ASSESSMENT OF THE CORROSION-MECHANICAL PROPERTIES OF THE LEFT MATERIALS AND FORECASTING THE SAFETY OF GAS TURBINE PARTS

Abstract

Purpose. Determination of the possibility of using the temperature-time parametric dependences of Miller-Larson, Manson-Haferd, and Sherby-Dorn for long-term prediction of the strength characteristics of parts subjected to oxidation and high-temperature sulfide-oxidation effects. Research methods. Long-term strength studies were performed on samples of ВЖЛ-12У and ЗМІ-3У alloys in synthetic ash (66.2 % Na2SO4, 20.4 % Fe2O3, 8.3 % NiO, 3.3 % CaO, 1.8 % V2O5) and an oxidizing environment at temperatures of 800 °C and 850 °C. The Miller-Larson, Manson-Haferd, and Sherby-Dorn temperature-time parametric dependences were used to predict the tensile strength of materials in an oxidizing and corrosive environment. The microstructure of the samples was studied using an optical microscope MIM-8M. Results. The results obtained indicate a high level of corrosion resistance of ЗМІ-3У samples at 800 °C and 850 °C and the possibility of determining the tensile strength of the material for a period of 1000, 5000, and 10000 hours by the calculation method. Tests of ВЖЛ-12У alloy samples in synthetic ash showed a discrepancy between the experimental time to fracture and the calculated value, regardless of the parametric method, which indicates a direct dependence of long-term strength on the degree of corrosion damage to the surface of the samples. Scientific novelty. The possibility of using the Miller-Larson, Manson-Haferd, and Sherby-Dorn temperature-time parametric dependences for long-term prediction of the strength characteristics of parts in an oxidizing environment has been confirmed. In a sulfide-oxide environment, the use of parametric methods to determine strength characteristics for up to 10,000 hours is possible only for corrosion-resistant alloys. Intensive corrosion damage to ВЖЛ-12У alloy leads to accelerated deformation, which limits the use of temperature and time dependencies for effective prediction of the time of failure of parts made of this material. Practical value. Determining a reliable method for predicting the strength characteristics of heat-resistant alloys in an oxidizing and corrosive environment allows reducing the time and financial costs of conducting lengthy field studies.