Volume 26, Issue 6 (November 1998)
Measurement of Fatigue-Creep Dynamic Back Stress and Strain Rate Equation of a Fe-Ni-Cr Alloy
A new testing method for measurement of dynamic back stress for fatigue-creep interaction with predominant creep at high mean stress is developed according to the principle of dropped stress creep. A series of dropped stress creep tests were performed repeatedly until an unlimited extensive incubation with zero creep rate at a given dropped stress occurred. The stress causing zero creep rate is defined as fatigue-creep dynamic back stress. The developed method was used successfully to measure the dynamic back stress for fatigue-creep interaction with predominant creep. The dynamic effective stress could yield a better description of the strain rate equation for the fatigue-creep interaction at high mean stress. Mean stress plays a predominant role in determining fatigue-creep strain rate.