Characterization of the Fatigue Behaviour of Austenitic Steel Using HTSL-SQUID

The experiments reveal characteristic cyclic deformation cureves and corresponding Eddy Current and SQUID signals according to the actual fatigue state. The extremely sensitive SQUID measuring technique provids the possibility to detect phase transformations in specimens fatigued at a temperature of T=300 deg C in which the phase fractions of plasticity induced martensite are extremely low. This information could not be detected with other nondestructive testing techniques. Light and electron microscopic investigations additionally confirm the correlation of the nondestructively obtained results with the measured fatigue induced stress-strain state of the material