Abstract: The upper and lower shell of the diaphragm accumulator are connected by an electron beam welding structure with a gasket. The structure is small and the depth-width ratio is large, so the welding process is prone to produce incomplete penetration defect at the root. In order to improve the defect detection rate of electron beam welding of diaphragm accumulator, the experimental study was carried out using phased array technique. Firstly, the structure model of the accumulator was established by CIVA ultrasonic simulation software, and the typical incomplete penetration defects at the root were analyzed. Then, the accumulator containing the artificial incomplete penetration defects at the root was made for the experiment and research and the detection process was developed according to the research results. The characteristic image of the defects was obtained as well. Finally, a batch of diaphragm accumulators produced by the accumulator manufacturer was tested for engineering application, and one incomplete penetration defect at the root was detected. And the precise location of the defect and its own height were determined, which verified the accuracy and reliability of the inspection process. The research results provide a reliable method for the welding quality inspection of electron beam welding of accumulator products in the actual production process.

Key words: accumulator, electron beam welding, phased array, CIVA simulation, incomplete penetration