The Influence of Specimen Size on Measurement of Thermal or Irradiation Creep in Pressurized Tubes

Sets of pressurized tubes constructed from a combination of three lots of HT9 and two heat-treatments were examined after irradiation in FFTF-MOTA at four different temperatures between 400 and 600°C. Diametral measurements indicated that small amounts of swelling occurred at 400°C, with the magnitude of the swelling varying from tube-set to tube-set. At 495, 550, and 600°C, no indications of swelling were observed. Over a limited stress range that decreased with increasing irradiation temperature, the irradiation creep was found to be proportional to the stress level and mirrored the swelling behavior, confirming the Bo + DS creep model. The creep compliance, Bo, appears to be about half of that observed in austenitic steels, whereas the creep-swelling coupling coefficient, D, appears to be comparable to that of austenitics. At the highest stress levels examined, the value of the stress exponent became much greater than 1.0. Higher irradiation temperatures resulted in creep behavior with pronounced thermal creep characteristics. A primary creep transient was observed at the three higher irradiation temperatures and increased in magnitude with increasing irradiation temperature, while a stress exponent between 1.0 and 2.0 was observed at 550°C.

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The Influence of Specimen Size on Measurement of Thermal or Irradiation Creep in Pressurized Tubes

Abstract: I_ll_l'_lB I_PI_I_! /'_E TLIIC "_ r%hF'_l li_E._l'_" le UNII I_AITE_'% _1_11_11._11_ I IVl_ vi I I II_ _._v_._ L-eMl i_ i_,.tllil I _J_._ i Frank

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References 13 publications

On the biaxial thermal creep-fatigue behavior of Ni-base Alloy 617 at 950 °C

On the biaxial thermal creep-fatigue behavior of Ni-base Alloy 617 at 950 °C

Variability of Irradiation Creep and Swelling of HT9 Irradiated to High Neutron Fluence at 400–600°C

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