SA-02-1(086) Creep Life Assessment Method of Weldments of Steam Pipes Based on Hardness Distribution Measurement and Hardness Normalized Creep Rupture Master Curves(Life Assessment of Thermal Power Plant 2)

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概要

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• Hardness measurement, creep rupture testing and/or creep interruption testing were conducted on 2.25Cr-lMo steel piping, its simulated HAZ material and CrMoV steel casting in the laboratory. Experimental results indicated that the ratio of instantaneous hardness to initial hardness HV/HVo was decreasing with increasing creep stress, temperature and time. We established mechanism based expressions of instantaneous hardness as the function of those creep conditions. The dominant softening mechanism of the base metal of 2.25Cr-lMo steel piping was attributed to carbide coarsening, while that of other materials was attributed to recovery of dislocation structure. We also found that Larson-Miller parameter (LMP) as the creep rupture life was correlated with the ratio of stress to initial (pre- creep) hardness σ/HVo for unused, laboratory aged and serviced materials. Moreover, the equation was also true for creep damaged materials by using instantaneous hardness HV in place of HVo. This fact suggested that if the σ/HV-LMP relationships of different materials were identical, the materials had similar creep softening behavior. The obtained creep softening and the creep rupture properties were applied to condition and remnant life assessment of actual weld portion of steam turbine pipes. If the initial hardness were known from product records, creep stress could be estimated under prescribed temperature and serviced hours. When creep stress was known, remnant life could be predicted using the creep rupture properties. This method is very useful for evaluating actual weld portions bearing complex stress conditions. To attain high accuracy for the life assessment of actual components, a special hardness measurement system was implemented.

• 社団法人日本機械学会の論文
• 2001-06-03

著者

• Harada Shigeru

  Keihin Product Operations Toshiba Corporation

• Fujiyama Kazunari

  Power And Industrial System Research And Development Center Toshiba Corporation

• Fujiyama Kazunari

  Power And Industrial Systems R&d Center Toshiba Corporation

• SAITO Kazuhiro

  Power and Industrial Systems R&D Center, Toshiba Corporation

• AHIKO Norio

  Thermal Power Plant Division, Toshiba Corporation

• ITOH Yoshiyasu

  Power and Industrial Systems R&D Center, Toshiba Corporation

• Ahiko Norio

  Thermal Power Plant Division Toshiba Corporation

• Itoh Yoshiyasu

  Power And Industrial Systems R&d Center Toshiba Corporation

• Saito Kazuhiro

  Power And Industrial Systems R&d Center Toshiba Corporation

• Saito Kazuhiro

  Power And Industrial Systems R & D Center Industrial And Power Systems & Services Company To

関連論文

• SA-02-1(086) Creep Life Assessment Method of Weldments of Steam Pipes Based on Hardness Distribution Measurement and Hardness Normalized Creep Rupture Master Curves(Life Assessment of Thermal Power Plant 2)
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