INFLUENCE OF HYDROGEN ABSORPTION ON DESTRUCTION AND MECHANICAL CHARACTERISTICS OF TITANIUM ALLOY

The effect of hydrogen absorption on the nature of destruction and mechanical characteristics of Ti ‒ 6Al ‒ 4V titanium alloy during operation in a hydrogen-containing medium at normal temperatures has been studied. The main mechanism of the hydrogen embrittlement process for (α + β) titanium alloys is described, which consists in the separation and subsequent decomposition of brittle hydride phases. In the course of the study, it was established that during the operation of samples from the alloy under the given composition and parameters of the operating environment there is a saturation of the metal with hydrogen, as evidenced by the increase in its content in the material after operation in comparison with the sample in the initial state. The mechanism of destruction of a metal sample saturated with hydrogen during operation in a hydrogen-containing medium is shown. The fracture surface morphology of the investigated specimen is characteristic of brittle fracture type. Large crater-shaped defects, signs of erosion and cracking are present on the surface of the sample near the fracture zone. The fracture structure is characterized by the presence of “saw teeth”, an extensive system of secondary micro-cracks and their interaction with the main crack is observed, which is a characteristic manifestation of hydrogen embrittlement of a titanium alloy. Near the fracture surface of the sample, degradation of the microstructure is observed, manifested in the formation of micro voids at the interface of the α/β phases initiating destruction. An increase in the microhardness of the metal of the part of the destroyed sample that was in direct contact with the working medium was found to be 35-38%, which may be due to the distribution of finely dispersed titanium hydrides in the region under consideration, which were formed as a result of hydrogen absorption of metal.

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