Pitting corrosion resistance of CA6NM as geothermal turbine blade material in simulated artificial geothermal brine

Abstract

Fatigue failure of turbine blades originating from pitting corrosion is a critical issue for power plant. Herein, we study the pitting corrosion resistance of cast CA6NM as turbine blade material in simulated geothermal environment with and without CO2 gas by using cyclic polarization measurement. Three different molybdenum and nitrogen content of CA6NM were used for experiments: (i) CA6NM with a molybdenum content of 1 wt.% and without addition of nitrogen, (ii) CA6NM with a molybdenum content of 2 wt.% and without addition of nitrogen, (iii) CA6NM with a molybdenum content of 2 wt.% and nitrogen content 0.1 wt.%. The measurement reveals CA6NM with molybdenum 2 wt.% and nitrogen 0.1 wt.% is the most resistance to pitting corrosion in simulated artificial geothermal brine with and without CO2 gas.