s/steel rods?

[Richard.]

Optimum, the helium mixes give the best surface finish with the least oxidation but if the welds are to be ground or blended then polished etc the there is no point in paying for a gas that gives a nicer "off the gun" finish. If the mig welds have to be left untouched and you want them to look as good as they can, bright, oxide free and good wetting in of the sidewalls then helium mixes are the way to go.
Quite a few options depending on if it's a standard or pulse MIG and if you are in dip or spray, we carry about 4 different arg/helium/O2 mixes for various processes.
You can't beat TIG with a big gas lens for super bright shiny welds that need little or no post finishing.

Optimum CO2 content is what I meant, I agree the finish given with helium mix is lovely in both mig and Tig.

 

[Jim Davey]

Ah I see, I've been doing some experimentation with TIG / hot wire feed and the results on helium mixes vs pure argon are worlds apart.

 

[Richard.]

Yeah I was using a 50/50 mix with Alu before Xmas. It was the first time I'd used this mix and the first thing I noticed straight away was how much less current I needed

 

[Jim Davey]

Yeah, it's a great cheat for maximising your chances of welding something that really needs a bigger machine if you're in a bind.

 

[backpurge]

Just to clear things up guys, MiG welding stainless needs around 2% co2 to stabilise the arc, further additions of helium will give improved results
If you are TIG welding stainless (300 series) argon is ok but argon/hydrogen mixtures will give you far better results than owt else, even helium, where possible I would advise rather than turn the heat down you are better speeding up to get optimism results

 

[johnakay]

thanks I'll get some thing sorted.
I dont want spends loads till I'm certain it will pay for itself.

 

[norlander]

Excellent thread. Learned some good stuff from it .