PSI - Issue 13

V. Pokhmurskii et al. / Procedia Structural Integrity 13 (2018) 2190–2195 V.Pokhmurskii, M.Khoma, V.Vynar, Ch,Vasyliv, N.Ratska, T.Voronyak I. Stasyshyn / Structural Integrity Procedia 00 (2018) 000–000 5

2194

а

b

c

e

d f g Fig. 5 - Surfaces of ferrite and pearlite in the initial state (a, d), in the presence of diffusion hydrogen (b, e); residual hydrogen (c, f). Fragile fracture products on the friction surface (g). 4. Conclusions Thus, by analyzing the changes in the microstructure, microrelief and microhardness of the surface of iron alloys with ferrite and pearlite structure under hydrogen desorption the following was established. 1. The concentration of diffusible hydrogen in the ferrite structure is less than in the pearlite, due to higher defectiveness of the last. The concentration of residual hydrogen in ferrite is higher due to the formation of numerous blisters and cracks where it accumulates. 2. The fragmentation of ferrite grains and their partial reorientation occurs after electrolytic hydrogenation. 3. Dynamic of the surface state changes of iron alloys with ferritic and pearlitic structures has been observed by the method of interferometry during 14 days after electrolytic hydrogenation. It's associated with high diffusion mobility and activity of hydrogen at the stage of non stationary diffusion and redistribution of stresses in the crystal lattices of metals. 4. Microhardness of ferrite and pearlite changes during the hydrogen desorption. 5. Desorption of diffusible hydrogen intensifies wear and friction of materials. The wear resistance of iron and steel increases at the presence of residual hydrogen. After hydrogen desorption, tribological behavior is determined by the adhesion interaction between the contacting pairs. References Pokhmurskyy V.І., Shwed M.M., Yaremchenko N.Y. 1977. Effect of hydrogen on the deformation and damage processes of iron and steel. 60 p. Zhang T.C., Jiang X.X., Li S.Z., 1997. Hydrogen-induced embrittlement wear of a high-strength, low-alloy steel in an acidic environment. Corrosion, 53, 200–205. Murakami Y., 2008. Basic mechanism of hydrogen embrittlement and its application to design and structural integrity, in: Proc. of International Hydrogen Energy Development Forum 2008, 109–121. Hirth J.P., 1980. Effects of hydrogen on the properties of iron and steel, Metallurgical and Materials Transactions A, 11A, 861-891. Shashkova L.V, 2013. Synergistic effects in non-equilibrium metal-hydrogen systems. LAMBERT Academic Publishing, 105. E.Fromm, E.Gebhart, 1980. Gases and carbon in metals, 350. Karpenko G.V., Krypiakevych R.I., 1962. Effect of hydrogen on the properties of steel, 196 p. Pokhmurskyy V.І., Fedorov V.V., 1998. Effect of hydrogen on the diffusion processes in metals. 238 p.