Oxidation and Hot Corrosion Behaviors of Service-Exposed and Heat-Treated Gas Turbine Vanes Made of IN939 Alloy

摘要

Oxidation and hot corrosion tests were conducted on service-exposed and heat-treated IN939 alloys at 830, 930 and 1030 degrees C for testing times up to 800h. The degradation behaviors were studied using optical and scanning electron microscopes. The oxidation results showed no tangible weight change in the samples at 830 degrees C. At 930 degrees C, after initial weight gain, the oxidation samples showed weight loss; whereas a continuous weight loss was observed at the higher temperature of 1030 degrees C. In the hot corrosion tests, however, a large weight loss occurred in the samples even at 830 degrees C, indicating aneffect of fuel impurities on the high-temperature behavior of the alloy. SEM observations revealed that the main features of oxidation and hot corrosion of the alloy were internal oxidation of aluminum and depletion of chromium in the regions beneath the surface scales.