RESISTANCE WELDING PROCEDURE FOR PRODUCTION OF ELECTRIC WELDED STEEL PIPE AND ELECTRIC WELDED STEEL PIPE WITH HIGH CONTENT OF Si OR HIGH CONTENT OF Cr Russian patent published in 2011 - IPC B21C37/08 B23K11/02 B23K11/34 B23K13/00 

FIELD: metallurgy.

SUBSTANCE: procedure consists in forming steel sheet in shape of pipe and in resistance weld jointing end surfaces. Regions on jointed end surfaces of an upper side of welding relative to a welding point of the above said resistance welding where temperature reaches 650°C or more are blown with reducing high temperature laminar plasma of reducing high temperature quazi-laminar plasma. Plasma is generated with a plasma gun of a cascade type by supplying voltage between the cathode and anode in cathode gas, by blowing anode gas for supply of plasma as working plasma gas and by controlling components of above said plasma working gas ensuring contents of H₂ from 2% by volume to less, than 50% by volume and mixture of gas Ar and gas N₂ and/or gas He or both and constant impurities in reducing high temperature laminar plasma or reducing high temperature quazi-laminar plasma of gas. A pipe is fabricated of steel sheet containing wt % Si 0.5-2.0 or Cr 0.5-26, and has a level of defect structure of the welding seam zone at resistance welding 0.01% and less.

EFFECT: pipe fabrication procedure stably decreasing defects of welding caused with oxides; reduced noise of plasma jet occurring during welding.

10 cl, 4 dwg, 5 tbl, 3 ex