| 摘要 |
PURPOSE:To obtain at a high speed a spiral bead which is excellent in peeling property of a slag and has an excellent shape, by controlling the composition and the softening temperature of a flux and the position of a specified section solidification rate of a bead. CONSTITUTION:A spiral pipe is welded by use of a flux which contains by wt% 35-46% SiO2 14-25% TiO2, 10-20% MnO, 1-10% Al2O3, 2-10% MgO, 10- 20% CaO and 2-8% CaF2, and the balance impurities, satisfies SiO2/TiO2= 1.5-2.9, and is >=130 deg.C softening temperature. In this case, a position of 40-70% sectin solidification rate of a bead showing a ratio of a solidified area in a section of the inside face or outside face molten pool to the inside face or outside face final bead sectional area is controlled as mentioned below. That is to say, a welding point is selected so that it comes to the lowest part of the pipe and the top of the pipe in case of the insde face welding and the outside face welding, respectively. |
