Thermal desorption study of selected austenitic stainless steels

Abstract

Residual hydrogen in stainless steel results in a steady outgassing from vacuum chamber walls, hindering the achievement of ultrahigh vacuum conditions. The total content, the binding states, and the diffusivity of residual hydrogen in austenitic stainless steels, which together define the room temperature hydrogen outgassing rate, have been investigated by thermal desorption spectroscopy (TDS). Seven different steel types have been studied by means of two different TDS systems. The study has been extended to include the effects of various postproduction treatments, aimed at reducing the hydrogen content and/or outgassing, namely vacuum firing and baking both in air and under vacuum. A large variety of hydrogen desorption peaks have been observed, which have been attributed to diffusible hydrogen, hydrogen trapping in the surface oxides or in lattice defects induced by precipitates, and steel recrystallization. The hydrogen depletion effectiveness of vacuum baking at different temperatures has been quantified, and the consequences of air baking have been clarified, leading to practical guidelines for technological applications.

Comparative study of the tritium distribution in metals

“…Baking stainless steel and Inconel prior to exposure to tritium reduces the tritium concentration in the enriched sub-surface layer. This may be due to an increased grain size as a result of the heat treatment causing corresponding decrease in the rate of grain boundary diffusion in baked metal [13,27] and to a reduction in the number of places in the sub-surface layer of baked metal which could be occupied by tritium.…”

Design and fabrication of a hydroformed absorber for an evacuated flat plate solar collector

“…Materials should also be able to withstand a bake-out at temperatures of 200 -400°C. Stainless sheet is commonly used for vacuum equipment [12,13] and can be vacuum baked [14] to reduce outgassing rates.…”

Atom probe, AFM, and STM studies on vacuum-fired stainless steels

“…There is a considerable body of work attempting to describe the hydrogen outgassing behaviour of SS during and after thermal treatment. For description of the outgassing rate basically two common models such as the diffusion limited model (DLM) and recombination limited model (RLM) have been discussed [2][3][4][5][6][7][8][9][10]. On the assumption made by Calder and Lewin [2], the outgassing rate of hydrogen from stainless steel should be limited only by the bulk diffusion rate in the fcc lattice.…”