BÖHLER FOX CN 20/25 M is a core wire alloyed electrode of the E 20 25 5 Cu N L B / E385-15 (mod.) type with a coating the maker describes as basic rutile, for molybdenum alloyed austenitic stainless steels. It works in the highly corrosive environments met in sulphur and phosphorus production, the pulp and paper industry, flue gas desulphurisation and desalination plants, fertiliser production and petrochemicals, acetic and formic acid production, pickling plants, and heat exchangers and power plants using brackish or seawater.
The base materials include 1.4505 (X4NiCrMoCuNb20-18-2), 1.4506 (X5NiCrMoCuTi20-18) and 1.4537 (X1CrNiMoCuN25-25-5). The deposit is over-alloyed in molybdenum to 6.3 percent by weight, which compensates segregation and improves the local corrosion resistance, and the pitting resistance equivalent PREN is at least 44. The fully austenitic structure gives high resistance to pitting and crevice corrosion in chlorides, the low carbon content protects against intergranular corrosion and the high nickel content against stress corrosion cracking.
- Classification EN ISO 3581-A: E 20 25 5 Cu N L B 2 2
- AWS classification A5.4 / SFA-5.4: E385-15 (mod.)
- Coating: basic
- Current: DC+
- Diameters: 2.5 / 3.2 / 4.0 mm
- Lengths: 300 and 350 mm
- Approvals: TÜV (04882), CE
A fully austenitic deposit with no ferrite calls for strict thermal discipline, because hot cracks start in craters and in the middle of wide beads. Run narrow, straight beads with a short arc and let the joint cool between layers. Dry the basic coating before work as the maker specifies. Pickle and passivate the joint afterwards if the vessel goes into acids.
