Abstract
Creep rupture behavior and microstructure evolution of modified casting 9Cr-1.5Mo-1Co steel welded joint were systematically investigated in this paper. Based on a series of creep rupture tests at 620°C under 110–170MPa, a curve of stress versus rupture time was achieved to evaluate the service life of welded joint. The results indicated that creep rupture is considered to occur in over tempered zone (OTZ) under relatively high stress above 130MPa while failure transferred to weld metal (WM) under lower stress below 130MPa. The ruptured specimens showed less ductility and necking with the decrease of stress. Microstructure characterization revealed OTZ with less grain boundaries than WM and relatively lower hardness than BM was more possible to deform in short-term creep rupture accompanied by the coarsening of M23C6. Besides, formation of Laves phase and deterioration of martensite lath structure were detected during long-term creep exposure. Mo segregation near M23C6 provided the condition for Laves phase to form adjacent to M23C6. The difference of plastic deformation resistance in each zones of welded joint and nucleation and coarsening of Laves phase in WM are considered as the main factors to result in the failure transition.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: 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.