Life prediction method used for nickel-base superalloy blade under thermal mechanical fatigue load

Abstract

The invention discloses a life prediction method used for a nickel-base superalloy blade under a thermal mechanical fatigue load. The problems of life prediction and joint representation of low cyclefatigue damage, creep damage and oxidation environment damage of the nickel-base superalloy blade under the TMF load are effectively solved; according to isothermal low cycle fatigue life data of nickel-base alloy under the condition of not causing high-temperature effects of creep, oxidation and the like, fitting is performed to obtain a strain life equation; in combination with a fatigue damagelinear accumulation theory, a fatigue damage model is obtained; a creep damage model is represented as temperature, stress and time functions; the oxidation environment damage is modeled based on an oxidation-cracking mechanism with a continuous oxidation layer at a crack tip; a continuous damage accumulation mechanism is adopted for the three models; and by virtue of stress, strain and temperature data of dangerous position points of the blade, accurate and reliable unified representation of fatigue, creep and oxidation interactive damage, and life prediction of a combined damage model to a nickel-base superalloy member under the thermal mechanical fatigue load is realized.

Description

technical field [0001] The invention relates to the field of life prediction of superalloy structural parts, in particular to a method for life prediction of nickel-based superalloy blades under thermomechanical fatigue load. Background technique [0002] Nickel-based superalloys are used as high-temperature structural materials due to their excellent strength, hardness, toughness, corrosion resistance and high temperature resistance. Nickel-based superalloy material technology develops with the technical needs of energy power, petrochemical industry, aerospace and other technologies, and is mainly used in high-temperature components of products and equipment in important industrial fields, such as aeroengine turbine blades, turbine disks and combustion chambers. Although nickel-based superalloys have many excellent physical and chemical properties, for aeroengine turbine blades, the thermomechanical fatigue (TMF) load will cause a lot of damage to the blades during service....

AI Technical Summary

Problems solved by technology

The advantage of method (1) is that the prediction process is very simple, but because it only focuses on the macroscopic scale and lacks the mechanism research on the grain microscopic scale, although the equation is simple and the parameters are easy to obtain, it lacks physical meaning and the technical acceptance is not high

For the method (2), the prediction step is very difficult, the equation expression is more complicated, there are many material parameters, the fitting process of the parameters is cumbersome and lacks experimental support, so the accuracy is insufficient, which greatly reduces the accuracy of the calculated life, and the parameters The value is cross-scale, not suitable for engineering application

So far, researchers at home and abroad have not proposed a reliable and clear physical meaning based on the fatigue, creep and oxidation interaction life prediction method of nickel-based superalloy blades under thermomechanical fatigue loads.

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