Hot Deformation Behavior of As-Cast 2101 Grade Lean Duplex Stainless Steel and the Associated Changes in Microstructure and Crystallographic Texture

Abstract

The hot deformation behavior of 2101 grade lean duplex stainless steel (DSS, containing similar to 5 wt pct Mn, similar to 0.2 wt pct N, and similar to 1.4 wt pct Ni) and associated microstructural changes within delta-ferrite and austenite (gamma) phases were investigated by hot-compression testing in a GLEEBLE 3500 simulator over a range of deformation temperatures, T (def) 1073 K to 1373 K (800 A degrees C to 1100 A degrees C)], and applied strains, epsilon (0.25 to 0.80), at a constant true strain rate of 1/s. The microstructural softening inside gamma was dictated by discontinuous dynamic recrystallization (DDRX) at a higher T (def) 1273 K to 1373 K (1000 A degrees C to 1100 A degrees C)], while the same was dictated by continuous dynamic recrystallization (CDRX) at a lower T (def) (1173 K (900 A degrees C)]. Dynamic recovery (DRV) and CDRX dominated the softening inside delta-ferrite at T (def) 1173 K (900 A degrees C). The dynamic recrystallization (DRX) inside delta and gamma could not take place upon deformation at 1073 K (800 A degrees C). The average flow stress level increased 2 to 3 times as the T (def) dropped from 1273 to 1173 K (1000 A degrees C to 900 A degrees C) and finally to 1073 K (800 A degrees C). The average microhardness values taken from delta-ferrite and gamma regions of the deformed samples showed a different trend. At T (def) of 1373 K (1100 A degrees C), microhardness decreased with the increase in strain, while at T (def) of 1173 K (900 A degrees C), microhardness increased with the increase in strain. The microstructural changes and hardness variation within individual phases of hot-deformed samples are explained in view of the chemical composition of the steel and deformation parameters (T (def) and epsilon). (C) The Minerals, Metals & Materials Society and ASM International 2016