Abstract: 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.

摘要： 通过Gleeble-3800热压缩实验研究了铸态超级双相不锈钢S32750(/%:0. 017C,0.53Si,0.93Mn,0.023P,0.001S,25.58Cr,7.00Ni,4.03Mo,0.28N)在变形温度为950～1200℃、应变速率为0.1～25/s、真应变为1条件下的热变形行为与组织演变规律。结果表明,超级双相不锈钢S32750热变形行为受变形温度和应变速率的影响明显。在950～1050℃、0.1/s变形时,流变曲线表现出"类屈服平台"特征;当变形温度为1100～1200或应变速率为10/s、25/s时,流变曲线为典型的动态再结晶特征。对其微观组织进行观察发现,铁素体在各变形条件下均发生动态再结晶;奥氏体在950℃和1200℃时基本不受应变速率影响,前者发生动态回复,后者发生动态再结晶。而在1050℃时,受应变速率影响较大:小应变速率下(0.1/s)下发生动态回复,大应变速率下(10/s)发生动态再结晶。