What is Submerged Arc Welding?

In Submerged Arc Welding (SAW) process, the arc and the molten weld metal are covered by an envelope of molten flux and a layer of unfused granular flux particles. The arc is literally submerged in flux, as such the process is relatively free of intense radiation of heat and light. In most typical open arc welding processes the resulting welds are very clean. Like Gas Metal Arc Welding (GMAW) process, SAW process makes use of a solid wire electrode that is consumed to produce filler metal. The arc currents are usually considered to be very high (500A to 2000A). The efficiency of transfer of energy from electrode source to the workpiece is very high (usually over 90%), since losses from radiation, convection and spatter are minimal. The deposition rate along with the weld reliability is good. A reduction in Cost and improved productivity in welding operations can, therefore, generate a considerable impact on the competitiveness of various manufacturing industries. At the time of welding, joint preparation and arc efficiency are the most important factors dominating the cost and productivity of the weld. The desired amount of weld penetration must be achieved in a single pass the welding speed will be the major factor that determines the welding time. The efficiency of the arc is determined by proper penetration as well as the productivity of quality welds. The filler material is an uncoated, continuous wire electrode, that is applied to the joint along with a flow of fine-grained flux, which is supplied from a flux hopper via a tube. The electrical resistance of the electrode should be as low as possible to facilitate welding at high current and so the welding current Is supplied to the electrode through contacts very close to the arc and immediately above it. The arc burns in a cavity, which it is filled with gas and metal vapour. The top of the cavity is formed by molten flux. The solidified weld and the solidified flux covers the weld in a thin layer and which must subsequently be removed. The excess flux can be reused again. It also has a thermal insulating effect that reduces heat losses from the arc. As a result, more of the input energy is there for the process of welding. There are greater thermal efficiency and a faster rate of welding. It has been found that there is greater thermal efficiency in submerged arc welding that shields metal arc. The thickness of the part is considered important in developing the desired penetration. The procedure for welding stainless does not show much difference in stool steel does not differ greatly from that of welding mild steel. The material being used is expensive and necessary conditions of service are usually required necessitating extra precautions and attention to detail. Stainless steel can be welded using either A C or DC with as short an Arc as possible in order to overcome any possibility of alloy loss across the arc. When using AC, slightly higher current and setting may be required. While welding in the flat position, stringer beads should be used and, if weaving is required, this should be limited to two times the electrode diameter. The heat input, which affects the corrosion resistance and leads to excessive distortion, should be limited by using the correct electrode diameter to give the required bead profile and properties at the maximum travel speed.