Fluxcore: 75/25 or CO2

CO2 has higher penetration, but more spatter.

Well I could not find any reference that states C25 has superior penetration over Co2 but I did find the following .

Welds I have sectioned - all settings unchanged.

Quote from reputable publication

Argon/Carbon Dioxide- C25(Argon 75% CO2 25%) Is widely used on thin steel where deep penetration is not necessary and where bead appearance is important. It is also handy for out of position welding on thin sheet metal or where fit-up is poor.

Carbon Dioxide-CO2 Produces deep broad penetration. Disadvantages are rough arc; making welding thin metals difficult and creates more spatter than C25

Many shops will run C25 exclusively for one important reason; there is so little spatter compared to straight CO2 that the difference in labour just in cleaning can cover most of the cost of using a mixed gas.

The weld profile also has a nicer appearance when a mixed gas is used. Most customers prefer a product that looks nice; Over one that may have penetration levels that are in excess of what is required (fit for service requirements).

John Noon

Rod: I agree with the penetration point. However, fluxcore will spray with either gas. CO2 doesn't ionize as well as Argon, Potblak pointed this out, therefore a higher current via voltage and wire speed *or* smaller wire diameter is required for spray, to eliminate spatter.

-- Rod Ryker... The intricacies of nature is man's cannon fodder.

Rod: Potblak, please refrain from top posting. :)

You are correct regarding the ionization per wire diameter, however CO2 has far more penetration due to the larger size of droplets of molten metal during the spray transfer. Naturally, these droplets are smaller than globular transfer which are much larger.

-- Rod Ryker... The intricacies of nature is man's cannon fodder.

Rod: John, the discussion is 75/25 vs CO2 *not* Ar vs CO2. There is a HUGE difference. :)

Rod: John, the discussion isn't with solid wire but with fluxcore.

Rod: Again, the discussion is regarding fluxcore.

Rod: John, John, John, John, John!

Well as you add CO2 to the mixture in increasing amounts the amount of penetration increases as well as the amount of spatter. All other variables unchanged.

various fluxcores I have run use CO2, 90/10, and 75/25 not that different from GMAW where a large variety of shielding gasses can be used for different purposes.

Never once mentioned solid wire the last I heard 75/25 was a Argon CO2 mixed gas.

It is common to weld thin metal with fluxcore at least in the shops I have worked in. Thin being anything under 1/4" down to 11 Ga.

Fluxcore on straight CO2 generates more spatter than C25 or straight argon. pretty much the same for GMAW welding.

CO 2 better penetration, but has a lot more splatter.

Rod: Let's start again. :)

1. Can you spray E71T-1 using CO2?
2. Run uphill E71T-1 CO2 then *75/25*, cut the coupons in half and report back.

-- Rod Ryker... The intricacies of nature is man's cannon fodder.

I agree wrt penetration, but not spatter. See my response to Ernie.

-- Rod Ryker... The intricacies of nature is man's cannon fodder.

Without going through what everyone else said here are some facts. For spray transfer with 0.035" wire use Argon CO2 mix with less than 21% CO2 to reduce splatter. CO2 content in the mix would be ideal at 17%, but should not be reduced to less than 15%. The 17% mix will provide higher weld energy (penetration) than argon/CO2/O2 mix's, but not as much as CO2 alone. The 17% will have a more concentrate arc and give deeper penetration than the wide, less concentrated arc from CO2 used by itself. The 17% CO2 mix is the recommended mix for FCAW in all positions, on carbon steels, low-alloy steels, and stainless steels.

Reference: Machinery's Handbook, and ASME Welding codes

Rod: Better yet, do what I asked John to do and weld E71T-1 with CO2 and 75/25 coupons, uphill, cut them in half and compare the results. Oh, and make sure to spray the CO2, read my reply to Ernie.

-- Rod Ryker... The intricacies of nature is man's cannon fodder.

Depends on your school of thought. A) Globular only, regardless of amperage B) Spray like transfer; larger droplets than spray but smaller than globular C) Spray transfer only, at all amperages

No 75/25 in the shop I am in now Only a 80/20 mix, some day when I feel like being fired I will try it with the flux core. If I get one more lecture from fellow employees about how steel has a sponge like structure and can soak up water it may be sooner than later.

WTF! Why would I want to do that? I was just providing some information, not presenting an argument. If you can't accept information without feeling challenged, go piss up a rope!

Rod: LOL. :) -- Rod Ryker... The intricacies of nature is man's cannon fodder.

I am confused. The first message that shows up when using google is below and does not say anything about solid wire or fluxcore.

A later message says the discussion isn't with solid wire.

I top posted because that seems better to me. Tough if you don't like it.

Dan