Effects of Ce on the precipitation behaviors and creep properties in 316LN austenitic stainless steel

The effects of Ce on the precipitation behaviors and creep properties in 316LN austenitic stainless steel (316LN) were studied by experiments and first-principles calculations. It found that Ce in 316LN induce intragranular Laves phase precipitates with an average diameter of 166 nm. Aside from Ce rich in TiN nanoparticles facilitates Laves phase precipitating by heterogeneous nucleation, the solute Ce atom attracting its surrounding Mo atoms favors Laves phase precipitating by homogeneous nucleation. These intragranular Laves phases strongly impede the dislocation climbing and thus enhance the creep resistance. Here, 0.032 wt.% Ce addition in 316LN considerably extends the creep life from 313 h to 556 h at 700 °C/150 MPa. These results provide a new insight into profoundly understanding the microalloying mechanism and effects of rare earth elements in heat-resistant steels.