Raw data: Microstructural Impact on Hydrogen Diffusion in Additively Manufactured 316L Stainless Steel

Hydrogen diffusion in 316L stainless steel produced by laser powder bed fusion (L-PBF) differs strongly from conventionally processed, solution-annealed material. The effective hydrogen diffusion coefficient of 1.9 × 10-13 m²/s is about 10³ times higher than in conventional samples. It is attributed to pipe diffusion along dislocation cells. Recovery signatures detected between 450 and 600°C allow for targeted modification of the microstructure. Annealing at 650°C for 2 h reduces the diffusion coefficient to 7.7 × 10-14 m²/s while preserving hardness. Hardness decreased only slightly from 237 HV1 to 232 HV1. This goes in line with unchanged melt pool boundaries, grain morphology, dislocation cell diameter, elemental segregation, and Si-Mn-O nano-precipitates, but decreased dislocation cell wall thickness and connectivity. Hydrogen pipe diffusion along cell walls can be reduced by annealing without sacrificing mechanical strength.