| 摘要 |
PROBLEM TO BE SOLVED: To obtain a coated electrode capable of producing a weld metal, which excels in cold toughness and notched fracture toughness after stress relief annealing in the welding of high tensile steel, by controlling the quantity of C, P, S, N and O of a steel core wire to a specific value or less, specifying the composition and content of coating flux, and also having an arc stabilizer, slag producing agent, and caking agent contained. SOLUTION: The circumference of a steel core wire, which is controlled to contain each equal to or less than 0.05 C, 0.010 P, 0.010 S, 0.005 N and 0.005 O in weight %, is covered by a coating flux containing 30-60 metallic carbonate, 8-20 metallic fluoride, 1.0-5.8 Si, 0.5-4.0 Mn, 0.3-1.0 Mo, 0.5-7.5 Ni, 0.02 or less Cr, 0.02-0.60 V, and 0.03-0.60 Ta and also containing other than the above an arc stabilizer, slag producing agent and caking agent. In addition, the average grain size of Ta is desirably 50-75μ. Consequently, a target weld metal can be obtained in the welding of a high tensile steel having 780 N/mm<2> grade or higher.
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