WELDED STEEL PIPE WELDED WITH A HIGH ENERGY DENSITY BEAM, AND A MANUFACTURING METHOD THEREFOR

摘要

Provided are a welded steel pipe that is welded with a high energy density beam so that there are no welding defects in the seam, and an efficient manufacturing method therefor. Specifically: a steel strip, while being continuously supplied, is formed into a cylinder so that the opposite ends of the steel strip face one another; the two ends are melted across their full thickness by means of a high-energy density beam that is emitted onto the two ends while applying pressure with a squeeze roll; a seam is formed by welding the two ends; protrusions on the seam on the outer and inner sides of the obtained welded steel pipe are removed by cutting; a repaired seam is then formed by re-melting and solidifying a region on the inner side of the welded steel pipe, said region having a depth of 0.5mm or more from the surface and a width of double or more the width of the seam, and the center line of the seam and the center line of the repaired seam are matched.