Читать книгу Welding Metallurgy - Sindo Kou - Страница 40

SAW is a process that melts and joins metals by heating them with an arc established between a consumable wire electrode and the metals, with the arc being shielded by a molten slag and granular flux, as shown in Figure 1.23. This process differs from the arc welding processes discussed so far in that the arc is submerged and thus invisible. The flux is supplied from a hopper, which travels with the torch. No shielding gas is needed because the molten metal is separated from the air by the molten slag and granular flux. DCEP is most often used. However, at very high welding currents (e.g. above 900 A), AC is preferred in order to minimize arc blow. Arc blow is caused by the electromagnetic (Lorentz) force as a result of the interaction between the electric current itself and the magnetic field it induces.

Figure 1.23 Submerged arc welding: (a) overall process; (b) welding area enlarged.