Experimental and numerical analysis of Pitting Corrosion in CUSTOM 450 Stainless Steel

Abstract

The present study aimed at the propagation of the pit in CUSTOM 450 Stainless Steel blades after the initiation stage. The depth of pits was measured by Eddy Current and the relationship between pitting corrosion time and pit depth was determined based on simulation and compared to the experimental results. Moreover, the electrolyte potential and the local strain distribution around the pit were displayed at different potentials and times. The pit growth increased rapidly for a certain period and then declined. For stressed and stress-free samples, the local strain distribution and pit depth growth were compared at 350 mVSCE potential. Based on the results, the presence of stress in the specimens accelerated the pitting corrosion growth in CUSTOM 450 stainless steel. To calculate the stresses on the blade surface, the model of the blade was constructed and two adjacent pits were created at the location of the fractured surface. The results show that the pits are turned into stress cracks after about 4 months corresponding to the result of the other references. To make a connection between accelerated pitting corrosion tests and the operating conditions of the gas turbine, the comparison of pitting time (simulation) was made for the stressed sample at 350 mVSCE potential and sample with real operating conditions.350 mVSCE potential and sample with real operating conditions.