Microstructural Evolution and Hot Deformation Behavior of Lean Duplex Stainless Steel 2101

Abstract

In this study, hot deformation behavior of lean duplex stainless steel 2101 (LDX2101) is investigated via isothermal compressive tests in the temperature ranges of 900–1150°C and the strain rate ranges of 0.01–10 s−1. The effect of temperature and strain rate on the hot workability, strain partitioning and flow behaviour of LDX2101 is systematically investigated. It is found that the peak stress decreased with an increase in deformation temperature and a decrease in strain rate. The softening mechanism of the ferrite and austenite is dynamic recovery (DRV) and dynamic recrystallization (DRX), respectively. Further increasing the strain rate promote the DRX. The hot processing map was constructed in the sample. There are two flow instability regions at lower strain rate and lower temperature due to the lack of sufficient extra stress for the discrepancy of deformation coordination between the ferrite/austenite phases. Moreover, brittle Cr2N precipitates are observed along the ferrite/austenite phase boundaries, which can act micro-cracks initiation position. Considering the hot processing map and microstructural evolution in LDX2101, the optimum hot processing parameters for LDX2101 are found to be in a strain rate range of 0.01–10 s−1 with the temperature range of above 1050°C and strain rate of 0.8–10 s−1.