Affiliation: | aInstitute of Materials Research, Slovak Academy of Sciences, Watsonova 47, 040 01 Košice, Slovakia bSlovak Energy Machinery, Továrenská 210, 93 528 Tlmače, Slovakia cInstitute of Physics of Materials, Academy of Sciences of Czech Republic, Žižkova 22, 616 62 Brno, Czech Republic |
Abstract: | Phase evolution in the weld metals of P92 and E911 steels weld joints were studied during ageing at 625 °C for up to 9000 h. The phases: ferrite + M23C6 + MX + Laves found by means of analytical TEM in the annealed states agree with the results of the thermodynamic calculation of equilibrium phases. The cross-weld hardness values, HV10, after 1000, 3000, and 9000 h ageing overlap each other and are approximately 15 units below that of the post-weld heat-treated (PWHT) state. Charpy impact energy with the notch at the centerline of the weld metal was measured. Its values decrease after ageing from approximately 60–80 to 12 J compared to the PWHT state. In 9–12%Cr steel with W this phenomenon can be explained by a priori heterogeneity in the weld metal, its large former austenite grain size, the precipitation and growth of M23C6 and Laves phase particles on grain and packet boundaries. |