Hey all, so 10 years ago I got a stainless exhaust that was meant to be tig welded. My joints are rusting way faster than the exhaust. Do you think the guy might have welded it with mild steel wire?
Looking for opinion on 'tig' welded exhaust (3 Viewers)
- Thread starter HarryHarrison
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Malleus
Far west of Siegen
Maybe, but what caused the material failure was poor material. All stainless steel is not created equal. Some isn't even stainless.
Here's a little bit of info on the topic: Ulbrich stainless steel
Here's a little bit of info on the topic: Ulbrich stainless steel
Stainless comes in many forms. 316 is best for exhaust. 304 or less and right there’s what you get. He almost certainly used a mild steel rod. The weld area will likely corrode faster than the stainless steel base metal because mild steel filler lacks the corrosion-resistant properties of stainless steel. This is especially problematic in environments exposed to moisture, chemicals, or high temperatures.
All accurate info. Has he said a much you could have hit it with galv paint or some other type to keep it from happening. It doesn't look as if it was even 304. Tbh it looks cheap . I didn't look where ya are located but even on the coast it shouldn't have done it that fast
- Thread starter
- #6
Haha wtf clearly you know nothing about vehicles and that generally exhausts are replaced multiple times during the life of the vehicle. I feel like you get surprised by trivial s*** multiple times a day if that's your only input
- Thread starter
- #7
To the three above pissesthebed thanks for your input and information 
EWheeler
GOLD Star
That pipe does not look like it is stainless.....I've never seen stainless corrode like that before. That looks like aluminized steel tubing?
There are TIG fillers that are meant to join stainless to carbon steel, so while it may have been TIG welded, it is possible they may not have used the correct filler?
Also, when you TIG weld stainless, you have to back purge the inside with an inert gas, otherwise you'll get lack of fusion and/or "surgaring" of the weld. Failure to back purge will lead to accelerated corrosion from the inside of the weld. To me it looks like those holes are coming from the inside and eating outwards?
When working with stainless, you have to take care to not contaminate it with iron from carbon steel. Proper practice is to chemically passivate the outside of the weld area after welding to neutralize any free iron and help form the oxidation layer over the weld so it doesn't corrode. Usually the corrosion I have seen is pinhole corrosion/failure due to contamination, not the complete corrosion of large surface areas like what is shown. I don't live in an area where salt is used though, so my experience with stainless & salt exposure is minimal as far as motorsports goes.
I did just work on a project for a desalination plant that takes sea water and gets rid of the salt through reverse osmosis. All of the piping was TIG welded SMO-254, a high grade stainless alloy: Alloy 254 Stainless Steel - Penn Stainless - https://www.pennstainless.com/resources/product-information/stainless-grades/6-moly-grades/alloy-254-stainless-steel/
Part of the welder qualification was an accelerated corrosion test of the weld coupon, and in my research it was shown that these alloys are VERY susceptible to corrosion failure if the heat input during welding is too high due to some changes in molecular structure. The joint could x-ray shoot
I say all this to help shed light on the fact that just because stainless material is used, even the proper filler, it does not mean it is fool proof corrosion resistant....
There are TIG fillers that are meant to join stainless to carbon steel, so while it may have been TIG welded, it is possible they may not have used the correct filler?
Also, when you TIG weld stainless, you have to back purge the inside with an inert gas, otherwise you'll get lack of fusion and/or "surgaring" of the weld. Failure to back purge will lead to accelerated corrosion from the inside of the weld. To me it looks like those holes are coming from the inside and eating outwards?
When working with stainless, you have to take care to not contaminate it with iron from carbon steel. Proper practice is to chemically passivate the outside of the weld area after welding to neutralize any free iron and help form the oxidation layer over the weld so it doesn't corrode. Usually the corrosion I have seen is pinhole corrosion/failure due to contamination, not the complete corrosion of large surface areas like what is shown. I don't live in an area where salt is used though, so my experience with stainless & salt exposure is minimal as far as motorsports goes.
I did just work on a project for a desalination plant that takes sea water and gets rid of the salt through reverse osmosis. All of the piping was TIG welded SMO-254, a high grade stainless alloy: Alloy 254 Stainless Steel - Penn Stainless - https://www.pennstainless.com/resources/product-information/stainless-grades/6-moly-grades/alloy-254-stainless-steel/
Part of the welder qualification was an accelerated corrosion test of the weld coupon, and in my research it was shown that these alloys are VERY susceptible to corrosion failure if the heat input during welding is too high due to some changes in molecular structure. The joint could x-ray shoot
I say all this to help shed light on the fact that just because stainless material is used, even the proper filler, it does not mean it is fool proof corrosion resistant....
