METHOD FOR COMBINED AUTOMATIC DOUBLE-SIDED LASER-ARC WELDING OF FIXED CIRCULAR BUTT JOINTS OF PIPELINES Russian patent published in 2024 - IPC B23K28/02 B23K26/348 B23K101/10 

FIELD: welding.

SUBSTANCE: invention relates to welding, namely to combined automatic double-sided laser-arc welding of fixed circular butt joints of pipelines from high-strength pipe steels. Welding is carried out in the environment of protective gases with an offset from the zenith and using the technique of scanning the laser beam of the outer seam with filling of narrow-gap "Y" groove of welded edges with filler wire according to technological scheme one welding bead in built-up layer of fixed circular butt joints of pipelines with two welding heads. Geometrical dimensions and shape of structural elements of laser-welded edges on the front side of the seam are made for narrow-gap grooving, and grooving of welded edges on the side of the seam root is made for arc welding. On the side of the weld root from inside the pipelines, automatic single-pass arc welding with a consumable electrode in the medium of protective gases is used, which is the first technological welding operation performed by a centring welding machine. Laser welding of correcting, filling and lining passes is performed by means of laser beam scanning technique; at that, lining pass is performed by laser beam with welding wire oscillation technique. Process parameters of arc and laser welding are selected so that to form welding thermal cycle, excluding formation of martensite structures in heat affected zone of welded joint. Prior to welding, induction preheating is carried out, and during welding induction concurrent heating of welded edges is not less than 75 mm in each side from welded edges to temperature from +100 to +150 °C regardless of ambient temperature.

EFFECT: obtaining welded joints of main pipelines, mechanical properties and geometrical parameters of which correspond to standard values, with reduction of defects of welded joint at increase of rate of construction of main pipelines.

1 cl, 4 dwg