Insights into the helium bubbles coarsening behavior in the post irradiated annealing 304L stainless steel processed by laser powder bed fusion

The results showed that material swelling due to helium bubble coarsening was almost not observed in either the LPBF or rolled samples after 10 h of annealing duration.

Rapid coarsening and swelling of bubbles occurred in the rolled samples, but only moderate bubble growth occurred in the LPBF sample after annealing for 100 h. After annealing for 300 h, the helium bubbles in both samples tended to grow steadily. For 10 h of annealing, the irradiated samples were in a disequilibrium state, and the apparent activation energy (E act) calculated by the Arrhenius model determined that helium atoms tended to diffuse through the displacement mechanism, and helium bubbles grew under the migration and coalescence (MC) mechanism.