Abstract
In modern fossil and nuclear power plants, the components are subjected to creep, fatigue, and creep-fatigue (CF) due to frequent start-up and shut-down operations at high temperatures. The CF interaction on the in-service P92 steel welded joint was investigated by strain-controlled CF tests with different dwell times of 30, 120, 300, 600 and 900 s at 650 °C. Based on the observations of the fracture surface by scanning electron microscope (SEM), the characteristic microstructure of fatigue-induced damage was found for the CF specimens with short dwell times (30 and 120 s). The hardness, elastic modulus and creep deformation near the fracture edges of four typical CF specimens with 30, 120, 600 and 900 s dwell times were measured by nanoindentation. Compared to specimens with post-weld heat treatment (PWHT), lower hardness and creep strength were found for all CF specimens. In addition, significant reductions in hardness, elastic modulus, and creep strength were measured near the fracture edges for the CF specimens with short dwell times compared to the PWHT specimens. Compared to PWHT specimens (0.007), the increased strain rate sensitivities (SRS) of 0.010 to 0.17 were estimated from secondary creep. The increased values of SRS indicate that the room temperature creeps behavior is strongly affected by the decrease in dislocation density after the CF tests.
Highlights
Creep-fatigue (CF) interaction is an important type of damage for the design of high temperature components and the evaluation of the structural integrity of nuclear power plants and fossil fuels [1]
The phenomenon of premature fracture can be qualitatively explained by the inhomogeneity of the welded joint, which consists of the base the metal (BM), the weld metal (WM), and the heat-affected zone (HAZ)
The materials are subjected to high stresses, as a high stress concentration may occur around the crack tips and creep voids if they remain for a long time
Summary
Creep-fatigue (CF) interaction is an important type of damage for the design of high temperature components and the evaluation of the structural integrity of nuclear power plants and fossil fuels [1]. Due to the high stress field under the nanoindentation indenter, the time-dependent deformation (creep) was clearly observed within only 500 s at room temperature [16,17,18,19,20] This creep deformation could sufficiently reflect the local creep resistance near cracks or creep voids under high stress. [22,23,24], the room-temperature creep behavior and strain rate sensetivity (SRS) were investigated in the BM, FGHAZ, CGHAZ and WM of P92 steel welds under prior CF loading. The creep behavior near the fracture edge (main cracks) of the CF-tested P92 steel welded joint has not been sufficiently investigated. Based on the observation of the fracture surface by scanning electron microscope (SEM), the intercation between creep and fatigue on the local creep behavior near the fracture edges of the P92 welded joint were systematically investigated
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
