Steel pipe submerged arc welding process

Submerged arc welding technology is suitable for pipeline, pressure vessel and tank, locomotive manufacturing, heavy construction and excavation of heavy industrial applications. It is suitable for industries requiring high productivity, especially those industries involving very thick materials, and can obtain many benefits from submerged arc welding technology. Its high deposition rate and walking speed have great impact on workers' productivity, efficiency and production cost This is also one of the key advantages of submerged arc welding process. Other advantages include excellent chemical composition and mechanical properties of weld, improved working environment comfort, and good weld shape and toe line.

Submerged arc welding is a wire feeding mechanism which uses granular flux to separate the arc from the air. As the name suggests, the arc is buried in the flux, which means that after the parameters are set, with the outflow of the next layer of flux, the arc is invisible. The welding wire is continuously fed by the torch moving along the weld, and the arc is heated to melt a section of welding wire, part of the flux and the base metal, forming a molten pool The thickness range of welding material is 1 / 16, - 3 / 4. It can be 100% penetration welding by single pass welding. If the wall thickness is not limited, multi pass welding can be carried out. The weld should be properly pretreated, and the appropriate combination of welding wire and flux should be selected.

Selection of flux and welding wire

It is very important to select the appropriate flux and wire for a specific submerged arc welding process to obtain good results. Although the submerged arc welding process itself is efficient, the production efficiency can be increased based on the wire and flux used. The flux not only protects the welding pool, but also helps to increase the mechanical properties and productivity of welding. The flux formula affects the current carrying capacity and slag release Discharge and current carrying capacity means that high deposition efficiency and high quality weld profile can be obtained. Slag release of specific flux will affect the choice of flux, because some fluxes are more suitable for some welding designs.

The flux selection of submerged arc welding includes active and neutral welding. One basic difference is that the active flux changes the chemical properties of the weld, while the neutral flux does not change. The active flux is characterized by silicon and manganese. These elements help to maintain the tensile strength of the weld under high heat input, help to keep the weld smooth at high speed, and provide good slag release Discharge capacity, in general, active flux can help reduce the risk of poor welding quality and expensive post weld cleaning and rework, but remember that active flux is usually suitable for single or double pass welding, and neutral flux is more suitable for large multi pass welding, because it helps avoid the formation of brittle and crack sensitive welds.

There are many kinds of welding wires for submerged arc welding, each of which has its own advantages and disadvantages. Some welding wires are prepared for welding under high heat input, while other welding wires are specially designed to help flux clean welding. Please note that the interaction between the chemical properties of welding wires and heat input will affect the mechanical properties of welding seam, and it can be greatly increased by selecting filler metal Productivity, for example, using metal cored wire with submerged arc welding process can increase deposition efficiency by 15% to 30% compared with using solid wire, while providing wider and shallower penetration profile. Due to its high travel speed, metal cored wire can also reduce heat input to reduce the risk of welding deformation and burn through.