Development of a Novel Cr21 Lean Duplex Stainless Steel and Its Hot Deformation Behavior

In this study, a novel Cr21 lean duplex stainless steel has been developed. In order to investigate the difference in hot workability between the novel steel and the conventional LDX2101, the hot deformation tests were carried out in the temperature ranges from 950 to 1150 °C and strain rate ranges from 0.01 to 10 s⁻¹ by using a thermo-mechanical simulator. The peak stress increased with an increase in strain rate and a decrease in deformation temperature. However, the peak stress of the novel Cr21 lean DSS was always higher than that of the conventional LDX2101 under the same deformation conditions. The novel steel with lower deformation activation energy can be more easily deformed than the LDX2101. Meanwhile, the processing maps based on the specific plastic work approach indicated that the novel steel possessed a narrower flow instability region than the LDX2101. The lower difference in softening rate between ferrite and austenite can lead to the better deformation coordination in the novel steel compared to the LDX2101. The excellent hot workability of the novel steel can be obtained due to the low strength difference between the dual phases and the inhibition of the thin lamellar structures along the rolling direction on the transverse propagation of small cracks originating from the edge of the hot-rolled plates.