Strain Rate Dependence of Hot Tensile Behavior, Microstructure Evolution, and Fracture Mechanism of Lean Duplex Stainless Steel 2101

Abstract

To improve the hot workability of lean duplex stainless steel 2101 (LDX 2101), the effects of strain rate on the hot tensile behavior, microstructure evolution, and fracture mechanism of LDX 2101 are systematically studied. Results indicate that ferrite is softened by continuous dynamic recrystallization (CDRX) and austenite may start through a mechanism analogous to CDRX at the low strain rate of 0.1 s−1. A softening mechanism similar to the discontinuous dynamic recrystallization (DDRX) is observed both in ferrite and in austenite at the strain rate of 5 s−1. The main fracture mechanism is a void accumulation fracture mode. Cracks form and propagate into the ferrite due to the low softening degree of austenite at the strain rate of 0.1 s−1. As the strain rate increases to 5 s−1, the dynamic recrystallization behavior of austenite increases due to the accelerated accumulation of dislocations and the high storage energy. The microhardness and strain distribution difference between ferrite and austenite decreases, and the crack propagation trend weakens, thus improving the thermoplasticity. The findings are of great significance for understanding the thermoplasticity of LDX 2101 and other two‐phase alloys.