Spoluautoři KUBOŇ Zdeněk, VODÁREK Vlastimil

Dissimilar welds are used extensively in the power generation industry in boiler tubing to accommodate changes in temperature, pressure and corrosion conditions between different locations. These joints are generally prone to failure in the HAZ on the side of the low alloy material. An important factor having a strong influence on the microstructural stability of heterogeneous welded joints is “up–hill” diffusion of interstitial elements driven by the activity gradients of these elements in welded materials. This phenomenon significantly affects development of microstructure and creep damage close to the fusion line between low alloy and high alloy steels. This paper is focused on microstructural evolution in two designs of heterogeneous P23/P91 welds during long-term creep exposure in the temperature range from 500 to 600oC. Welds A and B were manufactured using E-CrMo91B and Thyssen Cr2WV filler materials, respectively. Microstructural investigations were compared with the results of thermodynamic and kinetic modelling, which was carried out using the ThermoCALC and DICTRA software packages.