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.
Pitting corrosion is an importance phenomena in power generation steam turbine, as it is one of the main causes for blade failure, particularly in the last row of low pressure blading. In this work, the pitting corrosion resistance of the widely used blading alloy of wrought 410 stainless steel and that of the candidate alloy of cast CA6NM stainless steel were investigated. Cyclic polarization measurements for all samples were conducted in simulated solution of thermal and geothermal power plants. The experimental results show that the pitting potentials of the cast CA6NM steel were higher compared to those of the wrought 410 steel in all simulated solution. Both steels exhibited higher pitting potentials in CO2 containing simulated geothermal water than those in the other solutions. These results were correlated with microstructure of the steels observed by Scanning Eectron Microscope (SEM).
Coating process of martensitic stainless steel 420 (SS 420) as the base material component of the steam turbine blade component uses an Electroless NiP coating process. This process is one of the solution coatings that applied to stainless steel as a substrate to improve corrosion resistance. The goal of this research is to get an idea and information about the effect of surface roughness and stirring speed on the characteristics of Electroless NiP layer. Experimental parameters in this research were variations of 0.044 μm, 0.056 μm, 0.101 μm, and 0.164 μm surface roughness and variations of 4.9 rpm, 11.3 rpm, and 21.3 rpm stirring speed. Results showed that the surface roughness and low stiring speed causes the grain distribution becomes more uniform, whichis shown by Scanning Electron Microscopy (SEM) examination. Adhesion layer also increases along with increasing levels of surface roughness. The highest value of adhesion was 1.9 MPa at 0.164 μm and the lowest value of adhesion was 0.8 MPa at 0,044 μm.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.