Properties of Pipe Welds after Long-Term Thermal Exposure at 650°C

Abstract

This study examines the strength characteristics and microstructural evolution of welded joints in X10CrWMoVNb9-2 (P92) steel piping used for pressure-critical components in power generation systems. The research evaluates the effects of prolonged thermal exposure through 3,000 and 10,000 h annealing cycles at 650°C. Microstructural analyses were conducted using scanning electron microscopy (SEM), while mechanical performance was assessed via tensile testing. The investigation identified a direct correlation between microstructural degradation and diminished mechanical performance, a critical factor for high-temperature applications. Strength reductions were attributed to progressive coagulation of M23C6 carbides and Laves phase precipitation. The comparative analysis quantified property changes between the as-received parent material and weld metal, establishing baseline-to-aged condition performance metrics. These findings underscore the importance of microstructural stability in maintaining the operational integrity of P92 steel components under prolonged thermal stress, particularly in ultra-supercritical power plant environments.