Research Of Relationship Between Carbide Change And Remaining Life Of Gas Turbine Blades

Gas turbine is the key equipment in petrochemical system production,the blades operates long-period in the condition of high temperature and sometimes unplanned overtemperature phenomenon occurs when gas turbine is operating.The overtemperature makes microstructure deteriorate,that causes reduction of remaining life,and happens a sudden accident.So it investigates the microstructure and mechanical properties changes of gas turbine blades in the condition of simulated overtemperature,and prediction of remaining life of the blades have great practical significance.In this paper,the leaves material which has been used of GH864 alloy are carried out.for preheat treatment,the microstructure and properties have a certain degree of restoration; and then overtemperature treatment of 700℃,800℃,900℃,950℃,1000℃for fifteen hours and overtemperature treatment of 900℃,920℃,940℃,960℃,980℃,1000℃for one hour has been operated on the blades;The regulation of overtemperature and time to microstructure of alloys is researched;and the mechanical properties of GH864 alloys in overtemperature is tested.Based on the test results attain the method of prediction of remaining life.Researches shown that the change of overtemperature has a large effect on microstructure of material,matrix grain coarsening and carbide on grain boundary happen to chain segregation when the temperature increasing;but when the temperature more higher,the carbide on grain boundary have a certain degree of dissolution,the content of carbon increasing and the precipitation ofγ' phase growing up in matrix.The overtemperature time have less impact on the microstructure at the same overtemperature. The effect of overtemperature on the precipitation of carbide was analyzed by using physical and chemical analysis and X-ray diffraction,results shown the quantity of carbide precipitation increasing with the temperature rising,but grain boundary carbide precipitation will occur dissolution when the temperature higher.So as the hardness of the alloys,especially when the temperature is higher than 900℃decreases significantly.From durable tensile fracture can be seen,the material is mainly intercrystalline cracking,when the grain boundary has a larger size and number of carbide,the crack easily formed between the grain and rapid expansion.According analyzing and fitting test data,the mathematical model of prediction remaining life is deduced.,and the relation between the remaining time and quality of the carbide can also be obtained,from this we can predict the remaining life of turbine blades...