Consumables
Consumables questions test electrode and filler classification, storage, shielding gas and deposition. You must match the consumable to the base metal, process and WPS.
Core rules
- In AWS electrode classification, E7018 means covered electrode, 70 ksi minimum tensile strength, all-position (1), and low-hydrogen iron-powder coating (8). E6013 is a 60 ksi, all-position, high-titania electrode for general work.
- Low-hydrogen electrodes such as E7018 must be kept dry. Store in a holding oven and re-dry according to the manufacturer; damp electrodes promote hydrogen cracking.
- MIG/MAG solid wire ER70S-6 is a common mild-steel filler. Shielding gas choice affects transfer mode and penetration.
- FCAW uses a flux-cored wire; some are gas-shielded and some are self-shielded. Follow the manufacturer’s polarity and gas recommendation.
Worked example
A 5 kg box of E6013 electrodes is used with 65% deposition efficiency. Deposited metal = 5 × 0.65 = 3.25 kg. The remaining 1.75 kg is stub loss, spatter and coating. The reasoning is that deposition efficiency accounts for metal not becoming part of the weld.
Traps that cost marks
- Using damp E7018 because it “looks dry”.
- Reading 70 in E7018 as 70% efficiency rather than 70 ksi tensile strength.
- Using the wrong shielding gas for the transfer mode.
- Mixing stainless and carbon-steel filler wires.