The hot deformation and microstructure evolution of as-cast S32750 super duplex stainless steel (/% : 0.017C

0.53Si

0.93Mn

0. 023P

0. 001S

25. 58Cr

7. 00Ni

4. 03Mo

0. 28N) are investigated at different temperatures (950 〜1200℃ )

strain rates (0.1 ~ 25 /s) and strain (1) by Gleeble-3800 thermo-mechanical simulator. The results shows that the hot deformation behavior of S32750 was considerably affected by temperature and strain rate. The flow curves exhibit particularly yield-point-elongation-like effect at temperatures of 950 ~ 1050℃  and strain rate of 0.1/s

which is characterized by a non-strengthening plateau during the initial stages of plastic deformation. The flow curves show the dynamic recrystallization characteristic at temperatures of 1100 ~ 1200 °C or at strain rates 10 /s、25 /s. It is found that dynamic recrystallization occurs in ferrite at different deformation conditions. Whereas austenite undergoes dynamic recovery at 950℃ and dynamic recrystallization at 1200 °C

and the strain rate has a minimal effect on the microstructure evolution of austenite；when the deformation temperature is 1050℃

the strain rate plays an important role in the softening process

the austenite undergoes dynamic recovery at strain rate of 0. 1/s and dynamic recrystallization at 10 /s.