Recrystallisation rates in austenite measured by double compression and stress relaxation methods

Abstract

The feasibility of two mechanical testing methods, double compression and stress relaxation, for measuring the static recrystallisation rate in hot deformed austenite was studied. The results were verified by metallographic observations. The effect of recovery on the softening data in an interrupted compression test is eliminated when the reloading flow stresses are analysed at a total strain of 5% instead of the 0.2% offset strain used conventionally. A stress relaxation test provides consistent data on the recrystallisation event. In most instances, the stress present in the course of softening has no effect at all or only slightly enhances the recrystallisation rate. The accelerating effect is most pronounced, about 50-70%, at small strains and fine grain sizes.