| 摘要 |
High basicity melt flux for submerged arc welding use which is used when preparing high strength weld metal and gives sound, high toughness weld metal free of top slag-in is provided. The melt flux for submerged arc welding use which is used when welding the seams of UO pipe for pipeline use having a tensile strength of a base material of 800 MPa to 1200 MPa is melt flux for submerged arc welding use characterized by containing, by mass%, CaO: 5.0% to 25.0%, MgO: 1.0% to 5.0%, Al 2 O 3 : over 15.0% to 30.0%, CaF 2 : 30.0% to 50.0%, SiO 2 : 10.0% to 20.0%, and MnO: 0.5% to 15.0% and having a basicity B of 1.2 to 3.2. |
