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Up Topic Welding Industry / Technical Discussions / Mig welding stainless
- - By Proarc Date 07-17-2004 14:36
Welding 2x2 304 stainless tubing .120 wall. Would like to use 308L wire, .035 dia. ( I have it on hand). What gas shoud I use? Application is a ladder on a salt water dock. This is not to any code or standard. Can Tig the project, but there is 300 ft of tubing involed. Fitup will be mitered joints.



Thanks, Greg
Parent - - By Niekie3 (***) Date 07-18-2004 17:13
Hi Greg

For stainless Mig applications, Ar + 2% O2 normally does the job. You can also use one of the mixes with low CO2 content, but it must be low, or else you can start picking up problems with C contamination.

Regards
Niekie Jooste
Fabristruct Solutions
Parent - - By backpurge (*) Date 07-19-2004 17:08
As Niekie states you will get a far cleaner weld using argon + 2.5% CO2 than using a gas containing oxygen, the weld bead will also sit flatter due to the hotter arc produced when using CO2 additions, even better results can also be gained using an argon/CO2/helium mixture

Cheers - Bob
Parent - By swnorris (****) Date 07-19-2004 18:55
Hi Greg,

Shielding gases used to weld austenitic stainless steels include argon, argon/oxygen, argon/helium, and helium/argon/carbon dioxide. Argon/oxygen mixtures result in some oxidation in the weld pool that promotes better wetting action and improved arc stability than that obtained with pure argon. Argon/1% oxygen is very popular for welding with spray transfer. Helium/argon mixtures with 2-3% carbon dioxide additive are frequently used to weld stainless steels with short circuiting transfer. Helium additions to argon widen the penetration profile of the weld bead. As Niekie indicated, the addition of too much carbon dioxide will cause a loss of silicon and manganese, and can lead to an increase in carbon content in low grades of stainless. Carbon absorption could impair the corrosion resistance of the weld.

Here's a link to an interesting article in The Fabricator Magazine about selecting a shielding gas for stainless steel.

http://www2.thefabricator.com/Articles/Fabricating_Article.cfm?ID=903
Parent - - By Proarc Date 07-21-2004 19:17
Thanks for all the info. Project worked out well and was a lot faster than Tiging the whole peice. Nice to have some help from time to time.


Greg
Parent - - By Niekie3 (***) Date 07-21-2004 19:34
Hi Greg

So what gas did you end up using, and how did it weld?

Regards
Niekie Jooste
Fabristruct Solutions
Parent - By Proarc Date 07-27-2004 00:42
Niekie, Used argon + 2.5% CO2. Welded well, would have like to get the weld flatter, but penetration was good with good fill. Miller does not give any starting points for Stainless. Thanks again for your help.


Greg
Up Topic Welding Industry / Technical Discussions / Mig welding stainless

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