1. Failure Analysis of TP347H Austenitic Heat-Resistant Steel Tube in a 600 MW Subcritical Thermal Power Unit.
- Author
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Zhang, Jun, Yan, Jingming, Zhang, Jianwei, Zheng, Zhunbei, Yang, Zhanjun, and Zhou, Ning
- Subjects
AUSTENITIC steel ,STEEL tubes ,FAILURE analysis ,STRESS corrosion cracking ,TUBE bending ,MARTENSITIC structure - Abstract
The failure mechanism of TP347H austenitic heat-resistant steel tube serviced in boiler superheater in a 600 MW subcritical thermal power unit is presented in this paper. Through microstructure observation, energy-dispersive spectrometry analysis, and selected electron diffraction, the mechanism of TP347H superheater bend tube failure is found to be attributed to intergranular corrosion cracking, more M
23 C6 and primary NbC(N) phase precipitating and coarsening along the grain boundary and formation of high content of slip lines and α′-martensite structure. The α′-martensite kept the Kurdjumov–Sachs (K-S) orientation relationships with parent austenite phase (γ-parent), which generated in TP347H bend tube may be related to the deformation-induced martensite (DIM) during rolling and cold working. The α′-martensite nucleated mainly at the grain boundary intersection between the twin crystal and γ-parent and grew inwards along the twin band. The dislocation density at the intersection is larger, and the secondary NbC(N) phase inhibited the nucleation of α'-martensite. [ABSTRACT FROM AUTHOR]- Published
- 2024
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