c02 ok for 3mm steel?

[pondy]

does welding with c02 cause a weaker joint that if you was using argon/c02? i know that the arc is unastable when welding thin metal and have found that it welds thjicker stuff ok but i didnt know if the strengh effected at all? i can get both gases, c02 is £10 a bottle and mix is £45 a bottle, both rent free,

 

[Lawnmowerboy]

No, I use Co2 on my mini and have no problems atall

 

[Jim_gsxr1000]

co2 gives a bit more spatter, co2 argon mig gives less sparrer and more stable arc, dont thing there is much in it in terms of strenth

 

[Justme]

No, I use Co2 on my mini and have no problems atall

HA Ha a mini with 3mm steel.

I doubt it would be 3mm thick if you flattened it like a pancake lol


I would wait for Technical AL or someone of his background before using it for a critical weld. It def makes the weld pool cooler so must have some effect.

 

[DrNik]

i find when i was on pub gas the weld took more current to get penetration, now on argoshield its like buying a better welder, less spatter, lower amps to do the same job with argoshield, far nicer, even sounds smoother

 

[Lawnmowerboy]

correct me if I'm wrong but Co2 ADDS heat to the weld pool. Oxygen in some mixes heats 5x more effectively than Co2.

He asked about the effects of Co2 on THIN metal. If it's ok on thin metal then it will be fine with 3mm!

 

[backpurge]

correct me if I'm wrong but Co2 ADDS heat to the weld pool. Oxygen in some mixes heats 5x more effectively than Co2.

He asked about the effects of Co2 on THIN metal. If it's ok on thin metal then it will be fine with 3mm!

You're spot on re the CO2, it does produce a hotter weld, that is why gases designed for welding thicker materials have a higher CO2 content.

O2 however. is not 5x hotter than CO2, it's nearer 0.5

 

[pondy]

i thought i read that the c02 was a cooler gas and the argon was hotter? (what do i know, thats why im asking) this thread says the c02 gets less penetration and another says more?

 

[shenion]

Argon cools the area around the weld. The penetration is narrow. IT has higher arc conductivity so at a given voltage setting, it will have a bit higher current than CO2.

CO2 adds heat to the weld area via association/disassociation of the gas. It also cools the torch (torches will have a higher duty cycle rating with CO2.).

O2 adds heat to the weld pool by burning the surface of the weld pool (like a cutting torch.) IT is 5-8 times as effective as CO2 at adding heat to the weld. Rather than use 20% CO2, they can use 5% CO2 and add 2-3% of O2 and get the same weld profile.

 

[Drains]

i thought i read that the c02 was a cooler gas and the argon was hotter? (what do i know, thats why im asking) this thread says the c02 gets less penetration and another says more?

As said above, it's the other way round for heat. Co2 hot, argon cold. hence a mig weld with pure argon gives a raised bead. Co2 gives more penetration. There shouldn't be any issues with the strength of a Co2 weld, but it might not look so pretty unless you lather on a bit of anti-spatter.

It'll be fine.

 

[pondy]

Ok thanks for the input. Will stick with the cheaper co2 bottles. Not fussed to much about splatter just the strengh of the joint compaired using to 2 gases

 

[shenion]

With a welder that has a decent wire feeder, CO2 will be near spatter free.

Here's picture of 100% CO2, 0.8mm wire on 0.9mm steel:

That was with my Clarke 130EN. Was a bit hot as there was more weld on the back than the front. No spatter.

Here's the back:

 

[backpurge]

Argon cools the area around the weld. The penetration is narrow. IT has higher arc conductivity so at a given voltage setting, it will have a bit higher current than CO2.

CO2 adds heat to the weld area via association/disassociation of the gas. It also cools the torch (torches will have a higher duty cycle rating with CO2.).

O2 adds heat to the weld pool by burning the surface of the weld pool (like a cutting torch.) IT is 5-8 times as effective as CO2 at adding heat to the weld. Rather than use 20% CO2, they can use 5% CO2 and add 2-3% of O2 and get the same weld profile.

This illustrates how welding is not an exact sciende with differing opinions either side of the pond, in Europe the thinking is that CO2 transfers around twice as much heat across the arc than O2 (I have a graph somwhere which I will try and post) and whereas CO2 effects heat in the body of the weld and so has a major influence on penetration, fusion etc O2 will only heat the surface so influences spatter generation, weld profile etc. This why we always advise higher CO2 content gases for thicker material because they need a hotter, more deeply penetrating profile but the O2 content will always remain around 2%

 

[shenion]

Yeah, on this side of the pond, we don't use O2. 75/25 is the standard MIG gas for mild steel regardless of thickness.

O2 supposedly can cause trapped gases in the weld. The main reason it is not used is the added cost and 75/25 is specified in most weld procedures.