Hydrogen trapping in alloys studied by thermal desorption spectrometry

Abstract

Thermal desorption spectrometry (TDS) is a powerful experimental technique used to characterize hydrogen trapping in metals. The passage of hydrogen through a metal is hindered by lattice imperfections, which tend to attract and bind it. The susceptibility of materials to hydrogen embrittlement is directly related to the interaction between traps (defects) and hydrogen. Since trapping affects the metal's diffusivity, it has a major influence on the hydrogen assisted cracking (HAC) phenomenon. Hydrogen trapping is usually evaluated on the basis of reaction controlled mechanisms. Our studies are based on the measurements of temperatures of the gas desorption, the heating rate, and the activating energy. This paper reviews TDS′ applications in quantitative studies of hydrogen trapping and release behavior in crystalline metals. We will discuss both the mechanisms proposed for hydrogen embrittlement in hydride and non-hydride systems and the differences between hydrogen effects on light and heavy metals alloys. In this paper, we compared between duplex Ti–6Al–4V, magnesium (Mg) alloys, and duplex stainless steels (DSS) which can create hydrides in certain conditions. We discuss hydrogen-induced second phases formation, hydrogen's physical trapping, and how these processes affect hydrogen embrittlement in those alloys. In this research, we give another aspect to the trapping mechanism exposed to different hydrogen charging environments by low and high hydrogen fugacity. The main factors controlling the embrittlement phenomenon are the irreversible activation trapping energy, hydrogen fugacity, and second phases' contents. The trapping mechanisms in duplex Ti–6Al–4V, Mg, and DSS and the prediction of failure will be discussed in detail.