Influence of the Ambient Medium in the Course of Laser Treatment on the Resistance of Titanium to Hydrogen Embrittlement
- PDF / 5,294,354 Bytes
- 7 Pages / 594 x 792 pts Page_size
- 8 Downloads / 234 Views
INFLUENCE OF THE AMBIENT MEDIUM IN THE COURSE OF LASER TREATMENT ON THE RESISTANCE OF TITANIUM TO HYDROGEN EMBRITTLEMENT T. V. Pryadko,1, 2 V. A. Dekhtyarenko,1 and A. A. Shkola1 We study the kinetic parameters of the physicochemical interaction of hydrogen with annealed titanium and titanium whose surface layers are modified by laser treatment and differ, in their phase and chemical compositions, from the volume of the material. The possibilities of attainment of the maximum degree of protection of the material against hydrogen penetration and prevention of the possibility of deterioration of its operational characteristics caused by the appearance of hydrogen brittleness are determined. Keywords: titanium, laser treatment, surface layers, catalytic activity, hydrogen permeability, hydrogen brittleness.
Introduction Hydrogen dissolve in almost all metals and causes significant changes in their physicochemical and mechanical properties. Its influence on the metals often leads to severe consequences even in cases where, at first sight, there is no hazard of hydrogen-induced fracture. Therefore, the problem of decreasing the risk of hydrogen-induced damage to structures remains quite urgent. In [1, 2], it was assumed that the degradation of physicomechanical properties of metals in the presence of hydrogen is a complex process involving the adsorption, absorption, and diffusion of hydrogen atoms in the volume of the metal, where they interact with dislocations and promote the initiation and propagation of cracks, formation of voids filled with hydrogen under high pressures, creation of hydrides, decohesion, etc. For titanium and its alloys, it was shown [3] that it is reasonable to separate the direct and indirect effects of hydrogen. The direct influence of hydrogen is observed in the form of its direct action on the mechanisms of crack initiation and propagation. At the same time, the indirect influence is connected with the structural changes caused by the formation of hydrides (changes in the type of structure, in the sizes and morphology of the phases, etc.). In what follows, we analyze the indirect influence of hydrogen. The methods used to prevent hydrogen embrittlement are as follows: protective coatings, alloying used to decrease the rate of interaction of the metal with hydrogen-containing media and increase the maximum admissible concentrations of hydrogen, and periodic vacuum annealing of the products. Protective coatings are extensively used in the industry because they are economically efficient. The methods used for their production are very diverse: the electrolytic deposition of metals and alloys, ion implantation, thermochemical treatment, etc. The compositions of the applied protective films are also highly diverse: oxides, borides, nitrides, carbides, and silicides [4–6]. 1 2
Kurdyumov Institute for Metal Physics, Ukrainian National Academy, Kyiv, Ukraine. Corresponding author; e-mail: [email protected].
Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 56, No. 1, pp. 76–81, January–F
Data Loading...
