Welding line defect detection and identification method based on ultrasonic phased array and support vector machine

The invention discloses a welding line defect detection and identification method based on an ultrasonic phased array and a support vector machine, relates to a welding line defect identification method and belongs to the technical field of welding line defect identification. The welding line defect detection and identification method realizes thick-plate electron beam welding line defect nondestructive test and identification. The welding line defect detection and identification method comprises the following steps of detecting a welding line by an ultrasonic phased array sector scanning method to obtain a defect sector-scan image, extracting a principal component of the defect sector-scan image by a principal component analysis method, building a defect feature expression function, constructing a defect disaggregated model structure by a support vector machine binary decision tree method, constructing three sub-models based on a support vector machine, identifying pore defects by the sub-model I, then identifying crack defects by the sub-model II, and then distinguishing incomplete fusion defects and incomplete penetration defects by the sub-model III. The sub-models adopt a radial basis function. Sub-model parameters are optimized by a grid searching method. The welding line defect detection and identification method realizes detection and intelligent identification of pores, cracks, incomplete fusion defects and incomplete penetration defects of a thick-plate electron beam welding line. Correct recognition rates of the above four defects respectively are 94.5%, 92.5%, 95% and 93.5%.