METHOD FOR NONDESTRUCTIVE EVALUATION OF METAL STRUCTURAL STATE USING MICROINDENTATION Russian patent published in 2020 - IPC G01N19/08 G01N3/40 

FIELD: defectoscopy.

SUBSTANCE: invention relates to nondestructive inspection methods, in particular to a method of evaluating structural state of metal of a structure, including during its operation. On the prepared etched surface of single-type structures from metal of one grade in the initial and analyzed state, targeted microindentation of various structural components is carried out, as well as metal grain boundaries, determining as information parameters the fact of metal cracking during microindentation in range of 0–500 gs (through visual-optical inspection), minimum load value, at which cracking occurs, as well as ranges of values of microhardness of different structural components of metal (separately) obtained at identical load. Structural state of the metal of the analyzed structure is evaluated in accordance with the following criteria. Criterion of metal embrittlement is detection of cracking during microindentation in range of loads 0–500 gs (if this fact is not characteristic for metal of structure in initial state), or lower value of load, at which there is cracking of metal during microindentation of analyzed structure, in comparison with being in initial state. Criterion of diffusion redistribution of atoms from grain volume to their boundaries is shift or expansion of range of values of microhardness of any structural component towards lower values relative to corresponding range in initial state. Criterion of hardening of metal is shift or expansion of range of values of microhardness of any structural component towards higher values relative to corresponding range in initial state.

EFFECT: high accuracy and information content of estimating the structural state of a metal based on surface microindentation results.

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