Hi, I need an advice from an experienced welder in welding stainless steel.
I have to make a stainless steel water tank (120 X 75 X 100 cm box), and has to be waterproof using 4 mm sheets stainless.
So here's the problem. I only have an inverter and a mig welder with ARGON 82 % + CO2 18% mix. Amperage it will be no problem in both cases. I have been mig/stick welding for 6 years now and I have a lot of experience but not so much with stainless as I a have with mild steel.
Instead of using stainless rods and having no progress, I thought to use stainless mig wire with same gas as for regular steel mig wire (C18 mix). It doesn't make sense to buy trimix gaz for stainless because only this time I got to weld stainless.
Has anyone tried C18 gaz mix with stainless wire ? Should my welds hold and not crack in time ?
What do you think? How do I get more cheaper and better results ?
I need to do it fast and without crack problems.
What do you recommend me to do ?
Thanks in advance.
Your co2 level is way too high particularly if this is a water tank where corrosion is your enemy here. The biggest deal with what you want to do is not so much how you weld it but how you finish it. welds should be blended smoothly and treated with some form of pickling paste to remove all the heat tint and surface oxides or it will rust.
If changing the gas isn't an option then stick weld would be the better out of those two choices. Tig as said above would be my preferred choice.
Hi guys and thanks for the replies.I gave up the idea using stick rods. Today I have already buy 3 kg (3 spool) for the start of stainless mig wire and a full bottle of pure ARGON (200 Barr),thats because Argon + O2 (2%) isnt available in this area, and that mixt would have been ideal as I talked with a specialist, but I was told that pure ARGON it's the best choice and most of the welders use it for mig welding stainless.
I have prepared the sheets, cut with plasma and grind them down with an abrassive disc.
But I wonder If I need to clean it before with some acetone or some diluent? because I give it a few strikes and I have seen that a cleaning action is happening when welding, as though the material isnt just clean as supposed to. What do you think? Probably I should take some pics.
I do not worry about weld corrosion because obligatory the whole tank would be painted with some special thick(rubberized) paint resistant at water corrosion.
I am using 3 mm stainless ( not 4 mm as I said) and tried 150 A but I think the welds aren't penetrating. My welder is only 180 A at 15% Duty Cycle.
I should let 2 mm gap between sheets (butt welds)? And the rest of the welds would be corner weld (inside + outside) and there would be no problem for penetrating.
These are the results of my work. I'm satisfied how the welds came, and I had plenty of penetration to the other side. These are buttwelds and inside corner fillet. But I experienced much more stable arc and penetration at 180-200 amps than 130-155 amps. In the last 2 pics the amperage was maxed out. I used pure argon and stainless steel mig 308 LSi wire. It will be welded to the outside as well as the inside for better water proof.
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