what shielding gas to use?

[GreaseDog]

i bought a Lincoln MIG welder on Friday, ended up going with the Pro Mig 180.

i've got it set up for flux core right now, but when this spool is gone, i want to go gas.

what is the difference between different shielding gasses? the machine says its compatible with argon, CO2, and a mix. what's the deal there? pros and cons of all 3?

[SlvrdoHDmax]

At school all we use on MIG and FCAW is 75% CO2 and 25% Argon mix and it works great on anything Ive welded.

edit- sorry, i dont know any pros or cons of them all. i would imagine some gases are priced different but thats all i remember at the moment. Im pretty sure we went over it in class...

[CountryChevy15]

also interested to hear the pros and cons. Also what are some of the differences that i would see from switching from flux core to gas?

[SlvrdoHDmax]

Welding with hard wire will be more difficult and the metal needs to be cleaner, whereas with flux, there is less preparation and the machine does a lot of work for you. Using flux core, you can just move right along without using any special motions. An advantage you have with MIG is just being able to weld thinner material. The gas should still be used with flux core btw. I would trust my teachers word since he went to MWI and has been a welder for about 9/10 years. Also with flux, keep a stickout of 1/2 -3/4 inches and with mig keep it 1/4-3/8


flux can also have a nicer bead. very smooth and little to no ripples. I can weld beads all day with flux that look like a machine did them. Were building a 6x14 utility trailer in my class and weve used flux to weld everything so far.

[Lik3s4pr3zid3nt]

whew....lots of differences for different processes. If you end up doing regular GMAW with solid wire...there are a few different processes..you can either do short circuit, or spray arc. a common gas is probably 75/25, or 80/20. These gases can be used either for fluxcore or solid wire, short circuit.
yeah, a dual shielded fluxcore is always better than just the fluxcore its self.

When fluxcore welding, i usually use a pure CO2 mixture. For regular, light mig welding, i use a 75% argon, 25%CO2 . For spray, i use 92% argon, 8% CO2, but i dont think your welder will handle the load for spray.

again, these are my opinion, although i will add im a certified welder..its been awhile since ive welded though, cause i got laid off. my memory could be gone. lol hope this helps.

[Justin_Inc]

aluminum = Argon
Steel = Argon/Co2 mix

Straight CO2 is for steel, but its meant for hardfacing steel, and joining dissimilar steels together. It does not allow for anywhere near as nice of a weld as the CO2/Argon mix

There are other gas mixtures out there but thats the basics.

[GreaseDog]

got a 120# tank of 75/25 coming tomorrow. $250 delivered, and i own the tank.

[SlvrdoHDmax]

sounds like a good deal

[fastlt1]

They use pure CO2 alot in construction. Better penetration. Alot more splatter and not as pretty. LOL

[BlackSierra]

got a 120# tank of 75/25 coming tomorrow. $250 delivered, and i own the tank.

cool,good choice.

[Underpowered]

Welding with hard wire will be more difficult and the metal needs to be cleaner, whereas with flux, there is less preparation and the machine does a lot of work for you. Using flux core, you can just move right along without using any special motions. An advantage you have with MIG is just being able to weld thinner material. The gas should still be used with flux core btw. I would trust my teachers word since he went to MWI and has been a welder for about 9/10 years. Also with flux, keep a stickout of 1/2 -3/4 inches and with mig keep it 1/4-3/8


flux can also have a nicer bead. very smooth and little to no ripples. I can weld beads all day with flux that look like a machine did them. Were building a 6x14 utility trailer in my class and weve used flux to weld everything so far.

that is the first time i have ever heard that. we never use flux, and IMO it is easier to get a better weld with MIG. i don't know of anyone who uses flux wire.


but we use 75/25 both at home and at work.

[SlvrdoHDmax]

that is the first time i have ever heard that. we never use flux, and IMO it is easier to get a better weld with MIG. i don't know of anyone who uses flux wire.


but we use 75/25 both at home and at work.

Its what weve used to weld an entire 6x14 trailer. IMO its way easier than mig. On most joints all you have to do is drag the gun and keep the speed right and it makes a bead look perfectly smooth. Not one ripple. It could be the type of flux wire being used as well. With MIG there is usually some kind of motion to be made such as C-motions or half moons so that it will fill the joint correctly or to prevent overhang. It took me about a month to finish the MIG course and about 1 week to do flux. Flux is used a lot on structural and heavy machinery because of its excellent penetration and fusion. The stickout is also 1/2 to 3/4 inch so its much easier to see the puddle.

[Underpowered]

hmm, new one on me.

[1BadZ71Tahoe]

Stargon is where its at. :read:

Email Print
Argon-Carbon Dioxide-Nitrogen Mixtures -- Praxair's Stargon® SS Blend
Praxair's Stargon® SS gas blend is a carefully controlled blend of argon, carbon dioxide and nitrogen that is designed for joining a wide variety of stainless steels. It is well-suited for all-position welding as it can be used with all types of metal transfer (i.e. short circuiting, pulsed, and conventional spray). It produces excellent quality welds when joining light gauge material with short-circuiting transfer and offers cost savings when compared with the high-helium content gases currently used today.

With its controlled CO2 content, the Stargon SS blend can be utilized in most austenitic stainless steel applications, particularly where weld metal carbon control is required. The addition of nitrogen to the Stargon SS blend enhances arc performance by increasing its stability, improves weld penetration, and reduces distortion in the welded part. It also assists in maintaining weld metal nitrogen levels for materials such as duplex stainless steels where such chemistry control is critical to maintaining microstructural integrity and increased corrosion resistance.

Mixture
Composition %
Cylinder Volume Pressure Part

Ar

CO2

N2
Style (ft3) (psig) Number


Stargon® SS
>90

<10

<10
T 335 2,640 AR STAR 77-T

K 249 2,200 AR STAR 77-K


Benefits
» Very good arc stability
» Good weld penetration and surface appearance.
» Excellent chemistry control for good corrosion resistance.
» Reduced base metal distortion
» Controlled CO2 level for reduced weld carbon content resulting in improved corrosion properties; low levels of welding fume.
» Improved color match
» Very good short-circuiting performance – good bead shape with minimal spatter.
» Very good performance in pulsed spray – good bead shape and optimized travel speed.

Typical Applications
Pulsed and spray welding of dump truck bodies – excellent appearance, minimum spatter, little post weld clean-up.
» Joining thin gauge stainless in the food service industry where bead shape is important.
» Duplex stainless steel pipe and other pipe alloys commonly used in the chemicals industry.
» Architectural applications where minimal distortion and appearance are of concern.
» Thin gauge applications where low base material distortion is required.

[bodydroppedon20]

hmmm.... let me start off by telling you that i have 9 certs in welding and work as a union iron worker and in a fab shop, alot of the structures i work on we weld 70/18 stick or sometimes gas less flux core with a miller matic, flux has a very hight tensile and shear strength and gasless youl can weld outside and not worry about the wind blowing your gas away, but just like any welding your heat, steel, cleanlyness, and technique used all depict how strong it will be you dont want hight carbon steel and weld it with fluxcore say i.e. because its to much carbon and will just crack. as far as mixtures 75/25 is your best bet its the middlle of the mixtures and good all around. straight c02 is like welding with a sparkler its cheaper and runs a bit hotter. 98/2 is used for spray arc. real hot lots of infared that will burn you up, this is just the tip of the ice burg. im not gonna go into great detail about it but if i were you just go with 75/25 and make sure you have your welding leads hooked up right on the welder when you switch between flux core and hard wire