| 摘要 |
PROBLEM TO BE SOLVED: To provide a backed flux for submerged arc welding which can efficiently prevent the development of pock mark as a welding defect. SOLUTION: This flux has the composition having 10-80 wt.% SiO2-MgO base complex oxide containing >=0.05 reduction loss of weight in the reduction atmosphere at 800 deg.C, 30-60 wt.% SiO2, 30-50 wt.% MgO, or further, 0.01-30 wt.% MnO, and further, having 5-20 wt.% manganese oxide (in terms of MnO) and <=3 wt.% the total content of Li2O, Na2O and K2O. In this wave, this flux has the characteristic of <=20% reducing ratio of the vol. with heat treatment at 1100 deg. for 30 min or further, softening temp. of 1200-1300 deg.C.
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