Enhanced work hardening in ferrite and austenite of duplex stainless steel at 200 K: In situ neutron diffraction study

Ferrite-austenite duplex stainless steels exhibit excellent strength and ductility, making them attractive for applications in extreme environments. In this study, in situ neutron diffraction measurements were conducted during tensile testing at 293 K and 200 K to investigate stress partitioning and phase-specific deformation behavior at low temperatures. Phase stress was derived using a texture-compensated method to accurately evaluate stress partitioning and each phase’s contribution to the overall strength. Regardless of temperature, ferrite exhibited higher phase stress than austenite, acting as the harder phase. At 200 K, both ferrite and austenite showed increased strength and work hardening, with austenite exhibiting significant stacking fault development in addition to dislocation migration. The plastic deformation mode of ferrite at 200 K was similar to that at 293 K, governed by dislocation migration, but it became more effective. The stress contributions of ferrite and austenite during plastic deformation were comparable at both temperatures. No martensitic transformation was observed in the tested temperature range. The combination of strengthening and enhanced work hardening in both phases contributed to the high strength of duplex stainless steel at 200 K while maintaining ductility comparable to that at 293 K. • Duplex stainless steel was deformed at 293 K and 200 K. • In-situ neutron diffraction measurements and peak profile analysis were conducted. • Regardless of temperature, ferrite exhibited higher phase stress than austenite. • Stress contributions of ferrite and austenite remained similar at 293 K and 200 K. • Strengthening and enhanced work hardening in each phase contributed to high strength.