Research on welding defect examination technique based on phased array ultrasonic for high voltage transformer oil tank weldsLei Shi, Xiao Qi, Xinhui Li, Chenggang Hao, Fangsen Chai, Dongxu Han, Le Yang and Guang LiE3S Web Conf., 522 (2024) 01041DOI: https://doi.org/10.1051/e3sconf/202452201041