Difference between saw and hfw pipe

(1) submerged arc welding
Submerged arc welding use a continuous feed wire as electrode and filled metal. Welding, at the upper surface of the weld zone, covered with a layer of granular flux, burning arc in the flux layer of the end portion of the wire and a partial base material melted and formed weld. Under the action of heat in the electric arc, the upper part of the solder melting slag and the metallurgical reaction occurs with the liquid metal. Slag floating on the surface of the molten metal bath, the other hand, can also make the one hand to protect the weld metal, to prevent air pollution, and produce physical and chemical reaction with the molten metal, improvement the extreme and properties of the weld metal; weld metal but slowly Ling. The submerged arc welding can be employed a larger welding current. Compared with manual arc welding, the biggest advantage is good weld quality, high welding speed. Therefore, it is particularly suitable for straight seam welding large workpiece girth. And most mechanized welding. Submerged arc welding has been widely used in the welding of carbon steel, low-alloy structural steel and stainless steel. Joints slag can reduce the cooling rate, some of the high-strength structural steel, high carbon steel submerged arc welding can be used.

(2) high-frequency welding
The same frequency welding is solid resistance heat energy. Resistor thermal welding, using high-frequency current is generated in the workpiece so that the surface of the workpiece weld zone is heated to the melting or close to the plastic state, then applied (or not applied) upsetting force to achieve the binding of the metal. So it is a solid phase a resistance welding method. High frequency welding according to the high-frequency current to generate heat in the workpiece can be divided into contact with high-frequency welding and induction of high-frequency welding. Contacting the high-frequency welding, a high frequency current through the contact with the workpiece mechanical incoming workpiece. The induction of high-frequency welding, high frequency current through the workpiece the coupling effect of the external induction coil within the workpiece generates an induced current. High-frequency welding is a a strong specialized welding method, according to the product is equipped with special equipment. High productivity welding speed of up to 30m/min. Mainly used for the manufacture of pipes welded longitudinal seam or spiral seam.