pure argon on plain mild steel MIG?

[teddykan]

Folks
How would pure argon shielding gas perform for normal thin steel sheet for my next Daimler restoration project? Can I expect this to be better than pub gas in terms of risk of blowthrough?
I may go down the route of buying a argon diving bottle and use that as my shielding gas source.
teddykan

 

[Haze]

as I understand it argon co2 mix is the best for mild steel, I have no idea if pure argon has any benefits in this application, istr its used on tig for aluminium??? could be wrong..

 

[shenion]

My gas supplier gave me pure argon instead of Ar/CO2 mix. It will work. However, the weld pool will be less fluid and the welds will be taller.

Blowthrough would be a little easier as the welds will be narrower.

 

[TechnicAl]

Argon +20% CO2 is best
Argoshield Heavy or Coogar

 

[aametalmaster]

I have 3 gasse's to use at different times. CO2, 75/25 and Argon. The Argon will work in a pinch but as said dosen't wet out well but its fine with Silicon Bronze mig wire for bodywork...Bob

 

[snowcat]

pure argon burns too hot for straight lcms mig work wire sticks to the tip etc, hence why a % of Co2 is added to the mix.

 

[Gasman]

Pure argon is like CO2 in as much as it is capable of shielding the arc

However pure argon will not allow as much penetration as the correct mix which has 5% CO2,your welds will be taller (SO MORE TO GRIND BACK ) The weld will stick to your vehicle but may not be as strong.

I will send a PM.

 

[Haze]

pure argon burns too hot for straight lcms mig work wire sticks to the tip etc, hence why a % of Co2 is added to the mix.

argon burns?

 

[shenion]

5% CO2 will still have tall welds, most gases with 5% CO2 have 2-3% O2. O2 is far more effective than CO2 for wetting the weld (reduces the cooling effect of Argon).

Otherwise you want 75/25 or 80/20 for Ar/Co2 mixes. My tests show 75/25 to be best overall for general use of 2-gas mix. For light work or spray-mode transfer, 85/15% may be better.

My tests and write up can be found here: http://www.mig-welding.co.uk/forum/showthread.php?t=1944&highlight=custom+gas+mix

Also shows, penetration was the same, just the width varied.

 

[teddykan]

argon prices

According to established literature the argon arc acts as the carrier of metal to the workpiece, the CO2 is there to add more heat exothermically (the CO2 molecule disassociates at the arc and recombines in the weld pool) and the O2 is to act as wetting agent (lowers surface tension, gives flatter weld pool). In terms of costs, look at these:-

Dive bottle (pure argon)
15lt bottle £160
valve £30
regulator £44
15lt refill £15
re-test (2/5yr interval) £25


Industrial gas supplier
15lt bottle rent £70
regulator £30
refill + handling £55

bottle/yr 1 2 3
dive bottle
year 1 £249 264 279
year 2 15 30 45
year 3 40 55 70
TOTAL 304 349 394
average/yr £101.3 116.3 131.3

industrial
year 1 £155 210 265
year 2 £55 110 165
year 3 £55 110 165
TOTAL £265 430 595
average/yr £88.3 143.3 198.3

So a diving bottle looks like a worthwhile in the long term. In actual fact I need to factor in pub gas rental to my dive bottle feasibility calcs as I may mix my own at the MIG input hose (a pure argon bottle and pub gas bottle side by side!).

teddykan

 

[Gasman]

Thank you for the info teddykan, PLEASE tell us your having a laugh though

Put this into perspective, in the time that it has taken you to commission a feasibility study you could have completed another Jag by now (One really should get out more IMO)

You will be welding plates & panels onto an old car right?

Where does one acquire 15ltr industrial cylinders anyway?

If you attempt to blend your own co2/argon mix the bottom line is that it will not work consistently without another piece of kit costing more than your welder.

Perhaps add this to the calculations: £39.99 +VAT will buy you a proper 10ltr argon/co2 welding mix cylinder rental for three whole years. A fill would be £22.50+vat and a refundable deposit would be £25.75.
Inc delivery in Gloucester JOB DONE

 

[teddykan]

Gasman's offer

Hi Gasman (Andy?)
I'm glad you found it funny. I did chuckle to myself but sometimes I can get serious and go ahead with mapcap schemes.
Yes I've undertaken another Daimler DIY welding/restoration project and need quite some welding again.
I had meant to get back to your Glos service. Your 10lt bottle can store how many litres of argon-CO2 mix?
Can you remind me how your refundable deposit works
Thanks
teddykan

 

[snowcat]

argon burns?

no not really the right term to use but get into hotter welding say 40+ ovc then the argon tends to create a "hotter" weld causeing sticking and burn of contact tips shroulds etc, less penetration, + why use pure argon more expensive and the reason Mig mixtures have been invented is for that purpose. I use heavy all the time because 90% of the time im on 1/2+ plate in spray with 1.2 wire i see no reason to change, I use argon on the tig and sometimes if im doing something at bit special argon helium, simple as that Rant over.

 

[Haze]

one thing that I wonder, if it burns hotter why is there less penetration, mig in my experience suffers from cold start (which equals zero or no penetration) so why with argon + hotter weld the penetration is less?

 

[shenion]

I found little difference in penetration. Argon had a cooling effect on the weld so the weld pool does not flow. It builds up higher so you move the gun faster. If you do a zig-zag weld to get the same width as CO2 mixes, you will get the same penetration.

I would say CO2 is hotter as it brakes down and releases oxygen that will burn on the surface of the weld pool.

In reality, they probably are the same, just the heat dissipates differently.

CO2 effectively has more penetration as the wire speed is less. Hence you are moving the torch more slowly and putting heat longer in one spot. As it is so wide, once it reaches full penetration, you tend to blow through. Argon has a narrow penetration, so you tend to not blow through as the weld pool is narrow.

 

[snowcat]

one thing that I wonder, if it burns hotter why is there less penetration, mig in my experience suffers from cold start (which equals zero or no penetration) so why with argon + hotter weld the penetration is less?

Dont know that one when I did my C&G we were still in the days of mostly Arc and gas, But the guy who works for me part time has just done his ABC and which is nearly all mig and tig, His explanation is you need a % of impurities within the gas on a MIG application to create the corect weld profile. To be honest I still dont exacly trust mig on large plate situations say 3/4 up because of this cold lap situation, from that school i guess, however there are still many codeings that are structual that can only be done in arc because of the issue of cold lap and penatration.

 

[Haze]

are there no ways of dealing with the cold start? gas axe to make it hot first before you start running beads? just theorising here, Ive never welded anything thicker than 3 mm that wasnt just laying beads on scrap for practise.

 

[snowcat]

things like choke on the welder helps, pre gas etc, but your unlikly to find any of this on hobby kit.

 

[bucko]

im using pure argon ani it works fine i know its an old post but i thorght i would add this for anyone who find's this post like i did,
and i cant rember wich idot said argon bunrs it don't burn it's an inert gas i dosent burn or react with anything

 

[snowcat]

im using pure argon ani it works fine i know its an old post but i thorght i would add this for anyone who find's this post like i did,
and i cant rember wich idot said argon bunrs it don't burn it's an inert gas i dosent burn or react with anything

that idiot would be me pal, if you read the further post I was talking burn back in the arc due to the thermic conductivity of the gas , not the gas burning itself, Co2 helps to transfer the arc to the weld pool, O2 is active and stabilizes the arc...........

Try setting a machine in spray with pure argon and flux cored, your have huge troubles with both the weld pool, the transfer and thirdly the wire burning straight back to the machine......... this is why mixes are R&D and designed for the job and most importantly tested by people like the AWS and TWI........