Comparison of the corrosion behavior of austenitic and ferritic/martensitic steels exposed to static liquid Pb-Bi at 450 and 550 C

液体鉛ビスマス中の腐食挙動に及ぼす温度と合金元素の影響

倉田 有司; 二川 正敏  ; 斎藤 滋   

Kurata, Yuji; Futakawa, Masatoshi; Saito, Shigeru

加速器駆動核変換システムで使用される液体鉛ビスマス中での腐食挙動に及ぼす温度と合金元素の影響を明らかにするため、種々の鋼材を用いて、3000hの静的腐食試験を実施した。腐食試験は450C及び550Cの飽和酸素濃度の液体鉛ビスマス中で行った。この条件では、両方の温度で鋼材表面に酸化膜が形成した。450Cでは鋼材中のCr量の増加とともに、腐食深さは減少した。450Cでは、オーステナイト系ステンレス鋼でNiやCrの明らかな溶解は認められなかった。550Cでは、JPCAや316ssでNi及びCrの溶解が起こり、厚いフェライト層が形成した。その結果、これらのオーステナイト系ステンレス鋼の腐食深さは大きくなった。Si添加鋼は形成した緻密な保護酸化膜がNiやCrの溶解を防ぎ、550Cでも優れた耐食性を示した。

In order to study effects of temperature and alloying elements on corrosion behavior in liquid Pb-Bi which will be used for an accelerator driven system (ADS), corrosion tests of various steels were conducted under static liquid Pb-Bi condition. The tests were performed in oxygen-saturated liquid Pb-Bi at 450C and 550C for 3000h. Oxide films were formed during corrosion at 450C and 550C. Corrosion depth of steels decreased at 450C with increasing Cr content of steels. Austenitic stainless steels containing Ni didn't exhibit appreciable dissolution of Ni and Cr at 450C. The thick ferrite layer produced by dissolution of Ni and Cr was found in JPCA and type 316ss at 550C. For this reason the corrosion depth of austenitic stainless steels, JPCA and type 316ss became large. A Si-added austenitic stainless steel showed good corrosion resistance at 550C because a protective oxide film formed on the steel prevented dissolution of Ni and Cr into liquid Pb-Bi.