only be used at high temperatures in high vacuum atmosphere or protection gas atmosphere. The main application area of tungsten and its alloys is the lighting technology. After deforming and heat treatment doped (doped with potassium) tungsten appears to a no sag wire structure. This structure is very creep residence at very high temperatures. At the Plansee AG in Reutte, a special mill is used for wire rolling. Starting with the sinterrod the material is rolled in several steps down. At these milling steps there is a high degree of deformation. The aim of this diploma theses was to investigate, if under defined deformation parameters dynamic recovery or dynamic recrystallisation take place. The investigation were carried out at two different tungsten- materials, namely pure tungsten and tungsten doped with potassium. The crack behaviour of these materials should also be investigated at the given deformation parameters. The investigations were carried out by means of optical light microscopy, scanning electron microscopy and EBSD (Electron Back- Scatter Diffraction).