Dissimilar joints between modern 10% chromium steels and low-alloy steels are unavoidable in new installations or upgrades of steam turbine components. Welds between 10CrMo9-10 (P22) and X10CrMoVNb9-1 (P91) steel pipes are often required. This paper studies this heterogeneous weld from a steam turbine manufacturer's practical perspective. Two types of filler materials were used: P22- and P91-based weld metals. The integrity and mechanical properties of the prepared heterogeneous welds were evaluated according to the welding standard EN 288-3. Both approaches yielded satisfactory results. Additionally, creep rupture strength was evaluated. The creep rupture strength of both joints fell within the -20% scatter band of the P22 base material's creep rupture strength. The weld design with P91 filler material appeared to slightly outperform the P22-based approach for longer exposure times.

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