Electric resistance welding(ERW) vs submerged arc welding(SAW)

Electric resistance welding and submerged arc welding are both welding methods for connecting steel pipes. The differences between the two are as follows.

1. Different principles

Resistance welding uses the principle of resistance heating to apply a certain pressure on the surface of the workpiece to generate current between the contact surfaces and convert the electrical energy into heat energy, causing the corresponding area of the workpiece to heat up and melt. Under the turbulence and infiltration of the molten pool, metal welding is achieved. A method. ERW welded tube is made by this welding method.

Submerged arc welding uses the high temperature generated by the arc to melt two workpieces, and at the same time, filler metal is added to achieve the effect of bonding the two workpieces into one. In the process of submerged arc welding, electric current passes through the joint to generate arc light, which then melts the surface of the workpiece and forms a molten pool. After the molten pool reaches the required depth, the filling material is sent into the molten pool to complete the welding. Common submerged arc welded pipes include SSAW steel pipe (spiral submerged arc welded tube) and LSAW welded tube (Longitudinal double submerge arc welded tube)

2. Different scope of application

Since resistance welding uses resistance to generate heat from electric current to achieve welding, it is suitable for workpieces with small diameter, few welding points, small area, and simple shape; in addition, the temperature of the center part and the nearby area of this method are too high, and the temperature in the welding For workpieces with large diameters and relatively large wall thicknesses, since the ends are subject to greater thermal influence, they are prone to deformation, stress concentration, etc., which affects the dimensional accuracy of the workpiece.

In addition to the advantages of resistance welding, submerged arc welding can also weld workpieces with large diameters and relatively large wall thicknesses. Since the filling material can be controlled at the required location, the compound composition and atmosphere of the molten pool can also be better controlled. Greatly improves welding quality and stability.

3. Different welding quality

Resistance welding uses pressure to cause the corresponding area of the workpiece to heat up and melt, and pressure and heat are generated at the same time. Although the welding quality of this welding method is guaranteed, the welding speed is too fast, which sometimes leads to oxidation, deformation, cracks and other problems.

The welding quality of submerged arc welding is better, the filling material can be controlled at the required position, so the compound composition and atmosphere of the molten pool can also be better controlled, and the weld quality is more stable.

4. Different application fields

Resistance welding is suitable for welding small parts, such as small pressure vessels, assembly of electrical components, etc. Submerged arc welding is suitable for the welding of large workpieces, such as the manufacturing of steel structures and the welding and manufacturing of various structural components in large enterprises such as automobile factories, shipyards and machinery manufacturing plants.

Although resistance welding and submerged arc welding are both welding methods, there are differences in their principles, scope of application, and welding quality. Reasonable selection of welding methods and correct technical operations can not only ensure the welding effect, but also improve production efficiency and product quality.

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