EVALUATION OF HEAT TREATMENT PERFORMANCE OF POTENTIAL PIPE STEELS IN CCS-ENVIRONMENT

摘要

To resist the corrosive geothermal environment during carbon capture and storage CCS -such as: heat, pressure, salinity of the aquifer, CO_2-partial pressure, properties of pipe steels-require certain specification. For evaluation samples of differently heat treated high alloyed stainless injection-pipe steels AISI 420 X46Cr13, AISI 420J X20Cr13 as well as X5CrNiCuNb16-4 AISI 630 were kept at T=60°C and ambient pressure as well as p=100 bar for 700 h up to 8000 h in a CO_2-saturated synthetic aquifer environment similar to a possible geological situation in the northern German Basin. Corrosion rates and scale growth are lowest after long term exposure for steels hardened and tempered at 600°C to 670°C and pits -indicating local corrosion-decrease in diameter but increase in number as a function of carbon content of the steel. Martensitic microstructure is preferred with respect to these particular conditions.