The one instance I've found where flux core wire is preferable to solid core and gas is when welding outside when there is any kind of breeze. It doesn't take much air movement to blow the shielding gas away from the weld resulting in a very ugly porous weld.

Gas choice will normally depend on what your welding, but if the majority of the work is mild steel you can probably get by with straight CO2. The Lincoln site has a pretty good explanation.

MIG Welding FAQs


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