Submerged arc welding is an arc welding under flux layer combustion method. Welding arc between the wire and the weldment burning heat of the arc and arc welding wire ends near the base metal and solder melts, continue feeding the wire, and proceeds along a certain trajectory, an arc weld pool solidified metal is removed to weld the molten solder is solidified into a shell covering the surface of the weld slag, slag of molten pool and weld metal for protection against arcing and the pool by the outside air intrusion.


Submerged arc welding arc, wire, wire and shift interrupter such action is usually done by machine, it is known as submerged arc welding. SAW has the following advantages: ① high degree of mechanization, for welders require low skill levels; ② welding current, can be reduced weldments groove, high welding efficiency; ③ can be separated from molten solder metal contact with the air, the protective effect good, high weld quality; ④ covered with arc radiation, better working conditions. The disadvantage is that only in the flat position welding, welding equipment and tooling equipment demanding.


High-frequency welding to high frequency current heating of the workpiece, and then applying pressure welding joints (see figure) is formed. A high-frequency current is concentrated along the surface of a conductor and flow along the path of least inductance over principle, the current will be concentrated heating of the workpiece surface to be welded, the thermoplastic state is reached, or partially molten state, extruding the molten metal on the workpiece and pressing the metal oxide, is formed of welded joints. High-frequency welding common frequency range of 60 to 500 kHz. High frequency resistance welding high frequency welding points and two high-frequency induction welding.


① High Frequency Resistance Welding: the contact with the wheel or as a sub-electrode high-frequency currents in the workpiece, suitable for continuous longitudinal seam welded pipe and spiral lap seam welding, boiler tube and fin heat exchanger spiral welded fin, external diameter pipe can be 1200 mm and a wall thickness of 16 mm, ventral beam welding electrode thickness 9.5 mm, high productivity.
② high-frequency induction welding: a small diameter tube and the wall thickness of the workpiece by the induction heating coil can be welded to an outer diameter of 9 mm and 1 mm thin-walled tube. Commonly used in small diameter longitudinal pipe seam welding and brass can also be used girth weld, but power consumption is greater than the high-frequency resistance welding. The main parameters affecting the high-frequency welding quality is high-frequency power frequency, power, workpiece forming angle, welding speed and pressure from the squeeze, the electrode (or induction coil) and squeeze rollers. Major equipment frequency power supply, the workpiece forming apparatus and extrusion machinery. Stable high-frequency welding quality, high productivity and low cost. For high-efficiency automatic production line, the production of advanced methods slit tube.