Session: MF-09-01 Mechanistic Modelling of Deformation and Fracture-1

Paper Number: 123071

123071 - Hydrogen Effects on the Deformation Behavior of Single Crystal Austenitic Stainless Steel 316l 

Austenitic stainless steels are widely used in high-pressure hydrogen storage and delivery systems. Internal hydrogen is known to embrittle these alloys, but the mechanisms that lead to such material degradation are still being elucidated. The current work combines experimental and modeling efforts to investigate the effects of hydrogen on the deformation behavior of single crystal stainless steel 316L. Uniaxial tension and compression tests are performed on specimens with and without thermally precharged internal hydrogen along different loading directions in both single slip and multiple slip configurations. Hydrogen consistently increases the critical resolve shear stress (CRSS) in all conditions, similar to observations for polycrystalline specimens. Electron backscatter diffraction shows that hydrogen increases the amount of geometrically necessary dislocations and twinning, and atomic force microscopy is used to assess the slip localization on the surface of the specimens. Moreover, molecular dynamics simulations are employed to investigate the origins of the hydrogen-induced strengthening. Simulations are performed to assess the effects of interstitial hydrogen, vacancies and hydrogen-vacancy complexes, considering that hydrogen enhances the formation of vacancies. While the CRSS varies over a range of values due to statistical variability in the populations of atoms around the dislocations, the average strengthening contributions converge. All of these defects are shown to increase the CRSS for varied stress states and local atomic distributions. The results of this study provide valuable insights on the effects of hydrogen on the yield stress and deformation behaviors of austenitic stainless steels.

Presenting Author: Fernando Daniel León-Cázares Sandia National Laboratories

Presenting Author Biography: - BSc Mechanical Engineering at the Monterrey Institute of Technology, Mexico.
- MSc Materials Science and Engineering at The University of Sheffield, UK.
- PhD Materials Science and Metallurgy at the University of Cambridge, UK.
- Postdoctoral researcher at the University of Cambridge, UK.
- Postdoctoral researcher at Sandia National Laboratories, USA (currently).

Authors:

Fernando Daniel León-Cázares Sandia National Laboratories
Brian Kagay MPA University of Stuttgart
Josh Sugar Sandia National Laboratories
Xiaowang Zhou Sandia National Laboratories
Coleman Alleman Sandia National Laboratories
Joseph Ronevich Sandia National Laboratories
Chris San Marchi Sandia National Laboratories