Creep-fatigue life prediction and reliability analysis method for Martensitic steel

Abstract

The invention relates to a creep-fatigue life prediction and reliability analysis method for Martensitic steel. According to the method, first, mechanical work density is defined; second, a creep-fatigue life prediction model based on the mechanical work density is derived, and the randomness of stress and life is considered; and last, a P-delta(W

)-N<f> curve of creep-fatigue life is proposed, and a creep-fatigue life reliability analysis model is given. Compared with the prior art, the method has the advantages that prediction is more accurate, and reliability is higher.

Description

technical field [0001] The invention relates to the safe operation technology of the pressure-bearing parts of the thermal power generating set, in particular to a creep-fatigue life prediction method and its reliability analysis method for 9-12% Cr martensitic steel used in power plant furnace tubes. Background technique [0002] In the 1980s, the Oak Ridge Laboratory (ORNL) of the United States took the lead in developing an improved 9Cr1Mo heat-resistant steel, which was later included in the American Society for Testing and Materials (ASTM) heat-resistant steel standard with the T91 / P91 grade. Good creep resistance; in the 1990s, Japan launched T92 / P92 heat-resistant steel on the basis of P91 by reducing the content of Mo, adding Nb, V, and controlling the content of B and N elements. Compared with P91 steel It has more excellent high-temperature creep rupture strength. At the same time, Europe developed a heat-resistant steel named E911; on the basis of German X20CrMoV1...

AI Technical Summary

Problems solved by technology

However, under high-temperature and high-pressure environment, after repeated actions of unit start-stop and variable working conditions, this type of material will undergo creep-fatigue damage, which brings hidden dangers to the long-term safe and efficient operation of the generator set

[0004] In order to effectively evaluate the life of power plant furnace tubes, at present, the representative creep-fatigue life prediction methods mainly include the linear cumulative damage method, the ductility loss model, the strain range and strain energy division method, and the continuous damage mechanics model. Specific application conditions, when using, or need to determine more materi

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