Dependency of rate sensitive DRX behaviour on interstitial content of a Fe-Cr-Ni-Mo alloy

Abstract

In the present work the commonly stated but not explicitly demonstrated association between the chemical composition of a material, its stacking fault energy (SFE) and dynamic recrystallization (DRX) behaviour, is established using thermo-mechanical testing, microstructural characterization and thermodynamic calculations on a Fe-Cr-Ni-Mo model alloy with varying interstitial content (0.1 < (N + C) < 0.25 wt%). The thermodynamic calculation shows that SFE decreases from 27 mJ/m2 to 17 mJ/m2 with increase in interstitial content at room temperature. The values of SFE rise upto 205 mJ/m2 to 200 mJ/m2 at 1323 K. The alloy with minimum interstitial content and maximum SFE exhibits a sluggish DRX behaviour in the strain rate domain 0.1–1 s−1. The sluggishness gradually diminishes as the interstitial content is increased and SFE is decreased. The rate-dependency of nucleation is explained on the basis of interstitial content, which changes the SFE. The present investigation also elucidates the rate- dependent grain growth for the model alloy.