SUBMERGED WELDING WITH PULS ARC

The features of submerged arc welding with a pulsed arc (SWPA) have been studied. It is shown that an appropriate choice of SWPA parameters makes it possible to change the flows distribution in the weld pool and the thermal cycle characteristics of welding. With a constant heat welding input, the welds made by SWPA have a 20 ... 25% greater penetration depth and, accordingly, a smaller width compared to welding without the imposition of current pulses. The pulsed nature of the heat supply makes it possible to approximately halve the duration of the HAZ metal exposure at temperatures above 1000 °C and reduce the metal cooling duration by 30% in the range of 800...500 °C. As a result, in welded joints made by SWPA, the width of the HAZ coarse grain section decreases, and the austenite grain sizes in this welded joint section decreases by 2...3 times. The use of the SWPA process in low-alloy steels welding butt joints with a of 16 ... 32 mm plate thickness allows saving up to 30% of the base metal, welding wire, flux and electricity by changing the groove shape. The possibility of using the SWPA process for welding low-alloy steels with a tensile strength of up to 680 MPa without the metal preheating is shown.