High-temperature alloy grain size evaluation method based on ultrasonic phase velocity

The invention discloses a high-temperature alloy grain size evaluation method based on an ultrasonic phase velocity. The high-temperature alloy grain size evaluation method comprises the four steps of extracting original A wave information of a high-temperature alloy test block, calculating a longitudinal wave sound velocity of the test block, acquiring a phase velocity of the test block and constructing a comprehensive evaluation model. The high-temperature alloy grain size evaluation method has the technical effects that an attenuation coefficient spectrum is obtained through a two-medium multi-element Gaussian sound field model, and then a phase velocity spectrum is calculated according to the attenuation coefficient spectrum based on a K-K relational expression; compared with a phase difference algorithm for calculating the phase velocity, the algorithm disclosed by the invention is higher in stability, and the phase velocity of the curved-surface test block can be possibly extracted; moreover, in a process of using the K-K relational expression, the longitudinal wave sound velocity is used as a reference value, so that the high-temperature alloy grain size evaluation method actually integrates the advantages of a conventional ultrasonic longitudinal wave sound velocity method; meanwhile, the phase velocity and the dispersion degree of the phase velocity are considered, the multi-element sound velocity information is fully used, a comprehensive grain size evaluation model is constructed, and the precision of the sound velocity method for evaluating the grain size of high-temperature alloy is improved.