BÖHLER FOX Black is an electrode with a very thick acid coating, of the E7020-G type, developed for welding unalloyed steels that go to hot dip galvanizing after welding. The deposit with 0.5 percent molybdenum has an acicular ferrite and bainite structure with a very low silicon content.
The low silicon content has a practical job here: the zinc coating does not build up excessively on the weld and does not discolour it in the bath. The deposit stands up well to contact with molten zinc. The electrode runs on alternating current and on DC with the electrode negative, in the 4.0 and 5.0 mm diameters.
- Classification EN ISO 2560-A: E 42 0 Mo A 1 2
- AWS classification A5.5 / SFA-5.5: E7020-G
- Coating: acid, very thick coating
- Current: AC/DC-
- Diameters: 4.0 / 5.0 mm
- Lengths: 450 mm
- Approvals: CE
If the structure is going to a galvanizing plant, make the welds free of porosity and crevices, because moisture and pickling acid trapped in them evaporate violently in the zinc bath. Remove the slag completely and smooth the weld face, so that the zinc settles evenly. Give lap joints and closed sections vent holes. An acid coating needs dry storage, but not baking the way a basic one does.
