The test steel 316LN (/% : 0.011C

0.49Si

1.52Mn

0.016P

0.001S

16.65Cr

13.43Ni

2.18Mo

0. 153N) is Φ 180 mm round bar forged and primary-rolled from 7. 2 t ingot. The hot deformation behavior and structure evolution rule of steel 316LN with strain rate 0. 1 ~ 50 s

-1

at 1 050 ~ 1 200 ℃ has been studied by using thermal-simulated test machine Gleeble-3800

and a constitutive equation of steel 316LN is established by linear regression analysis. Results show that increase of deformation temperature is favorable for nucleation of dynamic recrystallization and promoting the development of dynamic recrystallization during hot deformation; in hot deformation process the material constant α is 0.006 1

the stress exponent n is 5.543 6 and the apparent activation energy is 550. 512 kJ/mol；

with increasing deformation temperature the number of dynamic recrystallized grains in steel increases

and the complete dynamic recrystallization occurs in steel deformed at 1 200 ℃.