Session: MF-02-04 Materials for Hydrogen Service-High Alloy Materials 1

Paper Number: 121708

121708 - Assessment of Microstructure Influence on Tensile Properties of Austenitic Stainless-Steel Tubing with Internal Hydrogen and Tritium 

This study aims to correlate the microstructure of 304L austenitic stainless steel, strain hardened and annealed, to previously reported tensile testing results of hydrogen and tritium-precharged 304L tubes with the same microstructures. Previously reported yield strengths suggested that annealed 304L is just as, if not more, sensitive to hydrogen than strain hardened 304L. Because both strain hardened and annealed 304L stainless steel tubing is used in hydrogen systems, it is necessary to understand the microstructural influences on the mechanisms for hydrogen embrittlement. By studying the recovery and recrystallization of 304L stainless steel, we can identify changes in the undeformed microstructure and, combined with measurements of the mechanical response in hydrogen, their relationship to hydrogen embrittlement mechanisms. This understanding of microstructure-property relationships in the presence of hydrogen can be useful for developing models of hydrogen-assisted fracture to aid component design and materials development. The recrystallization progression is studied by examining as received and annealed microstructures with scanning electron microscopy and electron backscatter diffraction (EBSD). We attempt to characterize dislocations through grain boundary angles and coincident lattices using EBSD. Microstructure and grain size are assessed qualitatively with optical microscopy, revealing a progression of microstructures from recovered through partially recrystallized to fully recrystallized with significant grain growth in the fully annealed material. Microstructure data is indexed, assessed, and correlated to the measured tensile properties of each microstructural condition in the unexposed materials and hydrogen or tritium-precharged materials.

Presenting Author: Natalie Wieber Battelle Savannah River Alliance - Savannah River National Lab

Presenting Author Biography: Natalie Wieber recently started her career in material science at Savannah River National Laboratory. Natalie earned her Bachelors of Science in material science and engineering from the University of Tennessee and her Masters of Science in material science and engineering from Michigan Technological University. After completing a fellowship with Department of Energy's National Nuclear Security Administration during her Masters program, Natalie chose to pursue materials research relevant to stockpile stewardship. She currently studies mechanical behavior of structural steels through fracture and fatigue testing, specifically hydrogen embrittlement of steel.

Authors:

Natalie Wieber Battelle Savannah River Alliance - Savannah River National Lab
Tim Krentz Savannah River National Laboratory
Joe Ronevich Sandia National Laboratories
Chris San Marchi Sandia National Laboratories