Hot deformation behaviour of microstructural evolution in 2507 Super Duplex Stainless Steel during high-temperature straining

Abstract

In this study, the flow behaviour, and microstructure evolution of the SDSS2507 were systematically investigated via hot compressive tests. Subsequently, the hot processing map was constructed according to the obtained stress–strain curves and corresponding equations. Additionally, metallographic examinations of hot compressed specimens found that the softening mechanism of the ferrite and austenite is dynamic recovery (DRV) and dynamic recrystallisation (DRX), respectively. With increasing the strain rate, it promotes the DRX in austenite. Moreover, micro-cracks could initiate from the ferrite/austenite phase boundaries or grain boundaries within the ferrite due to the strong discrepancy of deformation coordination between the two phases or precipitation of Cr₂N precipitates along the ferrite/austenite phase boundaries or ferrite grains at higher strain rate. Considering the hot processing map and microstructural evolution in SDSS2507, the optimum hot processing parameters for SDSS2507 are found to be in a low strain rate range of 0.1–3 s⁻¹ with the temperature range of above 950°C.