Microstructural Characterization and Study of Hydrogen Embrittlement in Austenitic and Ferritic Stainless Steels

Abstract

Hydrogen Embrittlement is a vital materials degradation phenomenon in stainless steels, leading to materials premature failure and decreased ductility in hydrogen-rich conditions. Duplex stainless steels (DSSs), with their special characteristics coming from dual-phase of ferritic-austenitic structure of roughly equal parts (50%-50%), containing a mixture of high rich elements such as chromium, molybdenum and nitrogen are widely used in chem-ical and energy industries because of their strength and corrosion resistance. Despite their long- standing reliability Duplex stainless steels (DSSs) in hydrogen rich-environments is one the most concern issue especially as interests in hydrogen technologies kept growing towards sustainable energy transitions. This research work seeks to study the chemical compositions and microstructures of the duplex stainless steel, evaluate the mechanical properties and determine the hydrogen con-tent and trap distributions to see how the effects of phase balance on the mechanical prop-erties of the duplex stainless steel. To achieve these, electrochemical hydrogen charging, slow strain rate tensile (SSRT), thermal desorption Analysis (TDA) and scanning electron microscopy (SEM) fractography was performed. The finding shows that the unaffected by hydrogen parameter is yield strength while on the other hands, time considerably decreased under hydrogen charging for tensile strength, elongation and fracture time. According to the thermal desorption analysis (TDA) meas-urement conducted, hydrogen uptake was confirmed with release curves dominated by peaks in the mid-range temperatures, indicative of characteristic trapping sites. The fracto-graphic results under SEM revealed that uncharged samples exhibit a ductile fracture char-acterized by uniform dimples in the uncharged, while hydrogen-charged samples exhibit a ductile-brittle mixture with both ductile dimples and brittle microcracks. These findings demonstrate that hydrogen ingress promotes embrittlement through ductility loss and alter-ing of the fracture modes.