Estimation of safety and durability of the turbine blades of gas-turbine engines

The improving reliability of stationary gas turbines depends on the guaranteed efficiency of turbine blades tested by the complex effects of high temperatures, mechanical loads, and aggressive medium. Turbine blades are critical parts with complex geometric forms made of nickel-base superalloys. The complexity of forecasting of their lifetime is explained by the data missing on the strength and corrosion resistance during their lifetime. The investigation of their characteristics takes much time and is expensive. Nowadays, the long-term strength calculations are carried out using various methods of extrapolation of the results of short-term tests. In order to forecast the high-temperature characteristics of alloys operating in an oxidizing medium, the time-temperature equations of the long-term strength by Miller-Larson, Cherby-Dorn, Manson-Haferd are most widely used. The studies of the possibility to use parametric time-temperature equations to forecasting the heat resistance of parts tested high-temperature sulfide-oxiding impact are presented. The most reliable parametric method of forecasting the trouble-free operation of the turbine blades has been determined. The analysis of the experimental and calculated values of the long-term strength was showed that under aggressive conditions, the calculation of the time to rupture is possible only for the corrosion-resistant alloys IN-738, ЗМИ-3У. A significant increase in the scattering of experimental and extrapolated features is characteristic, regardless of the method was considered. It was established to make a forecast for ВЖЛ 12У alloy with an increase in extrapolation time to 5,000 hours at 850 °C and above, it is impossible. The maximum resource calculation of trouble-free operation of parts allows not only to save expensive heatproof materials, decrease labor efforts for their manufacture and repair process, but also to increase the reliable operation of gas-turbine engines.