I am building a dash with some polished stainless. I have a tig and welding on it isn't a problem ,but how do I get it where it doesn't discolor and rust where it's welded. I have tried several different filler rods and even tried it without filler and it still looks bad. Anybody help me out? Thanks
I think you're going to get discoloration from heat no matter what you do but it should buff back out. As far as rusting goes.....may be an issue with whatever alloy of SS it is, but as far as filler rod I use 308L, 1/16", if I remember correctly. I've not polished welds ccmpletely to a show shine but have certainly cleaned them up and they've looked nice. Make sure your tungsten is really clean, really sharp, and don't use more heat than necessary. Oh, I use straight argon. Just my $.02 and there are better qualified people on the HAMB than me.
Be sure your using a good quality stainless rod.. That one bad thing about welding stainless, It will discolor and you can't hide it. No problem when your re polishing the whole thing. But a problem when trying to only do a portion of the stainless. We used to mask the welded area off and polish just that area. yes it sticks out but looks better if you keep it within a small masked area. Maybe "polisher" here on the Hamb can give you some ideas. here's his contact. http://www.jalopyjournal.com/forum/member.php?u=807
I use pure argon when welding with the TIG. No way to avoid the discoloration from the heat, but so long as you're using a pure stainless rod, I've never had a problem with rust
To avoid major discoloration, don't use filler, as it causes you to move too slow. You'll need a super tight seam, and close-tack the **** out of it (tack every 1/2 inch, or so, and peen it tight), so it can't open up between the tacks. Then, fuse it with super low amperage and a REALLY short arc. You can get a nice gold weld, that'll shine right back to silver with very little effort. Use 100% argon. G'luck... JOE
Make sure whatever disc you grind or sand the weld with is brand new. Then it won't have any steel embedded in it and transfer that to the workpiece.
One other thing. Only use a wire brush made with stainless wire to clean up the welds. A carbon steel brush will leave traces of carbon steel on your stainless and those traces will rust. With grinding discs, do the same thing. Only use a disc on stainless and don't switch between carbon and stainless using the same disc. If you do you will leave traces of carbon steel from the disc on the stainless you are grinding. When I worked at a nuclear plant, they had pretty strict controls on what tools, wire brushes, grinding discs, etc. got used on which pipe material. FWIW from what I know.
Pretty much what the other guys said about making sure that the area is clean before welding plus use LOW amperage. A lot lower than what you normally do for steel. Just so it barely melts. Also, the alloy of SS matters, some don't weld very well. The only other thing I can think of is sometimes they put a coating on SS. The first time I TIG'd a piece of SS I had exactly the same problem, the weld looked perfect but it was cast iron gray color and it rusted. Turned out I just was welding with too much amperage and was oxidizing the SS. Maybe your problem is the same.
Oh, I forgot if you are cutting the SS with a plasma before welding gring an extra amount off because the oxidized area from the plasma will give the same effect as you are talking about, gray and will rust. Golden brown weld is what you want.
If posible, cut strips of SS from the same material, use for filler instead of rod. Perfect color match!......OLDBEET
Be sure the wire brush you use is a 300 series type. Many of the cheap brushes are made from Martensitic 400 series, these types are magnetic and will rust. When you use them and apply water to quench the surface or leave it out over night sometimes the surface will develop light rust. You might try a wire with the "L" suffix (low carbon). The gold color comes from the right heat and travel speed. Are you using a argon backing or copper to prevent the backside of the weld from oxidation?
What everyone else said, plus use a longer post gas to cool the weld, then brush immediately should help.
One other thing to consider when polishing it on a buffer, don't use a wheel that was previously used on steel. It will imbed fragments of the steel into the stainless, and it will also create rust later.
Don't allow anything that contains iron to come in contact with your work. Or anything that has been used on iron or steel. Use a stainless rod preferably of similar grade to what your welding. Weld bluing can be removed with burn paste. To do the job properly it should be p***ivated too. That will not only remove the discoloration but will prevent the stainless from deteriorating from contamination for many more years. If you can't find somebody local to p***ivate them for you, and unfortunately the majority of welders and fabricators don't even know what it means, we can do it here. It's pretty quick and easy if you have the right gear.
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