**5. Conclusions**

In this paper, we have studied at the microscopic level the effect of charging AISI316 and AISI316L steels with hydrogen. We have used in situ X-ray computed tomography tests to analyze the fracture process of charged and uncharged samples. Our main findings are as follows:


Given these conclusions and regarding potential applications, 316L is better for use in vehicle tanks.

**Author Contributions:** E.M., J.A. designed and performed experiments, S.G. performed image analysis, P.L., Y.A., O.T., H.M. supervised the study and contributed to drafting of the final version of the manuscript. E.M. wrote the first draft of the manuscript. All the authors discussed the drafts and approved the final manuscript for publication.

**Acknowledgments:** Elodie Boller is acknowledged for her help as local contact during the ESRF experiment at the ID19 beamline.

**Conflicts of Interest:** The authors declare no conflict of interest.
