[Danielvetpath]

Hi guys - totally new here. My only experience is with mig welding. In the past, I have made some small hollow body sculptures (fish!) with 18 ga steel and mig welding. Limited to carbon steel, fight burn through and have lots of excess weld to remove. I would like to progress to tig to handle thin materials and limit excess weldment. Reading about tig SS, I am aware of benefits of purging and backing, but don't know if I need to apply it to small irregular/hollow/cosmetic/sculpture projects. If I don't use it and get sugaring, will the metal polish back to a stainless shine or just rust in the future? Use al foil to seal projects and purge them best I can? Thanks for any input. I am always impressed with the work others are doing on this and other forums. Thanks for the inspiration. Daniel

[Poland308]

If it's for art work and non structural you can get by without an internal purge. Apparently there is a flux you can apply to the back of SS that will help a lot to avoid issues with sugaring. Might be just what you need in this application. I haven't used it myself but others speek highly of it.

[LtBadd]

The best case is to purge if possible, not only will the weld be stronger, but you'll find it'll weld better with a back purge.
Yes you can use Al foil as a plug, the interior volume will dictate how long to purge and even if you don't get a perfect purge you'll still benefit from it.

If you can post some pics of what you're doing we can be more specific.

Welcome to the forums.

[LtBadd]

If I don't use it and get sugaring, will the metal polish back to a stainless shine or just rust in the future? Daniel

yes you can still polish as long as the base material is thick enough before you reach the contamination (sugaring)

[Otto Nobedder]

For small parts in this application, you can skip the purge and expect good results that will polish.

If your art starts to lean in to "structure", where strength is important, you will need to take a different approach.

Steve S

[big gear head]

If you don't shoot for 100% penetration then you probably won't have any trouble. Don't run it so hot that it burns through.

As for MIG, have you tried stitching instead of running a continuous bead? Run it hot and pulse the trigger so that you are just making connected spot welds in a line and you won't get as much build up.

[dynasty200sd]

To save on the cost of back purging decorative art work, the flux others have mentioned is Solar Flux Type B. It is a powder that is mixed with Methanol/Methyl Alcohol before applying.

Solar Flux

[Rick_H]

Like mentioned if not full pen, you can weld 16-18g with no sugaring, very easy if your welder has pulse.

[Danielvetpath]

Thanks, guys! Great suggestions. Gives me a direction to head. All of these projects are table-top size - nothing approaching structural yet!

[Rick_H]

I had some 13g scrap laying around after a repair tonight so I ripped out a sample so you could see he difference.

Setting are written on the metal but 70amps 25% background, 75% peak, 1.5pps, .045" filler. I moved to nearly the front of the puddle with each pulse, no backer or purge.

I've got 16g I tacked up, I'll weld that tomorrow or Monday, no filler, no backer, no push through and post up.

[Danielvetpath]

Wow! Thanks, Rick_H, appreciate the effort and input, Daniel

[Rick_H]

16g, 60amps, 2.5pps 50% peak, 50%background, 1/16tung, no filler. I typically would have run a little less.amps maybe 45-50 and 75% peak, 25% background but I have my Miller Maxstar 150sth out tonight and I can not adjust those settings..it has pulse but only 50%/50%

[Danielvetpath]

Thanks, again, Rick_H for posting more on this topic. I just sent you a pm. Daniel

[Danielvetpath]

Rick_H: Getting closer to working on a new project. Sorry my complete ignorance, but the learning curve is still steep for me. Regarding peak and background: Does this refer to %of max amps setting (e.g. at 100 amps 80% = max 80 amps and 20% = 20 background amps)? Also, how does PPS relate to percentage of time on max vs background? Thanks for any help.
Daniel