Flux Core MIG Welding

For me, I use flux core, because it’s more convenient, don’t have to buy gas.

when I had a design and manufacturing shop, then I used gas, it was a little cleaner, of course I used ‘anti spatter’.

the difference, using 0.030 wire, or 0.045”, with gas, you use less wire, cause you don’t have the flux core of the material.

like the Miller link says, you use what’s best for you, for me at the time being, it’s flux core.

I've probably used my Lincoln Mig for 500+ hours of continuous use using .35 flux core wire.

Structural or decorative. I've never had an issue with it.

I've used stick welders quite a bit, but don't need them as much.

I've used my same welder with gas, but don't need it.

I only weld about half a dozen times a year. I am far from an expert.

I was very unhappy with the mess from flux core wire. I now use gas only.

With my limited skill I was still a little unhappy with the appearance of my welds using gas and 0.035 wire. These were home projects using 1/8" or 3/16" mild steel. I switched over to 0.024" solid core wire and ran both the voltage and feed speed higher than the recommended settings table. With a little experimentation I was having near TIG looking welds that were clean, smooth and had very good penetration. I don't know what an expert analysis would report but they look good and they hold solid when I beat on them with a hammer. When I cut a cross section across a weld and grind it smooth the penetration profile looks very good.

Gas shielded or solid wire MIG will normally produce a stronger weld in the root, mainly due to the difference in polarity which causes the weld base to be hotter than it would be with gasless or flux cored MIG. The absence of flux also allows better observation of the weld pool as you proceed.

Gasless will produce a better lateral penetration at the sides of the arc, but will also leave a more domed finish to the weld, plus a covering of flux to later remove - this will not be present with gas MIG. Gasless is more forgiving of lack of cleanliness of the base metal.

Gasless will produce significantly more spatter which can be a chore to clean up, especially in confined sections of the work. Anti spatter sprays do help but produce their own set of fumes and cleanup needs - try spray on cooking oil as an alternative, the fumes are more agreeable but the aroma of hot cooking oil may make you a little peckish.

If working in a breezy environment, then gasless will be the better choice.

For the articles that you appear to intend welding, either would be sufficiently strong.

Whilst good quality flux cored wire is a little more expensive than solid core wire, the lack of need for gas and the related bottle hire or purchase costs generally makes it a cheaper alternative

All other things, including welding competency being equal, stick/MMA welding can produce a deeper and stronger weld than MIG, but would be a slower process and likely unnecessary for your purposes, and you would still have spatter and flux removal to contend with.

My personal preference for the task that you envisage would be DCTIG as it is ultimately more controllable with no spatter or flux fumes, but it does require a bit more skill, and you will again need shielding gas. A suitable TIG welder also gives you the option of AC welding of Aluminium if required.