Phased array ultrasonic evaluation method for grain size

Abstract

The invention provides a phased array ultrasonic evaluation method for grain size. The method comprises the following steps: obtaining an experimental longitudinal wave scattering attenuation coefficient by using primary bottom surface echo and secondary bottom surface echo; deriving a radiation sound field of the linear phased array probe according to the Huygens principle, receiving average sound pressure through the probe, defining a diffraction correction coefficient of the linear phased array probe, and calculating a final diffraction correction coefficient; obtaining a theoretical relationship between the grain size and the longitudinal wave scattering attenuation coefficient according to a Weaver ultrasonic scattering model, and obtaining an agent model of the grain size and the theoretical longitudinal wave scattering attenuation coefficient by using polynomial fitting based on a nonlinear least square method; and substituting the experimental longitudinal wave scattering attenuation after the diffraction loss is eliminated into the proxy model, and inverting a grain size value. According to the method, diffraction loss interference is eliminated, multi-angle acoustic beam information is fused, compared with a traditional method, relative errors are greatly reduced, and a feasible and reliable means is provided for grain size estimation of polycrystalline materials.

Description

technical field [0001] The invention belongs to the technical field of grain size evaluation, in particular to a phased array ultrasonic evaluation method of grain size. Background technique [0002] Grain size is an important factor affecting the mechanical properties of polycrystalline materials, such as yield strength, creep strength, and corrosion resistance. For example, the Hall-Petch effect shows that the hardness and yield stress of a material generally increase with decreasing grain size. However, during heat treatment, melting or machining, the actual grain size may deviate from the design value. Therefore, it is of great significance to effectively evaluate the grain size to ensure the safe service of key components. [0003] Grain size evaluation can be divided into destructive and non-destructive methods. Destructive methods are mainly metallographic and electron backscattered diffraction, but they can only detect local information, and require sophisticated ...

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Problems solved by technology

This requires consideration of not only the transmit delay for deflection or focusing, but also the receive delay for summing all received signals, which makes diffraction correction for phased-array probes more complex than conventional single-probe diffraction correction, which has not yet been implemented. There are calibration methods that can be used directly with phased array probes

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