| 摘要 |
PROBLEM TO BE SOLVED: To obtain stable bead forming properties free from a defective outward appearance having central recessed beads and burn through in CO2 welding by using a wire which is composed of a specified weight % C, Si, Mn, S and the balance Fe with impurities and whose constituents are adjusted so as to satisfy the specific relation. SOLUTION: The wire which is composed of, by weight, 0.04-0.12% C, 0.50-1.00% Si, 1.00-1.6% Mn, 0.003-0.015% S and the balance Fe with impurities and whose constituents are adjusted so as to satisfy the formula is used. Even if the adding quantities of C, Si, Mn, S are controlled in this range, since the center of beads is recessed or burn through is generated in vertical position downward welding when the total quantity of C, Si, Mn in the formula is 0.09 or less, the total quantity has to be adjusted to 0.09 or more. Further, in order to improve strength or toughness, 2.0% or less of Ti, Zr, V, Ni, Cr, Cu, Mo, B or the like may be added if necessary.
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