Abstract: With the rapid development of the manufacturing industry and the demand for high-precision quality inspection, ultrasonic phased arrays have become more and more widely used due to the advantages of fast, high-resolution real-time imaging. In this paper, an ultrasonic phased array combined processing imaging method is proposed based on the phase migration imaging algorithm to improve the imaging quality of the array scanning. Firstly, the simulation model is established by finite element software, and the image of the imaging area is reconstructed by using phase migration algorithm and two-dimensional inverse Fourier transform, which is compared with the traditional phased array imaging. In the experiment, the parallel focusing scan signal and the phased array single-transmit and single-receive time domain signal are extracted, and the obtained signal is processed by peak extraction, envelope, difference, etc. to improve the signal-to-noise ratio; finally, the processed signal is processed. De-delay weighted superposition is used to construct the array scan data matrix, The phase shift imaging results of phased array focus scanning are quantitatively compared with the phased array time-domain synthetic aperture imaging results and the phase shift imaging results of single transmitting and single receiving signal of array element.The results show that the phase shift imaging algorithm based on the phased array parallel focus scanning data can improve the imaging quality of the array scanning. Compared with the traditional Hilbert envelope extraction, the envelope signal extracted by this method is smoother and more stable, which is conducive to improving the imaging effect; In the process of detecting densely arranged porous carbon steel test blocks, the phased array focus scan phase shift migration imaging results compared with the imaging results of single shot single receive phase transfer algorithm with the same number of array elements and phased array time-domain synthetic aperture imaging results, the image signal-to-noise ratio of 11 transverse hole defects is increased by 12.98dB and 18.85dB on average, and the error rate of defect area is reduced by 3.74% and 4.05% on average.

Key words: ultrasonic testing, phased array B-scan, imaging quality, phase shift migration algorithm, signal to noise ratio