Surface pick-up of argon during hot isostatic pressing of material built by laser powder bed fusion

In prior studies, gas atomisation and L-PBF under argon atmosphere caused some pick-up of argon by the material. The gas used during HIP is argon which raises the question if the material can pick-up argon here as well. Hence, the impact of HIP on argon content of the near-surface and bulk in AM-material was investigated in this study. We found that the argon content near the surface increased significantly (of IN718, HX, C276), while the bulk content remained unchanged. Rough surfaces, time in HIP and especially oxidised surfaces prior to HIP all aggravated the argon pick-up. Since the influence of the surface argon pick-up on fatigue performance is not yet known, we recommend that critical components should be machined, blasted, ground or polished after HIP. If that is not possible, components should possess non-oxidised surfaces prior to HIP. By following these guidelines, any risk of a decline in performance of the material can be mitigated.

Automated summary

This study found that the argon content near the surface of the AM-material increased significantly during HIP, while the bulk content remained unchanged. Rough surfaces, time in HIP, and oxidised surfaces prior to HIP were all found to aggravate argon pick-up. Therefore, critical components should be machined, blasted, ground, or polished after HIP, or possess non-oxidised surfaces prior to HIP to mitigate any risk of a decline in material performance.