Determination of the Degree of Degradation of Steels of Steam Pipelines According to Their Impact Toughness on Specimens with Different Geometries of Notches

摘要

We analyze the characteristics of impact toughness KCU and KCV of 15Kh1M1F and 12Kh1MF heatresistant steels by using Menage and Charpy specimens, respectively, taken from the straight sections of the steam pipelines of a thermal power plant, their welded joints, and different zones of the bends. We reveal the specific features of their behavior depending on the period of operation and the number of shutdowns of the units. It is shown that, as a result of the in-service degradation of the metal, the KCU/KCV ratio significantly increases due to a more intense reduction of the crack-growth resistance as compared with the crack initiation resistance.