Materials Evaluation for Geothermal Applications in Germany

Abstract

The corrosion behavior of different high-alloyed metals including duplex and austenitic stainless steels as well as a nickel alloy were evaluated in artificial geothermal fluids simulating the conditions in some locations with geothermal potential in Germany. The suitability of carbon steel UNS G41300, stainless steels UNS S31603 UNS S31803, UNS S32760 and super austenitic steel UNS N08031 in these geothermal fluids obtained by electrochemical measurements and exposure tests is limited. The nickel alloy UNS N06059 shows an excellent corrosion resistance. Excluding its high cost, it is a very good alternative to be used in the construction of geothermal facilities having highly saline brines. Stainless and duplex steels exhibit a limited corrosion resistance concerning pitting and crevice corrosion. Beside of the higher alloyed materials, also the low-alloyed steel UNS G41300 could be employed as a constructional material for the geothermal power plant in stagnant highly acidic non saline environments, as long as the wall thickness of the material vs. corrosion rate is taken into account.