METHOD FOR DETERMINING FATIGUE DAMAGE OF METASTABLE AUSTENITIC STEELS Russian patent published in 2022 - IPC G01N29/07 

FIELD: testing.

SUBSTANCE: invention relates to methods for testing or analysing materials, and can be used to evaluate the actual condition of operated industrial facilities and machine parts, in particular, to determine the accumulated damage in the shell of nuclear power plants made of stainless metastable steels of the austenitic grade, subjected to cyclic deformations. Substance: in the controlled area of a structural element made of metastable austenitic steel, subjected to cyclic loading, the quantitative content of deformation-induced martensite is determined prior to and during operation; shear waves polarised along and across the direction of the applied load are excited in the same area, and the time delays thereof are determined. Fatigue damage Ψ in relative units is calculated by the formula: , wherein a and b are experimentally found coefficients, t₁ and t₂ are the time delays of shear waves polarised along and across the direction of the applied load, respectively, measured during operation of the element, t₀₁ and t₀₂ are the time delays of shear waves polarised along and across the direction of the applied load, respectively, measured prior to operation of the element, F and F₀ are the quantitative content of deformation-induced martensite measured prior to and after operation of the element, respectively.

EFFECT: increase in the accuracy of determining fatigue damage of metastable austenitic steels.

1 cl, 2 dwg