液体金属ナトリウムによるサーマルストライピングの下のき裂進展停留挙動

概要

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As a part of the development of a rational structural design method and in order to formulate a strength evaluation method for high-cycle thermal shock (thermal striping) in the high temperature structure, we have developed an original experimental facility which can provide cyclic thermal load with liquid sodium at a frequency of ω=0.01 to 2.0 Hz between a maximum temperature T_<max> of 550℃ and a minimum temperature T_<min> of 250℃. The following results are obtained. (1) The thermal behavior test using this facility for Type 304 S.S.has revealed that the temperature fluctuating region is limited near the surface and within 0.8 mm from the metallic surface under a cycling rate of ω=0.5 Hz or greater. (2) With the thermal striping condition of T_<max>=550℃, T_<min>=250℃, and ω=0.5Hz, the spaces of the dry clay-like cracks vary from 1 to 2 mm, and the cracks are arrested at a depth of approximately 1.6 mm after 2.0×10^6 cycles. (3) The above mentioned test verifies that the depth of the arrested crack can be roughly estimated by the linear elastic fracture mechanics of edge cracks distributed by a certain pitch.
社団法人日本材料学会の論文
1994-12-15