Irradiation effects on additively manufactured porous 316H stainless steel: A molecular dynamics study

The porous microstructures in additively manufactured 316H stainless steel (AM 316H-SS) may enhance radiation resistance by acting as defect sinks. This study employs molecular dynamics simulations to investigate the influence of pre-existing pore structures on radiation damage in AM 316H-SS produced via laser powder bed fusion. Using Fe-Ni-Cr interatomic potentials, we examined pore configurations ranging from 1 to 30,720 pores and primary knock-on atom (PKA) energies of 5, 10, and 15 keV. Results indicate that defect numbers increase significantly beyond 256 pores, with the 30,720-pore configuration exhibiting the highest defect retention. However, the 6-pore configuration, with a non-uniformly distributed pores, minimized surviving defects by leveraging a heterogeneous network of defect sinks that balances defect capture and bulk recombination, making it the most irradiation-resistant arrangement. PKA placement (corner vs. center) had minimal impact on defect production, validating the robustness of the approach. Higher pore densities influenced dislocation formation, leading to Shockley and Stair-rod dislocations and stacking fault tetrahedra. Increased PKA energy broadened and shifted radial distribution function peaks, indicating a transition to a more disordered state. Full width at half maximum analysis revealed a non-linear relationship between pore configuration, PKA energy, and structural damage. These findings offer valuable insights for designing radiation-resistant AM stainless steels for nuclear applications.