DETERMINATION OF SOFTENING KINETICS IN A MATERIAL BY MEASURING THE EVOLUTION OF HOT FLOW-STRESS

A new technique for estimating the time and temperature-dependent soft ening response of a deformed material is proposed. The hot flow stress is measured at various intervals in a quasistatic softening experimen t to determine the kinetics of softening. A major advantage of the pro posed technique is that a single specimen can be used to estimate the evolution of softening without having to cool and reheat the specimen for each measurement. High resolution strain measurement apparatus is used in the experiments, as minimizing strain is a critical requiremen t in properly performing the measurement. Test control requires optima l performance from the servohydraulic system which must operate near i ts threshold for reliable information to be obtained. Experimental res ults indicate that age hardening response as well as recovery and recr ystallization kinetics can be measured using this method.