Early detection of damage in cyclically loaded austenitic steel was performed with electromagnetic acoustic transducer measurements in total strain controlled low cycle fatigue tests at ambient and elevated temperature. The application of physically based measurement data, e.g. time of flight from electromagnetically activated ultrasonic signals in austenitic fatigue specimens and total strain, enables measurements of a new hysteresis relationship. This hysteresis gives, in analogy to the stress-strain hysteresis, information about the actual state of fatigue of the austenitic steel and shows significant changes in shape before specimen failure.