Hydrogen Solubility and Diffusion in Austenitic Stainless Steels Studied with Thermal Desorption Spectroscopy

Abstract

Hydrogen solubility and diffusion in austenitic stainless steels, namely AISI 310, AISI 301LN and AISI 201, are studied with thermal desorption spectroscopy (TDS) after electrochemical potentiostatic hydrogen pre‐charging. Temperature dependencies of hydrogen desorption for all studied steels manifest a complex main peak caused by hydrogen releasing from the steel lattice by diffusion. Depending on the steel and heating rate the peak is situated from 350 to 500 K and its shape reflects a specific of hydrogen diffusion in stainless steels, which are multicomponent alloys. Analysis of the TDS curves is based on the hydrogen diffusion model taking into account trapping of hydrogen atoms in the energetically deep interstitial positions in the steel crystal lattice. Diffusion coefficient of hydrogen and its total content after the same charging procedure are obtained from the TDS curves and compared for the studied steels.

Numerical modeling of thermal desorption mass spectroscopy (TDS) for the study of hydrogen diffusion and trapping interactions in metals

“…Moreover, these simulations were carried out on pure Fe, a material presenting a relatively high interstitial H diffusion coefficient, therefore allowing a homogeneous hydrogen distribution to be achieved at room temperature in a relatively short period of time. Now if a homogeneous charging was desired for an austenitic stainless steel or a Ni-base alloy, this charging would take upwards of days [26] or weeks depending on both the sample thickness and charging temperature. Therefore for the majority of analysis done for fcc materials, the conditions do not satisfy the necessary requirements for Choo-Lee-Kissinger [10,15] analysis.…”

“…In experimental practices the sample is generally subjected to a transfer time between the hydrogen charging and the start of TDS testing (for example the time to pump to a sufficient vacuum for mass spectrometer usage) or maybe a room or high temperature aging period [11,26,30]. A transfer time of 30 min at 298 K has been selected in order to mimic this inevitable aging period.…”

“…In reality during all experimental steps, trapping from lattice sites to TS can occur freely along with the retrapping of previously trapped H. Using this simplified model they have tried to fit experimental desorption spectra in order to derive the kinetic constants associated with specific TS but some spectral reproduction difficulties were encountered. They have attributed these difficulties to their simplifying hypothesis [26].…”

“…In these systems, trapping is not considered. Their proposed simulation approach, which takes into account the samples' experimental "history", has been adapted to a DTS through the use of the McNabb and Foster equations [13] by Yagodzinskyy et al [26].…”

Effect of hydrogen on plastic strain localization and fracture of steels

“…1. The method for studying the hydrogen diffusivity and the interaction of hydrogen with lattice defects was proposed in [7]. Based on these observation, the steel samples were electrolytically saturated with hydrogen in a thermostatted three-electrode electrochemical cell with graphite anode, operating at a controlled constant cathode potential of U = -600 mV (relative to silver chloride reference electrode) in a 1 N sulfuric acid solution containing 20 mg/l thiourea.…”