| 摘要 |
PROBLEM TO BE SOLVED: To provide a MAG welding method capable of connecting ends of steel tubes to each other without any melt-down of a weld metal from a groove even if any backing material is not used.SOLUTION: Ends 11 of steel tubes 1 are opposite to each other, and a root face of a groove 12 formed between the opposing ends 11 is set to be 0-1.5 mm, and a root gap is set to be 1-4 mm. The welding heat input in an initial layer of a weld layer is set to be 3-17kJ/cm when the angle clockwise from the line extending vertically upwardly from the axis of the steel tube 1 to the line connecting to a part to be welded to the axis of the tube is ≥0° and <60°; 2-12kJ/cm when the angle is ≥60° and <120°; 2-10kJ/cm when the angle is ≥120° and <180°; 2-11kJ/cm when the angle is ≥180° and <240°; 3-16kJ/cm when the angle is ≥240° and <300°; and 3-18kJ/cm when the angle is ≥300° and <360°, respectively. |
