Evaluation of Stresses Caused by Hydrogen Concentrated in the Metal
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EVALUATION OF STRESSES CAUSED BY HYDROGEN CONCENTRATED IN THE METAL M. H. Stashchuk1,2 and M. I. Dorosh1
UDC 539.3
A system of basic key equations for the components of hydrogen-induced stresses in a hollow cylindrical metal body is formulated from the viewpoint of the elasticity theory. The corresponding computational formulas are obtained. The components of the tensor of hydrogen-induced stresses are determined. Keywords: stress-strain state, hydrogen, hydrogen concentration, hollow metal cylinder.
For the last decades, the attention of numerous researchers is focused on the problem of hydrogen in metals. This is explained by its application in contemporary technologies in the stage of design of machine parts, structures, and buildings, as well as in the creation of materials operating under the conditions of interaction with hydrogen-containing media or in direct contact with hydrogen. Hydrogen atoms introduced in metals expand their crystal lattices [1–3]. Thus, in particular, we can mention the well-known experimental results on the expansion of crystal lattices in the course of dissolution of hydrogen in niobium [4], aluminum [5], and palladium alloys [6]. Under the conditions of hydrogenation or dehydrogenation of metals and under the influence of the stressed state, we observe the appearance of concentration inhomogeneities in the distribution of hydrogen. Independently of the cause of their appearance, they induce internal (hydrogen-induced) stresses [1]. Hence, it is necessary to take into account these stresses in contemporary technological projects for which the analysis of hydrogeninduced stresses is of crucial importance (e.g., in thermonuclear reactors, gas-oil pipelines, various filters, and numerous components of the oil-processing equipment). Hence, the fields of hydrogen-induced stresses should not be neglected in analyzing the influence of hydrogen on the behavior of materials. These studies were partially carried out in [1, 7, 8]. However, the attention was focused only to the one-sided influence of mechanical stresses on the distribution of hydrogen concentration [9–11]. The mutual influence of hydrogen concentration and the stress-strain state near stress concentrators was studied in [7, 8] with regard solely for the hydrostatic pressure. These results were pioneering and played an important role in the study of hydrogen elasticity of materials. However, the problem of determination of all components of the hydrogen-induced stresses and displacements in the metal remains unsolved up to now. Therefore, in order to make a contribution to these studies, we investigate the stress-strain state caused by the concentration of hydrogen in the metals. To determine the influence of hydrogen on metals, we estimate the stress field induced by the diffusion of hydrogen atoms. This problem is considered in the present work. The solution of this problem can be used to refine the available methods and approaches aimed at the estimation of the reliability and durability of hydrogenated materials or materials
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