Stress Relaxation Measurements of Meta-Dynamic and Static Recrystallization of Alloy 80A

Abstract

The stress relaxation method has been applied to the nickel-based alloy 80A to predict meta-dynamic (MDRX) and static recrystallization (SRX) kinetics. Compression tests were performed on a Gleeble 3800 system atr different temperatures (950-1200°C). The strain rate was varied in the case of MDRX and the pre-strain in the case of SRX. To investigate MDRX, the prestrain was set to twice the peak strain in order to reach steady state before holding. To focus on the interaction of MDRX and SRX, the pre-strain was set to the peak strain, where dynamic recrystallization (DRX) starts but does not yet reach steady state. Avrami type equations for the prediction of both the MDRX and SRX were adapted to feed a semi-empirical grain structure model.

Recrystallization behaviour of the nickel‐based alloy 80 A during hot forming

“…Consequently, a differentiation between these two mechanisms can be performed by varying the soak time of the pre‐strained specimens. Kleber and Sommitsch (2004) showed that for the alloy 80A the MDRX should be finished in about 1 s. In Fig. 8 the microstructures of specimens with different pre‐strains and soak times can be seen, where grain maps display the grains after the removal of all twins.…”