Creep Properties of P92 Pipe Weld after Annealing at 600 and 650°C

The operational integrity of supercritical steam power units necessitates comprehensive understanding of welded joint behaviour under high-temperature service conditions. Advanced steam cycle technology requires meticulous periodic evaluation of pressure-bearing components to ensure structural integrity throughout extended service periods. This requirement is particularly critical for components subjected to the most severe operational parameters, including superheater tubes, main steam pipelines, and steam collectors operating above critical temperature. For pressure components not directly exposed to exhaust gases, microstructural degradation represents the primary degradation mechanism governing component lifespan.P92 (X10CrWMoVNb9-2) steel, characterized by a tempered martensitic microstructure with 9% chromium content, has been extensively utilized for high-pressure applications in supercritical steam power generation systems. This advanced creep-resistant steel demonstrates superior mechanical properties, including exceptional high-temperature strength retention, oxidation resistance, and creep rupture strength under prolonged thermal exposure.Welded joints of pressure elements in steam boilers are potentially the weakest points when assessing their service life. These joints exhibit enhanced susceptibility to microstructural degradation and mechanical properties deterioration, particularly within the heat-affected zone (HAZ), during extended high-temperature operation. Therefore, systematic material characterization of welded joints relative to base material performance is essential for understanding long-term degradation mechanisms.This investigation presents systematic creep testing methodology and experimental results for P92 welded joint specimens subjected to annealing at temperatures of 600°C and 650°C for durations up to 10,000 hours. Both abridged and long-term creep tests were performed with the results of determination of creep strength and creep speed in steady state.