Behavior of steels in flowing liquid Pb/Bi at 420 – 600 °C after 4000 - 7200 h
Authors
G. Mueller, A. Heinzel, G. Schumacher, A. Weisenburger
Forschungszentrum Karlsruhe GmbH, IHM, Postfach 3640,
76021 Karlsruhe, Germany
Corrosion tests were carried
out on austenitic AISI 316L and 1.4970 steel and on martensitic MANET 10Cr
steel in flowing (up to 1.3 m/s) Pb/Bi. The concentration of oxygen in the
liquid alloy was controlled at 10-6 wt%. Specimens consisted of tube
and rod sections in original state and after alloying of Al into the surface.
Martensitic steels develop thick protective magnetite and spinel layers that
spall off and grow again during long term exposure (7200 h). At 600 °C the
oxide scale changes to thin protective spinel layers with partial dissolution
attack at some spots. Austenitic steels exhibit thin spinel layers at 420 °C
and thick spinel and magnetite layers at 550 °C which are protective. The
spinel layer is also replaced after it brakes off. Severe attack of the liquid
alloy occurs on austenite at 600 °C already in the 2000 h exposure period.
Steels with 8 - 15 wt% Al alloyed into the surface suffer no corrosion attack
at all experimental temperatures and exposure times.