§2.1A · Under Joining and cutting
Self-shielded or gas-shielded flux core: the CWI difference
Self-shielded (FCAW-S) and gas-shielded (FCAW-G) flux-cored wire differ in where the arc's protection comes from. FCAW-S gets all of it from what's packed inside the tube. FCAW-G shares the job with gas from a bottle, the setup shops call dual shield. That one difference decides where each one earns its keep.
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- §2.1A
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- Joining and cutting
2.1A.1Core or bottle
Both wires are tubes with flux packed inside, and both leave slag to chip. The difference is in how much work the core has to do. The other arc processes are in joining and cutting processes.
On an erection crew hanging steel at height, hauling bottles up and building wind screens around every joint costs more than the spatter. In a fab shop with still air and a gas manifold on the wall, the smoother arc of gas-shielded wire wins.
A self-shielded core carries gas-formers plus extra deoxidizers and elements that tie up nitrogen from the air. A gas-shielded core can go lighter on those, because CO2 or an argon mix from the nozzle does most of the shielding.
What changes at the machine
- Polarity. Self-shielded wires commonly run DCEN and gas-shielded wires DCEP. The wire's data sheet and the WPS have the final word.
- Stickout. Self-shielded wire is touchy about electrical stickout. Run it shorter or longer than specified and the core doesn't react the way it should, which is a classic route to porosity.
- Gas. Gas-shielded wire needs the right gas at the right flow, a clean nozzle and no draft across the arc.
Reading E71T-1
E = electrode. 7 = 70 ksi minimum tensile strength. 1 = all-position. T = tubular, meaning flux-cored. The designator after the dash is the usability class, and the filler spec ties it to whether the wire needs external gas. Read it off the spool label and match it to the WPS.
2.1A.2FCAW-S and FCAW-G at the spool
| Point | FCAW-S (self-shielded) | FCAW-G (gas-shielded) |
|---|---|---|
| Shielding | Flux core only | Flux core plus external gas |
| Cylinder and hoses | None | CO2 or argon mix, as the WPS names |
| Wind and drafts | Tolerates a breeze | Needs shelter, like GMAW |
| Arc feel | Harsher, more spatter | Smoother, less spatter |
| Slag | Yes | Yes |
| Common polarity | DCEN | DCEP |
| Where you see it | Field erection, outdoor structural | Shop fabrication, heavy plate |
≠ marks a row where the two differ.
2.1A.3Pick the wire
Picture the job site the stem describes before you choose: inside a shop, up on steel, wind or no wind. Parameter checks on the arc are covered in welding application and control.
0 of 6 tagged · 0 accepted
Tag 01
In FCAW, what is the primary function of the self-shielding flux core?
Remarks on every option
- A Speed depends on deposition and settings. The core's main job is shielding.
- B The base metal still needs cleaning before welding. The flux doesn't replace surface prep.
- C Correct: Self-shielded wire's core makes its own shielding gas and slag as it burns, so no gas bottle is needed.
- D The core doesn't cool anything. It burns in the arc to make shielding gas and slag.
Pick an option. The remarks on all 4 open here.
Tag 02
What is the primary advantage of using dual-shield FCAW over self-shielded FCAW?
Remarks on every option
- A Needing no gas cylinder is the self-shielded advantage. Dual-shield needs an external gas supply.
- B Dual-shield costs more to run because of the gas and gas equipment.
- C Correct: The added shielding gas gives a smoother arc, less spatter, and weld metal with better strength and toughness than most self-shielded wires.
- D Wind blows away external gas, so outdoor work is where self-shielded wins.
Pick an option. The remarks on all 4 open here.
Tag 03
Which type of FCAW wire is most suitable for outdoor welding?
Remarks on every option
- A Correct: Self-shielded wire makes its own shielding from the core, so wind can't strip away an external gas shield.
- B Metal-cored wire needs external shielding gas, so wind is a problem.
- C Gas-shielded wire depends on an external gas that wind blows away.
- D Dual-shield is gas-shielded flux-cored wire, so it has the same wind problem.
Pick an option. The remarks on all 4 open here.
Tag 04
Which of the following characteristics is a primary advantage of the FCAW process over GMAW?
Remarks on every option
- A FCAW leaves slag that GMAW doesn't, so clean welds are GMAW's edge.
- B Both run on similar wire feeders and power sources. Equipment cost isn't the difference.
- C Correct: Self-shielded FCAW needs no external gas, so it holds up in wind where a GMAW gas shield gets blown away.
- D Setup and settings are similar for both wire processes. Ease of use isn't FCAW's main edge.
Pick an option. The remarks on all 4 open here.
Tag 05
Which welding process uses a continuous tubular wire filled with flux?
Remarks on every option
- A PAW uses a tungsten electrode and a constricted plasma arc. There's no flux-filled wire.
- B Correct: FCAW feeds a continuous tubular wire with flux inside. The flux provides shielding, alone or with an external gas.
- C SMAW uses stick electrodes with the flux coated on the outside, not a continuous tubular wire.
- D GMAW feeds a solid wire and relies on external shielding gas, not a flux core.
Pick an option. The remarks on all 4 open here.
Tag 06
During a flux-cored arc welding (FCAW) operation, which type of residue typically forms on top of the weld pool after cooling?
Remarks on every option
- A Spatter is droplets thrown out of the arc, not a layer over the bead.
- B Dross is the residue under a thermal cut, not a welding layer.
- C Arc wash isn't a residue that covers the weld.
- D Correct: The flux core melts and floats to the top as slag, which covers the bead as it cools and gets chipped off.
Pick an option. The remarks on all 4 open here.
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