Effect of Ce on creep damage behavior of 316LN austenitic stainless steel at 700 °C

The effect of rare earth element Ce on creep damage behavior of 316LN austenitic stainless steel (316LN) at 700 °C was systematically investigated under stress ranging from 125 MPa to 200 MPa. The results show that the addition of 0.032 wt% Ce remarkably improves the rupture life of 316LN steel under various stress. Ce addition in 316LN steel decreases the nucleation stress, stabilizes stress concentrations at particles, and notably raises the cavity nucleation rate. Moreover, Ce addition suppresses cavity growth during creep, thus the cavity growth rate significantly decreases and the creep rupture ductility increases under high stress over 175 MPa. However, the anomalous growth rate was engendered in some cavities by Ce addition in 316LN steel under low stress below 150 MPa. Consequently, Ce addition in 316LN steel reduces the creep rupture ductility and changes the rupture mode from trans-granular dimple fracture under high stress to mixed fracture under low stress.