Microstructural Characterization of Hydrogen-Irradiated 316L Austenitic Stainless Steel using Uniform Proton Implantation

Abstract

This study investigates the microstructural response of 316L austenitic stainless steel (SS316L) to hydrogen loading, focusing on the role of pre-existing martensite. The use of austenitic steels in hydrogen and nuclear applications is crucial; however, their susceptibility to hydrogen embrittlement (HE), particularly in the presence of martensite, presents a significant challenge. Martensite in metastable SS316L acts as a fast diffusion pathway for hydrogen, leading to localised accumulation and increased HE susceptibility. This detrimental effect is compounded by irradiation. Samples of commercial SS316L were uniformly irradiated with 1 MeV protons at room temperature. The microstructure was characterised using SEM, EBSD, TKD and TEM techniques. Microstructural characterization revealed an austenitic matrix with annealing twins and fine, pre-existing martensite phases in both the as-received and hydrogen-implanted conditions. The martensite is attributed to cold rolling during processing. No noticeable radiation damage was observed in the as-implanted SS316L. Post-implantation annealing and nanohardness testing will be used in future work to further investigate how the irradiation and hydrogen affects the microstructure and HE