Zerstörungsfreie Früherkennung von Kriechschäden

The contribution presents the state of the art in Nondestructive Testing for the early detection of creep damage which occurs at seamless tube bends from CrMo-steels under load at temperatures >= 550 C. The damage is discused as cavitation and its further development to linked prorosity, mmicro- and macro-cracking in the 3rd stage of materials creep. Depending of the natural scatter of the material data and the component under inspection the use of the ultrasonic surface save give access to detect linked pores along grain boundaries and compored with conventional Nondestructive testing one gains one damage grade in detectability. Electromagnetic techniques are not effected by porosity (>= 2%) and show a strong influence of the microstructure and its change as function of creep.