Study on Shallow Surface Defects of T-type Welded Joints

Through the investigation of shallow surface defects of a T-type welded joint, the surface state of the joint in each process stage (welding state, annealing state, grinding state and shot peening state)was analyzed.The results show that the defects are burrs and closed oxide inclusion formed during grinding and shot peening. The main reason of the defects is unreasonable process. When the flat surface is manually polished, the oxide film and inclusions can be completely removed.However, the oxide scale in local position can not be cleaned due to narrow space during grinding of the weld surface of T-joint. Some of the oxide scale is injected into the matrix to form closed oxide inclusion during shot peening, and some remains on the surface in the form of burr.According to the results, the cross grinding method was proposed and the long shot peening after grinding was used to improve the shallow surface defects.