| 摘要 |
PURPOSE:To obtain a steel pipe having a weld metal of excellent SR characteristics by welding the seam part of a steel blank pipe contg. a specific amt. of C, Si, Mn and Nb by using a welding wire having a specific compsn. and a fused flux of a specific basicity having a specific compsn. CONSTITUTION:The seam part of a steel blank pipe contg., by wt%, <0.1 C, <0.3 Si, 1-2 Mn and <0.1 Nb is subjected to submerged arc welding by using the following welding wire and flux: The welding wire is composed, by wt%, of 0.01-0.2 C, <0.3 Si, 0.2-1.5 Mn, 0.5-3 Ni, 0.1-1 Mo and the balance Fe and unavoidable impurities. The fused flux contg., by wt%, 10-30 TiO2 and 0.1-1 B2O3 and having >=0.5 basicity B expressed by the formula is used. In the formula, N( ); the mol% of the compd. in ( ). |
