Corrosion-erosion test of SS316 in flowing Pb-Bi

流動鉛ビスマス中におけるSS316のコロージョン・エロージョン試験

菊地 賢司; 倉田 有司; 斎藤 滋   ; 二川 正敏  ; 佐々 敏信   ; 大井川 宏之 ; 若井 栄一  ; 三浦 邦明*

Kikuchi, Kenji; Kurata, Yuji; Saito, Shigeru; Futakawa, Masatoshi; Sasa, Toshinobu; Oigawa, Hiroyuki; Wakai, Eiichi; Miura, Kuniaki*

流動鉛ビスマス条件で、オーステナイト・ステンレス鋼の腐食試験を3000時間実施した。試験材はSS316は外径13.8mmの管であり、最高温度450C,温度差50C,流速1m/sである。試験後、管を切断し、光学顕微鏡、SEM,EDX,WDX,X線回折により分析した。鉛ビスマスはドレン後も、配管内部に付着していた。流動条件下での腐食量は0.1mm/3000時間であり、内面は凹凸が激しい。高温から低温部に質量の移行が観察され、低温部にはFe-Crの結晶粒が析出していた。粒径は0.10.2mmであり、化学組成は鉄:クロムが9:1であった。これらの結果は、静的な腐食試験では観察されず、流動試験で始めて見出された。

Corrosion test of austenitic stainless tube was done under the flowing Pb-Bi condition during 3000 hrs at 450C. Specimen is 316SS produced as a tubing form with 13.8 mm outer diameter, 2 mm thickness and 40 cm length. During the operation, maximum temperature, temperature difference and flow velocity of Pb-Bi at the specimen were kept at 450C, 50C, and 1m/s, respectively. After the test, specimen and components of the loop were cut and examined by optical microscope, SEM, EDX, WDX and X-ray diffraction. Pb-Bi adhered on the surface of the specimen even after Pb-Bi was drained out to the storage tank from the circulating loop. Different results from a stagnant corrosion test were that the specimen surface became rough and the corrosion rate was maximally 0.1mm/3000hrs. And mass transfer from the high temperature to the lower temperature area was observed: crystals of Fe-Cr were found on the tube surface in low-temperature part. The size of crystal was 0.1 0.2 mm. The depositing crystal was ferrite grain and the chemical composition ratio (mass%) of Fe to Cr was 9:1.