Rust in weld?

[Clearwater]

I was inspecting my CM still from a common manufacturer the other day and happened to just see a spec of brown catch my eye. It appears to be rust, but rather superficial as it rubs off (at least the bits I could reach with my finger). I've tried searching around and I'm afraid I'm not a welder, so some of the terms flew over my head. Am I correct in my thinking that I need to remove the rust and then somehow treat it to not happen again or is this an ongoing problem I will have unless I remove the problem area? Any help/direction appreciated. Picture attached.

[corene1]

You shouldn't need to treat it you should be able to take a CLEAN file and smooth the burn through down smooth. Sometimes when the welder is making your parts he will not purge the weld area and the will be some burn through if he cleans it up with a grinder that has been used on regular ferrous steel tiny particles will imbed themselves in the stainless contaminating it . they will rust out in time but you can file them out and should not have a problem.

[johnhopper1957]

Little bit of penetration in the weld, if you use a steel file it will make the problem worse as it is made from steel. It just needs to be cleaned up with a small flap disc that is made for stainless so it does not cause contamination.

Not a big deal, 5 minute job and you'll never have the problem again.

[corene1]

Little bit of penetration in the weld, if you use a steel file it will make the problem worse as it is made from steel. It just needs to be cleaned up with a small flap disc that is made for stainless so it does not cause contamination.

Not a big deal, 5 minute job and you'll never have the problem again.

Yes , you are right . The ones we use at work are tungsten carbide. a regular steel file would put steel remnants in the stainless. good call!

[frozenthunderbolt]

Here's hoping he used a stainless filler not mild steel . . .

[corene1]

Here's hoping he used a stainless filler not mild steel . . .

I was just looking at the picture again and the burn through does have an off color to it, but it is from a commercial manufacturer so I would assume it is SS filler just really hot. It is odd that the hole was drilled and then sanded before the weld but it wasn't finished off after the weld. picky picky picky

[Cardinalbags]

Perfect example of not using an argon purge on the backside of a Tig weld job.

Google stainless steel pickling paste. it can be applied by brush and then washed off. It will remove any discolouration of the heat affected zone.