Hydrogen Absorption into Austenitic Stainless Steels Under High-Pressure Gaseous Hydrogen and Cathodic Charge in Aqueous Solution

Abstract

Type 316L and Type 304 austenitic stainless steels, both deformed and non-deformed, were hydrogen charged cathodically in an aqueous solution as well as by exposure to high-pressure gaseous hydrogen in an attempt to identify suitable conditions of cathodic charge for simulating hydrogen absorption from gaseous hydrogen environments. Thermal desorption analysis (TDA) was conducted, and the amount of absorbed hydrogen and the spectrum shape were compared between the two charging methods. Simulations were performed by means of the McNabb-Foster model to analyze the spectrum shape and peak temperature, and understand the effects of deformation on the spectra. It was revealed that the spectrum shape and peak temperature were dependent directly upon the initial distribution of hydrogen within the specimen, which varied widely according to the hydrogen charge condition. Deformation also had a marked effect on the amount of absorbed hydrogen in Type 304 steel due to the straininduced martensitic transformation.

Effect of Surface Hydrogen Concentration on Hydrogen Embrittlement Properties of Stainless Steels and Ni Based Alloys

“…The technique can be a convenient alternative to those of HGE and IRHE. The comparison between the cathodic charging in the aqueous solution and the thermal charging in gaseous hydrogen was performed in terms of the hydrogen absorption 10) and the degrees of mechanical degradation 11) in commercial type 316L and 304(L) austenitic stainless steels. However, relationship between hydrogen embrittlement caused by cathodic charge (CHE) and those by HGE or IRHE has not been clarified yet in a wide range of steel materials.…”

Defects Responsible for Hydrogen Embrittlement in Austenitic Stainless Steel 304 by Positron Annihilation Lifetime Spectroscopy

“…HE also occurs in austenitic stainless steel 304 when hydrogen is added by cathodic electrolysis. 25) In this case, hydrogen is introduced only in the surface layer and yet the ductility reduction is induced throughout the bulk. It is anticipated that hydrogen diffuses to deeper regions inside the sample by applying stress, and that the defect formation is dependent on the depth, but no empirical evidence to support these assumptions exists to date.…”

“…Hydrogen was introduced in the samples by the electrolytic cathodic charging method. 25) The electrolyte was an aqueous solution of 3 mass% NaCl + 3 g/l NH 4 SCN and the charge was conducted at a constant electric current density of 50 A/m 2 for 48 hours at RT. The section of the sample where hydrogen was introduced has a gauge length of 20 mm and a width of 10 mm.…”

Surface vs diffusion in TDS of hydrogen

“…However, there are several works in which the distribution of hydrogen concentrations after standard charging was measured, see [19][20][21][22][23]. This work covers all standardized methods of charging samples: in gaseous hydrogen, in saline solution and cathode charging.…”