WIRE PACKED WITH FLUX FOR SELF-SHIELDED ARC WELDING FOR FIRE RESISTANT STEEL

摘要

PURPOSE:To obtain the weld metal having excellent high-temp. characteristics and impact toughness by incorporating a specific ratio, in total sum, of Mo and B into either or both of a steel sheath and a filling flux. CONSTITUTION:The wire packed with flux for self-shielded arc welding is constituted by packing the flux into the steel sheath. The flux compsn. is composed, by the total weight of the wire, of 2.0 to 8.0% one or 2 kinds of CaF2 and BaF2, 3.0 to 5.0% Al, 1.0 to 2.5% Mg, and 3.0 to 8.0% iron powder. In addition, 0.5 to 1.0% Mn and 0.1 to 0.3% C in total sum of the sheath and the flux are incorporated therein and 0.10 to 0.5 Mo and 0.005 to 0.0025% Nb in total sum of the sheath and the flux are incorporated therein. Further, 0.5Mo+10Nb is specified to 0.1 to 0.4%. One or more kinds of 0.05 to 0.7% Ni, 0.30 to 0.75% Cr, and 0.20 to 0.60% Cu in sum total are incorporated as additive components therein. The cost of the fire resisting application to the weld zone is reduced in this way.