[superclarkey]

Never really gave it much thought before what type of gas I use and how much difference it makes, I'm sure its been covered many times before so hopefully won't upset anyone asking.

I mainly weld bodywork stuff between 0.8-1.2mm (0.032"-0.047") thickness, with 0.6mm (0.23") wire, and 12gauge roll cage material 2.64mm (0.104"), with 0.8mm (0.30") wire.

BOC is my gas supplier, I currently use "BOC Argoshield Universal" which I believe is 12% Carbon dioxide, 2% Oxygen, 86% Argon (from spec sheets).

There are others I can get from my gas supplier, maybe you could be kind enough to tell me where these would be more useful and if needed?

Argoshield Light - 5% Carbon dioxide, 2% Oxygen, 93% Argon
Argoshield Universal - 12% Carbon dioxide, 2% Oxygen, 86% Argon
Argoshield Heavy - 20% Carbon dioxide, 2% Oxygen, 78% Argon

Be interested to know the differences and how I could use them to my advantage.

Thanks in advance.

[Artie F. Emm]

Page 12 of this excellent document
http://www.lincolnelectric.com/assets/g ... /c4200.pdf
starts a discussion of MIG shielding gas. It cover tri-mix gases, but a question for you: is a mix such as 25% co2 / 75% argon available to you? It should do a fine job on auto body stock, and may be an alternative for you.

[superclarkey]

I noticed when searching that people talk about 25/75 mix, but I've never found any so thats why I'm asking what is best for me in what is available from BOC.

Thanks for the link I will take a read when I finish work.

[noddybrian]

I'm going to catch some s#?t for saying this - but most of the members here are American & they tend to think 75/25 is the answer to everything without knowing why - it's just what they're used to - a couple of members may chime in with reason such as Len / Otto / Superior - but for the most part they won't have much experience with other mixes unless working somewhere using spray transfer in production work - most research I've seen seems to suggest mixes over 20% are of no advantage except to the supplier as CO2 is way cheaper than argon - as your in the UK the gases available are the BOC ones plus basically the same from Air Products - for the thickness your welding on I would stick to 5% for the simple fact it's cheaper than universal - either will work - used to be only 5% or 20% available but I believe they added 12% to allow small fab shops doing mixed light / medium work to run single gas stock - because the volume of it used is fairly low compared with the others it is more expensive last time I looked & nothing gets cheaper with our robbing bar stewards at BOC - on the plus side though I've never had & never heard of anyone getting bad gas from them which seems quite common across the pond.

[Superiorwelding]

I will chime in on this one soon.
-Jonathan

[Otto Nobedder]

The CO2 content serves a specific purpose, which is why there are so many blends.

The C and 2 O's disassociate in the plasma of the arc, and affect the carbon content of the weld interface.

I've been studying this in the IWE "Welding Engineer's Handbook", though about a third of it is over my head.

Each weld procedure should be evaluated for the best gas choice, but with so many non-professional welders in the U.S., 75/25 has proven to be an excellent compromise for most general-purpose welds with GMAW.

Sadly, few take time to consider what happens with a NON general-purpose weld, and 75/25 gets used anywhere a weld engineer wasn't involved in the gas choice.

Steve S

[soutthpaw]

That's where having a gas mixer comes in handy. You can set the co2 anywhere between 0 and 100% for any average shop the tri mixes are basically gimmicks. Oxygen adds heat so not sure why you would want it for body work at all. That's why spray transfer gas of 2% oxygen is common. Remember you can weld with 100% co2. Machines like the Miller passport were designed specifically for that gas. If you have an inductance control it helps a lot. Jody has a video on inductance with various gas mixes

[noddybrian]

I'm sure this thread could run a long time without achieving anything - bottom line is use what your WPS requires or if not to any code use what your comfortable with which I imagine will be C25 for most members - there are only a handful of members I'm aware of in the UK & they will be using BOC or Air Products neither of whom produce C25 for sale here - for most light gauge / hobby welding on thin material it is normal to use 5% here - the transition to 20% is usually around 10 > 12mm thickness material - obviously other blends are available for non carbon steel applications - despite it appearing counter productive to include 2% oxygen in a shielding gas I was led to believe it assists the impurity scavenging effect of the silicon in the filler wire & provides slightly better wetting out of the puddle edge at lower voltages - this can also help reduce undercut in some positions - most Mig welders can / will weld with anything from 100% CO2 > 100% Argon if set correctly by the operator - the suitability of any gas will vary with the job but for hobby use / non critical parts most will use one gas & stick with it - only thing I see against the C25 though I've never used it is the voltage threshold to achieve spray transfer will differ from other more suitable gasses.

[superclarkey]

Thanks for all the info, I've ordered a bottle of BOC Light to see if it helps me on the thiner body work welding.

[Braehill]

I usually don't comment on threads about Mig welding because I've done very little of it. I usually refer people to the best site that I know of to answer questions on mixes, weldreality.com . Long read but worth a look.

What I know about gases would lead me to believe that on sheet metal one should never be using 75/25. What I think is a selling point for it here is it has enough CO2 in it to make cheap welders weld hot enough to weld 3/16-1/4" light structural steel and still make a nicer weld than straight CO2.

I too think tri-mix gases are for the most part a gimmick. There are rare occasions where they are required but welding a rusty fender on a car is not one of them.

These are opinions from a person who has never burned through a 10# spool of wire in my whole life, so take it for what it is, an unproven opinion. There's a lot of these out there, I just don't usually give mine out.

Len

[Superiorwelding]

I would like to start a seperate thread on GMAW gasses and their use and this topic woul get buried in this thread. I will say that I disagree with some of weldreality.com view point. In talking to industry professionals that are industrial gas specialists they also disagree with some of what's said and have made the comment numerous times that the guy behind that website is a little bitter, as evidenced through the tone of articles. I am not bashing the guy whatsoever and use the site as reference as well I am just saying we have to take the good with the bad and do our own testing as well.

And not to disagree in a disrespectful manor but I have experience with several gas Tri mixes and can tell a difference in the settings, arc characteristics, bead profile, penetration/fusion, etc. Sometimes the difference is very little but it is there.
I also am agreeing with Len, I don't see the need for oxygen for sheet metal work but I guess it would help a little 110V machine look a little bigger and improve wet in at the toes.
-Jonathan

[superclarkey]

I think its always good to ask "but why" because I don't always except one persons answer, even if I know a subject well I will still ask peoples opinions because stuff isn't always set in stone, This is why I asked this (what could be taken as a simple question) and hoping for some better understanding of the differences and how I could use these small difference to better benefit from.

[Superiorwelding]

I think its always good to ask "but why" because I don't always except one persons answer, even if I know a subject well I will still ask peoples opinions because stuff isn't always set in stone, This is why I asked this (what could be taken as a simple question) and hoping for some better understanding of the differences and how I could use these small difference to better benefit from.

I for one am glad you asked. Shielding gas is a popular topic and asking these questions keep me on my toes for sure.
-Jonathan

[superclarkey]

BOC are rubbing there hands together as I just order a bottle of light to try out, will have a play and report back with what i can find.

As i do allot or bodywork stuff be interestion to see how it helps.

[682bear]

I would like to start a seperate thread on GMAW gasses and their use and this topic woul get buried in this thread. I will say that I disagree with some of weldreality.com view point. In talking to industry professionals that are industrial gas specialists they also disagree with some of what's said and have made the comment numerous times that the guy behind that website is a little bitter, as evidenced through the tone of articles. I am not bashing the guy whatsoever and use the site as reference as well I am just saying we have to take the good with the bad and do our own testing as well.

And not to disagree in a disrespectful manor but I have experience with several gas Tri mixes and can tell a difference in the settings, arc characteristics, bead profile, penetration/fusion, etc. Sometimes the difference is very little but it is there.
I also am agreeing with Len, I don't see the need for oxygen for sheet metal work but I guess it would help a little 110V machine look a little bigger and improve wet in at the toes.
-Jonathan

I'm learning here...

I have a Lincoln Weld-pak 100 that I am currrently using with a mix that is 25% CO2 and 75% argon... just reading between the lines about what you are saying, could I assume that going to a tri-mix would improve penetration? If so, would it be a significant amount?

I don't attempt to weld anything thicker than 1/8 inch mild steel with it anyway, but I was just curious...

-Bear

[Otto Nobedder]

Bear,

You don't need the expense of a Helium tri-mix for mild steel. You will get good results with the 75/25, and likely better results with 90/10.

The CO2 has a purpose in a steel weld, as the atoms disassociate and carbon blends with the puddle to provide a certain carbon content in the filler metal. The tri-mix is typically only 2.5% CO2, so you may not develop the rated strength of the wire. The wire manufacturer will recommend a gas or gasses that provide the best results.

Steve S

[Antorcha]

C25 is "Idjit gasz". It allows you to leave your machine on the same setting through a wide range of thicknesses, positions and wide differences of temps.
If youz know what them thar knobz is fer, and aren't afraid to use them, Beer bubbler will do all you need done.
I bought the mix coolaid for 2 decades. When I moved here they said "No got".
I even had to buy an adapter ! Pissed ! Primitive Cave People ! You can't weld like a real man without mix !
Then I remebered using straight Beer Bubbler for SEVERAL years before Miami Welding showed up with "the miracle".

Now they have C25 on the rack right here !
Maintaining my firm stance as a certified old fart. "I dunnedd dat overpriced chit "
I'm as happy with straight Beer Bubbler as I am without the other types of "drugs" from the eighties.

I wish them thar knobs were remote control because you DO need to adjust the machine rather frequently.......just a weeeee bit. C25 seems to eliminate that requirement.
Hey. Constantly adjusting them thar knobz also makes you look like an expert

[dirtmidget33]

Bear,

You don't need the expense of a Helium tri-mix for mild steel. You will get good results with the 75/25, and likely better results with 90/10.

The CO2 has a purpose in a steel weld, as the atoms disassociate and carbon blends with the puddle to provide a certain carbon content in the filler metal. The tri-mix is typically only 2.5% CO2, so you may not develop the rated strength of the wire. The wire manufacturer will recommend a gas or gasses that provide the best results.

Steve S

Got a curiosity question on this one. If CO2 is needed to introduce carbon into the filler mix to achieve full filler strength then how can say ER70-S6 be same chemically for MIG and TIG. Since TIG doesn't introduce any carbon to filler. Seems if filler needed the carbon there would be different filler make up for to different processes.

Not trying to start argument just asking. I do very little MIG only when I have to use machine at work cause they need it now instead of bringing it back to MR. TIGGY
My MR. MIGGY at home never gets used don't even have bottle of gas for him anymore.

[GreinTime]

Antorcha, I have to say you are probably one of my favorite people to read a response out of the blue from

[exnailpounder]

Thats a good question dirtmidget. I have wondered that myself. I wonder id it is something mixed into the alloy in TIG filler rods to add CO2? Kinda like removing 02 from copper rods...If anyone knows it will be Steve!

[Otto Nobedder]

I'll have to compel myself to do some metallurgy research this weekend... I have little doubt that E70 TIG rod and E70 MIG wire are not identical alloys, due to the shielding gas issue of the different alloys.

I can dig up a page or two from the IWE that explains (in PhD speak) how CO2 disassociates and contributes carbon to a weld puddle, but since that sucker is 1600 pages, I've not read the whole thing...

Steve S

[dirtmidget33]

Harris listed same chemical composition for TIG and MIG and AWS classification is same number. I was always told they where same. So if MIG is affecting filler . . . .just another reason for me to be the TIG snob I am

This is classification it listed
AWS A5.18 ER70S-6

Breakdown of alloy on Harris site.
MIG ER70-S2
Si - 0.80-1.15%
Mn - 1.4-1.85%
P - 0.025%
C - 0.06-0.15%
S - 0.035%

ER70-S2 TIG
Si - 0.8-1.15%
Mn - 1.4-1.85%
P - 0.025%
C - 0.06-0.15%
S - 0.035%

[Otto Nobedder]

Well, dirtmidget, that saves me a lot of work on the front end. Now I have to decipher that IWE thing about carbon content, and reconcile it with argon TIG.

Thanks for F@#King my weekend up...



Steve S

[ldbtx]

Well, dirtmidget, that saves me a lot of work on the front end. Now I have to decipher that IWE thing about carbon content, and reconcile it with argon TIG.

Thanks for F@#King my weekend up...



Steve S

Well, Steve, at least it's only 1600 pages...

ldb

[dirtmidget33]

Well, dirtmidget, that saves me a lot of work on the front end. Now I have to decipher that IWE thing about carbon content, and reconcile it with argon TIG.

Thanks for F@#King my weekend up...



Steve S

I have a special gift or knack for doing that to people's weekends