The tested stainless steel 409L (/% : 0.01C

0. 82 ~0. 86Si

0. 26Mn

0.002 ~0.006S

0. 034 ~0.041P

11.44 ~ 11. 51Cr

0. 24 ~0. 27Ti

0 ~0. 09Ce) is melted by a 10 kg vacuum induction furnace

forged to 30 mm x 30 mm square billet

cold rolled to 2 mm plate and annealed at 1100 ℃ for 5 min. The effect of Ce on structure annealed at 900℃ for 30 min and on thermal fatigue performance between 900 °C and ambient temperature in steel 409L has been studied. Results show that as the steel contains 0. 03%Ce

the annealed grain of steel 409L is fined and the thermal fatigue performance is best

as the Ce content in steel further increases

the annealed grains coarsen and the thermal fatigue performance of steel gradually decreases. With adding RE element Ce the TiN and Ti

N-Al

2

O

3

compound inclusions basically eliminate and the fined spherical titanium-nitrogen compound inclusions bearing Ce and Al-O-Ti compound inclusions bearing Ce form

and adding excessive Ce

the amount of inclusions at grain boundary increases led to decrease the thermal fatigue performance of steel.