Use of electrolytic hydrogenation to visualize the damage of long-term operated heat-resistant steel of TPP steam pipelines

Keywords

heat-resistant steel, fracture, degradation, hydrogenation.

Cite as

Tsybailo I. O., Svirska L. M., Solovei P. R., Krechkovska S. R., Datsko B. M., and Student O. Z. Use of electrolytic hydrogenation to visualize the damage of long-term operated heat-resistant steel of TPP steam pipelines. Physicochemical Mechanics of Materials. 2022. 58(5), 041-047.

Abstract

It was established that the effect of degradation of heat-resistant steel of TPP steam pipe­lines is more clearly manifested after its additional hydrogenation. On specimens of axial orientation, the negative effect of degradation was weaker near the outer surface of the pipe and increased as it approached its inner surface. An increase in the elongation of spe­cimens was considered to be a consequence of the operational defects under the influence of hydrogenation. It was recorded only near the inner pipe surface of tangential orientated specimens and caused by defects in its diametrical section as a result of thermal fatigue. Testing of radial specimens made it possible to reveal operational defects caused by dela­minations along the rolling texture. Fractographic analysis of specimens of hydrogenated steel demonstrated a large number of non-metallic inclusions delaminated from the matrix with lenticular flat fragments around them, formed due to shear fracture mechanism. In addition, areas of transgranular cleavage were recorded in the metal of pipes with a large number of shutdowns. These areas were considered as a fractographic sign of the embrit­tlement effect of internal hydrogen, cumulatively absorbed by steel both during operation on steam pipes and during electrolytic hydrogenating.

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