液体金属中のキャビテーション壊食に及ぼす液体金属種及び試験材料の影響

Effect of liquid metal composition and test material on cavitation erosion

矢田 浩基 ; 倉地 宏晃*; 月森 和之; 服部 修次*

Yada, Hiroki; Kurachi, Hiroaki*; Tsukimori, Kazuyuki; Hattori, Shuji*

3種類の組成の異なる鉛ビスマス合金中で磁わい振動によるキャビテーション壊食試験を行った。試験温度を融点と沸点を百分率で整理した相対温度を使用すると、相対温度14Cにおける各種鉛ビスマス中の壊食速度はイオン交換水中に比べて約1012倍、ナトリウム中では約25倍となる。また、試験後の材料の硬さを調査した結果、イオン交換水中よりも鉛ビスマス中でより加工硬化が進むことから、鉛ビスマス中ではより大きな気泡崩壊圧が作用したと考えられる。さらに、試験材料にSUS304, SUS403, 9Cr-1Mo鋼を用いて壊食試験を行い、壊食速度の違いは材料の硬さと平山のNi当量で整理が可能であることが明らかとなった。

Cavitation erosion tests using a vibratory apparatus were carried out to study the effect of liquid metal composition and test material of different stainless steels. The relative temperature was defined as the percentage between freezing and boiling points. At relative temperature at 14C, the erosion rate is 10-12 times in various lead - bismuth alloys, and 2-5 times in sodium, as compared with that in deionized water. When SUS304 was exposed to cavitation in PbBi, the surface was work hardened 20% harder compared with original surface. In deionized water, SUS304 was work hardened by 5%. Therefore, we can conclude that larger collapse pressure can be estimated to act on the specimen surface in lead - bismuth, as compared with that in water. The erosion rate of stainless steels depends on hardness and Hirayama's Ni equivalent. Erosion resistance is the highest for SUS304 and decreases in order of a 9Cr-1Mo steel and SUS403.