Comparative Study on Microstructures and Mechanical Properties of the Coarse-/Fine-grainedTP347HFGHeat-resistant Steel Tubes after High-temperature Aging
Received:April 26, 2024  Revised:June 26, 2024
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DOI:10.7643/issn.1672-9242.2024.10.018
KeyWord:TP347HFG heat-resistant steel tube  aging  austenite grain grade  secondary phase  microstructure  mechanical property
                 
AuthorInstitution
CHENG Xiang Anhui Xinli Electric Technology Consulting Co., Ltd., Hefei , China
BAO Zheng School of Materials Science and Engineering, Hefei University of Technology, Hefei , China
WANG Ruomin Anhui Xinli Electric Technology Consulting Co., Ltd., Hefei , China
MIAO Chunhui Electric Power Research Institute, Anhui Electric Power Co.Ltd., State Grid, Hefei , China
CHEN Guohong Electric Power Research Institute, Anhui Electric Power Co.Ltd., State Grid, Hefei , China
TANG Wenming School of Materials Science and Engineering, Hefei University of Technology, Hefei , China
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Abstract:
      The work aims to reveal the effect of austenite grain coarsening on the service reliability ofsteel tubes. Coarse-grainedspecimens were prepared via a pre-deformation and solid solution treatment method to simulate the abnormal growth state of the austenite grains of the TP347HFG steel tubes in long-term service. Microstructures and mechanical properties of the coarse-/fine-grained TP347HFG steel specimens aged at 650 ℃ for 3 600 h were comparatively studied. During high-temperature aging, the austenite grain sizes of the coarse-/fine-grained specimenswere almost unchanged, but the twin densities decreased. Secondary phase precipitation was not apparently different. The M23C6 phase particles preferentially precipitated and coarsened at the austenite grain boundaries, which was more severefor the M23C6 phase particles in the coarse-grained specimens. As the aging time prolonged, the variation tendencies of the room-/high-temperature tensile strengths and plasticity of the coarse-/fine-grainedspecimenswere basically consistent. The strengths at room temperature and high temperature did not obviously change, but the plasticity was greatly distinct. After aging at 650 ℃ for 3 600 h, the elongation after fracture at 600 ℃ of the coarse-grained specimendecreased by 30.4% than that of the fine-grained one. More attention should be paid to the high-temperature plasticity of the coarse-grained TP347HFG steel tube.
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