Versuche zur Natriumkorrosion austenitischer Werkstoffe bei 1000 °C

Abstract

Eine Reihe austenitischer Werkstoffe, die fur den Einsatz bei hohen Temperaturen hinreichende Festigkeit aufweisen, wurden auf ihre Bestandigkeit gegen flussiges Natrium bei 1000 "C untersucht. Die hochste Bestandigkeit wiesen austenitische Stahle rnit etwa 12% Nickel auf, aber auch die Werkstoffe rnit 32% Nickel und 20% Chrom zeigten nur maRige Gewichtsverluste, allerdings auch innere Korrosionseffekte. Nickelbasislegierungen wurden am starksten angegriffen und sind trotz ihrer hohen Festigkeit fur den Einsatz mit Natrium bei sehr hohen Temperaturen weniger geeignet.A series of austenitic materials with sufficiently high strength for the use at high temperatures were examined in respect to their compatibility with liquid sodium at lo00 "C. Austenitic steels with nickel contents of 12% showed the highest stability, but materials with 32% nickel and 20% chromium suffered also moderate losses of weight, however, additional internal corrosion effects. Nickelbase alloys were most severely attacked. They are less applicable for the use with sodium of very high temperatures in spite of their high temperature strengths.

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“…A similar trend in surface regression had been previously reported for alloys SS316 ( 14 An extreme example is noted in a review by Lai [48] where nickel alloy 617 is reportedly tested in sodium at a temperature of 1000°C for 1000 hours. The sample weight change was 13 to 25 mg/cm3, with an estimated materials removal depth of 17 to 31 µm [49]. The data are not acceptable for design, but the survival under such aggressive conditions is encouraging.…”

“…As described in §4.7.1, there is sparse data on Ni alloys in sodium at temperatures greater than 700°C. The few references indicate Ni is prone to leaching, but the level may be acceptable [45], [48], [49]. The project's attempt to validate this assumption in Phase 2 was unsuccessful due to issues with the experimental apparatus.…”