Abstract:At present, the petrochemical storage tank surface weld defect detection efficiency is low, and small targets are prone to leakage and misdetection. To address these problems, this paper proposes an improved weld defect detection method for YOLOv8n: YOLOv8-SDB.Firstly, the SPDConv(symmetric positive definite convolution) module is introduced into the backbone network to reduce the loss of detail information in the shallow feature extraction process and capture richer spatial and channel information;Secondly, BiFPN (weighted bi-directional feature pyramid network) is utilized to fuse multi-level features and improve the feature expression capability; Again, a lightweight and efficient upsampling operator, DySample (dynamic sampling), is used to improve the model feature reconstruction capability and reduce the computational complexity;Finally, the WIoU (wise intersection over union) loss function is employed to accelerate the convergence of the boundary regression loss and improve the regression accuracy.The improved algorithm is experimented on the weld defect dataset, and the experimental results show that the detection precision of the YOLOv8-SDB algorithm is 86.2%, the recall rate is 79.4%, and the average precision is 84%. This is an improvement of 3.4%, 2.8% and 3.9% over the YOLOv8n algorithm, respectively.