Results of corrosion tests in liquid Pb-Bi at JAEA; Temperature and oxygen concentration dependence, and corrosion properties of Si-enriched steels

原子力機構における液体鉛ビスマス中の腐食試験結果; 温度及び酸素濃度依存性とSi添加鋼の腐食特性

倉田 有司; 斎藤 滋   

Kurata, Yuji; Saito, Shigeru

加速器駆動核変換システムの核破砕ターゲット及び冷却材の候補材料である液体鉛ビスマス中での腐食特性を調べるため、種々の鋼材の静的腐食試験を実施した。実験結果より、温度,鉛ビスマス中の酸素濃度,鋼材中のCr, Ni, Siの腐食挙動に及ぼす影響を評価した。試験温度範囲は450-600Cである。温度の上昇は腐食の活性化をもたらし、550C以上では、粒界腐食,鉛ビスマスの浸入,フェライト化が激しくなる。酸素濃度が下がると、450Cでは、純鉄,316SSで明らかな影響が認められ、550Cでは、低酸素濃度で、腐食はさらに激しくなる。Siを1.5%添加したMod.9Cr-1Mo鋼及びSiを2.5%添加した316SSでは、550C飽和酸素の条件下で、添加したSiの耐食性改良効果が認められた。

Corrosion tests of various steels in liquid Pb-Bi have been conducted using static corrosion apparatus to study corrosion behaviour in liquid Pb-Bi, a promising candidate material of coolants and high-power spallation targets of accelerator driven systems for transmutation of radioactive wastes. Effects of temperature, oxygen concentration in Pb-Bi and elements in steels on corrosion behavior were estimated from test results. Tested temperature range was from 450C to 600C. Temperature increase produced active corrosion and grain boundary corrosion, penetration of Pb-Bi and ferritization became severe above 550C. Effect of oxygen concentration was clearly found in pure iron and 316SS at 450C and corrosion attack became severe under the low oxygen concentration condition at 550C. Mod.9Cr-1Mo with addition of 1.5%Si and 316SS with addition of 2.5%Si showed good corrosion resistance in liquid oxygen-saturated Pb-Bi at 550C.