Process and characteristics of submerged arc welding
1. Advantages of submerged arc welding
(1) With high welding productivity, submerged arc welding can adopt large welding current. At the same time, due to the concentration of arc heating, the penetration is increased. Single-wire submerged arc welding can penetrate the steel plate with no groove below 20mm at one time. Moreover, the welding speed of submerged arc welding is also faster than that of electrode arc welding. The welding speed of single wire submerged arc welding can reach 30~50 m/h, while the welding speed of electrode arc welding can not exceed 6~8 m/h, thus improving the welding productivity.
(2) The welding quality is good because the molten pool is protected by slag and flux, which makes it difficult for nitrogen and oxygen in the air to penetrate, and improves the strength and toughness of the weld metal. At the same time, because the welding speed is fast and the heat input is relatively reduced, the width of the heat affected zone is smaller than that of the electrode arc welding, which is conducive to reducing the welding deformation and preventing the overheating of the metal near the seam. In addition, the weld surface is smooth, flat and beautiful.
(3) Change the working conditions of welders due to the realization of
The welding process is mechanized, easy to operate, and the arc burns under the flux layer without the harmful effect of arc light, which can save the mask, and at the same time, it releases less smoke and dust, so the working conditions of welders have been improved.
(4) Saving welding materials and electric energy Due to the large penetration, no or less groove can be opened during submerged arc welding, which reduces the amount of filler wire in the weld, and also saves the base metal consumed due to groove processing. Because there is little spatter and no loss of electrode head during welding, welding materials are saved. In addition, the heat of submerged arc welding is concentrated and the utilization rate is high, so the electric energy consumed on the unit length weld is also greatly reduced.
(5) Wide welding range: submerged arc welding can not only weld carbon steel, low alloy steel, stainless steel, but also heat resistant steel, copper alloy, nickel base alloy and other non-ferrous metals. In addition, it can also be used for surfacing of wear and corrosion resistant materials. However, it is not applicable to the welding of aluminum, titanium and other highly oxidizing metals and their alloys.
2. Disadvantages of submerged arc welding
(1) Submerged arc welding is protected by granular flux, which is generally only applicable to flat welding or welding at positions with small inclination and fillet welding. For welding at other positions, special devices are required to ensure the coverage of flux on the weld zone and prevent the leakage of molten pool metal.
(2) During welding, the relative position of the arc and the groove cannot be observed directly. It is easy to produce welding deviation and incomplete penetration, and the process parameters cannot be adjusted in time. Therefore, it is necessary to use the automatic seam tracking device to ensure that the welding torch is aligned with the weld without welding deviation.
3) Submerged arc welding uses large current, and the electric field strength of the arc is high. When the current is less than 100A, the arc stability is poor. Therefore, it is not suitable for welding thin parts with thickness less than 1mm.
(4) The welding equipment is relatively complex, and the repair and maintenance workload is relatively large, and it is only applicable to the welding of straight long welds and circumferential welds, and some irregular welds cannot be welded.