Thermanit Chromo 9 V is a covered electrode with a basic coating for manual arc welding. The 9Cr-1Mo-VNb type deposit has a tempered martensitic structure and good mechanical properties after post weld heat treatment. The manufacturer directs it to tube, pipe, plate, forgings and castings made of creep resistant steels of the ASTM grade 91 class in thermal power and petrochemical plants, with approval for long term service up to 650 degrees C.
The base grades are 1.4903 (X10CrMoVNb9-1), 1.4955 (GX12CrMoVNbN9-1) and 10Cr9. The composition is restricted with respect to trace elements, and the sum of manganese and nickel below 1.2 percent by weight keeps the Ac1 temperature safely above 780 degrees C. The coating was designed for work under difficult site conditions, so the electrode handles predictably at a low diffusible hydrogen level. Production starts at the 2.0 mm diameter.
- Classification EN ISO 3580-A: E CrMo91 B 4 2 H5
- Classification EN ISO 3580-B: E6215-9C1MV H5
- AWS classification A5.5 / SFA-5.5: E9015-B91 H4
- Coating: basic
- Current: DC+
- Diameters: 2.0 / 2.5 / 3.2 / 4.0 / 5.0 mm
- Lengths: 250, 350 and 450 mm
- Approvals: TÜV (06173), CE
On site, where there is no workshop comfort, the commonest mistake on grade 91 steel is letting the joint cool during a break, so hold the preheat through the stoppages as well. Weld the root in boiler tube with the 2.0 or 2.5 mm diameter. After welding cool the joint to the procedure and temper it, because without that the martensite stays brittle. Hand the electrodes out from the quiver as you go and do not leave them in a damp tent.
