| 摘要 |
PROBLEM TO BE SOLVED: To provide a welded steel pipe excellent in earthquake-resistance and fire resistance, in which local buckling is hard to occur to bending stress worked in the case of a big earthquake and suitable for building columns. SOLUTION: This welded steel pipe is the one using a steel sheet as the material, and in which the chemical components contain, by weight, 0.05 to 0.18% C, 0.5 to 1.6% Mn, 0.05 to 0.50% Mo and 0.05 to 0.10% V, furthermore, PCM expressed by the following formula is regulated to 0.10 to 0.2, the following inequality is satisfied, and the work-hardening exponent in a tensile test in the pipe axial direction is regulated to >=0.10: (the elemental symbols denote the weight % of each element), PCM=C+Si/30+Mn/-20+Cu/20+Ni/60+Cr/20+ Mo/15+V/10+B×5 and C-12/51×V-12/48×Ti<=0.13.
|
