Analysis of the fracture of the welding head of the carbon steel\/stainless steel composite pipe seal

Based on the characteristics of a certain performance difference between the two materials of carbon steel matrix/stainless steel lining composite pipe, the fracture performance of the carbon steel/stainless steel composite pipe sealing and welding joint was analyzed. According to the forming characteristics of the composite pipe, the microstructure of each area of the joint, the morphology of the weld formed by the sealing layer and the stainless steel, and the micron-level gap between the two layers of materials are analyzed by the method of two corrosions and separate photographs. The results show that, due to the gap between stainless steel and carbon steel, and the grain orientation phase of the welded layer is highly consistent, it has high crack sensitivity. If carbon steel/stainless steel composite pipe joints do not improve the metal structure of the sealing layer, the solidification method and the position of the sealing welding, the sealing position is very likely to become the origin of the crack in the subsequent welding process