Hydrogen In Austenitic Steels Research Articles

Use of time-of-flight secondary ion mass spectrometry for the investigation of hydrogen-induced effects in austenitic steel AISI 304L

During the energy transformation from fossil fuels to renewable energy sources, the use of hydrogen as fuel and energy storage can play a key role. This presents new challenges to industry and the scientific community alike. The storage and transport of hydrogen, which is nowadays mainly realized by austenitic stainless steels, remains problematic [L. Zhang et al., Int. J. Hydrogen Energy 39, 20578 (2014)], which is due to the degradation of mechanical properties and the possibility of phase transformation by hydrogen diffusion and accumulation [P. Rozenak, Metall. Mater. Trans. A 45, 162 (2014)]. The development of materials and technologies requires a fundamental understanding of these degradation processes. Therefore, studying the behavior of hydrogen in austenitic steel contributes to an understanding of the damage processes, which is crucial for both life assessment and safe use of components in industry and transportation. As one of the few tools that is capable of depicting the distribution of hydrogen in steels, time-of-flight secondary ion mass spectrometry was conducted after electrochemical charging [O. Sobol et al., Surf. Interface Anal. 48, 474 (2016)]. To obtain further information about the structural composition and cracking behavior, electron-backscattered diffraction and scanning electron microscopy were performed. Gathered data of chemical composition and topography were treated employing data fusion, thus creating a comprehensive portrait of hydrogen-induced effects in the austenite grade AISI 304L. Specimens were electrochemically charged with deuterium instead of hydrogen. This arises from the difficulties to distinguish between artificially charged hydrogen and traces existing in the material or the rest gas in the analysis chamber. Similar diffusion and permeation behavior, as well as solubility, allow nonetheless to draw conclusions from the experiments [Y. Fukai and H. Sugimoto, Adv. Phys. 34, 263 (1985)].

Hydrogen embrittlement of austenitic steels: electron approach

AbstractA review of available hypotheses for hydrogen embrittlement (HE) in its relation to austenitic steels is presented. It is shown that the hydrogen-enhanced localized plasticity theory adequately describes the features of HE. Nevertheless, being developed within the frame of continuum mechanics, it overestimates the hydrogen-induced shielding of the elastic interaction between dislocations and does not take into account the hydrogen-induced change in the electron structure of austenitic steels.Ab initiocalculations and experimental studies of the electron structure show that the hydrogen in austenitic steels increases the concentration of free electrons,nf, and the interpretation of available experimental data shows that when designing steel, alloying the steel with elements that decreasenfimproves hydrogen resistance. Experimental tests are carried out, and their results are discussed. Based on the hydrogen-increased concentration of thermodynamic equilibrium vacancies in the interstitial solid solutions, a new model for hydrogen-induced shear localization is proposed.

Decrease of ductility due to hydrogen in Fe-Cr-Mn austenitic steel

Under 14 MeV neutron irradiation, hydrogen is produced due to the (n, p) reaction. One of the significant effects of hydrogen in austenitic steels is a decrease in ductility. In this investigation the objective is to clarify the behavior of hydrogen and to investigate the effect on the ductility in Fe-Cr-Mn austenitic steel. Hydrogen doping was simulated by electrolytic charging. In internal friction measurements, the hydrogen peak was found at 300 K, when the frequency was 600 Hz. This peak increased with charging time and saturated. The saturated peak height increased with the degree of cold work. This suggests that more hydrogen atoms are absorbed into cold worked materials. The work hardening coefficient and the ductility at the maximum load decreased with increasing hydrogen amount. The mechanism of the decrease in ductility is discussed in terms of dislocations behavior.